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Delete, Copy, and Undo
Cut Command
The Cut Command is used in the Edit Mode to delete the currently selected object(s). To delete a set of objects, first
select the objects. Then select the Cut command from the Edit Menu. For power system objects, such as buses,
generators or transmission lines, you are given an option of whether to delete just the display object(s), or delete both
the display object(s) and their underlying power system records. See Relationship Between Display Objects and the
Power System Model for further explanation of these choices. To delete only the display object(s) and never the
power system records from now on, select the Always Delete Object(s) Only option. You will not be prompted again.
You can disable this selection on the Default Drawing Options Dialog.
Unlike Delete, Cut also copies the selection into the paste buffer.
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Editing Oneline Diagrams
Copy Command
The Copy Command copies the currently selected object(s) into the paste buffer without deleting them. For power
system objects, such as buses, generators or transmission lines, you are given an option of whether to copy just the
display object(s), or copy both the display object(s) and their underlying power system records. See Relationship
Between Display Objects and the Power System Model for further explanation of these choices. To copy only the
display object(s) and never the power system records from now on, select the Always Copy Object(s) Only option.
You will not be prompted again. You can disable this selection on the Default Drawing Options Dialog.
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Paste Command
The paste command copies the contents of the paste buffer (if any) onto the display at the current cursor location.
Use the Paste command from the Edit Menu. Note that the paste buffer may contain both display objects and the
underlying power system records. When pasting, the display objects are pasted regardless of whether an identical
display object already exists on the oneline. In contrast, duplicate power system records are never pasted. This is
because, for example, it is acceptable to have two display objects referring to the same generator, but the generator
exists only as a single entity in the power system model. See Relationship Between Display Objects and the Power
System Model for further details.
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Editing Oneline Diagrams
Delete Command
The Delete Command is used in the Edit Mode to delete the currently selected object(s). To delete a set of objects,
first select the objects. Then select the Delete command from the Edit menu. For power system objects, such as
buses, generators or transmission lines, you are given an option of whether to delete just the display object(s), or
delete both the display object(s) and their underlying power system records. See Relationship Between Display
Objects and the Power System Model for further explanation of these choices. To delete only the display object(s)
and never the power system records from now on, select the Always Delete Object(s) Only option. You will not be
prompted again. You can disable this selection on the Default Drawing Options Dialog.
Unlike Cut, Delete does not copy the selection into the paste buffer.
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Undo Command
The Undo command is used in the edit mode to undo the last change made on the oneline diagram. The Undo
command will only undo graphical changes, and will not undo any data changes in the power system model. See
Relationship Between Display Objects and the Power System Model for inf ormation on the display/model
relationships.
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Properties of Simulator Objects
Chapter 7: Properties of Simulator Objects
This chapter provides a description of the properties of each of the Oneline Display Objects. Note that when you are
using the Simulator, you can obtain context sensitive help for oneline objects by positioning the cursor on the desired
object and pressing the F1 key. Of the many properties of the various objects in Simulator, some are relevant only to
the Edit Mode, and some only to the Run Mode.
The following material is included:
· Edit Mode Properties and Information
· Run Mode Properties and Information
· General Properties and Information
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Edit Mode Properties and Information
Zone Properties
Zone Information (Edit Mode)
The Zone Dialog is used in the Edit Mode to view information about a zone and to move one or more buses from one
zone to another. (See Zone Information (Run Mode) for help on the corresponding Run Mode version.) To view this
dialog, first select Case Information, Zones to view the Zone Records Display. Then, right-click on the desired zone
record and select Show Dialog to view this dialog.
The dialog has the following fields:
Zone Number
Zone number between 1 and 999. You can use the spin button immediately to the right of this field to move to
either the next zone (click the up arrow) or the previous zone (click the down arrow).
Zone Name
Alphanumeric identifier for the zone of up to eight characters in length. You can use this field to change the zone's
name, provided you click either Save or OK.
Find By Number
To find a zone by its number, type the number in the Number field and click this button.
Find…
If you do not know the exact zone number you are looking for, you can click this button to open the advanced
search engine.
Labels
To assign alternative identifying labels to the zone, click the Labels button.
Zone Buses Table
This table lists all of the buses in the zone. Number, name, voltage, area number, and area name are shown for
each bus. This table can be used to move buses to a different zone. Select the bus or buses you would like to
move with the mouse. Then, enter the Destination Zone Number, which is the zone to which you want to move
the selected buses. You may enter a zone number that does not already exist, too, so that the buses will be moved
to a brand new zone. In this case, be sure to provide the Zone Name, as well. Finally, click the Move Selected
Bus(s) to Destination Zone button to implement the move.
OK, Save, Cancel
OK saves any changes to the zone name and closes the dialog. Save saves any changes to the zone name, but
does not close the dialog. Cancel closes the dialog ignoring any changes.
Bus Properties
Bus Options (Edit Mode)
This dialog is used to view/modify information about each bus in the system during Edit Mode. It is very similar in
content to its Run Mode counterpart.
Bus Number
Unique number between 1 and 99,999 used to identify the bus. You can use the spin button immediately 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.
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.
Labels
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Properties of Simulator Objects
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected bus.
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.
OK, Save, 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 example, the Find By Number command to edit additional buses. Cancel closes the dialog without
saving any changes.
Bus Information
Area Number
Number of the bus’ area. Each bus must be associated with an area record. If a bus is specified as belonging to an
area that does not already exist in the model, the new area is created.
Area Name
Alphabetic identifier for the bus’ area. If the area already exists, you do not need to enter this value.
Zone Number
Number of the bus’ zone, between 1 and 999. Each bus must be associated with a zone record. If a bus is
specified as belonging to a zone that does not already exist in the model, the new zone is created. Zones provide a
useful mechanism for breaking up a large system. Buses can be assigned to zones independent of their area
assignments. Thus, a single area could contain multiple zones, or a single zone could span multiple areas. You
can use the Zone Dialog to list the buses in a particular zone and easily move a group of buses from one zone to
another.
Zone Name
Alphabetic identifier for the bus’ zone. If the zone already exists, you do not need to enter this value.
Owner Number
The number of the bus’ owner.
Owner Name
The name of the bus’ owner.
Substation Number
The number of the substation the bus is contained in.
Substation Name
The name of the substation the bus is contained in.
Nominal Voltage
The nominal voltage for the bus in kV.
System Slack Bus
Check only if the bus should be modeled as a system slack bus. Each case requires at least one slack bus.
Voltage (pu), Angle (degrees)
Current per-unit voltage magnitude and angle for the bus. If you are inserting a new bus into an existing system,
you should not change the initial per unit voltage values. Rather, when you first switch to Run Mode, Simulator
will estimate the voltage magnitude and angle at the new buses in such a way as to reduce the initial mismatches.
This automatic estimation is only available if you have not modified the voltage in any way.
Display
Orientation
Set the orientation of the bus. The current choices are right, left, up or down. For the current bus object shapes of
Rectangle and Ellipse, right and left are analogous to horizontal, up and down are analogous to vertical. Additional
shapes for buses may be available in the future for which right, left, up and down may have more specific impact on
the appearance of the bus object.
Shape
Sets the shape of the bus object.
Pixel Thickness
Thickness of the bus in pixels.
Width
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Specifies the horizontal axis of an elliptical bus or horizontal side length of a rec tangular bus.
Height
Specifies the vertical axis of an elliptical bus or the vertical side length of a rectangular bus.
Scale Height with Width
When this option is checked, changing the width will cause the height to automatically adjust to keep the same ratio
of width to height. To adjust the height independent of the width, uncheck this option or adjust the height separately
after adjusting the width.
Link to New Bus
If you have right clicked on a bus and opened the bus information dialog, you could change the bus number in the
Bus Number field and press this button to force the bus object on the diagram to link to the new bus number and
information in the load flow data.
Attached Devices
Load Summary Information
Displays the net MW and Mvar load at the bus. You cannot change either of these fields from this display. Select
the Add or Edit Bus Load Records to view the individual load records for the bus via the Load Dialog.
Shunt Admittance
The real (G) and reactive (B) components of shunt compensation at the bus, expressed in MW and MVR,
respectively.
Fault Parameters
This tab is only visible when viewing the bus information for a bus with attached load. 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.
Memo
This page of the dialog can be used to enter notes about the bus. Any information entered in the memo box will be
stored with the case when the case is saved to a PWB file.
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Properties of Simulator Objects
Bus Field Information
Bus field objects are used primarily to indicate various quantities associated with bus devices. Furthermore, some bus
f ield types, which are distinguished by an integrated spin button, may be used to change bus device properties.
The Bus Fields Information Dialog can be used to modify the properties of individual bus 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 associated with the field. Use the dropdown box to view a list of all buses in the case with valid
area/zone/owner filters.
Bus Name
Name of the bus associated with the field. Use the dropdown box to view a list of all buses in the case with valid
area/zone/owner filters.
ID
The ID field is used when showing generator or load fields. Generator ID fields are single-character, whereas load
ID’s are two characters in length.
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 displayed with the selected value.
Delta Per Mouse Click
Bus fields can be used not only to show various fields associated with bus devices, but they can also be used to
change some values. This is accomplished using spin buttons shown to the right of the bus field. When the up spin
button is clicked, the bus field value is increased by the amount specified in the delta per mouse click field. When
the down spin button is clicked, the bus field value is decreased by the same amount.
This field is only used for fields of the following types: Load MW, Load Mvar, Set point Gen MW, and Switched
Shunt Mvar. Specifying a nonzero value in this field causes the integrated spin button to appear as part of the bus
field on the oneline.
Maintain Constant Load Power Factor
This field only applies when you have chosen to display the Load MW for a bus, AND have set the Delta per Mouse
Click to a non-zero value. When this field is selected, changing the MW value for a bus load using the load spin
button in run mode will automatically adjust the Load MVAR to keep the load power factor constant. If this field is
unchecked and the Load MW is changed using the spin button, the Load MVAR will remain unchanged.
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.
Anchored
If the Anchored checkbox is checked, the bus field is anchored to its associated bus, which means that it will move
with the bus.
Rotation Angle in Degrees
The angle at which the text will appear on the diagram.
Type of Field
Used to determine the type of bus field to show. The following choices are available:
Bus Name
Name of the bus
Bus Number
Bus number (from 1 to 99,999)
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Bus Voltage
Bus voltage magnitude
Bus Angle
Bus voltage angle in degrees
Load MW
Total MW load at the bus
Load Mvar
Total Mvar load at the bus
Switched Shunt Mvar
Total Mvar capacitance at the bus
Gen MW Output
Total MW generation at the bus
Gen Mvar Output
Total Mvar generation at the bus
Gen AGC Status
AGC status of generator; status can be toggled in Simulator
Gen AVR Status
AVR status of generator; status can be toggled in Simulator
MW Marginal Cost
Bus MW marginal cost in $/MW ·hr; available only with OPF
Mvar Marginal Cost
Bus Mvar marginal cost in $/Mvar·hr; available only with OPF
MW Loss Sensitivity
Increase in losses f or 1 MW of generation over the nominal
Gen Setpoint Voltage
Voltage of generator on bus
Select a Field
Choose from any of 42 different 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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Properties of Simulator Objects
Shortest Path Between Buses
The Shortest Path Between Buses dialog provides a way to find the shortest electrical pathway between two buses in
the power system. To identify the shortest electrical path between buses, open the Bus Records display, right click on
one of the bus' records you are interested in, and choose Find Shortest Path Between Buses from the local menu.
When the Shortest Path Between Buses dialog opens, the first bus should be filled in for you. Enter the bus number of
the second bus in the second field, and then click Show Shortest Path Between Buses. The result will be the list of
the buses comprising of the shortest electrical connection between the two buses specified, in order from the starting
bus to the ending bus.
Substation Properties
Substation Information (Edit Mode)
The Substation Dialog is used in the Edit Mode to view information about a substation and to move one or more buses
from one substation to another. (See Substation Information (Run Mode) for help on the corresponding Run Mode
version.) To view this dialog, first select Case Information > Substations to view the Substations Records Display.
Then, right-click on the desired substation record and select Show Dialog to view this dialog.
The 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. You can use these fields to change the substation’s name or ID,
provided you click either Save or OK.
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.
Substation Buses Table
This table lists all of the buses in the substation. Number, name, voltage, area number and name, and zone
number and name are shown for each bus. This table can be used to move buses to a different substation. Select
the bus or buses you would like to move with the mouse. Then, enter the Destination Substation Number, which is
the substation to which you want to move the selected buses. You may enter a substation number that does not
already exist, too, so that the buses will be moved to a brand new substation. In this case, be sure to provide the
new substation a name and ID, as well. Finally, click the Move Selected Bus(s) to Destination Substation button to
implement the move.
Display Options
The Display Options tab of the Substation Information dialog allows you to choose the general appearance of the
substation object. Use the Width and Height fields to set the width and height of the substation object. The Shape
field allows you to choose what shape the substation object will take.
The Substation Layout Oneline field allows you to specify the same of the Simulator oneline diagram (pwd) file
that should be automatically opened if you click on the substation object on the diagram in run mode. If no oneline
is spec ified, Simulator will search for a default name of the format AreaName_SubstationName. If a diagram
cannot be found, then Simulator will not attempt to open any oneline diagrams when the substation is clicked.
Substation Generators, Loads, and Switched Shunts Tables
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These tables list all of the generators, loads, and switched shunts in the substation. Number, name, ID, status, and
additional fields for each type of device are shown.
Memo
Enter any text notes you wish in the Memo page. When the case is saved as a Simulator PWB file, the memo text
will also be saved.
OK, Save, Cancel
OK saves any changes to the substation name or ID, and closes the dialog.
Save saves any changes to the substation name or ID, but does not close the dialog.
Cancel closes the dialog ignoring any changes.
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Properties of Simulator Objects
Substation Field Options
Substation field objects are used to show different values associated with substations. This dialog is used to view and
modify the parameters associated with these fields.
Substation Number
Select the number of the substation for which you are inserting or viewing information of a substation field.
Find…
If you do not know the exact substation you are looking for, you can click this button to open the advanced search
engine.
Substation Name
The name of the currently selected substation.
Substation ID
The substation ID number.
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 appear on the diagram.
Field Value
Shows the current output for the super area 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.
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 super area field to show. The following choices are available:
Substation Name, Substation Number
Name or number of the selected substation.
Substation ID
ID string for the selected substation.
Max Nominal Voltage
Displays the nominal voltage of the highest nominal voltage bus in the substation.
Substation Load MW, Substation Load Mvar
Total Load MW or MVAR in the substation.
Substation Gen MW, Substation Gen MVAR
Total Generator MW or MVAR in the substation.
Select a Field
Select this option and click Find Field… to display the value of any other substation specific field.
Generator Properties
Generator Options (Edit Mode)
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This dialog is used to view and modify the parameters associated with each generator in the system. It can also be
used to insert new generators and sometimes to delete existing generators.
The Edit Mode version of the Generator Information Dialog is almost identical to the Run Mode version.
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 area/zone/owner 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 area/zone/owner 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 this 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 this 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
Alphabetic identifier for the terminal bus’ area.
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 are six additional areas of information on this dialog for specific aspects of generation:
Display Information
MW and Voltage Control
Costs
Fault Parameters
Owners, Area, Zone
Memo
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Properties of Simulator Objects
Generator Field Information
Generator field objects are used primarily to indicate various quantities associated with generation devices.
Furthermore, some generator field types, which are distinguished by an integrated spin button, may be used to change
generation device properties.
The Generator Fields Information Dialog can be used to modify the properties of individual generator 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 generator associated with the field is connected. Use the dropdow n box to view a
list of all buses with generators in the case with valid area/zone/owner filters.
Bus Name
Name of the bus to which the generator associated with the field is connected. Use the dropdown box to view a list
of all buses with generators in the case with valid area/zone/owner filters.
ID
ID of the generator associated with the field. Generator ID are two-character alphanumeric fields.
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 displayed with the selected value.
Delta Per Mouse Click
Generator fields can be used not only to show various fields associated with generation devices, but they can also
be used to change some values. This is accomplished using spin buttons shown to the right of the generator field.
When the up spin button is clicked, the generator field value is increased by the amount specified in the delta per
mouse click field. When the down spin button is clicked, the generator field value is decreased by the same
amount.
This field is only used for fields of the following types: Setpoint Gen MW, Setpoint Gen Mvar, and Gen Setpoint
Voltage. Specifying a nonzero value in this field causes the integrated spin button to appear as part of the
generator field on the oneline.
Rotation Angle in Degrees
The rotation angle at which the text field should be displayed.
Anchored
If the Anchored checkbox is checked, the generator field is anchored to its associated generator, which means that
it will move with the generator.
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 generator field to show. The following choices are available:
Gen MW Output
MW generation
Gen Mvar Output
Mvar generation
Gen AGC Status
AGC status of generator; status can be toggled in Simulator
Gen AVR Status
AVR status of generator; status can be toggled in Simulator
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Gen Setpoint Voltage
Voltage of generator on bus
Select a Field
Choose from any of the different generator 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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Properties of Simulator Objects
Generator Options: Display
This information is located on the Generator Information Dialog.
Display Size
The size of the generator.
Scale Width with Size
If checked, the Display Width will automatically be scaled to the appropriate setting when the Display Size is
changed. If unchecked, then only the length of the generator object will be affected by changing the value of the
Display Size.
Display Width
The width of the display object. This setting is automatically set if Scale Width with Size is checked and the value of
the Display Size field is changed, or the Display Width value can be set manually to a new value.
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 Generator
Links the object to a different generator in the data.
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Generator Options: MW Control
This information is located on the Generator Information Dialog.
The MW 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 anytime you manually change its output. You could
then place the generator back on AGC control if you wish it to participate in an area generation dispatch.
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
When running a simulation over time, the generator cannot change by more than this value per time step. The
global option for obeying generator ramp limits must be turned on.
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Properties of Simulator Objects
Generator Options: Voltage Control
This information is located on the Generator Information Dialog.
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, then 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.
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 Buses Dialog, which identifies
all buses that are being remotely regulated.
SetPoint Voltage
Specifies the desired per unit setpoint voltage value the generator is to regulate at the regulated bus. The regulated
bus need not be the generator terminal bus.
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. If the total value is different
from 100%, then all the regulation factors are normalized to obtain a percentage of regulation.
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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.
246
Properties of Simulator Objects
Generator Options: Fault Parameters
The parameters on this tab are used when running a fault analysis study.
Generator MVA Base
The assumed MVA base for the generator. This value is used when calculating fault analysis values for the internal
generator parameters.
Neutral Grounded
Check this check-box if the generator has the neutral grounded.
Generator Step Transformer
The resistance, reactance and tap setting for the generator step-up transformer, if one is being modeled internally
with the generator. By default, no internal transformer model is assumed.
Internal Impedance
These fields represent the internal impedance of the generator for all three sequences. By default, all three values
are initially the same as the load flow internal impedance of the generator. All three sets of values can be modified,
either manually or by loading values from an external file using the Fault Analysis Dialog.
Neutral-to-Ground Impedance
Neutral-to-ground impedance for the generator. These values get implemented with the zero sequence admittance
matrix. Note that the neutral-to-ground impedance will not be used, even if specified, if the original model for the
generator implicitly models the generator step-up transformer. This is because the implicitly modeled transformer is
assumed to have a delta winding on the generator side of the transformer, which isolates the generator from the
rest of the zero sequence network.
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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 you 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.
248
Properties of Simulator Objects
Generator Cost Description
The cost associated with operating a generator varies according to the output of the generator, with the general rule
that getting more power out of a generator costs more. In Simulator, there are two options for modeling generator
cost. The first employs the common cubic relationship
= ( ai + bi P
+ ci (P
+ di (P
$/Hour
Ci(Pgi)
gi
gi)2
gi)3 ) * fuel cost
where P
gi is the output of the generator at bus i in MW. The values ai, bi, ci, and di are used to model the generator's
input-output (I/O) curve. The I/O curve specifies the relationship between how much heat must be input to the
generator (expressed in MBtu per hour) and its res ulting MW output. Normally, the cubic coefficients remain constant
for a generator. The last term in the equation is the fuel cost, expressed in $/MBtu. This value varies depending on
the fuel used in a generator. Typical values would be $ 1.25/MBtu for coal and $ 2/Mbtu for natural gas. The resultant
equation is known as the fuel-cost curve. The values of the ai, bi, ci, di, and the fuel cost can be viewed and modified
using the Generator Information Dialog.
Simulator can also model generator costs using a piecewise linear model consisting of pairs of MW output and
incremental cost ($/MWhr) of generation, along with a fixed cost. These piecewise linear curves must be convex
curves, meaning the marginal cost of the current MW break point must be higher than the previous MW break point.
Such curves can be defined using the Generator Information Dialog or by loading data from generator cost data files.
249
Set Generator Participation Factors
Participation factor control is another of Simulator’s mechanisms for distributing an area’s responsibility to serve its
load, losses, and interchange. It is particularly well-suited to implementing automatic generation control (AGC) when
you do not have good economic information for an area’s generators. With participation factor control, the amount of
power that each generator contributes to meeting its areas load, loss, and interchange responsibilities is controlled by
the size of its participation factor. The unit that has the largest participation factor contributes the most, and the unit
that has the smallest participation factor contributes the least.
The Set Generator Participation Factors Dialog gives you a convenient way to define the participation factors for
multiple generators. You can set the participation factor according to a number of different formulae and then apply
this prescription to all generators in a specific area, all generators in a specific zone, all generators in the system, or all
generators whose display filters are currently set to true.
To display the Set Generator Participation Factors Dialog, you first need to open the Area Information Dialog and
switch to the Options page. The Area Information Dialog has a button labeled Set Participation Factors that is
enabled only if the Participation Factors is selected under the Area Control Options heading. Set the area on
participation factor control by selecting the Participation Factors option, and then press the Set Participation Factors
option.
The Set Generator Participation Factors Dialog is divided into two parts. The first part, which occupies the top half of
the form, allows you to indicate how the participation factors should be calculated or set for each generator. Your
options include:
Max MW Rating of Generator
The participation factor for each generator is set to the generator’s
maximum MW capability.
Difference Between Max and Current Output The participation factor for each generator is set to the generator’s
reserve power, so that each generator participates in proportion to
how much it has left to contribute.
Constant Value of
The participation factor for each generator is set to the same hard-
coded value.
File
The participation factor for each generator is read from a file. The
first line of the file should contain the keyword NUMBERS or NAMES
indicating whether generators are identified by bus number or by bus
name in the file. All subsequent lines should be comma-delimited
and contain three fields: the number or name of the generator’s bus,
the generator’s id, and the generator’s participation factor.
If you choose any of the first three options, you then must tell Simulator to what generators y ou want to assign the
participation factors. To assign the participation factors to all generators in a specific area, select the All Generators
in Area option, and then choose the area from the adjacent dropdown box. If you want to assign the participation
factors to all generators in a specific zone, select the All Generators in Zone option, and then choose the zone from
the adjacent dropdown box. If you want to assign the participation factor to all generators in the system regardless of
their area or zone affiliation, select the All Generators in System option. Finally, if you want to assign the
participation factor to just those generators whose display filter criteria evaluates to true, choose the All Generators
With Valid Display Filters option.
If you instead chose to read participation factors from a file, only those generators whose factors you read from the file
will have their factors set by this action. However, unless each generator’s associated area is set to control generator
output using participation factor control, this information will be ignored. To make sure that each generator’s area is
set to participation factor control, check the Set Corresponding Areas to Participation Factor Control box. Then,
each corresponding area will be set to participation factor control.
250
Properties of Simulator Objects
Generator Reactive Power Capability Curve
The reactive power output of most generators depends on the real power output of the generator. This dependence is
expressed using a reactive capability curve. Simulator models the reactive capability curve using a piecewise linear
approximation. The reactive capability curve is modified on the generator dialog and can be saved/loaded using the
Generator Reactive Capability Curve Auxiliary files.
Modeling a Reactive Power Capability Curve From the Generator Dialog
· Make sure the Use Capability Curve checkbox is checked.
· In the table immediately below the checkbox, prescribe the reactive capability curve using up to 50 points. The
points should be ordered by MW, in numerically increasing order. At each point specify the MW value, the
minimum reactive power value in Mvar, and the maximum reactive power value in Mvar. The first point should
correspond to the minimum MW output of the generator, while the last point should correspond to the maximum
MW output.
· To insert a new point, click on the desired column, and then right-click to display the table's local menu. Select
Insert Point.
· To remove a point, click on the desired column, and then right-click to display the table's local menu. Select
Delete Point.
· When finished be sure to select Save to save your modifications.
In the Run Mode, you can view the reactive power capability curve graphically by right-clicking on the generator to
display its submenu and then selecting Reactive Capability Curve .
Load Properties
Load Options (Edit Mode)
This dialog is used to view and modify the parameters associated with each load in the system. It can also be used to
insert new loads and sometimes to delete existing loads. It is nearly identical in structure to its Run Mode counterpart.
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. 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 area/zone/owner filters. You can use the spin button to cycle through the
list of load buses.
When you insert objects graphically, the Bus Number and Bus Name fields are usually set automatically to the bus
upon which you placed the object.
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 area/zone/owner 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
251
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. If the load owner is the same as the terminal bus owner,
the Same Owner as Terminal Bus box will be checked. Loads DO NOT have to be owned by the same owner as
the terminal bus.
Labels
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected load.
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 example, the Find By Number command to edit additional loads. Delete deletes the current load.
Cancel closes the dialog without saving your changes.
Specific load information can be found on the following pages of the Load Options dialog:
Load Information
OPF Load Dispatch
252
Properties of Simulator Objects
Load Options: Load Information
This page of the Load Options dialog contains information on the load magnitude and display settings.
MW and Mvar Value Fields
The MW and Mvar Value 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 can be modified by the user.
Display Size
Size of the load.
Scale Width with Size
If checked, the Display Width will automatically be scaled to the appropriate setting when the Display Size is
changed. If unchecked, then only the length of the generator object will be affected by changing the value of the
Display Size.
Display Width
The width of the display object. This setting is automatically set if Scale Width with Size is checked and the value of
the Display Size field is changed, or the Display Width value can be set manually to a new value.
Pixel Thickness
Thickness of the display object in pixels.
Orientation
Specifies the direction to draw the object.
Anchored
If checked, the object is anchored to its terminal bus. See Anchored Objects for details.
Link to New Load
Links the object to a different load record in the data.
253
Load Options: OPF Load Dispatch
This tab of the Load Options dialog contains settings for allowing the load to be included as an OPF Control. The
load(s) can then be dispatched in the OPF algorithm according to the assigned costs.
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 Output
Minimum and maximum load MW demand for OPF dispatch.
Available for AGC
If checked, the load will be available for redispatch during the OPF routine.
Fixed Benefit
Value of the load benefit at minimum demand.
Piece-wise Linear Benefit Curve
This table allows y ou to specify pairs of MW demand levels and corresponding load benefit values, which in turn
define the starting points and slopes of the piece-wise linear benefit curve segments. 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.
254
Properties of Simulator Objects
Load Field Information
Load field objects are used primarily to indicate various quantities associated with load devices. Furthermore, some
load field types, which are distinguished by an integrated spin button, may be used to change load device properties.
The Load Fields Information Dialog can be used to modify the properties of individual load 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 load associated with the field is connected. Use the dropdown box to view a list of
all buses with loads in the case with valid area/zone/owner filters.
Bus Name
Name of the bus to which the load associated with the field is connected. Use the dropdown box to view a list of all
buses with loads in the case with valid area/zone/owner filters.
ID
ID of the load associated with the field. Load ID fields are two characters in length.
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 displayed with the selected value.
Delta Per Mouse Click
Load fields can be used not only to show various fields associated with load devices, but they can also be used to
change some values. This is accomplished using spin buttons shown to the right of the load field. When the up
spin button is clicked, the load field value is increased by the amount specified in the delta per mouse click field.
When the down spin button is clicked, the load field value is decreased by the same amount.
This field is only used for fields of the following types: Load MW and Load Mvar. Specifying a nonzero value in this
field causes the integrated spin button to appear as part of the load field on the oneline.
Note that the Maintain Constant Load Power Factor option will allow you to specify a Delta per Mouse-click for
the MW load, and when the MW value is changed in run mode, the MVAR load will also change in such a way as to
keep the power factor of the load constant.
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.
Anchored
If the Anchored checkbox is checked, the load field is anchored to its associated load, which means that it will move
with the load.
Rotation Angle in Degrees
The angle at which the text is placed on the diagram, in degrees.
Type of Field
Used to determine the type of load field to show. The following choices are available:
Load MW
MW load
Load Mvar
Mvar load
Select a Field
Choose from any of the different load fields
Select OK to save changes and to close the dialog, or click Cancel to close the dialog without saving your changes.
255
Load Modeling
Each load can be modeled as having voltage and/or time variation. The voltage variation is modeled using the Base
Load Model fields on the Load Information. The time variation in the load is modeled using Area and Zone load
variation schedules. Thus the actual real and reactive value of each load is determined using the following equation:
MW
LoadMultiplier(t) * (SMW + IMW * V + ZMW * V * V)
Mvar
LoadMultiplier(t) * (SMvar + IMvar * V + ZMvar * V * V)
where
MW
current real power load in MW
Mvar
current reactive power load in Mvar
SMW
constant power MW value
Smvar
constant power Mvar value
IMW
constant current MW value (assuming 1.0 per unit voltage)
Imvar
constant current Mvar value (assuming 1.0 per unit voltage)
ZMW
constant impedance MW value (assuming 1.0 per unit voltage)
Zmvar
constant impedance Mvar value (as suming 1.0 per unit voltage)
V
per unit bus voltage magnitude
The Load Multiplier field is a potentially time varying field. Its value is given by
LoadMultiplier(t)
(Case Load Multiplier) * (Area Schedule Value) * (Zone Schedule Value)
The Case Load Multiplier allows you to scale all the loads in the case quickly and conveniently. This value is specified
on the Simulation Tab of the PowerWorld Simulator Options Dialog.
The Area Schedule Value scales all of the loads in an area based upon a time-dependent schedule. These values are
defined as part of a time sequence that can be established or modified by using the Time Sequence tool in Simulator.
Each area can have an associated schedule of load scales.
The Zone Schedule Value scales all of the loads in a zone based upon a time-dependent schedule. These values are
defined as part of a time sequence that can be established or modified by using the Time Sequence tool in Simulator.
Each zone can have an associated schedule of load scales.
Note that area and zone schedules of load scales are saved to and loaded from Time Sequence Binary (tsb) files.
Line Properties
Transmission Line/Transformer Options (Edit Mode)
The Line/Transformer Information Dialog is used to view and modify the parameters associated with each transmission
line and transformer in the system. You can also insert new transmission lines and delete existing transmission lines
from this dialog.
The Edit Mode version of this dialog is very similar in content to its Run Mode counterpart.
The Line/Transformer Information Dialog has 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 Numbers
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 Names
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.
256
Properties of Simulator Objects
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 search 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
Nominal voltage level of each terminal bus, in kV.
From and To Bus Area Name
Control area name in which each terminal bus is located.
Labels
Clicking on this button will open the Subscribed Aliases dialog listing all the labels or aliases assigned for the
selected branch.
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 example, the Find By Number command to edit additional transmission lines. Delete deletes the
current transmission line. Cancel closes the dialog but does not save any changes.
Parameters / Display
Transformer Control
This tab is only visible for transformer objects. See Transformer Modeling for details on modeling either LTC or
phase shifting transformers.
Series Capacitor
Fault 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.
Owners
Transmission elements can have up to four different owners, each with a certain owner percentage. To add an
owner of a transmission element, change one of the Owner fields to a new owner number, and update the owner
percentages accordingly. 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 you click Save or OK
on the line/transformer dialog.
257
Transmission Line/Transformer Options: Parameters/Display
Status
Current status of the device.
Resistance, Reactance, Shunt 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 limits.
Line Shunts
Select to view the Line Shunt Dialog. This dialog is used to change the values of the line shunts.
Calculate Per Unit Impedances
Clicking this button will open the Line Per Unit Impedance Calculator dialog, which can be used to convert actual
impedance and current limits to per unit impedance and MVA limits, and vice versa.
Length
If the length of the line is known, it can be entered here for informational purposes.
Convert Line to Transformer
Clicking this button turns the currently selected trans mission line into a transformer, making the transformer specific
fields available.
Pixel Thickness
Thickness of the display object in pixels.
Anchored
If checked, the object is anchored to its terminal bus, which means that it will move when you move the terminal
bus. See Anchored Objects for details.
Link to New Line
Use the Link to New Line button to create a new line corresponding to the entries you have made in the dialog.
This button performs the same function as pressing Save. Note that adding a new line to the case in this way does
not add a transmission line to the oneline display; the new line is present only in the model. You may then add the
newly modeled line to the oneline diagram in the usual way (such as select Insert, Transmission Line from the
main menu).
Symbol Segment
Only visible for transformer and series capacitor objects. This field specifies which "segment" of the branch
contains the transformer or capacitor symbol. A segment constitutes a section of the line between vertex points of
the line object, and are numbered starting at the from bus.
Symbol Size
Only visible for transformer and series capacitor objects. Specifies the size (width) of the transformer or capacitor
symbol on the branch.
Symbol Percent Length
The distance or "length" of the symbol on the segment of the branch which contains it.
258
Properties of Simulator Objects
Line Shunts Information
The Line Shunts Information Dialog is used to modify the parameters of transmission line shunts. The modeling of the
line shunts is explained below.
Line Shunts
Line shunts are included in the model as admittance-to-ground values at either the From end or the To end of a
transmission line. These values can represent many things, such as shunt-to-ground capacitors, reactors, zigzag
(or grounding) transformers, or equivalenced system values. Line shunt values are entered in per unit, with a
positive B corresponding to capacitors and a negative B corresponding to reactors. Mathematically, the line shunts
are included in the algorithm in the same manner that line charging capacitance is included using the Pi model.
Line shunt values can be modified from the Transmission Line Information dialog.
259
Line Per Unit Impedance Calculator Dialog
The Line Per Unit Impedance Calculator Dialog allows to convert actual impedance and current limit values to per unit
impedance and MVA limit values, and vice versa.
The dialog has the following elements:
Actual Impedance and Current Limits
This part of the dialog shows all the impedance related values in Ohms/length-unit as well as the transmission line
limits specified in Amps. If any of these values is modified, the corresponding per unit or MVA value will be
changed accordingly, taking into consideration the current line length, length units, and system base values.
Line Length
This value indicates the length of the line in miles or kilometers, depending on the units selected in Length Units .
The option When changing convert is used to convert the values when the length value is modified. The option
PU/MVA --> indicates that the actual impedance and current limits will be converted to per unit impedance and MVA
limits when the length value is changes. The option <-- Electrical specifies that the per unit impedance and MVA
limits will be converted to actual impedance and current limits when the length value is modified.
Length Units
This option indicates the length units. Choices are miles and kilometers. When this parameter is changed, the user
will be prompted to confirm to convert the actual impedance and current limits, as well as the line length values,
from the old units to the new units. If the answer is positive, then the actual impedance and current limits, and the
line length will be the same but they will be expressed in the new units selected. If the answer is negative, the
values will not change numerically but they still will be expressed in the new units selected.
System Base Values
The system base values show the power base, the voltage base, and the impedance base. These values can not
be modified in this dialog.
Per Unit Impedance and MVA Limits
This part of the dialog shows all the impedance related values in per unit as well as the transmission line limits
specified in MVA. If any of these values is modified, the corresponding actual or Amps value will be changed
accordingly, taking into consideration the current line length, length units, and system base values.
Set Actual Impedance and Current Limits According to a Conductor Type
With this option, the user can select a conductor type from the dropdown list and set the actual impedance and
current limits to the determined values for the selected conductor.
260
Properties of Simulator Objects
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.
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
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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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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 w hether 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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Transmission Line/Transformer Options: Series Capacitor
The Series Capacitor tab of the Line/Transformer Information dialog displays information relating to a series capacitor,
including its status.
Status
The capacitor itself has two status positions, Bypassed and In Service . When the series capacitor is in service,
the branch is modeled as a reactive branch, using the line parameters from the Parameters / Display page. If the
capacitor is bypassed, a low impedance branch is introduced to bypass the capacitor. Note that this is not the
same as the branch status of Open or Closed. The branch status is the indicator of whether or not the entire circuit
is operating (closed), regardless of Bypassed or In Service status on the capacitor itself.
Is Series Capacitor
If this box is checked, the branch can be treated as a series capacitor, with the series Status of Bypassed or In-
Service available.
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Properties of Simulator Objects
Multi-Section Line Information
Multi-section line records are used to group a number of series-connected transmission lines together so that their
status is controlled as a single entity. They are usually used to model very long transmission lines that require multiple
individual transmission line records if they are to be modeled accurately. In terms of line status, Simulator then treats
each multi-section line as a single device. In other words, changing the status of one line in the record changes the
status of the other lines in the record, as well.
Multi-section line records are not directly represented on the oneline diagrams. Rather, to view this dialog, right-click
the record of interest on the Multi-Section Line Records display and select Show Dialog from the resulting local menu.
To define a new multi-section line, switch to Edit Mode and, from the Multi-Section Line Records display, right-click
and select Insert from the resulting local menu.
Note: If any of the transmission lines comprising a multi-section line record are deleted, the entire multi-section line
record is deleted as well.
The Multi-Section Lines Dialog contains the following fields:
From Bus Number and Name
Number and name of the from bus for the record. If you are defining a new multi-section line, this must be the first
data item you specify.
To Bus Number and Name
Number and name of the "to" bus for the record. You cannot specify this value directly. Instead, use the table at
the bottom of the dialog to define the intermediate buses and to terminal.
Circuit
Two character identifier used to distinguish between multiple records joining the same from/to buses. The first
character of the circuit identifier must be an "&."
You can use the spin button immediately to the right of the circuit field to view other multi-section line records.
However if you have changed the record, you must select Save before moving to another record. Otherwise, your
changes will be lost.
From End Metered
If checked, the from end of the record is the metered end; otherwise the to end is metered.
Multi-Section Line Name
The name for the multi-section line.
Table
The table lists the dummy (or intermediate) buses and the to bus that comprise the record. The first column should
contain the first dummy bus number and the circuit ID of the transmission line joining the from bus with the first
dummy bus. The next column should contain the second dummy bus number and the circuit id of the transmission
line joining this bus to the first dummy bus. Continue until the last column contains the to bus and the circuit ID of
the transmission line joining the last dummy bus with the "to" bus.
Each transmission line comprising the multi-section line must already exist. If only one transmission line joins any
two buses, you may omit the circuit identifier.
OK
Saves any modifications and closes the dialog.
Save
Saves any modifications but does not close the dialog.
Cancel
Closes the dialog without saving modifications to the current record.
Delete
Deletes the current multi-section line record.
Note: If any of the transmission lines comprising a multi-section line record are deleted, the entire multi-section line
record is deleted as well.
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Line Field Options
Line field objects are used to show different values associated with transmission lines, transformers and dc lines. This
dialog is used to view and modify the parameters associated with these fields.
Find…
If you do not know the exact line identifiers you are looking for, you can click this button to open the advanced
search engine.
Near Bus Number
Bus associated with the near end of the object. All fields display values calculated at the near bus end. When
inserting fields graphically, this field is automatically set to the closest bus on the oneline.
Far Bus Number
Bus associated wth the far end of the object.
Circuit
Two-character identifier used to distinguish between multiple lines or transformers joining the same two buses.
Default is ‘1’.
Total Digits in Fields
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
Only used with the MVA Limit field type. Specifying a nonzero value for this field equips the MVA Limit Field with an
integrated spin button that can be clicked to increment or decrement the MVA Limit by the amount of the Delta Per
Mouse Click value.
Field Value
The current value of the field being displayed.
Field Prefix
A prefix that can be specified and displayed with the selected value.
Rotation Angle in Degrees
The angle at which the text will appear on the diagram.
Anchored
If checked, the line analog is anchored to its associated line.
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 line field to show. The following choices are available:
AC Line MW Flow
MW flow into the line or transformer at the near bus
AC Line Mvar Flow
Mvar flow into the line or transformer at the near bus
AC Line MVA Flow
Magnitude of MVA flow into the line or transformer at the near bus
AC Line Amp Flow
Magnitude of Amp flow (in amps) into the line at the near bus
AC Line MW Losses
Real power losses on the line or transformer in MW
AC Line Mvar Losses
Reactive power losses on the line or transformer in Mvar
DC Line MW Flow
MW flow into the dc line at the near bus
DC Line Mvar Flow
Mvar flow into the dc line at the near bus
MVA Limit
MVA limit for the line or transformer
DC Line Set point
Set point value for the dc line; see DC Transmission Line dialog
Select a Field
Choose from over 80 different fields
Select OK to save changes and close the dialog or Cancel to close the dialog without saving your changes.
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