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Properties of Simulator Objects
Series Capacitor Field Options Dialog
Series capacitor field objects are used to show field values specific to series capacitors. Use Line Fields to show
fields generic to transformers, series capacitors and transmission lines, such as the flow of power through the device.
The series capacitor fields dialog is used to view and modify the parameters associated with series capacitor specific
fields.
Near Bus Number
Bus associated with the near end of the series capacitor.
Far Bus Number
Bus associated with the far end of the series capacitor.
Circuit
Two-character identifier used to distinguish between branches joining the same two buses. Default is '1'.
Anchored
When checked, the text field will move with the series capacitor if the series capacitor is moved on the oneline
diagram.
Total Digits in Field
Total number of digits to show in the field.
Digits to Right of Decimal
Number of digits to show to the right of the decimal point.
Rotation Angle in Degrees
The angle at which the text will be placed.
Field Value
The value of the currently selected field.
Field Prefix
A prefix that can be specified and displayed with the selected value.
Include Suffix
If the Include Suffix checkbox is checked, the corresponding field units will be displayed after the current value.
Otherwise, only the value without unitswill be shown.
Type of Field
Designates the type of transformer field to show. The following choices are available:
Status
Capacitor status
Series Capacitance
Capacitance of series capacitor
Select OK to save changes and close the dialog or Cancel to close dialog without saving your changes.
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Transformer Field Options Dialog
Transformer field objects are used to show field values specific to transformers. Use Line Fields to show fields generic
to transformers and transmission lines, such as the flow of power through the device. The transformer fields dialog is
used to view and modify the parameters associated with transformer-specific fields.
Near Bus Number
Bus associated with the near end of the transformer.
Far Bus Number
Bus associated with the far end of the transformer.
Circuit
Two-character identifier used to distinguish between transformers joining the same two buses. Default is '1'.
Find…
If you do not know the exact transformer you are looking for, you can click this button to open the advanced search
engine.
Total Digits in Field
Total number of digits to show in the field.
Digits to Right of Decimal
Number of digits to show to the right of the decimal point.
Delta per Mouse Click
This value is used only with the Off-nominal Tap Ratio and Phase Shift Angle field types. When there is a
nonzero entry in this field, and the field type is valid, a spin button is shown to the right of the zone field. When the
up spin button is c licked, the field value is increased by this number; when the down button is clicked, the field value
is decreased by this amount.
Field Value
Shows the current output for the transformer field. Whenever you change the Type of Field selection, this field is
updated.
Field Prefix
A prefix that can be specified and displayed with the selected value.
Rotation Angle in Degrees
The angle at which the text is to appear on the oneline diagram.
Anchored
When checked, the text field will move with the transformer if the transformer is moved on the oneline diagram.
Include Suffix
If the Include Suffix checkbox is checked, the corresponding field units will be displayed after the current value.
Otherwise, only the value without units will be shown.
Type of Field
Designates the type of transformer field to show. The following choices are available:
Off-nominal Tap Ratio
Actual tap ratio
Phase Shift Angle
Actual phase shift in degrees
Off-nominal Tap Position
Tap position in steps, usually ranging from L16 to R16
Automatic Control Status
The status of the control for the transformer
Select OK to save changes and close the dialog or Cancel to close dialog without saving your changes.
DC Line Information
DC Transmission Line Options
This dialog is used to view and modify the parameters associated with each two-terminal dc transmission line in the
system. It can also be used to insert new two-terminal dc transmission lines or to delete existing ones.
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Properties of Simulator Objects
This dialog has four separate pages: Line Parameters, Rectifier Parameters, Inverter Parameters, and Actual Flows.
The Actual Flows page is not used in Edit Mode. The separate pages can be accessed using the tabs shown at the
top of the dialog. These pages can be used to view/change the modeling parameters associated with the dc lines.
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DC Line Options: Line Parameters
This page is used to enter parameters associated with the dc line itself.
Rectifier and Inverter Bus Numbers and Names
These fields indicate the numbers and names of the rectifier and inverter ends of the line. When graphically
inserting a dc line, these fields are automatically determined based upon the starting and ending buses used in
drawing the line. When investigating existing dc line records, you may use the Find By Numbers button to identify a
dc line between a specific rectifier - inverter pair. You may also use the spin control to cycle through the list of dc
line records modeled in the case.
Circuit ID
This field is not currently used, since only one dc transmission line can exist between each inverter-rectifier pair. It
is hard-coded to be 1.
Area Name
Names of the areas in which the rectifier and inverter buses are located.
Status
Operating status of the DC transmission line. If the status is Open, then no power can flow on the DC line
regardless of the control mode setting. If the status is closed, then the control mode will dictate how power flows on
the line.
Control Mode
The initial control mode for the line. Specify Blocked to disable the dc line, Power to maintain specified MW power
flow through the line, or Current to maintain specified current flow through the line.
Setpoint
If the line operates in the Power Control Mode, Setpoint should indicate the desired power flow in MW. To specify
power flow at the rectifier end, enter a positive value. Enter a negative value to specify power flow at the inverter
end. If the dc line operates in Current Control Mode, enter the desired line flow in amps.
Resistance
Resistance of the dc Line.
Sched. Voltage
Scheduled dc line voltage in kV. The value of Rcomp is used to determine whether this value specifies the inverter
end or the rectifier end.
Switch Voltage
When the line operates in the Power Control Mode, this is the inverter voltage level in kV at which the line switches
from constant power to constant current control.
Rcomp
Compounding resistance. The compounding resistance dictates whether the inverter voltage is scheduled (Rcomp
= 0), or the rectifier voltage is scheduled (Rcomp = dc line resistance). Simulator does not currently support
scheduling the voltage at a point along the DC line (0 < Rcom < dc line resistance), but instead will treat any non-
zero value of Rcomp as scheduling the voltage at the rectifier.
Setpoint Specified At
Indicates which end of the DC transmission line the Setpoint value is designated. This will be the terminal where
the setpoint value is maintained. The opposite terminal flow value will be a calculated quantity.
Metered End of Line
Indicates which end of the DC line is assumed metered for Area interchange calculations.
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Properties of Simulator Objects
DC Line Options: Rectifier Parameters
This page is used to enter parameters associated with the rectifier end of the line.
# of Bridges
Number of valve bridges in series.
Base Voltage
Base ac voltage in kV on primary side of transformer.
XF Ratio
Transformer ratio.
XF Tap
Transformer tap setting.
XF Min/Max Tap, XF Tap Step
Transformer minimum and maximum tap settings, and the tap's step size.
Commuting XF Resistance and Reactance
Commuting resistance and reactance for the transformer, in ohms.
Minimum, Maximum, and Actual Firing Angle
Minimum, maximum, and actual values of the firing angle for the rectifier.
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DC Line Options: Inverter Parameters
This page is used to enter parameters associated with the inverter end of the line. Entries are identical to the Rectifier
Page, except here they are associated with the inverter.
# of Bridges
Number of valve bridges in series .
Base Voltage
Base ac voltage in kV on primary side of transformer.
XF Ratio
Transformer ratio.
XF Tap
Transformer tap setting.
XF Min/Max Tap, XF Tap Step
Transformer minimum and maximum tap settings, and the tap's step size.
Commuting XF Resistance and Reactance
Commuting resistance and reactance for the transformer, in ohms.
Minimum, Maximum, and Actual Firing Angle
Minimum, maximum, and actual values of the firing angle for the rectifier.
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Properties of Simulator Objects
DC Line Options: Actual Flows
Shows the actual real and reactive power flows into the line at the rectifier and the inverter, as well as the voltage at
both ends (in kV) and the line current in amps. The contents of this page are valid only when Simulator is in Run
Mode.
Multi-Terminal DC Line Information
Multi-Terminal DC Record Information
This dialog is used to view and modify the parameters associated with multi-terminal DC records. It is also used when
inserting new multi-terminal DC records.
The Multi-Terminal DC Record dialog can be used to inspect and modify the model of a multi-terminal DC network
record. To view the Multi-Terminal DC Record, simply right-click on the record of interest in the Multi-Terminal DC
Record Display and select Show Dialog from the resulting popup menu. The dialog has the following fields:
Record Number
Unique number between 1 and 999 which identifies the current multi-terminal DC record.
Number of Devices
Lists the number of DC buses, converters, and DC Lines that form the multi-terminal DC network.
Control
The control method used when solving the multi-terminal DC network.
Controlling Converter
The AC converter bus number where the DC voltage is being controlled.
MTDC Network Status
Status of the entire Multi-terminal DC network. If this field is set to Closed, the entire DC subnetwork of the MTDC
model is considered disconnected in the load flow c ase.
DC Buses Tab
This page of the dialog displays the DC bus records for the multi-terminal DC network. The display on this page
exhibits the same features as other case information displays. To view the specific information for a DC bus, right-
click on the record of interest and choose Show Dialog from the popup menu.
DC Converters Tab
This page of the dialog displays the DC converter records for the multi-terminal DC network. The display on this
page exhibits the same features as other case information displays. To view the specific information for a DC
converter, right-click on the record of interest and choose Show Dialog from the popup menu.
DC Lines Tab
This page of the dialog displays the DC line records for the multi-terminal DC network. The display on this page
exhibits the same features as other case information displays. To view the specific information for a DC line, right-
click on the record of interest and choose Show Dialog from the popup menu.
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Multi-Terminal DC Bus Information
This dialog is used to view and modify the parameters specific to multi-terminal DC network buses. The dialog is also
used to enter values for new multi-terminal DC buses when inserting a Multi-Terminal DC Record.
To view the Multi-Terminal DC Bus Record dialog, right-click on a bus record in the DC Buses tab of the Multi-Terminal
DC Record dialog and select Show Dialog from the resulting popup menu. The dialog has the following fields:
DC Bus Number, DC Bus Name
The number and name identifiers for the selected DC bus.
AC Bus Number
The AC bus number connected to the DC bus through an AC / DC converter. If the selected DC bus is a bus that is
internal to the DC multi-terminal network (not directly connected to an AC bus,) this field will be 0.
Area Number, Area Name
The number and name identifiers of the control area the DC bus is contained in.
Zone Number, Zone Name
The number and name identifiers of the zone the DC bus is contained in.
Ground Resistance
Resistance to ground of the DC bus, entered in Ohms. This field is currently only for storage of values supported by
other load flow formats, and is currently not used by Simulator.
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Properties of Simulator Objects
Multi-Terminal DC Converter Information
This dialog is used to view and modify the parameters specific to multi-terminal DC network buses. The dialog is also
used to enter values for new multi-terminal DC buses when inserting a Multi-Terminal DC Record.
To view the Multi-Terminal DC Bus Record dialog, right-click on a bus record in the DC Buses tab of the Multi-Terminal
DC Record dialog and select Show Dialog from the resulting popup menu. The dialog has the following fields:
Converter Parameters
Number of Bridges
Number of bridges in series for the selected converter.
Converter Type
R for rectifier or I for inverter.
Commutating Impedance
Commutating impedance per bridge, in Ohms.
Firing Angle Limits
The maximum and minimum firing angle limits, in degrees.
Transformer Parameters
AC Base
The primary AC base voltage, in kV.
DC Base
The DC base voltage, in kV.
Transformer Ratio
Actual transformer ratio.
Tap Settings
Displays the actual tap setting, the tap step, and maximum and minimum tap values for the converter transformer.
Control Parameters
Setpoint
The setpoint control value at the converter. For the voltage-controlling converter, this field is set to 0. For the
remaining converters, this field displays MW when in Power mode, or Amps when in Current mode.
Margin
Rectifier margin, entered in per-unit of the DC power or current. This field is currently only for support of other load
flow formats, and is not used by Simulator.
DC Participation Factor
Converter participation factor. This field is currently only for support of other load flow formats, and is not used by
Simulator.
Voltage
The DC Voltage magnitude at the DC side of the converter.
Solved Parameters
Firing Angle
The firing angle of the converter, as determined during the load flow solution.
DC Current
The calculated DC current at the converter DC terminal.
MW, MVAR
The real and reactive power delivered to (or absorbed from) the AC system by the converter.
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Multi-Terminal DC Line Information
This dialog is used to view and modify the parameters specific to multi-terminal DC network buses. The dialog is also
used to enter values for new multi-terminal DC buses when inserting a Multi-Terminal DC Record.
To view the Multi-Terminal DC Bus Record dialog, right-click on a bus record in the DC Buses tab of the Multi-Terminal
DC Record dialog and select Show Dialog from the resulting popup menu. The dialog has the following fields:
From and To DC Bus Number
The DC bus numbers of the From and To buses in the multi-terminal DC network. These fields must contain valid
DC bus numbers of the selected multi-terminal DC record. AC bus numbers from the load flow case are not
acceptable bus numbers for a multi-terminal DC line.
DC Circuit
The circuit identifier for the DC line.
DC Resitance and DC Inductance
The resistance and inductance of the DC line. Resistance is in Ohms, and is used for solving the load flow of the
DC network. The inductance is in milliHenries, and is not used for solving the load flow. The inductance field is
currently only for support of other load flow formats, and is not used by Simulator.
Transformer Properties
Transmission Line/Transformer Options: Transformer Control
Transformers are used to transfer power between different voltage levels or to regulate real or reactive flow through a
particular transmission corridor. Most transformers come equipped with taps on the windings to adjust either the
voltage transformation or the reactive flow through the transformer. Such transformers are called either load-tap-
changing (LTC) transformers or tap-changing-under-load (TCUL) transformers.
Another type of transformer is known as a phase-shifting transformer (or phase shifter). Phase-shifting transformers,
which are less common than LTC transformers, vary the angle of the phase shift across the transformer in order to
control the MW power flow through the transformer. This type of control can be useful in controlling the flow of real
power through a transmission system.
Off-nominal Turns Ratio and Phase Shift Degrees
The Line/Transformer Dialog displays several transmission line and transformer properties. For transformers, this
dialog box also shows information about the LTC or phase shifter controls. The Off-nominal Turns Ratio field
indicates the voltage transformation, while the Phase Shift Degrees field show the phase shift angle. If the
transformer is not on automatic control, these values can be changed manually. The off-nominal tap ratio
determines the additional transformation relative to the nominal transformation. This value normally ranges from
0.9 to 1.1 (1.0 corresponds to no additional transformation). For phase-shifting transformers the phase shift value
normally ranges from about -40° to 40°. The phase angle field can be non-zero for LTC and fixed transformers,
most notably +/- 30° if the transformer configuration is a delta-wye or wye-delta configuration. The transformer
configuration is very important when performing a fault analysis study.
When in Edit Mode, the dialog also reveals the type of transformer. Valid types are 1) No Automatic Control (in which
the taps are assumed fixed), 2) AVR (automatic voltage regulation), 3) Reactive Power Control, and 4) Phase Shift
Control. The type of transformer CANNOT be modified in the Run Mode.
Simulator provides you with a great deal of flexibility in being able to specify which transformers will actually be used
for automatic control in the Power Flow Solution. For a transformer to be used for voltage or flow control, three criteria
must be met.
· The transformer's Automatic Control Enabled field must be checked on its Line/Transformer dialog. This field can
also be modified on the Transformer Records display.
· The transformer's area must have automatic transformer control enabled. This is specified on the Options Tab of
the Area Records display.
· Transformer control must not be disabled for the entire case. This is specified on the Power Flow Solution Tab of
the PowerWorld Simulator Options Dialog.
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Properties of Simulator Objects
The area and case enforcement of transformer control are also accessible from the Run Mode Line/Transformer
Dialog.
Automatic Control
The Automatic Control fields are only visible on the Edit Mode Line/Transformer Dialog.
No Automatic Control
On this control setting the transformer will operate at the given off-nominal turns ratio and phase shift, and will
remain fixed at those values during the entire solution process unless manually changed by the user.
AVR (Automatic Voltage Regulation)
When on automatic voltage control, the transformer taps automatically change to keep the voltage at the
regulated bus (usually one of the terminal buses of the transformer) within a voltage range between the
minimum voltage and maximum voltage values (given in per unit). These values can be seen by clicking on the
Automatic Control Options button. Note that automatic control is possible only if a regulated bus has been
specified.
The tap position for an LTC transformer is indicated on the oneline by the number of tap step positions from the
nominal position (i.e., the position when the off-nominal tap ratio is equal to 1.0). When the off-nominal ratio is
greater than 1.0, the transformer's tap is said to be in the "raise" position, and an 'R' appears after the number.
Likewise, when the off-nominal ratio is less than 1.0, the transformer's tap is said to be in the "lower" position,
and an 'L' appears after the number. For example, with a step size of 0.00625 and an off-nominal ratio of 1.05,
the tap would be in position 8R. The tap position can be changed manually only when the transformer has
been set off automatic voltage control. For this case, clicking on the tap position with the left button raises the
tap one step, while clicking on the tap position with the right button lowers the tap one step.
Simulator will also detect instances when controlling transformers are in parallel, and will employ checks during
the solution routine to prevent the controllers from fighting each other and potentially going to opposite tap
solutions, which could result in unwanted loop flow through the transformer objects. This option is enabled by
default, but can be turned off in the Power Flow Solution General Options.
Transformer Reactive Power Control
When on automatic reactive power control, the transformer taps automatically change to keep the reactive
power flow through the transformer (measured at the from b us) within a user-specified range. The reactive
power control parameters can be seen by clicking the Automatic Control Options button.
Phase Shift Control
When a transformer is on phase shift control, the transformer phase shift angle automatically changes to keep
the MW flow through the transformer (measured at the from bus ) between the minimum and maximum flow
values (given in MW, with flow into the transformer assumed positive). The limits on the phase shifting angles
are specified in the minimum and maximum phase fields (in degrees). These values can be seen by clicking on
the Automatic Control Options button. The phase shift angle changes in discrete steps, with the step size
specified in the Step Size field (in degrees). The MW Per Phase Angle Step Size provides an estimate of the
change in the controlled MW flow value if the phase angle is increased by the step size value.
Specify Transformer Bases and Impedances
Shows the Transformer Bases and Impedances Dialog. This dialog allows the user to specify the transformer
parameters in per unit on the transformer base (taken as its rating). Click OK to convert all the transformer
parameters values to the system base specified in the General Power Flow Solution Options.
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Transformers Bases and Impedances Dialog
Typically the impedances and tap values of transformers is already assumed to have been converted to unity tap base
and bus nominal voltage base. However, some load flow formats provide the taps and impedances on specific
transformer bases, which are different than the bus voltage and unity tap base assumptions. In these cases,
Simulator will convert parameters from the transformer bases to the unity tap and bus nominal voltage base. Display
of the impedances and tap values normally displayed in the Line/Transformer Options dialog are displayed on the
Simulator assumed bases. However, if you wish to view the original transformer values on the transformer supplied
bases, this dialog will display the original values. You can modify the original values stored here in this dialog. Note
that when you do so, the converted values that Simulator stores on the system bases will also be automatically
updated to reflect the change that has been made to the original values on the transformer bases.
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Properties of Simulator Objects
Transformer Impedance Correction Table Display
The Transformer Impedance Correction Display shows information about all the transformer impedance correction
tables in the case. The Transformer Impedance Correction Display is used to model the change in the impedance of
the transformer as the off-nominal turns ratio or phase shift angle is varied.
The Correction Display is a class of Case Information Display and therefore can be used in a manner consistent with
all other case information displays. It has a local menu from which you can print, copy, and modify its information as
well as view the information dialog of its associated correction tables. When in Edit Mode, you can define new tables
using the Insert option, or delete existing tables using Delete. You can also sort the transformer impedance correction
information by clicking on the heading of the field by which you want to sort.
To show this display select Case Information > Other > Transformer Impedance Correction Tables.
The display contains the following fields by default:
Table
Shows the table number for the record. Table number must be between 1 and 64. Each table record occupies two
lines on the display. 1, 2, … 11
Transformer Impedance Scaling Factors
The next eleven columns show the actual fields in the table. The first line shows the off-nominal turns ratio, or
phase shift angle, while the second line shows the associated scaling factor for the transformer’s impedance.
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Transformer AVR Dialog
The Transformer AVR Dialog is used to view the control parameters associated with load-tap-changing (LTC)
transformers when they are used to control bus voltage magnitudes. To view this display, click the Automatic Control
Options button on the Line/Transformer Information Dialog. Note that the button will not respond to the click if the No
Automatic Control option is selected under the Automatic Control group.
This dialog has the following fields:
Regulated Bus Number
The number of the bus whose voltage is regulated by the control.
Current Regulated Bus Voltage
The present voltage of the regulated bus.
Voltage Error
If the regulated bus' voltage falls outside the regulating range of the transformer (as defined by the Minimum
Voltage and Maximum Voltage fields), the Voltage Error field indicates by how much the voltage deviates from the
control range.
Minimum Voltage
The minimum acceptable voltage at the regulated bus.
Maximum Voltage
The maximum acceptable voltage at the regulated bus.
Current Tap Ratio
The tap ratio of the transformer for the current system state.
Minimum Tap Ratio, Maximum Tap Ratio
Minimum and maximum allowable off-nominal tap ratios for the LTC transformer. Typical values are 0.9 and 1.1.
Tap Step Size
Transformer off-nominal turns ratio increment. The off-nominal turns ratio is either incremented or decremented
f rom 1.0 in integer multiples of this value. Default value is 0.00625.
Voltage to Tap Sensitivity
Shows the sensitivity of the voltage magnitude at the regulated bus to a change in the transformer's tap ratio. You
can use this field to assess whether or not the transformer can effectively control the regulated bus voltage. In an
ideal case, such as when the LTC transformer is being used to control the voltage at a radial load bus, the
sensitivity is close to 1.0 (or -1.0 depending upon whether the tapped side of the transformer is on the load side or
opposite side of the transformer). However, sometimes the transformer is very ineffective in controlling the voltage.
This is indicated by the absolute value of the sensitivity approaching 0. A common example is a generator step-up
transformer trying to control its high-side voltage when the generator is off-line. Simulator automatically disables
transformer control if the transformer sensitivity is below the value specified on Power Flow Solution Tab of the
PowerWorld Simulator Options dialog.
Impedance Correction Table
This field specifies the number of the transformer's corresponding transformer impedance correction table.
Transformer impedance correction tables are used to specify how the impedance of the transformer should change
with the off-nominal turns ratio. If this number is 0, then no impedance correction table is associated with the
transformer, and the impedance of the transformer will thus remain fixed as the tap ratio changes. Valid impedance
correction table numbers range from 1 to 63. To assign an existing impedance correction table to the transformer,
enter the existing table's number. To view the existing impedance correction tables, click the Insert/View
Impedance Correction Table button, which brings up the Transformer Impedance Correction Dialog. To define a
brand new impedance correction table for the transformer, enter an unused table number and then click Insert/View
Impedance Correction Table to prescribe the correction table. Note that the association between a transformer and
an impedance correction table is not finalized until you select either OK or Save on the Line/Transformer Dialog.
View Transformer Correction Table or Insert Transformer Correction Table
Click on this button either to view or to insert transformer correction tables. Clicking on this button displays the
Transformer Impedance Correction Dialog. Note that the table must prescribe at least two points in order to be
defined.
280
Properties of Simulator Objects
Transformer Mvar Control Dialog
The Transformer Mvar Control dialog is used to view the control parameters associated with load-tap-changing (LTC)
transformers that are used to control the Mvar flow through the transformer. To view this display, click on the
Automatic Control Options button on the Line/Transformer Information Dialog.
When used to control reactive power, the LTC transformer always controls the reactive power flow at the from end of
the transformer (i.e., the tapped side), with positive flow assumed to be going through the transformer to the to bus.
Therefore the regulated bus field is not used.
The dialog has the following fields:
Mvar Flow at From Bus
The current Mvar flow as measured at the from end of the line. This is the parameter the transformer tries to
control.
Mvar Error
If the Mvar flow at the from end violates the limits defined by the Minimum Mvar Flow and Maximum Mvar Flow
fields, the Mvar Error field indicates by how much the flow falls outside the control range.
Minimum Mvar Flow, Maximum Mvar Flow
Minimum and maximum allowable reactive power flow as measured at the from bus. The transformer attempts to
regulate the reactive flow to fall within this range.
Current Tap Ratio
The transformer's present off-nominal turns ratio.
Minimum Tap Ratio, Maximum Tap Ratio
Minimum and maximum allowable off-nominal tap ratios for the LTC transformer. Typical values are 0.9 and 1.1.
Tap Step Size
Transformer off-nominal turns ratio increment. The off-nominal turns ratio is either incremented or decremented
from 1.0 in integer multiples of this value. Default value is 0.00625.
Mvar to Tap Sensitivity
The amount of Mvar shift that would be implemented by switching one tap position from the current position. This
sensitivity indicates the ability of the transformer to control Mvars.
Impedance Correction Table
Specifies the number of the transformer's corresponding transformer impedance correction table. Transformer
impedance correction tables are used to specify how the impedance of the transformer should change with the off-
nominal turns ratio. If this number is 0, no impedance correction table is associated with the transformer, and the
impedance of the transformer will thus remain fixed as the tap ratio changes. Valid impedance correction table
numbers range from 1 to 63. To assign an existing impedance c orrection table to the transformer, enter the existing
table's number. To view the existing impedance correction tables, click the Insert/View Impedance Correction Table
button, which brings up the Transformer Impedance Correction Dialog. To define a brand new impedance
correction table for the transformer, enter an unused table number and then click Insert/View Impedance Correction
Table to prescribe the correction table. Note that the association between a transformer and an impedance
correction table is not finalized until you select either OK or Save on the Line/Transformer Dialog.
View Transformer Correction Table or Insert Transformer Correction Table
Click on this button either to view or to insert transformer correction tables. Clicking on this button displays the
Transformer Impedance Correction Dialog. Note that the table must prescribe at least two points in order to be
defined.
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Transformer Phase Shifting Information
The Transformer Phase Shifting Dialog is used to view the control parameters of phase-shifting transformers. To view
this display, click on the Automatic Control Options button on the Line/Transformer Information Dialog, provided that
the Phase Shift Control option is chosen from the Automatic Control group.
Regulated Bus Number
Number of the terminal bus of the phase shifter regulated by the phase shifter. When control is active, the phase
shifter will automatically change its phase shift to keep the MW flow at this bus at the desired value.
Current MW Flow
Current MW flow through the transformer measured at the regulated bus terminal.
MW Error
If the current MW flow falls outside the minimu m/maximum MW flow limits, the MW Error field indicates by how
much the flow violates the regulating range.
Minimum MW Flow, Maximum MW Flow
Minimum and maximum allowable MW flow through the phase shifter.
Current Phase Angle (Degrees)
The phase angle of the transformer for the current solved system state.
Minimum Phase Angle, Maximum Phase Angle
Minimum and maximum allowable phase shift in degrees.
Step Size (Degrees)
Phase shift change per step in degrees.
MW Flow to Phase Sensitivity
The sensitivity of the controlled MW flow to changes in the transformer's phase. This sensitivity indicates the
transformer's ability to regulate its MW flow.
Impedance Correction Table
Specifies the number of the transformer's corresponding transformer impedance correction table. Transformer
impedance correction tables are used to specify how the impedance of the transformer should change with the off-
nominal turns ratio. If this number is 0, no impedance correction table is associated with the transformer, and the
impedance of the transformer will thus remain fixed as the tap ratio changes. Valid impedance correction table
numbers range from 1 to 63. To assign an existing impedance correction table to the transformer, enter the existing
table's number. To view the existing impedance correction tables, click the Insert/View Impedance Correction Table
button, which brings up the Transformer Impedance Correction Dialog. To define a brand new impedance
correction table for the transformer, enter an unused table number and then click Insert/View Impedance Correction
Table to prescribe the correction table. Note that the association between a transformer and an impedance
correction table is not finalized until you select either OK or Save on the Line/Transformer Dialog.
View Transformer Correction Table or Insert Transformer Correction Table
Click on this button either to view or to insert transformer correction tables. Clicking on this button displays the
Transformer Impedance Correction Dialog. Note that the table must prescribe at least two points in order to be
defined.
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Properties of Simulator Objects
Transformer Field Options Dialog
Transformer field objects are used to show field values specific to transformers. Use Line Fields to show fields generic
to transformers and transmission lines, such as the flow of power through the device. The transformer fields dialog is
used to view and modify the parameters associated with transformer-specific fields.
Near Bus Number
Bus associated with the near end of the transformer.
Far Bus Number
Bus associated with the far end of the transformer.
Circuit
Two-character identifier used to distinguish between transformers joining the same two buses. Default is '1'.
Find…
If you do not know the exact transformer you are looking for, you can click this button to open the advanced search
engine.
Total Digits in Field
Total number of digits to show in the field.
Digits to Right of Decimal
Number of digits to show to the right of the decimal point.
Delta per Mouse Click
This value is used only with the Off-nominal Tap Ratio and Phase Shift Angle field types. When there is a
nonzero entry in this field, and the field type is valid, a spin button is shown to the right of the zone field. When the
up spin button is clicked, the field value is increased by this number; when the down button is clicked, the field value
is decreased by this amount.
Field Value
Shows the current output for the transformer field. Whenever you change the Type of Field selection, this field is
updated.
Field Prefix
A prefix that can be specified and displayed with the selected value.
Rotation Angle in Degrees
The angle at which the text is to appear on the oneline diagram.
Anchored
When checked, the text field will move with the transformer if the transformer is moved on the oneline diagram.
Include Suffix
If the Include Suffix checkbox is checked, the corresponding field units will be displayed after the current value.
Otherwise, only the value without units will be shown.
Type of Field
Designates the ty pe of transformer field to show. The following choices are available:
Off-nominal Tap Ratio
Actual tap ratio
Phase Shift Angle
Actual phase shift in degrees
Off-nominal Tap Position
Tap position in steps, usually ranging from L16 to R16
Automatic Control Status
The status of the control for the transformer
Select OK to save changes and close the dialog or Cancel to close dialog without saving your changes.
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Three Winding Transformer Information
The Three Winding Transformer Dialog is used to create, modify or delete three winding transformer records in Edit
Mode, or to view information for a specific three winding transformer record in run mode. Note that all the values
displayed on this dialog are on the system MVA base. If the records were created them from a file, the values are
automatically converted to the system base. If a three winding transformer record is entered manually, the parameters
need to be entered into Simulator computed with the same system MVA base Simulator is using.
This dialog has the following controls:
Primary Winding
This section of the dialog displays the primary winding terminal bus number, nominal kV, and fixed tap value (in per
unit). In addition, the automatic tap changer is assumed to be on the primary winding of a three winding
transformer. Therefore the LTC field displays the tap changer tap value (in per unit) on the primary winding.
Secondary Winding
This section of the dialog displays the secondary winding terminal bus number, nominal kV, and fixed tap value (in
per unit).
Tertiary Winding
This section of the dialog displays the tertiary winding terminal bus number, nominal kV, and fixed tap value (in per
unit).
Star Bus (Internal Node)
This section of the dialog displays the internal node parameters of the three winding transformer model. Three
winding transformers are modeled as three two winding transformers connected at the three winding transformer
terminal buses to a common or internal node, referred to as the star bus. The parameters displayed for the star bus
are the bus number, voltage (in per unit), and angle.
Primary-Secondary, Secondary-Tertiary, and Tertiary-Primary Impedance
These are the actual three winding transformer winding to winding impedances, in per unit on the system base.
These values are used to compute the equivalent two winding transformer impedances for the two winding
transformers used to model the three winding transformer operation.
Circuit ID
The circuit identifier for the three winding transformer.
Status
The status of the three winding transformer. If checked, the three winding transformer model is in service,
otherwise the equivalent model is treated as out of service.
Mathematically equivalent two-winding transformers
This table displays the three two winding transformers that are mathematically equivalent representations of the
three winding transformer. If you read the three winding transformer record from a file, the two winding equivalent
transformers are created automatically. If you are inserting a three winding transformer manually, you can set the
parameters for the primary, secondary and tertiary windings in the fields above, then click the Set Two-Winding
Equivalent Transformers button to have Simulator automatically create the two winding transformer records for
you. You can also right-click in this table and insert, modify or delete two winding transformers manually if you
already have the two winding transformer representations created.
Once you are finishedwith the dialog, you can click Save or OK to save any changes. If you wish to abandon any
changes you have made, click Cancel.
Switched Shunt Properties
Switched Shunt Information (Edit Mode)
This dialog is used to view and modify the parameters associated with each switched shunt in the system. It can also
be used to insert new switched shunts and sometimes to delete existing shunts. Only one switched shunt is permitted
at each bus. Switched shunts usually consist of either capacitors to supply reactive power (in MVR) to the system, or
reactors to absorb reactive power. The switched shunts are represented by a number of blocks of admittance that can
be switched in a number of discrete steps. If at least one block is in service, the shunt is said to be online. The
shunt’s corresponding circuit breaker can be used to determine and to toggle the switched shunt’s status.
The Edit Mode version of this dialog is very similar in content to its Run Mode counterpart.
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Properties of Simulator Objects
Bus Number
Unique number between 1 and 99,999 used to identify the bus to which the switched shunt is attached. You can
use the spin button immediately to the right of the number to move to the next switched shunt (click the up arrow) or
the previous switched shunt (click the down arrow).
Find By Number
To find a switched shunt by its bus number, enter the number into the Bus Number field. Then click this button.
Bus Name
Unique alphabetic identifier for the bus to which the switched shunt is attached, consisting of up to eight characters.
Find By Name
To find a switched shunt by its bus name, enter the bus name into the Bus Name field (case insensitive). Then click
this button.
Shunt ID
Since multiple switched shunts are allowed on a single bus, each switched shunt has a unique Shunt ID.
Status
Open or closed status of the switched shunt.
Labels
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected load.
Find…
If you do not know the exact switched shunt bus number or name you are looking for, you can click this button to
open the advanced search engine.
Display Size
Size of the switched shunt.
Scale Width with Size
Automatically scales the width of the symbol when the object is resized.
Display Width
Width of the switched shunt symbol.
Pixel Thickness
Thickness of the display object in pixels.
Orientation
Specifies the direction in which to draw the object.
Anchored
If checked, the object is anchored to its terminal bus. See Anchored Objects for details.
Link to New Shunt
Adds a new record in the data or links the selected shunt to a different record.
OK, Save, Delete, and Cancel
OK saves your changes and closes the dialog. Save saves your changes but does not close the dialog; this allows
you to use, for ex ample, the Find By Number command to edit additional switched shunts. Delete deletes the
current switched shunt; this option is not available when inserting objects graphically - use the cut command
instead. Cancel closes the dialog but does not save any changes.
Parameters
Nominal Mvar
The Nominal Mvar field gives the initial amount of reactive power the device would supply (in Mvars) if its terminal
voltage were 1.0 per unit.
Nominal MW
This field is only visible when a switched shunt object has been read from a file as a Bus Shunt. In that case, it is
possible for the bus shunt to have both a MW and MVAR component. The MW component will be displayed here.
In general, switched shunts of other control types do not have MW components, and this field will not be displayed.
If you change a switched shunt read as a bus shunt to another form of control, the MW component will remain, but
has no controllability.
Control Mode
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Determines whether the switched shunt has a fixed value, or whether the amount of reactive power supplied by the
device changes in either discrete steps or continuously in order to maintain its terminal voltage within the voltage
range specified in the Voltage Regulation fields. This field can be changed (except in Viewer). However, for a
switched shunt to be used for automatic control, three fields must be set correctly: 1) the Control Mode field must be
set to either Discrete or Continuous , 2) the corresponding area’s Auto Shunts property must be true, and 3) the
case-wide Disable Switched Shunt Control option, which can be set on the Power Flow Solution Tab of the
PowerWorld Simulator Options Dialog, must not be checked.
Note: automatic control of switched shunts is disabled if the voltage regulation high value is not greater
than the low value; they should not be equal unless in the continuous mode.
Note the additional control mode called Bus Shunt (Fixed). This is analogous to the shunt MW and MVAR values
that can also be stored at the bus level. The difference is that bus shunts stored directly with the bus cannot be
turned on and off in the load flow; rather they are always included in the load flow solution. Bus shunts that are
represented as switched shunt objects on Bus Shunt control, however, are mathematically exactly the same and
can be turned on or off. The reason for the differentiation of the Bus Shunt versus normal Fixed control is that the
Bus Shunt control type is intended to identify the difference between a bus s hunt and a transformer that MAY have
controllability, but is currently turned of off control by being set to a Fixed value.
Voltage Regulation
When the switched shunt is on automatic control, its reactive power is changed in discrete steps or continuously to
keep the voltage at the regulated bus within the per unit voltage range defined by High Value and the Low Value.
In the case of discrete control, the amount of reactive power supplied by this device changes in discrete amounts,
thus the High Value should be greater than the low value. The necessary voltage range depends upon the size of
the switched shunt blocks. In addition to a voltage range for discrete control, a specific Target Voltage can be
specified as well. The target voltage will try to be met, either approximately under discrete control, or exactly under
continuous control (either true continuous or discrete with a continuous shunt correction element.) The number of
the regulated bus is shown in the Reg. Bus # field.
Switched Shunt Blocks
The amount of shunt reactive power (susceptance) is specified in the Switched Shunt Block field. The columns in
this field correspond to different blocks of reactive power. The first row indicates the number of steps in each block,
and the second row gives the amount of nominal Mvars per step (assuming 1.0 per unit voltage). You may model
both capacitors and reactors. The reactors should be specified first, in the order in which they are switched in,
followed by the capacitors, again in the order they are switched in. The sign convention is such that capacitors are
positive and reactors negative. Shunt blocks are switched in order from left to right.
Control Parameters
Single Largest Step
This option only applies when a switched shunt is set on discrete control. If checked the switched shunt will switch
in EITHER all of the available reactor blocks OR all of the capacitor blocks at once when the voltage falls outside
the given range. Whether the reactor or capacitor blocks switch is determined by which limit is violated. A switched
shunt with this option checked will only switch ONCE during a load flow solution, and then remains fixed at the new
output for the remainder of the same solution calculation.
Use Continuous Element
If this option is checked, then Simulator will use a continuous element to fine-tune a discrete controlled switched
shunt by injecting or absorbing additional MVARs to try and obtain the target voltage of the controlled bus.
Minimum and Maximum Susceptance
The minimum and maximum susceptance range for the continuous correction element.
Use High Target Voltage
Check this box to use the target voltage specified in the High Target Value edit box when the regulated point goes
above the High limit. This will give a different target value if the voltage goes out of range on the high end than the
low end. If the voltage goes out of range on the low end, the original target value on the Parameters page will be
used. If this box is unchecked, only the target value on the parameters page will be used, whether the violation is
high or low.
Short Circuit Parameters
Typically switched shunts are treated as open circuits in the zero sequence data for fault analysis. However, it is
possible to define zero sequence admittance blocks to be used. The blocks work similarly to the load flow Switched
Shunt Blocks discussed above. Usually there will be the same number of blocks in the zero sequence data as in the
load flow data. Simulator will determine how many blocks were switched in for the pow er flow solution, and then use
the zero sequence block data to calculate the zero sequence admittance for the same number of blocks.
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Properties of Simulator Objects
Switched Shunt Field Information
Switched shunt field objects are used primarily to indicate various quantities associated with switched shunt devices.
Furthermore, some switched shunt field types, which are distinguished by an integrated spin button, may be used to
change switched shunt device properties.
The Switched Shunt Fields Information Dialog can be used to modify the properties of individual switched shunt fields
on the oneline. The dialog displays the following fields:
Find…
If you do not know the exact bus number or name you are looking for, you can click this button to open the
advanced search engine.
Bus Number
Number of the bus to which the switched shunt associated with the field is connected. Use the dropdown box to
view a list of all buses with switched shunts in the case with valid area/zone/owner filters.
Bus Name
Name of the bus to which the switched shunt associated with the field is connected. Use the dropdown box to view
a list of all buses with switched shunts in the case with valid area/zone/owner filters.
ID
ID of the switched shunt associated with the field.
Total Digits in Field
Total number of digits to show in the field.
Digits to Right of Decimal
Number of digits to show to the right of the decimal point.
Field Value
The current value of the field being displayed.
Field Prefix
A prefix that can be specified and dis played with the selected value.
Delta Per Mouse Click
Switched shunt fields can be used not only to show various fields associated with switched shunt devices, but they
can also be used to change some values. This is accomplished using spin buttons shown to the right of the
switched shunt field. When the up spin button is clicked, the switched shunt field value is increased by the amount
specified in the delta per mouse click field. When the down spin button is clicked, the switched shunt field value is
decreased by the same amount.
This field is only used for Switched Shunt Mvar fields. Specifying a nonzero value in this field causes the integrated
spin button to appear as part of the switched shunt field on the oneline.
Rotation Angle in Degrees
The angle at which the text is placed on the diagram, in degrees.
Anchored
If the Anchored checkbox is checked, the switched shunt field is anchored to its associated switched shunt, which
means that it will move with the switched shunt.
Include Suffix
If the Include Suffix checkbox is checked, the corresponding field units will be displayed after the current value.
Otherwise, only the value without units will be shown.
Type of Field
Used to determine the type of switched shunt field to show. The following choices are available:
Switched Shunt Mvar
Total Mvar capacitance at the bus
Select a Field
Choose from any of the different switched shunt fields
Select OK to save changes and to close the dialog, or click Cancel to close the dialog without saving your changes.
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Run Mode Properties and Information
Bus Properties
Bus Information (Run Mode)
This dialog is used to view information about each bus in the system. It can be displayed by right-clicking on any bus
and choosing Bus Information Dialog. This dialog can only be reached in Run Mode, but has a similar Edit Mode
counterpart. The Bus Information Dialog has the following fields:
Bus Number
Unique number between 1 and 99,999 used to identify the bus. You can use the small arrow immediately to the
right of the number to view a list of all buses in the case with valid display filters. Or you can use the spin button
further to the right of the number to move to the next bus (click the up arrow) or the previous bus (click the down
arrow).
Find By Number
To find a bus by its number, enter the number into the Bus Number field and then click this button.
Bus Name
Unique alphabetic identifier for the bus consisting of up to eight characters. You can use the small arrow
immediately to the right of the bus name to view a list of all bus names in the case with valid display filters.
Find By Name
To find a bus by its name, enter the bus name into the Bus Name field (case insensitive) and then click this button.
Find…
If you do not know the exact bus number or name you are looking for, you can click this button to open the
advanced search engine.
Labels
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected bus.
Area Number, Name
Each bus is associated with an Area record. These fields show the number and name of this area. See Area
Records Display for more details about areas.
Zone Number
Each bus is associated with a Zone record. This field is '1' by default. See Zone Records Display for more details
about zones. You can also use the Zone Dialog to list the buses in a particular zone and to easily move a group of
buses from one zone to another.
Voltage (per unit)
Bus voltage in per unit notation. You may enter a new per unit voltage magnitude. However, the only effect this
has is changing the initial voltage guess used in the iterative solution. If you would like to change the reference
voltage for a generator, please see Generator Information Dialog.
Voltage (kV)
Bus voltage in actual kilovolts.
Angle (degrees)
Voltage angle at the bus in degrees. You may enter a new voltage angle. However, the only effect this has is
changing the initial voltage guess used in the iterative solution EXCEPT AT THE SLACK BUS. Changing the angle
for the slack bus will shift the voltage angle for all the buses in the slack bus' island by a similar amount.
Owner Number, Owner Name
Number and name of the bus’ owner.
Substation Number, Substation Name
The number and name of the substation the bus is contained in.
Status
Status of the bus, either connected or disconnected. A disconnected bus is not energized. You can use this field to
change the status of the bus. When the bus is initially connected, selecting Disconnected opens all of the
transmission lines incident to the bus, disconnecting the bus from the rest of the system. Selecting Connected
closes all of the lines incident to the bus unless they attach to another disconnected bus.
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Properties of Simulator Objects
System Slack Bus
Checked only if the bus is a system slack bus. This value can only be changed in the Edit Mode.
View Owner Dialog
Clicking on this button will open the bus’ owner dialog.
View Substation Dialog
Clicking on this button will open the substation dialog for the s ubstation the bus is contained in.
Device Info
Load Information
Displays the total MW and Mvar load at the bus. You cannot change either of these fields from this display. Select
the View/Edit Bus Load Records to view the individual load records for the bus. Selecting this button displays the
Load Dialog.
Generator Information
Displays the total MW and Mvar generation at the bus. You cannot change either of these fields from this display.
Select the View/Edit Generator Records to view the individual generator records for the bus. Selecting this button
displays the Generator Dialog for the first generator at the bus.
Shunt Admittance
Shows the real and reactive components of the shunt admittance to ground. Entered in either MW or Mvar,
assuming one per unit voltage. B is positive for a capacitor and negative for a reactor. If B corresponds to a
switched device, consider using a switched shunt.
Fault Analysis Load Parameters
The parameters on this tab are used when running a fault analysis study. The values represent the total load at the
bus for the negative and zero sequence as equivalent admittances. By default, these values are zero. For load
buses, these values can be changed by the user, or they can be specified by loading short circuit data from within the
Fault Analysis Dialog. It is also possible to define these values as non-zero at a bus where no load exists in the load
flow, but it is not usually desirable to do so.
OPF
This tab is only available if you have the Optimal Power Flow (OPF) add-on tool for PowerWorld Simulator. This tab
displays the MW marginal cost (Locational Marginal Price) for the bus when performing an OPF solution. The page
also breaks down the LMP into its cost components.
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Substation Properties
Substation Information (Run Mode)
This dialog is used in the Run Mode to view and modify information associated with a substation record. It displays
different information from the Edit Mode version of the substation dialog. To display it from Run Mode, first select
Case Information > Substations from the main menu to bring up the Substation Records Display. Right-click on the
substation of interest and choose Show Dialog. The Run Mode Substation Dialog has the following fields:
Substation Number
An integer identifier for the substation. You can use the spin button immediately to the right of this field to move to
either the next substation (click the up arrow) or the previous substation (click the down arrow).
Substation Name and ID
Two alphanumeric identifiers for the substation.
Find By Number
To find a substation by its number, enter the number into the Substation Number field, then click this button.
Find By Name
To find a substation by its name, enter the name into the Substation Name field, then click this button.
Find By Sub ID
To find a substation by its substation ID, enter the ID into the Substation ID field, then click this button.
Find…
If the exact substation number, name and ID are not known, you can use the Find Dialog to search for and select a
substation from a list of substations.
Labels
Clicking this button will open a dialog displaying the list of defined labels for the substation. New labels can also be
added for the substation from the dialog as well.
View All Flows at Substation
Clicking this button will open a quick power flow display listing the buses contained in the substation.
Information
Load and Generation
Real and reactive load, generation, shunts, losses, and interchange for the substation.
Generation AGC Range
Total amount of generation increase or decrease available for all generators in the substation.
Bus Voltages
Summary information on all buses in the substation, including total number of buses, number of dead
(disconnected) buses, and minimum and maximum bus voltage and angle within the substation.
Buses
The Buses table identifies the buses in the substation, and provides summary information on each.
Gens
The Gens table identifies the generators in the substation, and provides summary information on each.
Loads
The Loads table identifies the loads in the substation, and provides summary information on each.
Switched Shunts
The Switched Shunts table identifies the switched shunts in the substation, and provides summary information on
each.
Substation Tie Lines
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Properties of Simulator Objects
The Substation Tie Line Table identifies the flows on all of the substation's ties to other substation.
291
Generator Properties
Generator Information (Run Mode)
This dialog is used to view information about each generator in the system. Many fields on this display can also be
changed (except in Viewer). Here we describe the Run Mode version of the Generator Information Dialog. The Edit
Mode version is very similar.
Bus Number
Unique number between 1 and 99,999 used to identify the bus to which the generator is attached. The dropdown
list enumerates all generator buses in the case that meet the criteria established by display filters. You may select
a bus number directly from the dropdown list, or you may use the spin buttons to cycle through the list of generator
buses.
Bus Name
Unique alphabetic identifier for the bus to which the generator is attached, consisting of up to eight characters. Use
this dropdown box to view a list of all generator bus names in the case with valid display filters.
ID
Two character alphanumeric ID used to distinguish multiple generators at a bus; '1' by default.
Fuel Type
Type of fuel used by the generator this model represents. In most cases, this field is unnecessary for normal load
flow analysis, and hence the default value is Unknown. However, this value can be useful during the Security
Constrained OPF analysis.
Unit Type
The type of unit the generator represents, such as combined cycle, steam, hydro, etc.
Find By Number
To find a generator by its number and ID, enter the number into the Bus Number field and the ID into the I D field.
Then click the Find By Number button.
Find By Name
To find a bus by its name and ID, enter the bus name into the Bus Name field (case insensitive) and the ID into the
ID field. Then click the Find By Name button.
Find…
If you do not know the exact generator bus number or name you are looking for, you can click this button to open
the advanced search engine.
Status
Status of the generator, either Closed (connected to terminal bus) or Open (not connected). You can use this field
to change the status of the generator.
Area Name
Name of the area in which the generator's terminal bus is located.
Same Owner as Terminal Bus
Read-only check-box that indicates whether the generator’s owner is the same than the terminal bus’ owner.
Labels
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected generator.
There additional sections of generator information available from the Run Mode generator dialog:
Power and Voltage Control
Generator Cost Information
OPF
Fault Parameters
Owners, Area and Zone
Memo
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Properties of Simulator Objects
Generator Information: Power and Voltage Control
The Power Control grouping fields are used to show/change the values associated with the real power output of the
generator.
MW Output
Current real power output of the generator.
Minimum and Maximum MW Output
Minimum and maximum real power output limits for the generator. Simulator will not let the MW output go below its
minimum value or above its maximum value if the Enforce MW Limits option is exercised.
Available for AGC
Determines whether or not the generator is available for automatic generation control (AGC). Normally this box
should be checked. However, there are times when you would like to control the generator output manually (such
as if you are using the generator to remove a line limit violation), in which case you should leave this box
unchecked. A generator is also placed on "manual" control any time you manually change its output. You could
then place the generator back on AGC control by using this dialog.
Enforce MW Limits
If checked, the minimum and maximum MW limits are enforced for the generator, provided the Enforce Generator
MW Limits field is also checked on the Limits Tab of the PowerWorld Simulator Options Dialog . If this box is
checked and a generator is violating a real power limit, the generator's MW output is immediately changed.
Participation Factor
The participation factor is used to determine how the real power output of the generator changes in response to
demand when the generator is available for AGC and the area is on participation factor control. When you open a
case using the PTI Raw Data Format, this field is initialized to the per unit MVA rating of the generator, since
participation factor information is not stored in the PTI format.
MW Ramp Limit
Specifies the maximum rate at which the real power output of the unit can be changed (in MW/minute). This rate is
needed because of the mechanical and thermal stresses that arise when the output of a generator is changed.
Since changing the output too quickly can damage a generator, the program will enforce this limit. You can
command Simulator to ignore the limit by removing the check from the Enforce Generator Ramp Limits option on
the Limits Tab of the PowerWorld Simulator Options Dialog. Then the output of the generator will change
instantaneously.
Loss Sensitivity
Shows how the losses for an area will change for an incremental increase in the generation at the bus. This
information is useful in determining the economic dispatch for the generation. The implicit assumption in calculating
this field's value is that the incremental change in generation will be absorbed by the system "slack bus." This field
cannot be changed.
Voltage Control
The Voltage Control grouping is used to show/change values associated with controlling the voltage/reactive power
output of the generator.
Mvar Output
Current reactive power output of the generator. You can manually change this value only if Available for AVR is
not checked.
Min and Max Mvar Output
Specify the minimum and maximum allowable reactive power output of the generator.
Available for AVR
Designates whether or not the generator is available for automatic voltage regulation (AVR). When the AVR field is
checked, the generator will automatically change its reactive power output to maintain the desired terminal voltage
within the specified reactive power range. If a reactive limit is reached, the generator will no longer be able to
maintain its voltage at the setpoint value, and its reactive power will then be held constant at the limit value.
Use Capability Curve
If checked, the generator's reactive power limits are specified using a reactive capability curve that prescribes the
dependence of the generator's reactive power limits on its real power output. Otherwise, the fixed values given in
the Min Mvar Output and Max Mvar Output fields are used. The generator reactive capability can be defined
using the table that appears at the bottom of the dialog. Please see Generator Reactive Power Capability Curve for
details.
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Regulated Bus Number
Number of the bus whose voltage the generator is regulating. This is usually, but not always, the generator's
terminal bus. Multiple generators can regulate the same remote bus, but the regulated bus must not be another
generator bus. If the generator is at a slack bus, it must regulate its own terminal voltage. Select Case
Information, Others, Remotely Regulated Buses to view the Remotely Regulated Bus Records Dialog , which
identifies all buses that are being remotely regulated.
Desired Reg. Bus Voltage
Specifies the desired per unit voltage for the generator at the regulated bus. The regulated bus need not be the
terminal bus of the generator.
Actual Reg. Bus Voltage
Shows the actual per unit voltage at the regulated bus. If the generator is on AVR and has not reached a reactive
power limit, the actual regulated bus voltage should be equal to the desired regulated bus voltage. This field cannot
be changed.
Remote Reg %
This field is only used when a number of generators at different buses are regulating a remote bus (i.e., not their
terminal buses). This field then specifies the percentage of the total reactive power required by the remote bus to
maintain its voltage that should be supplied by this generator. The default value is 100.
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Properties of Simulator Objects
Generator Options: Costs
The Costs tab of the Generator Information dialog (run mode) is used to show/change values associated with the cost
of operation of the generator. See Generator Cost Information for details. Cost data can also be saved/loaded using
the Generator Cost Data files.
Cost Model
Simulator can model generators as not having a cost model, or having either a cubic cost model or a piecewise
linear model. The cost model type you choose determines the content of the remainder of this dialog
Unit Fuel Cost
The cost of fuel in $/MBtu. This value can be specified only when you have chosen to use a cubic cost model.
Variable O&M
The Operations and Maintenance costs. Only used for cubic cost models.
Cost Shift, Cost Multiplier
The cost shift and cost multiplier allow you to easily apply a shift to the cost function for the purpose of assessing
how variations in bids impact profit. The cost function is affected based on the following equation:
(Original Cost Function + Cost Shift) * Cost Multiplier
Cubic Cost Coefficients A, B, C, D
For cubic cost models of the form C(Pgi) = (d*Pgi^3 + c*Pgi^2 + b*Pgi + a) * (fuel cost), specify the cost curve's
coefficients. These coefficients can be specified only when you have chosen to use a cubic cost model.
Piecewise Linear Table
If you have chosen to use a piecewise linear cost model, a table appears that allows you to specify pairs of MW
output levels and corresponding generator operating costs. To insert a new point on the cost curve, right-click on
the table and choose Insert New Point from the resulting local menu. To delete an existing point from the cost
curve, right-click on the table and choose Delete Point from the resulting local menu. To edit an existing point in the
table, simply enter your changes to the appropriate cells.
Fixed Cost
The fixed cost associated with operating the unit. This cost is independent of the generator's MW output level and
is added to the cost prescribed by the piecewise linear model to obtain the total cost of operating the generator in
$/MWHr. This option can be specified only for piecewise linear cost models.
Convert Cubic Cost to Linear
Use this option to create a piecewise linear cost function from the cubic cost function specified by the coefficients A,
B, C, and D and the fuel cost. Specify the number of break points, and hence the number of segments, in the
Number of Break Points field. Click the Convert to Linear Cost button to create the piecewise linear function that
approximates the cubic cost function. This action switches Cost Model option to Piecewise Linear and displays the
Piecewise Linear Table that identifies the piecewise linear curve’s breakpoints.
Marginal Cost (run mode only)
Shows the marginal cost of producing real power at the generator at its current output level, dC
i(Pgi)/dPgi.
ED/OPF Cost (run mode only)
This is the cost of production for this generator following an economic dispatch or optimal power flow solution,
including the scaling from the cost shift and cost multiplier fields.
Unscaled Cost (run mode only)
The cost of production of the generator, ignoring the cost multiplier and cost shift. This cost is the result of the
original cost function by itself.
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Generator Information: OPF
The fields on this tab display information regarding the generator’s participation in an OPF load flow solution.
OPF MW Control
The type of control the generator is allowed during an OPF solution. The generator can be set to No control during
OPF, control only if its AGC property is set to Yes, or to always be controlled by the OPF regardless of the AGC
status of the generator.
Fast Start Generator
The generator is being treated as a fast start generator during the OPF solution.
Generator MW limits
The MW limits of a generator can be altered in this location if you wish for the generator to use different limits than
originally assigned in the load flow case, without actually changing the original values. Simply change the Current
Min MW Limit and Current Max MW Limit to alter the limits observed by the generator during and OPF solution.
MW Marginal Cost for Generator’s Bus
The OPF solved marginal cost at the generator’s terminal bus.
Initial, Final and Delta MW Output
The MW output information for the generator resulting from the OPF run.
Initial, Final and Delta Hourly Cost
The hourly cost information for the generator resulting from the OPF run.
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Properties of Simulator Objects
Generator Options: Owners, Area, Zone
This information is located on the Generator Information Dialog.
This tab is used to display or change the generator’s owner information, area information, and zone information
Owners
Currently, Simulator supports up to four owners for generators. To add an owner of a generator, change one of the
Owner fields to a new owner number, and update the owner percentages accordingly. To modify an owner's
percentage of ownership, simply modify the value in the percentage field for that owner. If you set the percentage
of an owner to 0, that owner will be removed from the list of owners for the device. You can also remove an owner
from owning part of a device by changing the owner field for that owner to 0. Note that if you do not set the new
owner percentages of all specified owners such that the total is 100%, Simulator will normalize the percentages
such that the total is 100% when y ou click Save or OK on the generator dialog.
Area Number, Area Name
The area number and name to which the generator belongs. Note that you can change the area of the generator to
be different than the area of the terminal bus. If you do so, you will be prompted to confirm that you wish to place
the generator within a different area than that of the bus to which it is electrically connected.
Zone Number, Zone Name
The zone number and name to which the generator belongs. Note that you can change the zone of the generator
to be different than the zone of the terminal bus. If you do so, you will be prompted to confirm that you wish to place
the generator within a different zone than that of the bus to which it is electrically connected.
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Load Properties
Load Information (Run Mode)
The Load Information Dialog can be used to inspect and modify the model of a bus load. To view the Load
Information Dialog, simply right-click on the load of interest and select Load Information Dialog from the resulting local
menu. This is very similar to its Edit Mode counterpart. The dialog has the following fields:
Bus Number
Unique number between 1 and 99,999 used to identify the bus to which the load is attached. The dropdown box
provides a list of all load buses with valid display filters. You can use the spin button to cycle through the list of
load buses.
Bus Name
Unique alphabetic identifier for the bus to which the load is attached, consisting of up to eight characters. The
dropdown box lists the names of all load buses in the case with valid display filters.
ID
Two-character ID used to distinguish multiple loads at a bus. By default, the load id is equal to "1 ." An identifier of
'99' is used to indicate an equivalent load.
Find By Number
To find a load by its number and ID, enter the number into the Bus Number field and the ID into the ID field. Then
click this button.
Find By Name
To find a load by its name and ID, enter the bus name into the Bus Name field (case insensitive) and the ID into the
ID field. Then click this button.
Find…
If you do not know the exact load bus number or name you are looking for, you can click this button to open the
advanced search engine.
Status
Status of the load, either Closed (connected to terminal bus) or Open (not connected). You can use this status field
to change the load's status.
Area Number, Area Name
Number and name of the area the load is a member of.
Zone Number, Zone Name
Number and name of the zone the load is a member of.
Owner Number, Owner Name
Number and name of the owner the load is a member of. Loads DO NOT have to be owned by the same owner as
the terminal bus.
Substation Number, Substation Name
Number and name of the substation the load is a member of.
Labels
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected load.
Load Information
Base Load Model, Current Load
The Base Load Model fields are used to represent the amount of base real and reactive load at the bus. Usually
this load is modeled as being "constant power," meaning that the amount of load is independent of the bus voltage
magnitude. However, Simulator also permits modeling "constant current" load, for which the load varies in
proportion to the bus voltage magnitude, and "constant impedance" load, for which the load varies in proportion to
the square of the bus voltage magnitude. Values in these fields are specified in MW and MVR assuming one per
unit voltage. All six fields in the Base Load Model section can be changed.
Load Multiplier
The actual load at the bus is equal to the base value multiplied by the corresponding load multiplier. The load
multiplier is a potentially time varying value specifying how the load is scaled. The load multiplier depends upon the
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Properties of Simulator Objects
area load multiplier, the zone load multiplier, and the case load multiplier. See Load Modeling for more details. The
load multiplier value cannot be changed on this dialog.
Bus Voltage Magnitude
Voltage magnitude of the load’s terminal bus.
OPF Load Dispatch
The information on this tab displays the load information resulting from the load’s participation in an OPF solution
Benefit Model
If this field is set to none, the load will not be dispatchable in the OPF solution. If the option is set to Piecewise
Linear, the load is dispatchable during the OPF, according to the following fields.
Min. and Max. MW Demand
The minimum and maximum MW demand the load must operate within during the OPF solution.
Available for AGC
The load is only available for redispatch during the OPF solution if this option is checked.
Fixed Benefit
Value of the load benefit at minimum demand.
Piece-wise Linear Benefit Curve
This table the MW demand levels and their corresponding load benefit values, which in turn define the starting
points and slopes of the piece-wise linear benefit curve segments.
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Line/Transformer Properties
Line/Transformer Information (Run Mode)
The Line/Transformer Information dialog box is used to view information about each transmission line and transformer
in the system. You may use this dialog also to change many of the properties of lines and transformers (except in
Viewer).
The Run Mode version of this dialog is very similar in content to its Edit Mode counterpart.
The Line/Transformer dialog sports the following fields:
From Bus Number and Name
From Bus number and name. For transformers, the from bus is the tapped side.
To Bus Number and Name
To Bus number and name.
Circuit
Two-character identifier used to distinguish between multiple lines joining the same two buses. Default is '1'.
Find By Number
To find a line or transformer by its bus numbers, enter the from and to bus numbers and the circuit identifier. Then
click this button. Use the spin button to cycle through the list of lines and transformers in the system.
Find By Name
To find a line or transformer by the names of its terminal buses, enter the from and to bus names and the circuit
identifier. Then click this button.
Find…
If you do not know the exact from and to bus numbers or names you are looking for, you can click this button to
open the advanced s earch engine.
From End Metered
This field is only used for lines and transformers that serve as tie lines, which are lines that join two areas. If this
field is checked for a tie line, then the from end of the device is designated as the metered end. Otherwise the to
end is metered. By default, the from end is metered. The location of the metered end is important in dealing with
energy transactions because it determines which party must account for transmission losses.
Default Owner (Same as From Bus)
Read-only check-box that indicates whether the line’s owner is the same than the from bus’ owner.
From and To Bus Nominal kV
From and To bus nominal voltage levels.
From and To Bus Voltage (p.u.)
The actual terminal bus voltages of the transmission element, in per unit.
From and To Bus Area Name
Names of the areas in which the From and To buses are located.
Labels
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected branch.
Parameters
Status
Current status of the device.
Resistance, Reactance, Charging (B)
The resistance, reactance, and the total charging susceptance (that is, B, not B/2) of the device (in per unit).
Limits
Ratings for the transmission line or transformer in MVA. Simulator allows the use of up to eight different limit sets.
Has Line Shunts
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Properties of Simulator Objects
Indicates whether or not line or transformer has shunt compensation. You cannot directly change the value of this
field. Rather, use the Line Shunts / Series Capacitor button to view/modify existing line shunts or to enter new line
shunts. Line shunts are expressed in terms of the per-unit conductance and susceptance at each end of the line or
transformer.
Line Shunts
Select to view the Line Shunts Information Dialog. This dialog is used to change the values of the line shunts.
Line Flow
These next fields show the actual real and reactive power flow at both ends of the device (because of real and
reactive losses these numbers may be different), and its percentage MVA loading.
Transformer Info
This fields on this tab are enabled only if the branch is a transformer. See the Transformer Modeling help for more
information on transformer types and controls.
Off-nominal Turns Ratio
The off-nominal tap ratio for the transformer.
Phase Shift Degrees
Phase angle for the transformer. This field is usually non-zero only for phase shifting transformers or wye-delta and
delta-wye connected transformers, but can be non-zero for an LTC or fixed transformer on rare occasions.
Automatic Control Enabled
Check this box to enable automatic control of the transformer. Note that automatic control will be implemented only
if
(1) transformer control has been enabled for the transformer's area (see Area Display for details) and (2)
transformer control has not been disabled for the entire case (via the Disable Transformer Control option on the
Power Flow Solution tab of the PowerWorld Simulator Options Dialog). The Line/Transformer Dialog gives you
convenient access to these control options through the Case Control Enabled and Area Transformer Control
Enabled check boxes.
Case … Control Enabled and Area Transformer Control Enabled
Both of these boxes must be checked for a transformer to be controlled. Case Control Enabled has to be checked
for any transformer in the entire case to be controlled and Area Transformer Control Enabled has to be checked
for any transformer in that area to be controlled. Checking these does NOT automatically make the entire case or
entire area on control.
Automatic Control Options…
Depending on the type of control of the transformer, this button will open up the control options for LTC Control,
MVAR Control, or Phase Shifter Control.
Series Capacitor
The parameters on this tab are enabled when the selected branch is a series capacitor. If the branch is a series
capacitor, the Is Series Capacitor box will be checked. In addition, the Status field for series capacitors will be
enabled, allowing you to change the Bypassed or In Service status of the series capacitor. The series capacitor status
IS NOT the same as the branch status of Open or Closed.
Fault Analysis Parameters
The parameters on this tab are used when running a fault analysis study. The values represent the zero sequence
impedance and zero sequence line shunt admittances for the analysis. By default, the positive and negative sequence
line impedances and line shunt admittances are the same as the load flow impedance. The same fields are used for
transformers, along with the configuration field. The configuration field defines the winding type combinations for the
transformer (wye, delta, etc.) As a default, Simulator assumes a grounded wye to grounded wye transformer, which
has the same model as a transmission line. Usually transformers are not of this type, and the proper type would need
to be defined either manually or loaded from an external file in order for the fault analysis to be accurate.
OPF
The OPF tab is only visible if you have the OPF (Optimal Power Flow) add-on tool for PowerWorld Simulator.
Enforce Line Flow Limit
This check box must be checked if the branch limit is going to be enforced when running an OPF solution. If this
box is not checked, the OPF routine will allow the branch to violate its branch limits.
Treat Limit as Equality Constraint
If checked, the OPF solution will attempt to solve the load flow while keeping the flow on the branch at its limit.
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Maximum MVA Flow
The largest MVA flow value measured on the line, either at the From or To bus.
Present MVA Limit
The limit enforced by the OPF for the branch. This is set in the OPF constraint options, and is related to the original
branch limits.
Maximum Percentage
The highest percentage of flow measured on the line, either at the From or To bus.
Limit Marginal Cost
The cost of enforcing the branch MVA limit.
Flow Limit Unenforceable
If the line limit could not be maintained in the OPF solution, this box will be checked to indicate such. This check
box cannot be changed manually.
Line was Included in OPF Solution?
Specifies whether or not the branch flow and limit was included as a constraint in the OPF solution. In general,
branches that are not near their limit and do not appear to be changing flow dramatically towards their limit will be
ignored in the OPF calculation to speed up the solution. No and Yes indicate whether or not the OPF process
determined that the line needed to be included. The user can initially force the branch to be included or not
included with these two fields. By choosing Always , the branch will be included in the OPF solution constraints
regardless of the propensity of the line to be approaching it's limit.
From/To Bus MW Marginal Costs
Displays the marginal costs of the branches terminal buses, following the solution of the OPF.
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Properties of Simulator Objects
Transformer AVR Dialog
The Transformer AVR Dialog is used to view the control parameters associated with load-tap-changing (LTC)
transformers when they are used to control bus voltage magnitudes. To view this display, click the Automatic Control
Options button on the Line/Transformer Information Dialog. Note that the button will not respond to the click if the No
Automatic Control option is selected under the Automatic Control group.
This dialog has the following fields:
Regulated Bus Number
The number of the bus whose voltage is regulated by the control.
Current Regulated Bus Voltage
The present voltage of the regulated bus.
Voltage Error
If the regulated bus' voltage falls outside the regulating range of the transformer (as defined by the Minimum
Voltage and Maximum Voltage fields), the Voltage Error field indicates by how much the voltage deviates from the
control range.
Minimum Voltage
The minimum acceptable voltage at the regulated bus.
Maximum Voltage
The maximum acceptable voltage at the regulated bus.
Current Tap Ratio
The tap ratio of the transformer for the current system state.
Minimum Tap Ratio, Maximum Tap Ratio
Minimum and maximum allowable off-nominal tap ratios for the LTC transformer. Typical values are 0.9 and 1.1.
Tap Step Size
Transformer off-nominal turns ratio increment. The off-nominal turns ratio is either incremented or decremented
from 1.0 in integer multiples of this value. Default value is 0.00625.
Voltage to Tap Sensitivity
Shows the sensitivity of the voltage magnitude at the regulated bus to a change in the transformer's tap ratio. You
can use this field to assess whether or not the transformer can effectively control the regulated bus voltage. In an
ideal case, such as when the LTC transformer is being used to control the voltage at a radial load bus, the
sensitivity is close to 1.0 (or -1.0 depending upon whether the tapped side of the transformer is on the load side or
opposite side of the transformer). However, sometimes the transformer is very ineffective in controlling the voltage.
This is indicated by the absolute value of the sensitivity approaching 0. A common example is a generator step-up
transformer trying to control its high-side voltage when the generator is off-line. Simulator automatically disables
transformer control if the transformer sensitivity is below the value specified on Power Flow Solution Tab of the
PowerWorld Simulator Options dialog.
Impedance Correction Table
This field specifies the number of the transformer's corresponding transformer impedance correction table.
Transformer impedance correction tables are used to specify how the impedance of the transformer should change
with the off-nominal turns ratio. If this number is 0, then no impedance correction table is associated with the
transformer, and the impedance of the transformer will thus remain fixed as the tap ratio changes. Valid impedance
correction table numbers range from 1 to 63. To assign an existing impedance correction table to the transformer,
enter the existing table's number. To view the existing impedance correction tables, click the Insert/View
Impedance Correction Table button, which brings up the Transformer Impedance Correction Dialog. To define a
brand new impedance correction table for the transformer, enter an unused table number and then click Insert/View
Impedance Correction Table to prescribe the correction table. Note that the association between a transformer and
an impedance correction table is not finalized until you select either OK or Save on the Line/Transformer Dialog.
View Transformer Correction Table or Insert Transformer Correction Table
Click on this button either to view or to insert transformer correction tables. Clicking on this button displays the
Transformer Impedance Correction Dialog. Note that the table must prescribe at least two points in order to be
defined.
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Transformer Mvar Control Dialog
The Transformer Mvar Control dialog is used to view the control parameters associated with load-tap-changing (LTC)
transformers that are used to control the Mvar flow through the transformer. To view this display, click on the
Automatic Control Options button on the Line/Transformer Information Dialog.
When used to control reactive power, the LTC transformer always controls the reactive pow er flow at the from end of
the transformer (i.e., the tapped side), with positive flow assumed to be going through the transformer to the to bus.
Therefore the regulated bus field is not used.
The dialog has the following fields:
Mvar Flow at From Bus
The current Mvar flow as measured at the from end of the line. This is the parameter the transformer tries to
control.
Mvar Error
If the Mvar flow at the from end violates the limits defined by the Minimum Mvar Flow and Maximum Mvar Flow
fields, the Mvar Error field indicates by how much the flow falls outside the control range.
Minimum Mvar Flow, Maximum Mvar Flow
Minimum and maximum allowable reactive power flow as measured at the from bus. The transformer attempts to
regulate the reactive flow to fall within this range.
Current Tap Ratio
The transformer's present off-nominal turns ratio.
Minimum Tap Ratio, Maximum Tap Ratio
Minimum and maximum allowable off-nominal tap ratios for the LTC transformer. Typical values are 0.9 and 1.1.
Tap Step Size
Transformer off-nominal turns ratio increment. The off-nominal turns ratio is either incremented or decremented
from 1.0 in integer multiples of this value. Default value is 0.00625.
Mvar to Tap Sensitivity
The amount of Mvar shift that would be implemented by switching one tap position from the current position. This
sensitivity indicates the ability of the transformer to control Mvars.
Impedance Correction Table
Specifies the number of the transformer's corresponding transformer impedance correction table. Transformer
impedance correction tables are used to specify how the impedance of the transformer should change with the off-
nominal turns ratio. If this number is 0, no impedance correction table is associated with the transformer, and the
impedance of the transformer will thus remain fixed as the tap ratio changes. Valid impedance correction table
numbers range from 1 to 63. To assign an existing impedance correction table to the transformer, enter the existing
table's number. To view the existing impedance correction tables, click the Insert/View Impedance Correction Table
button, which brings up the Transformer Impedance Correction Dialog. To define a brand new impedance
correction table for the transformer, enter an unused table number and then click Insert/View Impedance Correction
Table to prescribe the correction table. Note that the association between a transformer and an impedance
correction table is not finalized until you select either OK or Save on the Line/Transformer Dialog.
View Transformer Correction Table or Insert Transformer Correction Table
Click on this button either to view or to insert transformer correction tables. Clicking on this button displays the
Transformer Impedance Correction Dialog. Note that the table must prescribe at least two points in order to be
defined.
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Properties of Simulator Objects
Transformer Phase Shifting Information
The Transformer Phase Shifting Dialog is used to view the control parameters of phase-shifting transformers. To view
this display, click on the Automatic Control Options button on the Line/Transformer Information Dialog, provided that
the Phase Shift Control option is chosen from the Automatic Control group.
Regulated Bus Number
Number of the terminal bus of the phase shifter regulated by the phase shifter. When control is active, the phase
shifter will automatically change its phase shift to keep the MW flow at this bus at the desired value.
Current MW Flow
Current MW flow through the transformer measured at the regulated bus terminal.
MW Error
If the current MW flow falls outside the minimum/maximum MW flow limits, the MW Error field indicates by how
much the flow violates the regulating range.
Minimum MW Flow, Maximum MW Flow
Minimum and maximum allowable MW flow through the phase shifter.
Current Phase Angle (Degrees)
The phase angle of the transformer for the current solved system state.
Minimum Phase Angle, Maximum Phase Angle
Minimum and maximum allowable phase shift in degrees.
Step Size (Degrees)
Phase shift change per step in degrees.
MW Flow to Phase Sensitivity
The sensitivity of the controlled MW flow to changes in the transformer's phase. This sensitivity indicates the
transformer's ability to regulate its MW flow.
Impedance Correction Table
Specifies the number of the transformer's corresponding transformer impedance correction table. Transformer
impedance correction tables are used to specify how the impedance of the transformer should change with the off-
nominal turns ratio. If this number is 0, no impedance correction table is associated with the transformer, and the
impedance of the transformer will thus remain fixed as the tap ratio changes. Valid impedance correction table
numbers range from 1 to 63. To assign an existing impedance correction table to the transformer, enter the existing
table's number. To view the existing impedance correction tables, click the Insert/View Impedance Correction Table
button, which brings up the Transformer Impedance Correction Dialog. To define a brand new impedance
correction table for the transformer, enter an unused table number and then click Ins ert/View Impedance Correction
Table to prescribe the correction table. Note that the association between a transformer and an impedance
correction table is not finalized until you select either OK or Save on the Line/Transformer Dialog.
View Transformer Correction Table or Insert Transformer Correction Table
Click on this button either to view or to insert transformer correction tables. Clicking on this button displays the
Transformer Impedance Correction Dialog. Note that the table must prescribe at least two points in order to be
defined.
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Transformer Impedance Correction Tables Dialog
The Transformer Correction Tables Dialog is used to view information about the transformer impedance correction
tables. These tables are used on some LTC or phase shifting transformers to model the impedance of the transformer
as a function of the off-nominal turns ratio or phase shift. The dialog has the following fields:
Transformer Impedance Correction Table Number
Number of the impedance correction table, between 1 and 63. Use the spin button immediately to the right of this
field to step through the list of defined tables. If you have made changes to a particular table, you must click Save
before moving to another correction table; otherwise, y our changes will be lost.
Table Entries
Used to insert/edit/delete the actual entries in the impedance correction table. In the first row, enter either an off-
nominal turns ratio for an LTC transformer, or a phase shift in degrees for a phase shifting transformer. The entries
in the first row must be entered in strictly ascending form. In the second row, enter the scale factor to apply to the
transformer impedance. The transformer's nominal impedance is multiplied by the scale factor to obtain the actual
value. Note that at least two columns must be used.
Right-click on the table to invoke its local menu, which allows you to delete and to insert columns. To insert a new
column, click on the column before which you want to insert a new column and select Insert New Point from the
local menu. To delete a column, position the cursor on the column you want to delete and select Delete Point.
Table is Used by the Following Transformers
Lists all the transformers in the case that use this impedance correction table. A single table may be used by any
number of transformers. To associate a table with a transformer, use the Transformer AVR Dialog for LTC
transformers or the Transformer Phase Shifting Dialog for phase shifters.
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Properties of Simulator Objects
Switched Shunt Properties
Switched Shunt Information (Run Mode)
The Switched Shunt Information Dialog box can be displayed by placing the cursor on its symbol and right-clicking.
This is very similar to its Edit Mode counterpart. The dialog has the following fields:
Bus Number
Unique number between 1 and 99,999 used to identify the bus to which the switched shunt is attached. This
dropdown list identifies the buses in the case with switched shunts that also have valid display filters. Use the spin
button to step through the list of shunts in the case. Note that only one switched shunt is allow ed at each bus.
Find By Number
To find a switched shunt by its bus number, enter the number into the Bus Number field. Then click the Find By
Number button.
Bus Name
Unique alphabetic identifier for the bus to which the switched shunt is attached, consisting of up to eight characters.
This dropdown box lists the names of all the switched shunt buses in the case with valid display filters.
Find By Name
To find a switched shunt by its name, enter the bus name into the Bus Name field (case insensitive). Then click the
Find By Name button.
Shunt ID
Since multiple switched shunts are allowed on a single bus, each shunt is identified by a unique ShuntID.
Status
Status of the switched shunt, either Closed (connected to terminal bus) or Open (not connected). On the oneline,
the switched shunt can be opened by placing the cursor on the (red) circuit breaker box and clicking, and it can be
closed by placing the cursor on the (green) box and again clicking. You can also use this status field to change the
switched shunt's status. Note that the switched shunt is only available for automatic control when its status is
closed.
Labels
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected load.
Find…
If you do not know the exact switched shunt bus number or name you are looking for, you can click this button to
open the advanced search engine.
Parameters
Nominal Mvar
Amount of reactive power that would be supplied by the switched shunt if its terminal voltage were one per unit
(capacitive is positive).
Actual Mvar
Actual reactive power in Mvar being injected into the system by the switched shunt (capacitive is positive). The
Actual Mvar field is equal to the Nominal Mvar field multiplied by the square of the terminal buses per unit voltage.
Nominal MW
This field is only visible when a switched shunt object has been read from a file as a Bus Shunt. In that case, it is
possible for the bus shunt to have both a MW and MVAR component. The MW component will be displayed here.
In general, switched shunts of other control types do not have MW components, and this field will not be displayed.
If you change a switched shunt read as a bus shunt to another form of control, the MW component will remain, but
has no controllability.
Actual MW
This field is only visible when a switched shunt object has been read from a file as a Bus Shunt. The value
displayed is the actual real power in MW being injected into the system by the shunt. The Actual MW field is equal
to the Nominal MVAR field multiplied by the square of the terminal buses per unit voltage.
Control Mode
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