PowerWorld Simulator version 11. Manual

Cost Shift $/MWh, 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

Fixed Cost

The fixed operating cost of the generator.

MWh Break x, MWh Price x

The remainder of the display is populated with MWh Break and MWh Price pairs. These pairs define the break

points of the piecewise linear curve. The MWh Break value is a MW output value of the generator. The MWh Price

value is the corresponding marginal cost of producing an additional MW of power at that MW output level.

Therefore entering the break points of the piecewise linear curve in this manner defines the slopes of the next

section of the curve, starting at the current MW Break point and up to but not including the next defined break point.

The last MWh Break and MWh Price pair defined will define the marginal price of the unit from that break point

location to the maximum output of the generator.

A requirement of the piecewise linear cost curve is that it must be convex, meaning the next MWh Price must be

higher than the previous MWh Price.

These fields will be disabled unless the Cost Model type is set to Piecewise Linear.

390

Text-Based Information Displays

Generator Cubic Cost Display

The Generator Cubic Cost Display presents detailed cost information for each generator in the case set to use a cubic

cost model. The Generator Cubic Cost 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 records as well as view the information dialog of its associated generators. The Quick Power Flow List and

Bus View Display tools are available for finding more information on the generator’s terminal bus. You can also sort

the generator records by clicking on the heading of the field by which you want to sort. Additionally, you can choose to

restrict the records shown by the Generator Cubic Cost Display according to the constraints of the area/zone/owner

filters. Finally, you can use the local menu’s Insert and Delete options when the application is in Edit Mode to insert a

new generator into the case or to delete an existing generator.

To show the generator cubic cost display, select Case Information > Generator/Load Cost Models > Generator

Cubic Cost Models .

By default, the generator records display contains the following fields:

Number, Name

Number and name of bus to which the generator is attached.

Area Name of Gen

Name of the area to which the generator belongs. The generator can belong to an area which is different than the

area of which its terminal bus is a member.

Alphanumeric ID used to distinguish multiple generators at the same bus; ‘1’ by default.

Status

The Open / Closed status of the generator. This is a toggleable field.

AGC

Designates whether the generator’s real power output is governed by automatic generation control. If the AGC field

is set to Yes, the generator is on automatic generation control (AGC). When a generator is on AGC, its real power

output can be varied automatically. Usually the purpose for AGC is to keep the area interchange at a desired value.

You can click on this field to toggle its value (except in Viewer). Please see Area Control for more details.

Gen MW

Current real power output of the generator.

IOA, IOB, IOC, IOD

Parameters used to model the cost characteristic of the generator. Please see Generator Cost Information for

details. Please note that these values can be saved/loaded using the Generator Cost Data auxiliary file.

Fuel Cost

The fuel cost of the type of fuel for the generator.

Variable O&M

Operations and Maintenance costs for the generator.

Fuel Type

An informational field that can be set to the type of fuel the generator uses.

Unit Type

An informational field that can be set to reflect the type of unit the generator is, such as combined cycle, steam,

hydro, etc.

Cost Shift $/MWh, 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

Cost $/Hr

Operating cost for the generator in $/hr.

Incremental cost to produce an additional MWh. This can be expressed as dC(Pgi)/dPgi, where C denotes the

generator’s cost of operation in $/hr and Pgi expresses the current MW output of the unit. In a lossless system, the

incremental dispatch is equal to the generator’s lambda value.

391

Text-Based Information Displays

Generator Piecewise Linear Cost Display

The Generator Piecewise Linear Cost Display presents detailed cost information for each generator in the case set to

use a piecewise linear cost model. The Generator Piecewise Linear Cost 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 records as well as view the information dialog of its associated

generators. The Quick Power Flow List and Bus View Display tools are available for finding more information on the

generator’s terminal bus. You can also sort the generator records by clicking on the heading of the field by which you

want to sort. Additionally, you can choose to restrict the records shown by the Generator Piecewise Linear Cost

Display according to the constraints of the area/zone/owner filters. Finally, you can use the local menu’s Insert and

Delete options when the application is in Edit Mode to insert a new generator into the case or to delete an existing

generator.

To show the generator piecewise linear cost display, select Case Information > Generator/Load Cost Models >

Generator Piecewise Linear Cost Models .

By default, the generator records display contains the following fields:

Number, Name

Number and name of bus to which the generator is attached.

Area Name of Gen

Name of the area to which the generator belongs. The generator can belong to an area which is different than the

area of which its terminal bus is a member.

Alphanumeric ID used to distinguish multiple generators at the same bus; ‘1’ by default.

Status

The Open / Closed status of the generator. This is a toggleable field.

AGC

Designates whether the generator’s real power output is governed by automatic generation control. If the AGC field

is set to Yes, the generator is on automatic generation control (AGC). When a generator is on AGC, its real power

output can be varied automatically. Usually the purpose for AGC is to keep the area interchange at a desired value.

You can click on this field to toggle its value (except in Viewer). Please see Area Control for more details.

Gen MW

Current real power output of the generator.

Min MW

Minimum MW output of the generator.

Max MW

Maximum MW output of the generator.

Fuel Cost

The fuel cost of the type of fuel for the generator.

Fuel Type

An informational field that can be set to the type of fuel the generator uses.

Unit Type

An informational field that can be set to reflect the type of unit the generator is, such as combined cycle, steam,

hydro, etc.

Cost Shift $/MWh, 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

Fixed Cost

The fixed operating cost of the generator.

MWh Break x, MWh Price x

The remainder of the display is populated with MWh Break and MWh Price pairs. These pairs define the break

points of the piecewise linear curve. The MWh Break value is a MW output value of the generator. The MWh Price

value is the corresponding marginal cost of producing an additional MW of power at that MW output level.

393

Text-Based Information Displays

Load Displays

Load Display

The Load Display presents data describing each load in the case. The Load 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 loads. The local menu also affords the opportunity to insert new loads into the model or to delete existing

ones. Moreover, it enables you to invoke the Quick Power Flow List and Bus View Display for the load’s terminal bus.

You can also sort the load information by clicking on the heading of the field by which you want to sort. Additionally,

you can choose to restrict the information shown by the Load Display according to the constraints of the

area/zone/ow ner filters.

To show the load display, select Case Information > Loads .

The load display contains the following fields by default:

Number, Name

Number and name of bus to which the load is attached.

Tw o-character ID used to distinguish multiple loads at the same bus; ‘1’ by default.

Status

Either Closed if the load is connect to its bus, or Open if it is not. You can click on this field to toggle its value. If the

load is open, the entire load record is dimmed.

MW, Mvar, MVA

Total real, reactive, and complex power for the load. Loads may be both voltage dependent and time dependent.

The total load is the sum of the constant power, constant current, and constant impedance components. See Load

Information and see Load Modeling for more information.

S MW, S MVAR, I MW, I MVR, Z MW, Z MVR

These six fields describe the composition of the load at the bus assuming 1 pu bus voltage. The SMW and SMVAR

fields indicate the constant power portion of the load, the component that does not vary with bus voltage magnitude.

The IMW and IMVR fields express the constant current part of the load, which varies in proportion to the bus

voltage magnitude. Finally, ZMW and ZMVR indicate the constant impedance portion of the load, which varies with

the square of the voltage. The sum of the SMW, IMW, and ZMW fields yields the base MW load at the bus

(assuming 1pu voltage), and the sum of the SMVR, IMVR, and ZMVR fields provides the base MVR load at the bus

(assuming 1 pu voltage). Please see Load Modeling for more details on how bus load is modeled.

395

Load Variation Schedules

The Load Variation Schedules Display identifies load variation profiles that have been defined. These profiles can be

assigned to areas or zones to prescribe how the load within the areas or zones should vary over time. PowerWorld

employs a load model in which all the loads in the case are first scaled from their Base Case values by the Case Load

Multiplier. This provides a convenient means of changing the load level for the entire case. Furthermore, for each

area and zone the loads can be modeled to change proportionally with time (i.e., they are all scaled from their base

values by the same value) according to a piecewise linear model whose values can be displayed and modified using

the Schedules Dialog. The Load Variation Display identifies information that specify various piecewise linear

variations that can be applied to the loads in an area or zone.

The Load Variation Schedules 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 load profiles. The local menu also affords the

opportunity to define new load profiles or to delete existing ones, or to enable or disable a particular profile. You can

also sort the load variation information by clicking on the heading of the field by which you want to sort. Additionally,

you can choose to restrict the records shown by the Load Display according to the constraints of the area/zone/owner

filters.

To show the load display, select Case Information > Others > Load Variation Schedules.

The load display contains the following fields by default:

Name

The name of the load profile schedule. This name may contain up to 24 characters.

Enabled

Indicates whether the current load variation will be applied to any area or zone that has been defined to use it. An

area may be associated with a particular load variation through either the Options Tab of the Area Information

Dialog or the Load Schedule field of the Area Case Information Display. Likewise, zones may be associated with a

particular load variation through either the Options Tab of the Zone Information Dialog or the Load Schedule field of

the Zone Case Information Display.

Value

The current value of the load multiplier prescribed by the schedule.

Type

Simulator recognizes three types of load profiles. Daily load profiles describe a load variation that is common to all

days for which the simulation is performed. Weekly load profiles chart load variation across an entire week. Finally,

weekend load profiles permit a distinction between how load is to vary during a weekday and how it is to vary on a

weekend day. The Type field will thus contain one of three values: daily, weekly, or weekend.

# Time Points

Indicates the number of segments in the piecewise linear model. A load profile having n time points defines the

load multiplier at n points in time. Time points may be added or deleted using the Load Schedule Dialog.

396

Text-Based Information Displays

Load Benefit Models Display

The Load Benefit Models Display presents detailed cost information for each load in the case set to use a piecewise

linear benefit model. The Load Benefit Models 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 records as well as view the information dialog of its associated loads. The Quick Power Flow List

and Bus View Display tools are available for finding more information on the load’s terminal bus. You can also sort the

load records by clicking on the heading of the field by which you want to sort. Additionally, you can choose to restrict

the records shown by the Load Benefit Models Display according to the constraints of the area/zone/owner filters.

Finally, you can use the local menu’s Insert and Delete options when the application is in Edit Mode to insert a new

load into the case or to delete an existing load.

To show the generator piecewise linear cost display, select Case Information > Generator/Load Cost Models > All

Load Benefit Models .

By default, the generator records display contains the following fields:

Number, Name

Number and name of bus to which the load is attached.

Area Name of Gen

Name of the area to which the load belongs. The load can belong to an area which is different than the area of

which its terminal bus is a member.

Alphanumeric ID used to distinguish multiple generators at the same bus; ‘1’ by default.

Status

The Open / Closed status of the load. This is a toggleable field.

AGC

Designates whether the generator’s real power output is governed by automatic generation control, since effectively

dispatching a load can be viewed as dispatching negative generation. If the AGC field is set to Yes , the load is on

automatic generation control (AGC). When a load is on AGC, its real power output can be varied automatically.

Usually the purpose for AGC is to keep the area interchange at a desired value. You can click on this field to toggle

its value (except in Viewer). Please see Area Control for more details.

Gen MW

Current real power demand of the load.

Min MW

Minimum MW demand of the load.

Max MW

Maximum MW demand of the load.

Fixed Benefit

The fixed benefit of the load.

Benefit Model

The type of model this load is currently using. Can be either Piecewise Linear or None.

MWh Break x, MWh Price x

The remainder of the display is populated with MWh Break and MWh Price pairs. These pairs define the break

points of the piecewise linear curve. The MWh Break value is a MW demand value of the load. The MWh Price

value is the corresponding marginal benefit of extracting an additional MW of load at that MW output level.

Therefore entering the break points of the piecewise linear curve in this manner defines the slopes of the next

section of the curve, starting at the current MW Break point and up to but not including the next defined break point.

The last MWh Break and MWh Price pair defined will define the marginal benefit of the load from that break point

location to the maximum demand of the load.

A requirement of the piecewise linear benefit curve is that it must be concave, meaning the next MWh Price must be

lower than the previous MWh Price. In other words, as more load is supplied, the less the benefit it is providing.

This is how a load can be dispatched along with generation, according to marginal costs (and marginal benefits.)

These fields will be disabled unless the Cost Model type is set to Piecewise Linear.

397

Line and Transformer Displays

Line and Transformer Display

The Line/Transformer Display presents data describing each transmission line and transformer in the case. The

Line/Transformer 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 w hich you can print, copy, and modify its information

as well as view the information dialog of its associated branches. The local menu also affords the opportunity to insert

new lines or transformers into the model or to delete existing ones. Moreover, it enables you to invoke the Quick

Power Flow List and Bus View Display for each branch’s terminal buses. You can also sort the line and transformer

information by clicking on the heading of the field by which you want to sort. Additionally, you can choose to restrict

the information shown by the Line/Transformer Display according to the constraints of the area/zone/owner filters.

To show the line/transformer display, select Case Information > Lines and Transformers.

The contents of the display depends upon the application’s operating mode.

The line/transformer display shows the following fields by default:

From Bus Number and Name

From Bus number and name. For transformers, the from bus is the tapped side. Right-clicking on either of these

fields brings up the display’s local menu from which you may select Quick Power Flow List or Bus View Display to

obtain more information about the from bus .

To Bus Number and Name

To Bus number and name. Right-clicking on either of these fields brings up the display’s local menu from which you

may select Quick Power Flow List or Bus View Display to obtain more information about the to bus .

Circuit

Two-character identifier used to distinguish between multiple lines joining the same two buses. Default is ‘1’.

Status

The service status of the branch. This field is toggleable.

Xfrmr

Yes or no field signifying if the branch is a transformer or transmission line. This field cannot be changed.

From MW, From Mvar, From MVA (Run Mode default)

Real, reactive, and complex power flowing into the line at the from bus.

Lim MVA, Max Percent

The current MVA limit of the branch, and the amount of the actual flow as a percentage of the MVA limit.

MW Loss, Mvar Loss (Run Mode default)

Real and reactive power losses on the transmission line or transformer. Since reactive power losses include the

effect of line charging, the reactive power losses may be negative.

Resistance, Reactance, Capacitance (Edit Mode default)

Indicates the branch’s R, X, and line charging in ohms.

Lim A MVA, Lim B MVA, Lim C MVA (Edit Mode default)

Identifies the first three limit settings. Five additional limits can be set, for which the columns can be added using

the Display/Column options from the local popup menu. All limits are expressed in MVA.

See Transformer Display for viewing transformer specific fields.

398

Text-Based Information Displays

Multi-Section Lines Display

The Multi-Section Line Display lists the multi-section lines that exist in the case. The Multi-Section Line Display is

used to functionally group a number of transmission lines together. They are usually used to model very long

transmission lines that require the use of multiple individual transmission line information to be modeled accurately.

Simulator then treats each multi-section line as a single device with regard to line status. That is, changing the status

of one line in the record changes the status of the other lines in the record as well.

Each multi-section line record consists of the "from" bus, one or more "dummy" buses and the "to" bus. Each dummy

bus must have only two lines connected to it, each of which are members of the multi-section line record. See Multi-

Section Line Information for details.

The Multi-Section Line 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 multi-section line information. The local menu also affords the

opportunity to insert new multi-section lines into the model or to delete existing ones when the application operates in

the Edit Mode. Moreover, it enables you to invoke the Quick Power Flow List and Bus View Display for the line’s

terminal buses. You can also sort the multi-section line information by clicking on the heading of the field by which you

want to sort. Additionally, you can choose to restrict the information shown by the Multi-Section Line Display

according to the constraints of the area/zone/owner filters.

To show this display select Case Information > Others > Multi-Section Lines.

The display contains the following fields by default:

From Bus #, From Name

Number and name of the multi-section lines from bus . Right clicking on one of these fields invokes the display’s

local menu from which you can select either Quick Power Flow List or Bus View Display to find more information

about the from bus .

To Bus #, To Name

Number and name of the multi-section lines to bus . Right clicking on one of these fields invokes the display’s local

menu from which you can select either Quick Power Flow List or Bus View Display to find more information about

the to bus .

Circuit

Two-character circuit identifier for the multi-section line. The first character in the identifier should always be an "&."

Sections

Number of individual lines within the multi-section line record.

Status

Current status of the record. Note, the status is Closed only if all the lines in the record are closed, and is Open

only if all the lines in the record are open. Otherwise the status is Mixed.

399

Transformer Display

The Transformer Display identifies all transformers in the case. The data presented in the Transformer Display

supplements the data presented in the Line/Transformer Display by presenting transformer-specific information.

Consult the Line/Transformer Display for the transformer flows.

The Transformer 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 transformer. You can find a specific transformer using the names

or numbers of its terminal buses, and you can learn more about a particular transformer’s terminal buses by choosing

either Quick Power Flow List or Bus View. When in Edit Mode, you can delete an existing transformer from the case.

You can also sort the transformer information by clicking on the heading of the field by which you want to sort.

To show this display select Case Information > Transformers Controls .

The Transformer Display contains the following fields by default:

From Bus Number and Name

From Bus number and name. The From Bus is the tapped side. You may view either the Quick Power Flow List or

the bus view display for the From Bus from the local menu.

To Bus Number and Name

To Bus number and name. You may view either the Quick Power Flow List or the bus view display for the To Bus

from the local menu.

Circuit

Two-character identifier used to distinguish between multiple transformers joining the same two buses.

Status

The service status of the transformer. This field is toggleable.

Type

Type of transformer. Possible values include

Fixed

The tap positions are fixed

LTC

The tap ratio changes to regulate bus voltage

Mvar

The tap ratio changes to regulate reactive power flow

Phase

The phase angle changes to regulate real power flow

Tap/Phase

Indicates the tap ratio for LTC and fixed transformers and the phase shift angle in degrees for phase-shifting

transformers.

XF Auto

If the value of this field is Yes , the transformer will automatically change its tap or phase angle to keep the regulated

value within the specified regulation range, provided that the Auto XF field of its associated area is set to Yes and

transformer tap/phase control has not been disabled for the entire case. The Auto XF field of individual areas is set

from the Area Display, and case-wide transformer control can be set from the Power Flow Solution tab of the

PowerWorld Simulator Options Dialog. Click on this field to toggle its values.

Reg Bus

For an LTC transformer, this is the number of the bus whose voltage is controlled by the transformer. For phase

shifting transformers, the real power is always controlled at the tapped bus.

Reg Value

For an LTC transformer, this is the present per unit voltage at the regulation bus. For a phase shifting transformer,

this is the present real power flow through the transformer measured on the "from" (tapped) side.

Reg Error

The error is the difference between the regulated value and the respective limit of the regulation range specified by

Reg Min and Reg Max. If the regulated value is within the regulation range, then the error is zero. The error is

negative if the regulated value falls below the regulation range, and it is positive if the regulated value exceeds the

regulation range.

Reg Min, Reg Max

Minimum and maximum values for the regulation range. For LTC transformers, these fields represent per unit

voltage at the regulated bus. For phase shifting transformers, these fields represent actual MW flow through the

400

Three Winding Transformer Display

The Three Winding Transformer Display shows information about all the three winding transformer devices in the

case. Three winding transformers are modeled in Simulator as a grouping of two winding transformers, connected at

a common midpoint or "Star" bus. The Three Winding Transformer Display is a way to view all the terminal connection

points for the three winding transformers and the power delivered at each of the terminals.

The Three Winding Transformer 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 three winding transformers. When in Edit

Mode, you can define new three winding transformers using the Insert option, or delete existing three winding

transformers using Delete. You can also sort the three winding transformer information by clicking on the heading of

the field by which you want to sort.

To show this display, select Case Information > Others > Three Winding Transformers.

This display contains the following fields by default:

Pri Bus Num, Sec Bus Num, Ter Bus Num

These are the primary winding, secondary winding and tertiary winding terminal bus numbers for the three winding

transformer connections.

Pri, Sec and Ter MW and MVAr

These fields display the real and reactive power delivered at each of the three winding transformer terminals.

Circuit

The circuit identifier for the three winding transformer.

402

Text-Based Information Displays

DC Lines Display

The DC Line Display presents data describing each dc line in the case. The DC Line 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 records as well as view the information dialog of its

associated dc lines. You can also sort the dc line records by clicking on the heading of the field by which you want to

sort. Additionally, you can choose to restrict the records shown by the DC Line Records Display according to the

constraints of the area/zone/owner filters.

To show the dc line records display, select Case Information > DC Lines, and click on the DC Lines tab.

By default, the dc line records display contains the following fields:

Number

Each dc line must be assigned a unique number, typically between 1 and 40.

Rect Number, Rect Name, Rect MW, Rect Mvar

Number and name of the rectifier bus, and the real and reactive power flow from the rectifier into the dc line. You

may right-click on any of the rectifier-related fields and select Quick Power Flow List or Bus View from the local

menu to view additional information about the rectifier bus.

Inv Number, Inv Name, Inv MW, Inv Mvar

Number and name of the inverter bus, and the real and reactive power flow from the inverter into the dc line. You

may right-click on any of the inverter-related fields and select Quick Power Flow List or Bus View from the local

menu to view additional information about the inverter bus.

Control Mode

Specifies how flow on the dc line is controlled. If this field is set to Power, then the line’s MW flow is the control

parameter. If the control mode is defined as Current, then the line’s current is the control parameter.

Setpoint

Specifies the initial value of the control parameter, which is expressed either in MW or in amps depending on the dc

line’s control mode.

Set kV

Specifies the voltage of the dc line in kV.

403

Multi-Terminal DC Record Display

The Multi-terminal DC Line Display presents data describing each multi-terminal DC line in the case. The Multi-

Terminal DC Line 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 records. The local menu also affords the opportunity to insert

multi-terminal DC line records into the model or to delete existing ones.

To show the Multi-Terminal DC Line display, select Case Information > DC Lines from the main menu bar, and click

on the Multi-terminal DC Lines tab of the transformer case information display.

The Multi-terminal DC Line display shows the following fields by default:

Number

The record number of each multi-terminal DC record.

Num Conv

The total number of converters in each multi-terminal DC network.

Num Buses

The total number of DC buses in each multi-terminal DC network.

Num Lines

The total number of DC lines in each multi-terminal DC network.

Mode

The control mode of the multi-terminal DC network: 0 is Blocked control, 1 is Power control, and 2 is Current control.

V. Cont. Bus

The number of the AC converter bus at which the DC voltage is controlled.

404

Text-Based Information Displays

Switched Shunt Displays

Switched Shunt Display

The Switched Shunt Display identifies all switched shunt devices in the case. Switched shunts are used in power

systems either to inject additional MVR into the system (capacitive shunts) or to absorb excess reactive power

(inductive shunts). They may also be used to regulate bus voltage within some specified range.

The Switched Shunt 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 loc al menu from which you can print, copy, and modify its information

as well as view the information dialog of its associated switched shunts. You can find a specific switched shunt using

its bus name or number, and you can learn more about a particular shunt’s terminal bus by choosing either Quick

Power Flow List or Bus View. When in Edit Mode, you can insert a new shunt into the case or delete an existing

shunt. You can also sort the switched shunt information by clicking on the heading of the field by which you want to

sort. Additionally, you can choose to restrict the information shown by the Load Display according to the constraints of

the area/zone/owner filters.

To call up the Switched Shunt Display, click Case Information > Switched Shunts .

The Switched Shunt Display contains the following fields by default:

Number, Name

Number and name of terminal bus to which the switched shunt is attached. Only one switched shunt is allowed per

bus. Use the right menu options to inspect either the Quick Power Flow List or the Bus View Display for the

terminal bus.

Circuit identifier for the switched shunt device.

Reg Bus Num.

Number of the buswhose voltage is regulated by the switched shunt. If the regulation bus is the same as the

terminal bus, this field is blank.

Status

The service status of the switched shunt. This field is toggleable.

Control Mode

Control Mode for the switched shunt. A switched shunt may operate either as Fixed if its reactive value is to be held

constant, as Discrete if its reactive output is controlled automatically in discrete steps to regulate its terminal

voltage, or as Continuous if its reactive injection is allowed to vary over a continuous spectrum of values to regulate

its terminal voltage. A shunt will be switched either discretely or continuously to regulate its terminal bus’ voltage

between its high and low voltage limits provided the Auto Shunt field of its corresponding area is set to Yes and

switched shunt control has not been disabled for the entire case. You may set the value of the Auto Shunt field

from the Area Display, and you can control case-wide enforcement of shunt switching from the Power Flow Solution

tab of the PowerWorld Simulator Options Dialog. This Control Mode field is toggleable.

Regulates

Can be set to regulate either bus voltage or generator MVAR output.

Actual Mvar

The reactive power currently supplied by the switched shunt.

Volt High

Per unit high-voltage limit for the regulation range. It is important for discrete shunt control that Volt High exceed

Volt Low by a nontrivial amount; otherwise, the output of the shunt may oscillate during the Power Flow Solution.

Volt Low

Per unit low-voltage limit for the regulation range.

Reg Volt

Actual per unit voltage at the regulated bus. When Control Mode is either Discrete or Continuous, this voltage

should be between Volt Low and Volt High.

Deviation

Deviation of the regulated bus’ actual per unit voltage from the desired regulation voltage. If the actual voltage is

within the regulation range, this field is zero. If the voltage is greater than Volt High, the deviation is positive. It is

negative if the actual voltage is less than Volt Low.

Nominal Mvar

405

Text-Based Information Displays

Interface Displays

Interface Display

The Interface Display is used to show the net real power (MW) flow on a group consisting of one or more of the

following devices: 1) transmission lines (AC and DC) and/or transformers, 2) total tie-lines between two adjacent

areas, 3) total tie-lines between two adjacent zones, 4) Generators and Loads, 5) Injection Groups, and 6)

Contingency Actions . Interface information is useful because secure power system operation often requires that the

flow on such groups be less than some limit value. For example, interface information could be used as "proxies" for

other types of security constraints, such as voltage or transient stability limitations. Another major potential use for

interfaces is in the Optimal Power Flow solution to monitor flows on groups of devices, such as a set of transmission

lines, generation leaving a plant, load demanded in a certain region, etc. Interface information can also be extremely

useful for summarizing the flows occurring on a large network. Interface flows can be monitored using the Limit

Violations Display.

The Interface Display presents more detailed information for each interface that has been defined for the case. The

Interface 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 interfaces. The local menu also affords the opportunity to insert new

interface definitions either singly (Insert) or as a group (Automatic Insertion) into the model or to delete existing ones.

In addition, PowerWorld has also added options for reading NERC flowgate files (Load NERC Flowgates) and writing

NERC flowgate files (Save NERC Flowgates) to the local menu.

You can sort the interface information by clicking on the heading of the field by which you want to sort. Additionally,

you can choose to restrict the information shown by the Interface Display according to the constraints of the

area/zone/owner filters.

To show the interface display, select Case Information > Interfaces.

Interface information can be saved in the "*.aux" auxiliary file format. See Auxiliary Files for details.

The Interface display contains the follow ing fields:

Number

Numeric identifier for the interface.

Name

Alphanumeric identifier for the interface (24 characters maximum).

MW Flow

Current MW flow on the interface. This flow is the sum total of the Base MW Flow and the Contingent MW Flow.

MW Limit

Current rating for the interface in MW.

Percent

The actual MW flow on the interface as a percentage of the MW limit.

Monitor Direction

The current direction in which the MW flow is being monitored. The possibilities are From - To, To - From, or Both.

MW A Limit, MW B Limit, MW C Limit

These three fields display the values of the three possible limits for the interface.

Has Contingency

This is a Yes or No field that will be set to Yes if any of the elements making up part of the interface are at a device

limit.

Contingent MW Flow

If the interface defined contains a contingency action, the Contingent MW Flow is the approximated flow amount

that would be added to the interface should the contingency occur.

Base MW Flow

The base MW flow is the flow on the interface prior to any considered contingency elements.

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Nomogram Display

The Nomogram Display is used to modify and create Nomogram definitions. Nomograms are combinations of two

interfaces for monitoring combined flows on the interfaces concurrently. These Nomogram interfaces will have a limit

definition that defines a region of allowed flow on the interfaces, and can be monitored in many tools in Simulator as

potential constraints, such as the contingency analysis reporting of interface violations. Another major potential use

for nomograms is in the Optimal Power Flow solution to monitor the flow on a pair of interfaces. Nomogram

information can also be extremely useful for summarizing the flows on a pair of interfaces whose operation and

allowed flow are closely tied together. Nomogram flows can be monitored using the Limit Violations Display.

The Nomogram Display presents more detailed information for each nomogram that has been defined for the case.

The Nomogram 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 nomograms.

You can sort the nomogram information by clicking on the heading of the field by which you want to sort. Additionally,

you can choose to restrict the information shown by the Interface Display according to the constraints of the

area/zone/owner filters.

To show the interface display, select Case Information > Nomograms.

Nomogram information can be saved in the "*.aux" auxiliary file format. See Auxiliary Files for details.

The Nomogram display contains the following fields:

Name

Alphanumeric identifier for the nomogram.

Int A Flow

Current MW flow on the first interface of the interface pair forming the nomogram. This flow is the sum total of the

Base MW Flow and the Contingent MW Flow.

Int B Flow

Current MW flow on the second interface of the interface pair forming the nomogram. This flow is the sum total of

the Base MW Flow and the Contingent MW Flow.

% Limit, Max Nomo-interface

The actual MW flow on the nomogram as a percentage of the combined nomogram limit.

Monitor

Indicates whether or not the nomogram should be monitored either for violations or as a constraint in the Optimal

Power Flow.

Limit Group

The name of the limit group the nomogram is a member of for limit monitoring.

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Text-Based Information Displays

Injection Groups Displays

Injection Group Display

The Injection Group Records Display presents data describing each injection group in the case. It 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 records as well as view the Injection Group Dialog. You

can also sort the injection group records by clicking on the heading of the field by which you want to sort.

To show the Injection Group Records Display, select Case Information > Injection Groups

By default, the Injection Group Records display contains the following fields:

Name

The name of the injection group. To change the name of an injection group, simply type a new name in the

corresponding cell.

Number of Gens

Identifies the number of generators contained in the injection group.

% Gen PF

Indicates the degree to which generators will contribute to the output of the injection group relative to loads. An

injection group that has a % Gen PF value of 100.0% receives all of its output from generator points; an injection

group that has a % Gen PF of 50% and a % Load PF of 50% receives equal contributions from its constituent loads

and generators.

Number of Loads

Identifies the number of loads contained in the injection group.

% Load PF

Indicates the degree to which loads will contribute to the output of the injection group relative to generators. An

injection group that has a % Load PF value of 100.0% receives all of its output from load points; an injection group

that has a % Load PF of 50% and a % Gen PF of 50% receives equal contributions from its constituent loads and

generators.

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Injection Group Dialog

The Injection Group Dialog provides information about injection groups and allows you to modify them. Specifically,

the Injection Group Dialog lists the number of generators and loads contained in the group and the percentage

contribution of generators and loads to the injection group’s output. The Injection Group Dialog also houses the

Participation Points Records display, from which you can add and delete points from the injection group’s list of

participants and change various attributes of the points.

To view the Injection Group Dialog for a particular injection group, open the Injection Group Records display by

selecting Case Information > Injection Groups from the main menu. Find the injection group in which you are

interested, and right-click it. Then select Show Dialog from the resulting local menu.

The Injection Group Dialog contains the following fields and controls:

Name

Identifies the injection group whose information is currently displayed. You can select a different name from this

dropdown box to display information for another injection group.

New, Delete

To insert a new injection group from this dialog, press New , and supply the name you want to give the new injection

group. To delete the injection group that is currently being shown, click Delete .

# Gens

Displays the number of generators contained in the injection group.

# Loads

Displays the number of loads contained in the injection group.

% Gen Part., % Load Part.

Displays the relative contributions of generators and loads to the output of the injection group.

Participation Points

The tab on the right hand side of the Injection Group Dialog lists the points that make up the injection group. This

display is called the Participation Point Record Display. By right-clicking on this display, you can add and delete points

from the injection group, and you can change the properties of specific points.

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Text-Based Information Displays

Participation Point Records Display

The Participation Point Records display shows information about the points that comprise a particular injection group.

You can access this display for a particular injection group only from the Injection Group Dialog.

The Participation Point Records 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

records as well as view the Generator Dialog or Load Dialog for a particular point. It also allows you to add

participation points to the group through the Add Participation Points Dialog, and to delete participation points. You

can also sort the participation point records by clicking on the heading of the field by which you want to sort.

The Participation Point Records display shows the following fields by default:

Point Type

Every participation point is either a generator (GEN) or load (LOAD).

Number

Identifies the number of the bus to which the generator or load is connected.

Name

Identifies the name of the base to which the generator or load is connected.

Identifies the ID of the generator or load.

AutoCalc?

If the value of AutoCalc is YES, the participation factor of the point is re-calculated with every use to be consistent

with the way the point’s participation factor was initially defined. If the value of AutoCalc is NO, the participation

factor is assumed fixed at its present value.

Initial Value

Indicates how the participation factor of the point was originally computed. For generators, the possible values of

this field are

SPECIFIED

The participation factor was specified as a constant.

MAX GEN INC

The participation factor was defined as the difference between the generator’s

maximum MW output and its present MW output.

MAX GEN DEC

The participation factor was defined as the difference between the generator’s

present MW output and its minimum MW output.

MAX GEN MW

The participation factor was defined as the maximum MW output of the

generator.

For loads, the Initial Value property can assume only two possible values:

SPECIFIED

The participation factor was specified as a constant.

LOAD MW

The participation factor was defined as the size of the load in MW.

The Initial Value field is important if you intend to save the injection groups to an auxiliary file and use them with

another case that might have a different generation dispatch or load profile. If you specify the Initial Value for a

point as GEN MAX INC, for example, and load the point from an auxiliary file into another case, Simulator will re-

calculate the point’s participation factor to match the generator’s positive MW reserve in that case.

The Initial Value field is also important if the AutoCalc field is set to YES, because AutoCalc uses the rule defined

by the Initial Value field to recalculate the participation factor with every use. For example, if Initial Value is MAX

GEN INC and AutoCalc is YES, the point’s participation factor will be updated to match the generator’s MW reserve

every time the point is accessed.

When you toggle the value of the Initial Value field, the point’s participation factor, shown in field ParFac, will update

to match the new definition. The Initial Value field must equal SPECIFIED for you want to change the value of the

point’s ParFac field by typing the new value directly into the field.

If AutoCalc is NO and you do not intend to use the injection group with any other case, then you should either

ignore this field or set its value to SPECIFIED.

ParFac

Indicates the participation factor of the participation point. The participation factor defines the relative contribution of

the point to the total output of the injection group. The load or generation change for each point is calculated based

on the value of the participation factor, with values for points having the largest participation factors experiencing

the greatest change.

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Text-Based Information Displays

Island Displays

Island Display

The Island Display presents information on the system’s islands. An island consists of a group of buses that are

electrically connected via ac transmission lines and transformers and thus operate in synchronism with one another.

Multiple islands can be connected together via dc transmission lines. Each island requires a slac k bus. All systems

have at least one island, which may encompass the entire system.

The Island 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. You

can also sort the islands information by clicking on the heading of the field by which you want to sort.

To show this display select Case Information > Islands . The display is only available in run mode.

You cannot modify any fields on this display.

The display has the following fields for each island:

Slack Bus Number, Slack Bus Name, Slack Bus Area

Number, name and area of the slack bus for the island. Each island requires at least one slack bus.

Total Buses

Total number of buses in the island.

Energized

Indicates whether the island is connected to a source of power.

Gen MW, Gen Mvar

Total real and reactive generation for the island.

Load MW, Load Mvar

Total real and reactive load for the island.

Scheduled Exports

The power scheduled to be provided by the island to other regions of the system. Because the island is isolated

from the rest of the system, this export requirement is currently not met.

DC MW Exports

The power provided by the island to other regions of the system across a DC line.

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Transactions Displays

Base MW Transactions Display

The Base MW Transactions Display is a quick way to view the defined base transactions between areas within the

load flow case.

The Matrix of Base Transactions display is set up as a matrix of transactions, with the areas listed as both the

column and row identifiers. It is important to note that the direction of the base transaction is such that the area

represented by the row is assumed the exporting area, and the area represented by the column is assumed the

importing area. For example, if there is a 50 MW transaction from area one to area two, you will see a +50 in the

matrix in row 1, column 2. However, if you look at row 2, column 1, you will see a - 50. This is because the grid is

displaying the EXPORT from area two to area one, but since area two is importing, not exporting, the value is

represented as negative.

Each row and column position, with the exception of the diagonal positions (it does not make sense for an area to

export to itself), can be directly modified by the user in this information display. As you type a value in one of the

matrix positions, Simulator automatically fills the symmetric matrix position with the negative of the value you enter.

This makes for a quick and easy location for adding and removing base transactions from the case.

Note that you cannot modify Unspecified transactions in the Base MW Transactions display. This makes sense, as

the unspecified transactions have only one associated area. To modify unspecified transaction amounts, you must

open the Area Information Dialog for the area you wish to modify, and change the Unspecified transac tion amount.

The List of Base Transactions is just another way of showing the base transactions between areas. The List of

Base Transactions 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, or modify its records as

w ell as view the information dialog of its associated areas. You can also sort the area records by clicking on the

heading of the field by which you want to sort.

By default, the List of Base Transactions display contains the following fields:

Export Area Number, Export Area Name

Exporting area number and alphanumeric identifier.

Other Area Number, Other Area Name

Importing area number and alphanumeric identifier.

MW Transfer

Value of the transfer in MW.

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Text-Based Information Displays

MW Transactions Display (Scheduled)

The MW Transactions Display lists the MW transactions that have been defined for the case. Please note that this

display shows only the scheduled transactions between areas, not the base transactions. See Area Transaction

Modeling for a description of the difference between the two.

The MW Transactions 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 MW Transaction Information dialog of its associated transactions. The local menu also

affords the opportunity to define new MW transactions using the same MW Transaction Information Dialog or to delete

existing ones. You can also sort the MW transaction information by clicking on the heading of the field by which you

want to sort. Additionally, you can choose to restrict the information shown by the Load Display according to the

constraints of the area/zone/owner filters.

To call up the MW Transactions Display, click Case Information > MW Transactions from Run Mode.

This MW Transactions Display contains the following fields by default:

Seller Area Name, Buyer Area Name

Names of the selling and buying areas.

Type

Designates the firmness of the transaction: either firm (non-recallable) or nonfirm (recallable).

Enabled

Indicates whether the transaction is active or inactive. Inactive transactions will not be modeled as part of the

simulation. This is a toggleable field. For inactive transactions, the information fields are printed in gray text.

Sched MW

Scheduled MW value for the transaction. The scheduled MW will equal the actual MW for the transaction except

during ramp periods. The duration of the ramp periods can be specified from the Simulation tab of the PowerWorld

Simulator Options Dialog. You can also disable the enforcement of generator ramp limits from the Limits tab of the

same dialog.

Actual MW

Actual MW value for the transaction. When a transaction is inactive, its actual MW value is zero.

Buy Price ($/MWhr)

Price the buyer pays for the transaction in $/MWhr. The seller receives this amount, minus any wheeling charges.

Start Time, End Time

Starting and ending time for the transaction. To model transactions without a starting or ending time, model it as a

base transaction.

Day Type

Designates how to model the transaction for different days of the week. This field can assume one of four possible

values. A value of Specified Days forces Simulator to model the transaction only for the days specified in the Start

Day and End Day fields. A value ofWeek Days indicates that the transaction will be modeled every day Monday

through Friday, but not on the weekends. Transactions with a Day Type of Every Day are modeled both on

weekdays and weekend days. Finally, transactions with a Day Type ofWeekend occur only on the weekend. This

is a toggleable field.

Start Day, End Day

For transactions having a Day Type of Specified Days , the Start Day and End Day fields define the days for which

the transaction will be modeled. These fields are ignored if the transaction’s Day Type is not Specified Days.

Wheeling Cost

The amount of the buy price being paid as Wheeling charges.

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Scheduled MW Transactions Information Dialog

The MW Transactions Information Dialog is used to modify or insert new scheduled transactions. You can display this

dialog from the local menu of the MW Transactions (Scheduled) list display.

The dialog has the following fields:

Buyer Area, Seller Area

Shows the buying and selling area associated with the transaction. You can only modify these fields when you are

inserting a new transaction from the MW Transactions list display. Otherwise to change either the buyer or the

seller you need to first remove the transaction and then insert a new one.

Transaction Amount (MW)

MW amount of the transaction. Each transaction can only have a single value. By default, this value equals the

MW Blocks for Transactions option that is specified on the Simulation Tab of the PowerWorld Simulator Options

Dialog.

Ramping (Minutes)

The length of time over which the transaction will increase from zero to its scheduled amount. By default, this value

equals the Transaction Ramp Time option that is specified on the Simulation Tab of the PowerWorld Simulator

Options Dialog.

Transaction Type

Designates the transaction as either non-firm (recallable) or firm (non-recallable). Simulator currently does not use

these identifiers in any of its calculations. They are provided for your bookkeeping.

Buyer’s Price ($/MWhr)

Price the buyer is paying for the transaction in $/MWhr. The seller is receiving this amount, minus any wheeling

charges. Modifying the Buyer’s Price automatically changes the Seller’s Price by a corresponding amount.

Wheeling Price ($/MWhr)

Indicates the total paid to areas that wheel power between the two transacting parties. This field is visible only if

you have defined wheeling areas using the Wheeling Areas Dialog.

Seller’s Price ($/MWhr)

Price the seller is receiving for the transaction in $/MWhr. Modifying the Seller’s Price automatically changes the

Buyer’s Pr ice by a corresponding amount.

Start Time, End Time

Starting and ending time for the transaction, entered in the form of hh:mm.

Start Day, End Day

The start and end days for the transaction. These values are obeyed only when Day Type is Specified Days.

View/Modify Wheeling Areas

Pressing this button brings up the Transaction Wheeling Dialog, which can be used to identify those areas that will

provide and bill transmission service for the transaction. Such areas are called wheelers.

Day/Time Type

Specifies the days on which the transaction will take place. Select Specified Days if the transaction should be

modeled only on the days you have specified using the Start Day and End Day fields. Select Every Day if the

transaction should occur between Start Time and End Time every day of the week, including weekends. Select

Week Days if the transaction should occur between Start Time and End Time only on days Monday through

Friday. Select Weekends if the transaction should occur between Start Time and End Time only on Saturdays and

Sundays. Finally, select Always On if the transaction should be modeled at all times during the simulation.

Transaction Enabled

This box will be checked if the defined transaction is currently being used for the simulation.

416

Text-Based Information Displays

Wheeling Areas Dialog

When two areas participate in a power transaction, the power that is exchanged likely will flow through one or more

neighboring areas that are not directly participating in the transaction. If a significant portion of the power flows

through a particular entity, that entity likely will try to bill the transacting parties for transmission service. Such an entity

is called a wheeler. The Wheeling Areas Dialog allows you to identify areas that will wheel power as part of the

transaction, and at what cost.

You may invoke the Wheeling Areas Dialog from the MW Transaction Information Dialog by clicking on the

View/Modify Wheeling Areas button.

The table that occupies the left half of the Wheeling Areas Dialog identifies each wheeling area that has been defined

for the transaction. This table is a Case Information Display and thus exhibits properties and controls common to all

case information displays.

To define a new wheeling area for a transaction, specify an area name (or an area number) and click the Add New

Area By Name (or the Add New Areas By Number) button. If you choose to identify new wheeling areas by number,

you may add more than one new wheeling area at a time by specifying a range of area numbers. New wheeling areas

are added to the Wheeling Areas in Transaction table, with the wheeling cost set equal initially to a default value of

$2/MWHr. You can change the wheeling charge by specifying a new value in the grid.

To delete a wheeling area, right-click on the row of the record you wish to delete and select Delete from the resulting

local menu.

To abort the wheeling area definition process without saving changes, click Cancel. To save changes and close the

dialog, click OK.

417

Limit Violations Displays

Limit Violations

The Limit Violations Dialog allows you to see buses, lines, or interfaces that exceed their limit.

The following fields are shown on the display:

Elements To Show

Change this value to modify which elements are displayed in the Buses, Lines, and Interfaces. Set it to…

All Elements

to show all Buses, Lines and Interfaces regardless of monitoring settings.

Monitored Elements

to only display Buses, Lines and Interfaces that meet the conditions for

monitoring. See Limit Monitoring Settings for more information on setting

which values are monitored.

Violating Elements

to only display Buses, Lines and Interfaces that are violating. See Limit

Monitoring Settings for more information on setting what is considered a

violation.

Number of Bus Voltage Magnitude Violations

Shows the total number of bus voltage magnitude violations. These violations are shown on the Bus Voltage

Magnitude Limit Violations Display. This field is read-only.

Low Voltage Suspects

Shows the total number of buses whose voltages have fallen below a designated threshold to indicate a low voltage

solution is being reached in some location in the system.

Number of Line/Transformer Violations

Shows the total number of violations reported on Line and Transformer Limit Display. This field is read-only.

Number of Interface Violations

Indicates the total number of interface violations. These violations are shown on the Interface Violations Display.

This field is read-only.

Limit Group Values

This part of the dialog shows information about the Limit Groups that are defined. For more information see Limit

Monitoring Settings.

Buses, Lines, Interfaces and Nomograms Tabs

These tabs contain tables showing lists of the respective elements. Since these tables are another variety of the Case

Information Displays, you may interact with it in a familiar manner. Click on any of the field headings to sort by that

field. Right-click on the display to call up the display’s local menu. From the local menu, you can print the violations,

copy the violation records to the Windows clipboard for use with another application, modify the format and content of

the violations listing, view the information dialog of the respective element, and view the Quick Power Flow List or Bus

View Display.

The default fields for each tab are as follows:

Buses Tab

Number, Name

Bus number between 1 and 99,999, and its alphanumeric identifier.

Area Name

Alphanumeric identifier of the bus’ area.

Monitor

Specifies whether the individual element is eligible for monitoring. See Limit Monitoring Settings for more

information.

Limit Group

The limit group the element belongs to. See Limit Monitoring Settings for more information.

PU Volt

Bus’ per unit voltage magnitude.

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Text-Based Information Displays

Volt (kV)

Bus’ actual voltage magnitude in kV. This is the per unit voltage magnitude multiplied by the bus’ nominal

voltage.

Lines Tab

From Bus Number and Name

"From" bus number and name. For transformers, the from bus is the tapped side. Right- clicking on either of

these fields allows you to see all the flows measured at the "from" bus using the Quick Power Flow List or Bus

View Display local menu options.

To Bus Number and Name

"To" bus number and name. For transformers, the to bus is the untapped side. Right-clicking on either of these

fields allows you to see all the flows into the "to" bus using the Quick Power Flow List or Bus View Display local

menu options.

Circuit

Two-character identifier used to distinguish between multiple lines joining the same two buses.

Monitor

Specifies whether the individual element is eligible for monitoring. See Limit Monitoring Settings for more

information.

Limit Group

The limit group the element belongs to. See Limit Monitoring Settings for more information.

Used Limiting Flow, Limit, Used % of Limit

The flow at the end of the branch selected for measurement, and its MVA or Amp limit. The percentage

equivalent of the flow to it’s limit is given in the Used % of Limit column.

MVA or Amps?

Units used with the Max Flow and the Limit field. All flows are expressed either in MVA or amps.

Interfaces Tab

Number, Name

Number and alphanumeric name identifiers for the interface.

Monitor

Specifies whether the individual element is eligible for monitoring. See Limit Monitoring Settings for more

information.

Limit Group

The limit group the element belongs to. See Limit Monitoring Settings for more information.

Interface MW Flow

Current MW flow on the interface.

MW Limit

Interface limit in MW.

Percent

Percentage loading of the interface, calculated as MW Flow/MW Limit * 100.

Nomograms

Name

Alphanumeric name identifier for the nomogram.

Monitor

Specifies whether the individual element is eligible for monitoring. See Limit Monitoring Settings for more

information.

Limit Group

The limit group the element belongs to. See Limit Monitoring Settings for more information.

Interface A Flow

The MW flow on the first nomogram interface forming the nomogram.

Interface B Flow

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Text-Based Information Displays

Limit Monitoring Settings

Simulator offers many tools to study the capabilities of a power system. Examples include:

· Limit Violations Display

· Contingency Analysis

· Available Transfer Capability

· Optimal Power Flow

· Security Constrained OPF Overview

· Voltage Adequacy and Security Tool

All of these tools make extensive use of power system limits. Limits for various power system elements include:

· MVA (or Amp) limits on transmission lines and transformers

· MW limits on Interfaces

· High and low voltage limits for Buses

The accuracy of all these limits is very important, as is the specification of which limits should be monitored. While

ensuring the accuracy of input data such as power system limits must be left to the user, PowerWorld Simulator

provides several ways to specify which limits should be monitored. Limit Monitoring is specified according to settings

for the Area, Zone and Limit Group to which the power system element belongs. A power system element is

monitored only if ALL of the following conditions are met.

Conditions for Monitoring an Element’s Limit

· Its Monitor field is set to YES

· Its Limit Group is Enabled

· Its Area is set to Report Limits and it meets the KV range for reporting

· Its Zone is set to Report Limits and it meets the KV range for reporting

The Limit Monitoring Settings Dialog gives you ability to specify all these settings to setup the limits you want to

monitor, and thus enf orce in the various tools that Simulator provides.

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Limit Monitoring Settings Dialog

The Limit Monitoring Settings Dialog gives you ability to specify which limits you want to monitor, and thus enforce in

the various tools that Simulator provides. In general, keep in mind that a bus, transmission line/transformer, or

interface’s limit is monitored only if the following conditions are met.

Conditions for Monitoring an Element’s Limit

· Its Monitor field is set to YES

· Its Limit Group is Enabled

· Its Area is set to Report Limits and it meets the KV range for reporting

· Its Zone is set to Report Limits and it meets the KV range for reporting

The tabs on the Limit Monitoring Settings Dialog allow you to change these settings.

Buses, Lines, and Interfaces Tabs

Each tab shows a list of the respective type of power system element. The important columns include

Monitor :

toggle this between YES and NO to set whether the specific element

should be monitored.

Limit Group :

toggle this value to specify which Limit Groups the element belongs to

Note: If Use Area/Zone Filters on List Displays is checked then the Area/Zone/Owner Filters will effect what is

displayed on these lists.

Note: If Elements to Show is set to Monitored Elements, then only elements which meet the conditions for

monitoring will be displayed in these lists.

Area Reporting and Zone Reporting Tabs

These tabs display all the Areas and Zones in the system. The important columns are

Report Limits :

toggle this between YES and NO to set whether the specific element

should be monitored.

Report Min kV and Report Max kV: Only buses and lines within this kV range will be monitored.

Nomogram Tab

This tab displays any defined Nomograms in the system. The important columns are

Monitor :

toggle this between YES and NO to set whether the specific element

should be monitored.

Limit Group :

toggle this value to specify which Limit Groups the element belongs to

Modify/Create Limit Group Tab

Every power system elements belongs to a single Limit Group. By default, all power system elements are in the

same Limit Group that is named "Default". New limit groups can be added by right-clicking in the table and

choosing Insert from the popup menu. Additional limit groups give the flexibility of assigning devices to different

groups, where each group can have its own set of defined limit information.

The limit group stores important values regarding the enforcement and monitoring of the power system elements

within the Limit Group. The values are

Branch Percentage:

The percentage to which Simulator’s study tools will limit a line or

transformer. Typically this is 100%, but it can be modified. In

Contingency Analysis, then lines will be flagged as violated if they exceed

this percentage. In performing an Optimal Power Flow, all attempts will be

made to keep the line below this percentage.

Line Rate Set:

You may define eight different ratings to transmission lines or

transformers (for more information see Line/Transformer Information).

Change this value to specify which rating set should be used for

lines/transformers in the limit group.

Amps or MVA:

Limits for transmission lines and transformers are always entered in MVA.

However, when reporting limit violations, it is common to check

transmission line limits in terms of their amp loading. If the Treat Line

Limits As Equivalent Amps is checked, the limits for transmission lines are

reported in amps rather than MVA. If this box is not checked, limits for

both transmission lines and transformers are expressed in MVA.

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Text-Based Information Displays

For reference, note that the amp rating of a line is derived from the MVA

rating using the formula

Interface Percentage:

The percentage to which Simulator’s study tools will limit an interface.

Typically this is 100%, but it can be modified. In Contingency Analysis,

then interfaces will be flagged as violated if they exceed this percentage.

In performing an Optimal Power Flow, all attempts will be made to keep

the interface below this percentage.

Interface Rate Set:

You may define eight different ratings to an interface. Change this value

to specify which rating set should be used for interfaces in the limit group.

Nomogram Percentage:

The percentage to which Simulator’s study tools will limit a nomogram.

Low PU Volt:

Buses will be flagged as violated if they fall below this per unit voltage.

High PU Volt:

Buses will be flagged as violated if they go above this per unit voltage.

Disabled:

Set the value to YES to ignore all power system element limits in the Limit

Group. Set the value to NO to monitor limits according to the settings of

the Limit Group.

Contingency Line Rate Set:

This field specifies the rating set used for post-contingency monitoring of

Lines/Transformers.

Interface Contingency Rate Set: This field spec ifies the rating set used for post-contingency monitoring of

Interfaces during Contingency Analysis.

Limiting End:

Specified as higher or lower, this field determines whether the higher or

the lower flow amount on the element is used for reporting a limit violation.

If you use higher, it is possible that the lower flow is not violating the line

limit. If you use lower, then you are guaranteed that the element limit is

being violated at both ends of the element.

Use Limit Cost:

If this field is set to yes, you are enabling the capability to have a cost

function associated with enforcing constraints. This cost function can be

viewed as similar to a generator cost function, in that as the constraint

becomes overloaded by larger amounts, the marginal cost of enforcing the

constraint will increase. For setting the piecewise linear limit cost curve,

right-click and choose show dialog from the popup menu to access the

Limit Group Dialog.

Often monitoring elements according to Area and/or Zone is all that you need. However, if you need to monitor

specific groups of power system elements and not others then you need to create some new Limit Groups.

Elements To Show

Set to Monitored Elements to only display Buses, Lines, and Interfaces that meet the conditions for monitoring.

Set to All Elements to show all Buses, Lines and Interfaces regardless of monitoring settings.

Save/Load Monitoring Settings

The Save and Load Monitoring Settings buttons allow the user to save the current set or load a previously saved set

of Limit Monitoring Settings options. The options are saved in a PowerWorld Auxiliary File text format.

Limit Group Values

The values regarding the currently selected Limit Group are graphically displayed here to make them easier to

modify.

Do not monitor radial lines and buses

Check this box to ignore limits on radial lines and buses throughout the case.

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Limit Group Dialog

The Limit Group Dialog reflects much of the same information that is summarized in the Limit Monitoring Settings

Dialog’s Modify/Create Limit Groups page. The same information can be changed here as on the previously

mentioned display. One important feature that is unique to this dialog is the ability to define a piecewise linear limit

cost curve, which can be used for setting up "soft" constraints used in the Security Constrained Optimal Power Flow.

Disabled

Check this option to ignore all power system element limits in the Limit Group. Leave the box unchecked to monitor

limits according to the settings of the Limit Group.

Add New Limit Group

Clicking this button will create a new limit group, displaying a dialog in which the name for the new limit group can

be spec ified.

Rename Limit Group

Clicking this button will display a dialog in which a new name for the current limit group can be specified.

Lines/Interfaces

% of Limit for Reporting (Branches)

The percentage to which Simulator’s study tools will limit a line or transformer. Typically this is 100%, but it can be

modified. In Contingency Analysis, lines will be flagged as violated if they exceed this percentage. In performing an

Optimal Power Flow, all attempts will be made to keep the line below this percentage.

Line/Transformer Rating Set

You may define eight different ratings to transmission lines or transformers (for more information see

Line/Transformer Information). Change this value to specify which rating set should be used for lines/transformers

in the limit group.

Line/Transformer Contingency Rating Set

This field specifies the rating set used for post-contingency monitoring of Lines/Transformers.

Treat Transmission Line Limits as Equivalent Amps

Limits for transmission lines and transformers are always entered in MVA. However, when reporting limit violations,

it is common to check transmission line limits in terms of their amp loading. If the Treat Line Limits As Equivalent

Amps is checked, the limits for transmission lines are reported in amps rather than MVA. If this box is not checked,

limits for both transmission lines and transformers are expressed in MVA.

For reference, note that the amp rating of a line is derived from the MVA rating using the formula

Limiting End of Line

Specified as higher or lower, this field determines whether the higher or the lower flow amount on the element is

used for reporting a limit violation. If you use higher, it is possible that the lower flow is not violating the line limit. If

you use lower, then you are guaranteed that the element limit is being violated at both ends of the element.

% of Limit for Reporting (Interfaces)

The percentage to which Simulator’s study tools will limit an interface. Typically this is 100%, but it can be modified.

In Contingency Analysis, interfaces will be flagged as violated if they exceed this percentage. In performing an

Optimal Power Flow, all attempts will be made to keep the interface below this percentage.

Interface Rating Set

You may define eight different ratings to an interface. Change this value to specify which rating set should be used

for interfaces in the limit group.

Interface Contingency Rating Set

This field specifies the rating set used for post-contingency monitoring of Interfaces during Contingency Analysis.

% of Limit for Reporting (Nomograms)

The percentage to which Simulator’s study tools will limit a nomogram.

Use Limit Cost

If this field is checked, you are enabling the capability to have a cost function associated with enforcing constraints.

This cost function can be viewed as similar to a generator cost function, in that as the constraint becomes

overloaded by larger amounts, the marginal cost of enforcing the constraint will increase.

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Text-Based Information Displays

Once the box is checked, the table for defining the limit cost function will become enabled. The starting point (%

Flow) must be at or above 100%. You can then begin inserting additional points in the piecewise linear curve by

right-clicking in the table and selecting Insert Point from the popup menu, followed by entering the new percent flow

and marginal cost. Note that the cost function must be strictly increasing, meaning the next marginal cost value

must be equal to or greater than the immediately previous value.

When constraints are given the ability to use this limit cost curve, it effectively gives the optimal power flow the

ability to "dispatch" the limit of the elements according to the marginal costs of the limit cost curve. You are

determining the point on the limit cost curve where the shadow price of enforcing the constraint is met. Thus the

OPF routine will determine how much you will allow the element to be overloaded by giving the element the

piecewise linear curve. The OPF will solve the problem, and optimize the constraints as it determines shadow

prices for each constraint and adjusts the limit accordingly during the iterations of the routine. Since these are

somewhat flexible limit assignments to the elements, they are sometimes considered "soft" constraints.

Buses/Summary

Low Per Unit Limit

Buses will be flagged as violated if they fall below this per unit voltage.

High Per Unit Limit

Buses will be flagged as violated if they fall below this per unit voltage.

Low-voltage solution flag

Enter a per unit value at which you wish to measure a voltage and consider the solution to be a low voltage solution.

Include Out-Of-Service Buses

Check this check-box to include out-of-service buses.

Elements using Limit Group

Lists the number of elements that are members of the selected limit group.

Ownership Displays

Owner Data Information Display

The Owner Data display will display the owners sorted by owner number, and show the total number of devices, as

well as a breakdown of the number of specific devices. The owner display will also summarize the total device output

or demand for the owned devices, such as generator output and load demand.

You can right click on the owner grid to open the local menu, from which you can perform various actions and view an

informational regarding the owner selected in the grid. Once an owner dialog is displayed for a particular owner, you

can browse through information on all the owners.

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Owner Dialog

The Owner Dialog displays summary information about the devices designated as owned by the selected owner.

The dialog for an individual owner displays each of the elements for that owner, along with the percentage of

ownership, in the device pages labeled Buses, Loads, Generators, and Lines.

The dialog also contains a memo page for making comments or notes about the selected owner.

General Info

Load and Generation

The information in the Load and Generation section provides a summary of the total injections of the owned

devices. This includes a total of all the load, generation, and shunt injections owned.

Summary of Owner Objects

This information section simply lists a total number of all owned devices. Note that buses and loads do not

currently have fractional ownership. However, generators and transmission lines do have the capability to be

partially owned by more than one owner. Therefore it is possible to see fractional ownership amounts for the

number or generators or lines.

Generator Costs and OPF Results

This information provides a summary of LMP and cost information determined by running an Optimal Power

Flow solution. The information provided is determined only for devices owned by the selected owner.

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PowerWorld Simulator version 11. Manual - page 11