PowerWorld Simulator version 11. Manual

Tutorial: Contingency Analysis - Page 3

Simulator allows you to automatically generate a contingency list containing branch, generator and/or bus outages.

To accomplish this, click the Auto Insert button on the Contingency Analysis Dialog. This opens the Auto Insertion

of Contingencies Dialog. Click on the dialog shown below for more information about its contents.

Auto Insertion of Contingencies Dialog

We will insert contingencies for all branches and generators. This will require two executions of the auto insert tool.

· Click to remove the checkmark in Delete Existing Contingencies.

· Verify that Single Transmission Line or Transformer is selected.

When using the Auto Insert tool, you can limit the contingencies inserted to only those meeting a defined filter. We

want to insert contingencies for all branches and generators so no filtering is desired.

· Click to remove the checkmark in Use Area/Zone Filters.

· Verify that no other filter options are selected.

· Click the Do Insert Contingencies button to accept the remaining default values and automatically insert the

branch contingencies.

· Click Yes when asked to confirm the insertion of 11 contingencies.

Note that the Contingencies Tab of the Contingency Analysis Dialog now shows 12 contingencies.

· Right-click on the list display of the contingencies tab and select Auto Insert Contingencies from the local menu.

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Tutorial: Contingency Analysis - Page 4

When running the Contingency Analysis, the user has three options:

Run every contingency on the list of contingencies (click Start Run on the Contingencies Tab, click Start on

the Summary Tab or select Run Contingency Analysis from the local menu of the list of contingencies)

Run a single contingency (discussed in the advanced tutorial section) or

Run a single contingency then save the post-contingency state as the new reference state (also discussed

in the advanced tutorial section)

We will run every contingency in the list for this portion of the tutorial.

· Press Start Run on the Contingencies Tab. Note: Pause and Abort buttons are available on the dialog while the

contingency analysis is running. These may prove useful when processing a long list of contingencies.

The results from the run are shown in the Contingency Analysis Dialog.

Contingency Analysis Dialog - Contingencies Tab

Note: The Refresh Displays after Each Contingency option (lower right) can slow down the analysis significantly when

running a long list of contingencies.

The contingency analysis results are sorted on the contingencies tab in descending order by worst violation. We see

that there were three violations resulting from the contingency analysis (one for each of the first three contingency

records displayed) and that no unsolvable load flows resulted (as shown in the Status Section of the Contingencies

Tab.) If you enlarge the Contingency Analysis Dialog (by dragging either side or the corner of the pane) you see more

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Run Mode Tools and Options

information in the Status Window, specifically, "Finished with 3 Violations and 0 Unsolvable Contingencies. Initial

State Restored."

Contingency Analysis always stores a Reference State or pre-contingency state. The Reference State stores

information pertaining to: buses, switched shunts, limit groups, loads, branches, generators, areas / super areas, and

power flow solution options.

Both prior to and following completion of solving a list of contingencies, the reference state is loaded into memory.

This ensures that all contingency analysis solutions start from a common base case and that the system is restored to

its initial state following a solution. The last sentence in the Status portion of the dialog, "Initial State Restored," tells

the user that the simulation case was restored to the reference state upon completion of the Contingency Analysis

Run. See Contingency Case References for more information on the Reference State.

The Violations Section (lower left) of the Contingencies Tab provides a description of each violation resulting from the

execution of the contingency selected in the list of contingencies. Scroll through the list of contingencies to view

information about the resulting violations for each.

Note: You can hide the Contingency Definition section of the Contingencies Tab by clicking the

button.

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Run Mode Tools and Options

Tutorial: Contingency Analysis - Page 6

· Click on the Lines, Buses, Interfaces Tab of the dialog.

The Lines, Buses and Interfaces Tab contains four sub-tabs: Lines/Transformers, Buses, Interfaces, and Nomogram

Interfaces. The information contained on each of the sub-tabs provides an alternate method of viewing information

similar to that contained on the Contingencies Tab. The individual tabbed sheets show all model objects defined in the

case (subject to area/zone/owner filters) whether each is associated with a specific contingency or not.

Contingency Analysis Dialog - Lines, Buses, Interfaces Tab

The user can select any model object on its respective sheet to see how many times a violation occurred on the

device during the contingency analysis. When a particular device is selected that had at least one violation during the

contingency run, the Contingencies and Contingency Definition sections give the details of the specific contingencies

that caused the violation (or violations) on the selected device. For example, on the Lines/Transformers sub-tab:

· Select the line from 2 to 5 as shown above. This line had one violation on the most recent contingency analysis

run. The contingencies section shows which contingency caused the violation and the contingency definition

section details the elements that define the contingency.

· Switch back to the Contingencies Tab of the dialog.

· Scroll down in the list of c ontingencies and select the contingency labeled SET LOAD AT BUS 2…

· Right-click on the element displayed in the Contingency Definition Section of the Contingencies Tab

· Select Show Dialog from the local menu.

· Modify the element’s Action to: Set To 600 MW (const pf) using the Action Type, Amount, &in fields of the

Contingency Element Dialog.

· Click OK to close the dialog. The Contingency Definition should now show SET LOAD AT BUS 2 (2) TO 600.00

MW (cnst pf).

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· Click Start Run on the dialog and Yes when asked to confirm.

· Following the run, the Status field now shows, "Finished with 7 Violations and…" The increase in load resulted in

four contingencies not present during the last run.

· Again select the contingency labeled SET LOAD AT BUS 2… on the list display. The Violations section shows the

four branch violations that occurred for the selected contingency.

· Now switch to the Lines, Buses, Interfaces tab.

· Select the line from 2 to 5. This line experienced violations under two contingencies during the run. The

Contingencies section now shows the details of both contingencies (opening line 5 to 7 and changing the load at

bus 2) that caused overloads on the line. Notice that the information in the Contingency Definition section is

specific to the Contingency selected in the Contingencies section.

Note: The Show Related Contingencies and Show Other Violations buttons (on the Contingencies and Lines,

Buses, Interfaces tabs respectively) provide a fast method of switching between the two tabs and viewing related

information.

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Run Mode Tools and Options

Tutorial: Contingency Analysis - Page 7

You now have enough information to effectively utilize PowerWorld Simulator’s Contingency Analyss tool. The

remaining portions of the tutorial introduce the full capabilities of the Contingency Analysis tool and provide links to the

applicable Help files.

Contingency Records

There are four methods of defining contingencies. See Defining Contingencies for more information. Contingency

Records can also be saved to or loaded from a file.

Contingency Blocks and Global Actions

The user may desire to have a common set of actions occur during more than one (or all) contingencies. Instead of

repeatedly defining the same contingency element (or elements) in multiple contingencies, Simulator provides the

option to use Contingency Blocks and/or Global Actions.

A Contingency Block is a set of contingency actions that can be defined and then called upon by individual

contingency records.

Global Actions are actions defined by the user that will occur during all contingencies.

Contingency Solution Options

By default, the contingency analysis will use the same options as the power flow algorithm when solving each

contingency. You may also override these options for all contingencies, and/or for a specific contingency. This results

in the ability to set the power flow solution options in contingency analysis at three different levels

1 Contingency Specific Options (see Contingency Definition Dialog)

2 Contingency Analysis Options (see Contingency Options Tab)

3 General Power Flow Solution Options (see Power Flow Solution Options)

When Simulator executes a particular contingency, it will first look at options specified for that contingency. Any

options defined for the contingency will be used. Other options set to "use default" will look to the Contingency

Analysis Options. Again, any options defined for contingency analysis will be used. Finally, options marked in the

Contingency Analysis Options as "use default" will be set to the same setting as the power flow solution options.

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Tutorial: Contingency Analysis - Page 8

Reference State

The Reference State (introduced on page 4 of the tutorial) can prove very useful to advanced users if they know how

to exploit its capabilities. When running a list of contingencies the reference state is loaded into memory prior to

executing each contingency. The system is restored to the reference state following the contingency analysis run. In

addition to running an entire contingency list, the user also has the option to solve individual contingencies by right

clicking on the desired contingency - on the Contingencies tab of the Contingency Analysis Dialog - and selecting

either Solve Selected Contingency or Solve and Set as Reference from the local menu.

Solve Selected Contingency causes Simulator to first load the reference state into memory then solve the

contingency. THE SYSTEM STATE IS NOT RESTORED TO THE REFERENCE STATE FOLLOWING THE

SOLUTION; the system state then reflects the power system flows of the post-contingency state. The advantage of

this approach is the ability to implement a contingency and then modify the system looking for possible actions that

might mitigate violations caused by the contingency. Be aware; however, that prior to solving another contingency,

Simulator will reset the system state to the reference state thereby removing all modifications made following the

previous contingency solution. The user may also automatically restore the system state to the reference state by

selecting Other > Restore Reference from the Contingency Analysis Dialog.

Solve and Set As Reference acts the same as Solve Selected Contingency with one exception. After executing the

contingency, the post-contingency state is automatically set as the reference state. As a result, all subsequent

contingencies will use the post-contingent state as the Reference State.

Make-up Power Sources

Power injection contingency actions result in power imbalances - typically picked up by the system slack - that may

result in Power Flow Convergence Problems. Simulator provides the option of specifying Make-up Power Sources for

generation, load, injection group, and switched shunt contingencies to both offset the resulting imbalance and provide

a more realistic simulation. See Make-up Power Sources for more information.

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Run Mode Tools and Options

Tutorial: Contingency Analysis - Page 9

Contingency Elements

A contingency element consists of a single Contingency Action and its associated Model Criteria, Status and

Comment (optional). Multiple Contingency Elements can be defined for a single Contingency.

Contingency Action - Click here for a list of available contingency actions.

Model Criteria - Model Criteria are criteria under which the contingency action will occur and consist of both Model

Conditions and Model Filters.

Status - The status field of a contingency element can take one of four values: CHECK, ALWAYS, NEVER or

POSTCHECK.

· CHECK - The action will be executed if the Model Criteria are true or if no Model Criteria are specified. Check is

the default status setting.

· ALWAYS - The action will always be executed, regardless of the Model Criteria.

· NEVER - The action will never by executed, regardless of the Model Criteria. This allows you to disable a particular

contingency action without deleting it.

· POSTCHECK - Following completion of all CHECK and ALWAYS actions, the contingency analysis tool runs the

load flow solution. POSTCHECK actions are then addressed recursively until all are complete. The execution of

POSTCHECK actions follows the same rules as CHECK actions with the exception of not being checked until the

load flow has been solved. If the Model Criteria specified for the POSTCHECK action are met in the solved load

flow solution (or if no Model Criteria are specified), then the action is taken and the load flow is again resolved. If

the model conditions are not met, the action is skipped.

For more information, see Contingency Definition Display.

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Tutorial: Contingency Analysis - Page 10

Contingency Analysis Dialog - Options Tab Overview

The bulk of the Options Tab contains five sub-tabs, each of which concerns a different aspect of the contingency

analysis. A brief description of the actions allowed via each sub-tab follows. Click on the headings below for more

information on each.

Modeling Sub-tab

The modeling tab allows the user to:

· Define the Contingency Analysis Load Flow Calculation Method

· Specify Limit Monitoring Settings

· Instruct Simulator to retry the solution using the Robust Solution Process following a failure to converge

· Specify the use of specific solution options for contingencies

· Specify Make-up Power for the post-contingency solution

Advanced Limit Monitoring Sub-tab

The Advanced Limit Monitoring Tab allows you to shape how limit violations are detected and reported.

Advanced Modeling Sub-tab

The Advanced Modeling tab allows the user to:

· Define Contingency Blocks and Global Actions (refer to Page 7 of the tutorial)

· Define Model Criteria (Expressions, Conditions and Filters)

· Specify Model Criteria Options

· Define Bus Load Throw -Over Records - BLTR’s provide the capability to define how load at a bus should be

transferred to a different bus if the original terminal bus becomes disconnected from the system during a

contingency

· Define Generator Maximum MW Responses in Post-Contingency - allows the user to limit the absolute MW

response of a generator during a contingency

· Define Generator Line Drop Compensation (LDC) and Reactive Curent Compensation (RCC) - LDC and RCC

controls allow the user to model the real-time control done at some real generators

· Specfy a post-contingency aux file to be loaded at the start of each contingency. This allows the setting of very

specialized post ctg settings.

· Specify how reactive power is modelled for DC calculation methods

Report Writing Sub-tab

Simulator can produce a report that details the results of the contingency. The Report Writing Tab allows you to control

the content and appearance of the report.

Miscellaneous Sub-tab

The Miscellaneous sub-tab provides options pertaining to the loading and saving of contingency records as well as

specifying how the reference state should be established when the contingency analysis tool is accessed.

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Run Mode Tools and Options

Fault Analysis Dialog

The Fault Analysis dialog can be used to perform a fault analysis study on the currently loaded power system. A fault

study can only be performed while Simulator is in run mode, since the load flow must be validated and solved before a

fault study can be calculated. If you are observing fault analysis results in the fault analysis dialog and switch to edit

mode, the dialog will automatically be closed and the fault analysis results will be cleared from memory.

Simulator stores fault data in the PowerWorld binary file along with the load flow data, but by default most other load

flow formats store fault data in separate files. The fault data can be stored in and loaded from an external file, but if no

fault data is present in a PowerWorld binary file or loaded from an external file before a fault analysis is run, Simulator

will use the load flow data as default values for the analysis. Fault data values can also be modified for specific

devices by opening a specific device's information dialog and looking at the Fault… tab. Devices that require

sequence specific data for fault analysis are buses (for sequence load injections), generators, switched shunts,

transmission lines, and transformers.

NOTE: New in version 10!

Phase shifts in a fault analysis calculation can be very important for calculating the correct fault currents and voltages

throughout the system. The phase shifts that are applied for transmission lines and transformers are taken from the

load flow values of phase entered with each specific transmission element. While transformers can have their

transformer configurations specified (i.e. Delta-Wye, Grounded Wye-Delta, etc.), these configurations are NOT used to

determine phase shift angles, ONLY to determine the proper grounding on each side of the transformer. The phase

shifts that are applied are taken from the load flow data phase values for the transmission elements. If no phase shifts

are entered in the load flow data, the fault analysis will treat all elements as having zero phase shift. Phase shift

values can be entered manually for each transmission element, but are also included in most load flow formats and

will be read into Simulator when loading a load flow data file.

Note that the bus chosen for the fault is always set to a 0 degree reference, and all other buses are shifted according

to this reference.

Fault Data

The Fault Data tab is where the type and location of the fault are specified, and where the results of the fault analysis

can be seen in tabular format.

Fault Location

Choose to perform the fault at a bus location, or at a point somewhere on a line. If Bus Fault is selected, the only

information needed is the bus number, which needs to be entered in the Fault Bus field. If an in-line fault is desired,

the from and to bus numbers, circuit ID, and location of the fault (entered in percent of total line length, measured

from the From Bus) will need to be given. Selecting the Fault… option from the bus or line local menus will

automatically set up the Fault Location fields.

Fault Type

Choose from one of four types of fault to calculate at the fault location:

Single Line - to - Ground

Computes a single phase line - to - ground fault using a user defined ground

fault impedance. The phase evaluated is always referenced as phase A.

Line - to - Line

Computes a line - to - line fault, assuming an impedance of 999 + j999 to

ground. Phases B and C are always referenced as the faulted phas es.

3 Phase Balanced

Balanced three-phase line fault - to - ground using a user-defined ground fault

impedance.

Double Line - to - Ground

Computes a line - to - line - to - ground fault, using a user defined ground fault

impedance.

Current Units

Allows you to choose to observe the fault currents in per unit current or actual Amps.

Oneline Display

The string grids at the bottom of the Fault Analysis dialog will display the fault results in tabular format, but the

results can also be viewed graphically on the oneline diagram by selecting an option from this group of options.

Any of the three phase values can be selected for display individually, or all three phases can be viewed

simultaneously. Viewing all three phases of information simultaneously can result in an abundance of information

on the diagram at one time, so selective placement of the necessary bus and line fields may need to be considered

when planning on viewing the fault analysis results graphically on the oneline diagram.

The fields necessary on the oneline diagram for display of the fault analysis results are:

· Bus Voltage and Bus Angle fields need to be present for a bus. When choosing to view fault analysis results, these

two fields will be identified, and the actual load flow values will be replaced by the fault phase voltages (in per unit)

and angles (in degrees).

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· AC Line MW Flow and AC Line Mvar Flow fields need to be present for a line. These two fields will be identified,

and the MW and Mvar values will be replaced by the fault phase current magnitudes (in Amps or per unit) and

angles (in degrees).

· Gen MW Output and Gen Mvar Output fields need to be present for a generator. These two fields will be identified,

and the MW and Mvar values will be replaced by the generator terminal fault phase current magnitudes (in Amps or

per unit) and angles (in degrees).

Fault Current

Displays the magnitude and angle of the current at the fault location during the fault.

Calculate

Pressing this button will run the fault analysis. In order for the results to be calculated, the power flow has to be in a

solved state for the results to have any relevance. Therefore the first thing performed when Calculate is pressed is

to solve the power flow. You can observe this by viewing the Message Log when you run the calculation. Once the

power flow has been solved, then the fault analysis calculations are run and the results displayed.

Clear

Pressing Clear will clear any fault analysis results currently in memory and displayed on the dialog.

There are also five informational displays at the bottom of this dialog for showing the fault analysis calculation results:

Buses

Lines

Generators

Loads

Switched Shunts

Fault Options

The Fault Options tab is where an impedance to ground can be defined at the fault location, where fault data can be

loaded from or saved to an external file, and zero-sequence mutual impedances can be viewed or changed.

Fault Impedance

For any of the fault types calculated, a Fault Impedance can be included. A Resistance and Reactance can be

entered as the path to ground of the fault, and is taken into account when calculating the fault current used to

determine the rest of the fault values.

Load Data / Save Data

These two buttons allow loading from and saving to external files. Currently the two types of files supported are

PSS/E Sequence Data files (.seq) and PowerWorld Simulator Auxiliary files (.aux). Either one of these formats can

be loaded and saved.

Zero Sequence Mutual Impedances

Zero sequence mutual impedances can be stored and modified in the Mutual Impedance Records table. Usually

the zero sequence mutual impedance parameters are read in from a sequence data file. However, it is also

possible to insert and delete mutual impedance records from this table by right-clicking in the table and selecting

Insert or Delete from the local menu. When Insert or Show Dialog are chosen from the mutual impedance table

local menu, the Mutual Impedance Record dialog will open, from which a mutual impedance record can be inserted

or modified.

Pre-Fault Profile

Changing this option determines the pre-fault voltage profile to be used for the fault analysis calculations. The pre-

fault profile selection affects the sequence Y-bus values, fault currents, and post-fault voltages.

Profile Options

Additional pre-fault profile options are available when the pre-fault profile selected is either Flat IEC-909 or Flat

Classical.

XF Turns Ratios Set to 1

If checked, all transformer tap ratios are assumed at their nominal tap position.

Line Charging Set to 0

If checked, line charging capacitance is ignored in all calculations.

Shunt Elements

Shunt elements (bus and line shunts) can optionally be treated normally,

ignored in the positive sequence only, or ignored in all sequences.

IEC Parameters

This option only applies to the Flat IEC-909 pre-fault profile. The pre-fault

voltage magnitude can be specified for each bus. In addition, a generator

power factor angle (in degrees) can be specified for use when generator

currents need to be calculated based on bus voltage and power (real and

reactive) delivered by the generator.

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Run Mode Tools and Options

Mutual Impedance Records

The Mutual Impedance Records table is a Case Information Display and can be customized like any other case

information display. The zero sequence mutual impedance records displayed in this table can be either read from a

sequence data file, or created manually by choosing Insert… from the local menu.

The common fields displayed on the Mutual Impedance Records display are:

L1 From Bus, L1 To Bus, and L1 Ckt ID

These fields represent the from bus number, to bus number, and circuit identifier for the first mutually coupled line.

L2 From Bus, L2 To Bus, and L2 Ckt ID

These fields represent the from bus number, to bus number, and circuit identifier for the second mutually coupled

line.

Mutual R, Mutual X

The mutual impedance, in terms of the resistance and reactance (per unit). The dot convention of the mutual

impedance assumes the From bus of each line to be the dotted terminal, with the sign of the mutual impedance

values being set according to this convention.

L1 Mut. Start, L1 Mut. End

The starting point and ending point of the mutually coupled portion of the first mutually coupled line. The values are

between 0 and 1, and represent a position on the line as a percentage of the total line length. These fields are only

used when evaluating an in-line fault to determine the affect of the mutual impedance on each side of the fault point

on the line.

L2 Mut. Start, L2 Mut. End

The starting point and ending point of the mutually coupled portion of the second mutually coupled line. The values

are between 0 and 1, and represent a position on the line as a percentage of the total line length. These fields are

only used when evaluating an in-line fault to determine the affect of the mutual impedance on each side of the fault

point on the line.

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Mutual Impedance Record Dialog

The Mutual Impedance Record dialog can be used to modify or add zero sequence mutual impedance records to the

sequence data for a case. When the dialog is opened using the Show Dialog… option from the Mutual Impedance

Records table local menu, the information for the record selected in the table will automatically be displayed. The

information for that record can be modified, or a different record can be selected by selecting different lines in the Line

1 and Line 2 Identifier sections. Note that the drop down list of buses for the From Bus fields always contain all the

buses in the case. However, once the From Bus has been selected, the drop down list of the corresponding To Bus

field will only contain bus numbers of buses that are connected to the From Bus. If a mutual impedance record

already exists for the lines selected, the information for that record will be displayed. If a mutual impedance record

does not exist for the selected lines, then the mutual impedance fields will display default values. When the default

values are changed, and either Save or OK are selected, a new mutual impedance record is added to the data.

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Run Mode Tools and Options

Contour Type

Object

Simulator can contour several different values. To specify what Simulator should contour, first choose the type of

object; the options are Bus, Line, Interface, Area, Generator or Substation. This selection narrows the set of

quantities that can be contoured, which is specified in the Value dropdown box.

Note: to contour a value for a type of object, representations of that type of object must be present on the oneline

diagram. Choosing to contour an object type that is not represented on the diagram will result in no contour being

drawn on the diagram.

Value

Select the quantity to contour from the Value dropdown box or click the Find Value button to find the desired field.

See NOTE at the end of this help topic.

Current Filter

The name of the advanced filter that is currently applied to the contour.

Define a Filter

If you wish for the contour to be limited to only certain devices that meet specific criteria, click on this button to

define an Advanced Filter for the contour.

Pixel Options

In order to optimize the speed of drawing, the user must specify the Influence Region as well as the Contour

Resolution. Also, when contouring line or interface objects, the number of data points used to represent that line

must be chosen.

No Data Color

This setting allows you to choose the contour color around devices that have no data for the type of contour

selected. The choices for No Data Color are Specific Color, Color Map Percentage, and Background Color. By

default, Specific Color is selected and set to white. If you wish to change the specific color to use, click on the color

box to the right and choose a different color from the popup dialog. If you select Color Map Percentage, the Color

Map % field will become enabled, and you can select a value from 0 to 100. The value you enter will associate the

No Data Color with the color located at that percentage in the selected color map. Lastly, if Background Color is

chosen, the No Data Color will always be whatever color has been set as the normal background color for the

oneline diagram.

Draw Color Key

Checking this box will cause the contour to draw a color key showing which colors are mapped to which values.

You can also give the color key a title, unit label, and specify the number of digits to display in numerical values.

Title

Title for the color key.

Entry Labels

Units of the contoured value displayed on the color key.

Label Digits to Right of Decimal

Number of decimal places of the contoured value displayed on the color key.

Color Map

Choose from various predefined color maps using the color map combo-box. A color map, along with the values

specified, defines how values are mapped to a color on the contour image.

If a color map showing both high and low values is desired (such as for bus voltages), use of "Blue = Low, Red =

High" is recommended. If a color map showing only high values is desired (such as for line flows), use of "Weather

Radar, Nominal to High" is recommended.

A user may also define additional color maps by going to the Custom Color Map Tab.

Reverse Color Map Colors

Check this check-box to reverse the colors of the selected color map, so the low color becomes the high color, and

vice versa.

Brightness

Modify the brightness track bar to change the brightness of the color map.

Use absolute value

Check this check-box to use the absolute values of the quantity selected at the Value dropdown box (above).

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Ignore Above Max

Check this check-box to completely ignore values above the maximum percentage. This means that data which is

larger than the Max % will not be used in calculating the contour image.

Values

These values along with the color map define how to convert your values into a color for the contour. The values

are:

Maximum

The largest value allowed in the contour. All values above this will be mapped

to the highest color. This value corresponds to 100% in the color map.

Break High

This value is used by some color maps to highlight a lower limit. This value

corresponds to 75% in the color map.

Nominal

This value is the nominal value for the contour. Values around this will be

mapped to the middle color. This value corresponds to 50% in the color map.

Break Low

This value is used by some color maps to highlight a lower limit. This value

corresponds to 25% in the color map.

Minimum

The smallest value allowed in the contour. All values below this will be mapped

to the lowest color. This value corresponds to 0% in the color map.

Note: a representation of the color map is shown to the right of the values.

Ignore Below Min

Check this check-box to completely ignore values below the minimum percentage. This means that data which is

smaller than the Min % will not be used in calculating the contour image.

Ignore Zero Values

Check this box to completely ignore zero values in the contour.

Interpretation

This combo box specifies how to interpret the values of the data points. The options are:

Fixed Values

The data point values are not modified. The maximum, minimum, nominal, and

break values are the ones entered directly in the units of the value being

contoured.

Dynamic Values

The data point values are not modified. However the maximum, minimum,

nominal, and break values are determined dynamically from the data point

values as follows: Maximum = Maximum data point value; Minimum = Minimum

data point value; Nominal = Average data point value; Break High = (Max +

Average)/2; and Break Low = (Min + Average)/2.

Standard Deviations

All the data point values will be used to determine a mean and standard

deviation. The data point values will then be converted to represent the

number of standard deviations they are from the mean. Thus a value equal to

the mean will be changed to a 0, a value 1.5 standard deviations higher than

the mean will be changed to 1.5, and so on.

Percentiles

All the data point values will be sorted from lowest to highest. The value will

then be set equal to the 100 times the sort location divided by the number of

data points. Thus the highest value will be given a value of 100 and the lowest

a value of 1.

Save Contour Image with Oneline

Checking this box will allow a displayed contour to be saved with a oneline diagram. If a contour is saved with a

oneline diagram, the next time the oneline diagram is opened the contour will automatically be redrawn as well.

Continuously Update Contours

Normally contouring is only done on a snap shot of the power system state. However, you can also set

PowerWorld to automatically update the contour every time the display is redrawn. In this way, an animation of the

contour can be created. If you would like to create this animation, simply check the Continuously Update Contours

checkbox. Note, however, that this will slow down the animation of the display, as the program must recalculate the

contour at each step. If this slows down your display too much, try lowering the contour resolution to speed it up.

Note Regarding Values

Contours of most values create an image where the color around a data object is primarily related to the value of

only that object. Some values however create "density-like" contours, where the color is related to the sum of the

data object's values nearby. These include:

Bus / Load MW

Bus / Load Mvar

Bus / Load MVA

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Contour Type Options

Object

Simulator can contour several different values. To specify what Simulator should contour, first choose the type of

object; the options are Bus, Line, Interface, or Area/Zone. This selection narrows the set of quantities that can be

contoured, which is specified in the Value dropdown box.

Value

Then select the quantity to contour from the Value dropdown box or click the Find Value button to find the desired

field. Note: see Contour Type for more information.

Define a Filter

If you wish for the contour to be limited to only certain devices that meet specific criteria, click on this button to

define an Advanced Filter for the contour.

Current Filter

The name of the advanced filter that is currently applied to the contour.

Influence Region

This track bar determines how far away each data point influences the contour image. A larger influence region

results in each data point influencing more of the contour at the expense of longer screen refresh times.

Use Dynamic Influence Region

Dynamic influence distance determines how far out the contour should go when determining which buses influence

the contour value for a screen point. The actual distance is the minimum of either 1) a common value for all screen

points that depends upon user parameters [e.g., the dynamic region points value]), and now 2) the distance that

includes the number of buses associated with the dynamic influence field. The primary reason for this option is

speed, particularly when zoomed in on dense portions of the display. You should not see much impact on the

contour itself.

Kind of Value

This option allows you to choose to contour based on the Actual Value or the Density Value. The Actual Value uses

the weighted average of the data for computing the contour. The Actual Value method is most commonly used for

contouring in Simulator. On occasion, the weighted average method does not work as well. One example is

contouring generator MW values. If you have four buses in close proximity, each with 100 MW of generation, and

compare the contour with a single bus with 400 MW of generation, the contour based on the weighted average will

look drastically different, despite the amount of generation being the same in each region. Using the Density Value

option to do a weighted sum method will correct the disparity, and the contour around these two different groups of

generation would look basically the same.

Use Fade to Value

Checking this check box will allow to use the Fade to Value and Begin Fade Percentage options.

Fade to Value

The value to which a data point's value fades as it moves away from its location.

Begin Fade Percentage

While moving away from a data point, the data point’s value decays towards the "Fade to" Value. The Begin

Fade Percentage specifies when the contour starts to fade as a percentage of the largest distance for which

this data point influences the contour.

Contour Resolution

This value determines the relative resolution of the contour. Increasing the contour resolution increases the level of

detail represented on the map but will lengthen screen refresh times. Reducing the screen refresh time will yield

less detail and shorter screen refresh times.

582

Run Mode Tools and Options

Custom Color Map

Color Map

Choose from various predefined color maps using the color map combo-box. A color map, along with the values

specified, defines how values are mapped to a color on the contour image.

If a color map showing both high and low values is desired (such as for bus voltages), use of "Blue = Low, Red =

High" is recommended. If a color map showing only high values is desired (such as for line flows), use of "Weather

Radar, Nominal to High" is recommended.

A user may also define additional color maps by going to the Custom Color Map Tab.

Reverse Color Map Colors

This check-box reverse the mapping of the color map, converting the colors corresponding to the high values into

the colors for the low values, and vice-versa.

Brightness

Modify the brightness track bar to change the brightness of the color map.

Make Discrete Color Map

Check this check-box to make a discrete color map, that is without having smooth transitions between colors.

Contour Type Values to Use

These check-boxes signify which values from the Contour Type Values Tab are used by the Color Map. There

must be at least two contour type values checked.

Color Grid

The color grid on the right side of this page allows you to change the colors for each percentage breakpoint. In

addition, you can add or delete breakpoints as well.

To change the color for a specific breakpoint, simply left-click on the color for the breakpoint you want to change.

The Color dialog will open, and you can choose a new color for that breakpoint.

To add a breakpoint, right-click on a breakpoint position above or below where you would like the new breakpoint

inserted. A popup menu will open, and you can select Add Above or Add Below, depending on where you wish the

new breakpoint to be. Simulator will insert the breakpoint, and will automatically set the color and percentage at the

midpoint between the two breakpoints above and below the inserted breakpoint. You can then click on the color to

change it, or click on the percentage to type in a new value. The new percentage value should be between the

values of the adjacent breakpoints.

To delete a breakpoint, right-click on the breakpoint you wish to delete, and choose Delete from the popup menu.

Color By…

This option allows the user to interpret the breakpoints values as percentage values or as direct values.

Save As New

To save the present color map as a new color map, click this button. Then specify a name for the new color map.

Save

To save changes that have been made to the present color map, click this button.

Rename

To rename the present color map, click this button.

Delete

To delete the present color map, click this button.

Store Color Maps in File

To store all custom color maps in a file for loading into another case, click this button. If you have saved any

custom color maps with the current case, you will be prompted to choose a file name and location for saving the

custom color maps.

Load Color Maps from File

If you have created custom color maps in a different case and saved them to a file, you can click this button to load

those color maps into your current case.

583

Functional Description of Contour Options

Functional Description of the Contour Options

The previous help topics discussed basic contour options in the order they are arranged on the dialog. The dialog is

arranged so that the most important options are on the first tab and other on the Contour Type Options tab. This help

topic discusses the options in a manner which better describes how the contour is actually created. A contour is

calculated generally by a five-step process

Build a list of all possible data points (graphical locations)

Remove items that meet criteria from the list of data points

Assign a value to each data point

Calculate "virtual values" on a grid of points

Convert each "virtual values" into a color to create the contour image

Step 1: Build a list of data points (graphical locations)

The following options determine a list of potential data points (could also be called graphical locations) which will be

used to calculate the contour image.

Object - Simulator can contour several different values. To specify what Simulator should contour, first choose the

type of object. This corresponds to the type of display object that is drawn on the oneline diagram. For instance if

you want to contour a substation value, then you must have substations drawn on your diagram. This selection

narrows the set of quantities that can be contoured, which is specified in the Value dropdown box.

Data points Per Line - The contouring algorithm for lines is no different than for points, except that each line is

represented by several points. For objects which are represented by graphical lines, this option will specify the

number of data point which should be used to represent the line.

Step 2: Remove items that meet criteria from the list of data points

After a complete list of potential data points is made, there are then several options for filtering out things from this

list which you do not want to effect the calculation of the contour image.

Filter - If you wish for the contour to be limited to only certain devices that meet specific criteria, click on this button

to define an Advanced Filter for the contour

Ignore Above Max - Check this check-box to completely ignore values above the maximum percentage. This

means that data which is larger than the Max % will not be used in calculating the contour image

Ignore Above Min - Check this check-box to completely ignore values below the minimum percentage. This

means that data which is smaller than the Min % will not be used in calculating the contour image

Ignore Zero Values - Check this check-box to completely ignore values that are zero.

Step 3: Assign a value to each data point

After Step 2, a list of potential data points has been created and a value must now be assigned to each data point.

The following options specify how this is done.

Value - select the quantity to contour from the Value dropdown box or click the Find Value button to find the desired

field.

584

Run Mode Tools and Options

Use absolute value - This check-box will modify the Value specified so that it uses the absolute value.

Interpretation - When interpretation is set to either Standard Deviations or Percentiles, then the value of the data

point will be modified.

If Standard Deviations is chosen, then all the data point values will be used to determine a mean and standard

deviation. The data point values will then be converted to represent the number of standard deviations they are

from the mean. Thus a value equal to the mean will be changed to a 0, a value 1.5 standard deviations higher

than the mean will be changed to 1.5, and so on. Similar,

If Percentiles is chosen, then all the data point values will be sorted from lowest to highest. The value will then

be set equal to the 100 times the sort location divided by the number of data points. Thus the highest value will

be given a value of 100 and the lowest a value of 1.

Step 4. Calculate "virtual values" on a grid of points

After Step 3, we now have a list of data points and a value assigned to each data point. We now must create a grid

of points that represents "virtual values" throughout the entire graphical space. The values on this grid will be

calculated based on the data point values

Contour Resolution - setting determine the size of the grid of points which will be superimposed on the present

oneline diagram. The higher the resolution the more number of grid points will be used to represent the contour

(and thus make the calculation of the contour image slower)

Influence Region - each data point value will effect only the grid locations that are "near" it. The distance that is

considered "near" is determined by the Influence Region. Setting the influence region higher will result in each data

point effecting a larger portion of the contour image (and thus making the calculation of the contour image slower)

Kind of Value - The calculation of the virtual value at a particular grid point is done by first building a list of data

points that are within the "influence distance" of the grid point. The Kind of Value setting determines what proc ess

is used to calculate the virtual value from this list of values.

Actual Value (Weighted Average) - The virtual value is calculated as the weighted average value, weighted

by the distance from the grid point. This means that virtual value half-way between two data points will be the

average of the two data point values.

Density of Values (Weighted Sum) - The virtual value is calculated as the sum of value that within the

influence region. This means that virtual value half -way between two data points will be the sum of the two

data point values.

Actual Value (Only Closest) - The virtual value is assigned as the value of the closest data point.

Influence

Distance

Influence

d_inf

Distance

Data Point #1

d_inf

Data Point #2

Grid Point

Fade to Value and Begin Fade Percentage - In the middle of a contour image the colors look consistent because

the virtual values are calculated using a good number of data points which surround it. Sometimes at the edge of a

585

contour image however, the colors can become skewed because there are very few data points influencing it.

Using a fade to value can help this situation, but will skew the entire contour image in general instead. Without

using the fade to value, the raw data point values will be used when calculating virtual value.

When using the fade to value, w hile moving away from a data point, the data point’s value decays towards the

"Fade to" Value. The Begin Fade Percentage specifies when the contour starts to fade as a percentage of the

largest distance for which this data point influences the contour.

Step 5. Convert each "virtual values" into a color to create the contour image

After Step 4, a grid of virtual values has been calculated. At this point, must specify how these numbers map to

colors. This done through the user of a Color Map.

Color Map - Choose from various predefined color maps using the color map combo-box. A color map, along with

the values specified, defines how values are mapped to a color on the contour image. A user may also define

additional color maps by going to the Custom Color Map Tab.

Brightness - this value is used to brighten or darken the colors specified in the color map.

Values - These values along with the color map define how to convert your values into a color for the contour. The

values are:

Maximum - The largest value allowed in the contour. All values above this will be mapped to the highest color.

This value corresponds to 100% in the color map.

Break High - This value is used by some color maps to highlight a lower limit. This value corresponds to 75%

in the color map.

Nominal - This value is the nominal value for the contour. Values around this will be mapped to the middle

color. This value corresponds to 50% in the color map.

Break Low - This value is used by some color maps to highlight a lower limit. This value corresponds to 25%

in the color map.

Minimum - The smallest value allowed in the contour. All values below this will be mapped to the lowest color.

This value corresponds to 0% in the color map.

Interpretation - Most frequently this option will be set to Fixed Values meaning values for maximum, break high,

etc… are entered directly in the units of the value being contoured. If Interpretation is set to Standard Deviations

or Percentiles then as mentioned earlier the values mean something different. The options Dynamic Values will

process this list of data point values and automatically set the values as follows: Maximum = Maximum data point

value; Minimum = Minimum data point value; Nominal = Average data point value; Break High = (Max + Average)/2;

and Break Low = (Min + Average)/2.

No Data Color - It is likely that some the grid points will not be within the influence of any of the data points. The

color of these points is determined by no data color setting.

586

Run Mode Tools and Options

Distribution Factors

Power Transfer Distribution Factors

The Power Transfer Distribution Factor (PTDF) display is used to calculate the incremental distribution factors

associated with power transfers between two different areas or zones. These values provide a linearized

approximation of how the flow on the transmission lines and interfaces change in response to transaction between the

Seller and the Buyer. These values can then be visualized on the onelines using animated flows (see below for

details). The transaction for which the PTDFs are calculated is modeled by scaling the output of all generators on

AGC in the source and sink areas in proportion to their relative participation factors. Generators in the source area

increase their output, while generators in the sink area decrease their output.

An important aspect to consider in calculating the PTDF is how the losses associated with the transfer are allocated.

Simulator assumes that the Seller increases the output of its generators by 100% of the transfer amount, while the

Buyer decreases the output of its generators by 100% minus any change in system losses. In other words, the

Buyer accounts for the entire change in the system losses. Of course it is possible that a transfer may result in

decreased system losses; for that case, the Buyer’s generation will be greater than 100% of the transfer.

To Calculate the Power Transfer Distribution Factors:

Perform an initial Power Flow Solution.

In Run Mode, select Tools > Power Transfer Distribution Factors (PTDFs) from the main menu to open the

Power Transfer Distribution Factors Dialog.

Supply the requested information on the Power Transfer Distribution Factors Dialog and click the Calculate

PTDFs button. The distribution factors are calculated and displayed for the element set of your choice in the

table at the bottom of the dialog.

The animated flows that appear on the oneline diagram may represent either actual flows or PTDF values. To

specify that the display should show distribution factors, click the button labeled Visualize PTDFs . Once this button

is clicked, the flow arrows on all open onelines will represent distribution factors, and the c aption of the button will

change to Visualize Actual Power Flows. Click the button again to visualize actual power flows instead of

distribution factors.

Note that when calculating PTDF values for interfaces that include contingent elements, the PTDF values reported are

actually what are referred to as an Outage Transfer Distribution Factor (OTDF). See Line Outage Distribution Factors

(LODFs) for more information.

587

Power Transfer Distribution Factors Dialog

The PTDF Dialog enables you to control and to view the results of power transfer distribution factor calculations. You

access this dialog by selecting Tools > Power Transfer Distribution Factors (PTDFs) from the main menu in Run

Mode only.

The dialog has the following options:

PTDF Type

This option allows you to choose to define a single direction PTDF using the Seller and Buyer Type related fields,

or to define multiple transfer directions between many different entities. If you choose to use multiple directions, the

Seller and Buyer Type fields are replaced by the Direction Records display for viewing and defining directions.

Seller Type, Buyer Type

Distribution factors can be calculated for power transfers between combinations of areas, zones, super areas,

participation groups, or to a slack bus. Use the seller type and buyer type options to indicate the type of the selling

and purchasing entities. These fields are only present for single direction PTDF's.

Seller, Buyer

These dropdown boxes allow you to select the selling and buying entities. Their contents are filled when you select

the seller and buyer types. These fields are only present for single direction PTDF's.

Reverse Buyer/Seller

Click this button to re-calculate PTDFs for the direction that is the reverse of the direction currently shown. For

example, if you have just calculated PTDFs for a transaction from area A to area B, press this button to calculate

and display PTDFs for a transaction from area B to area A. This option is only present f or single direction PTDF's.

Linear Calculation Method

PTDFs may be calculated using either the full power flow Jacobian or only a portion of it. If you select the

Linearized AC Approximation option, the sensitivity of the monitored element’s flow will be calculated as a

function of both its real and reactive power components to the voltage magnitude and angle of its terminal buses.

When using the AC method, losses are included in the calculation. Simulator assumes that the change in losses is

taken care of by the Buyer.

If you instead select the Lossless DC Approximation option, branch flow sensitivity is calculated by estimating the

real power that flows through the monitored element only from the difference in angles measured across its

terminals. This method assumes that there are no losses.

The Lossless DC with Phase Shifters Approximation option is similar to the Lossless DC, except additional

constraints are placed on the calculations that assume that the change in flow across active phase-shifting

transformers is zero.

Calculate PTDFs

Click on this button to update the PTDF values. The results table will reveal the latest calculations.

Calculate MW-Distance

Click this button to open the MW * Distance Calculations form. This form allows you to calculate MW * Distance

values for the transaction for which you calculated PTDFs. See MW-Distance Calculations for more information.

Increase in Losses

This is a read-only field that indicates the change in system losses caused by the transfer from the selling area to

the buying area. The change is expressed as a percentage of the transfer amount. This will only be non-zero when

using the Linearized AC calculation method.

Automatically Update

If checked, the PTDFs are automatically updated every time the power flow is solved.

Use Area/Zone Filters

If this box is checked, then the results table at the bottom of the dialog will include only records associated with

devices located in areas or zones included in the area/zone/owner filter set.

Only Show Above %

Restricts the result set to show only those PTDFs that exceed a specified value. Many line-loading relief routines,

for example, disregard elements having a PTDF of less than 5%.

Visualize Actual Power Flows, Visualize PTDFs

Select to toggle the onelines between showing the actual power flows and the PTDF flows. Selecting this button

changes the Flow Vis ualization field for all the visible onelines. You can also change this field manually using the

Oneline Display Options Dialog.

588

Run Mode Tools and Options

Highlight Counter Flows

If this box is checked, then the PTDFs that are directed counter to the existing flows on the system are highlighted

on the oneline using the Counter Flow Highlight Color. Double click on the color to change its value.

Tables of Results

The tables of results occupy the bottom of the PTDF Dialog. They are a set of case-information displays and thus

share many characteristics common to all other case information displays. The tables will show results for

lines/transformers, interfaces, areas, zones, generators, and phase shifters. The tables feature a local menu from

which you can print, copy, or modify its records as well as view the information dialog of its associated element. You

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

Lines/Transformers

Shows the transaction distribution factors for the lines and transformers. The following fields are shown:

From Bus #, From Bus Name, To Bus #, To Bus Name, Circuit

Identifiers for the transmission line or transformer.

From % PTDF

Distribution factor associated with the MW flow at the "from bus" end of the line or transformer, specified as a

percentage of the transaction amount.

To % PTDF

Distribution factor associated with the MW flow at the "to bus" end of the line or transformer, specified as a

percentage of the transaction amount.

% Losses

Shows the percentage of the PTDF assigned as losses.

Nom KV (Max) and Nom KV (Min)

Displays the maximum and minimum nominal voltages for the line. This is useful for identifying transformers

and which end of the PTDF relates to which nominal voltage.

Interfaces

Shows the transaction distribution factors for the interface records. The following fields are shown:

Interface Name

Alphanumeric identifier for the interface.

Interface Number

Numeric identifier for the interface.

% PTDF

Distribution factor associated with the MW flow through the interface, specified as a percentage of the

transaction amount. A positive value indicates the transaction would result in an increase in the flow through

the interface.

Interface MW Flow

Amount of real power flowing on the interface.

Has Contingency

Signifies if an element of the interface is violating a limit.

Areas and Zones

Shows the impact the transaction has on the losses for the area or zone. The following fields are shown:

Area/Zone Number and Name

Number and name identifiers for the area or the zone

Losses %

Change in the losses in the area or zone, specified as a percentage of the transaction amount. A positive

number indicates that the transaction would result in increased losses in the area or zone, while a negative

number indicates that the transaction would result in decreased losses.

Gen Chg %

Total change in all of the generators in area or zone, specified as a percentage of the transaction amount. For

areas, this field should show 100% in the selling area, and 100% minus the change in system losses in the

buying area.

Generators

Shows the marginal participation of each generator in the transaction. The following fields are shown:

Bus Number, Bus Name, Gen ID

589

Generator’s terminal bus number and alphanumeric identifier, and the id for the generator.

Area Number, Area Name

Name and number of the generator’s area.

Gen Change %

Assumed participation of the generator in the transaction, specified as a percentage of the transaction amount.

This value is directly proportional to the participation factor for the generator, provided the generator is available

for AGC and is free to move in the specified direction (i.e., is not at a MW limit). The generator’s participation

factor and AGC status are modified on the Generator Dialog, which can be displayed by right-clicking anywhere

in the record’s row in the table and selecting the Show Dialog option.

Phase Shifters

Shows the transaction distribution factors for the phase shifters. This applies when using the Lossless DC with

Phase Shifters calculation method. The following fields are shown:

From Number, From Name, To Number, To Name, Circuit

Identifiers for the phase shifter.

Status

Indicates whether or not the phase shifter is in-service.

Phase (Deg)

The current phase angle of the transformer.

XF Auto

Indicates if the phase shifter is currently enabled for automatic control.

Deg per MW

This field indicates the amount of angle change, in degrees, that would be required to keep the flow across the

transformer constant for a one MW transfer between the seller and the buyer.

Tap Min, Tap Max

The minimum and maximum tap positions for the phase shifter.

590

Run Mode Tools and Options

Line Outage Distribution Factors (LODFs)

Line Outage Distribution Factors (LODFs) are a sensitivity measure of how a change in a line’s status affects the flows

on other lines in the system. On an energized line, the LODF calculation determines the percentage of the present

line flow that will be show up on other transmission lines after the outage of the line. For example, consider an

energized line, called LineX, whose present MW flow is 100 MW. If the LODFs are found to be

LODFs for LineX outage

LineX

-100%

LineY

+ 10%

LineZ

30%

This means that after the outage of LineX, the flow on LineX will decrease by 100 MW (of course), LineY will increase

by 10 MW, and LineZ will decrease by 30 MW.

Similarly, sensitivities can by calculated for the insertion of a presently open line. In this case, the LODF determines

the percentage of the post-insertion line flow that will show up on other transmission line after the insertion.

To calculate the LODFs:

Perform an initial Power Flow Solution.

In Run Mode, select Tools > Other Sensitivities > Line Outage Distribution Factors (LODFs) from the main

menu to open the Line Outage Distribution Factors Dialog.

Supply the requested information on the Line Outage Distribution Factors Dialog and click the Calculate

LODFs button.

What else are LODFs used for?

LODFs are used extensively when modeling the linear impact of contingencies in Simulator. This is true for the

calculation of PTDFs for interfaces w hich contain a contingent element, as well as when performing Linear ATC

analysis that includes branch contingencies.

When calculating "PTDF" values for interfaces that include contingent elements, the PTDF values reported are

actually what are referred to as an Outage Transfer Distribution Factor (OTDF). An OTDF is similar to PTDF,

except an OTDF provides a linearized approximation of the post-outage change in flow on a transmission line in

response to a transaction between the Seller and the Buyer. The OTDF value is a function of PTDF values and

LODF values. For a single line outage, the OTDF value for line x during the outage of line y is

OTDFx = PTDFx + LODFx,y * PTDFy

where PTDFx and PTDFy are the PTDFs for line x and y respectively, and LODFx,y is the LODF for line x during

the outage of line y. More complex equations are involved when studying contingencies that include multiple line

outages, but the basic idea is the same.

When performing Linear ATC analysis along with calculating OTDFs, Simulator determines the linearized

approximation of the post-outage flow on the line. This is similarly determined as

OutageFlowX = PreOutageFlowX + LODFx,y* PreOutageFlowY

where PreOutageFlowX and PreOutageFlowY are the pre-outage flow on lines x and y.

591

Line Outage Distribution Factors Dialog

The LODF Dialog enables you to control and to view the results of Line Outage Distribution Factor calculations. You

access this dialog by selecting Tools > Other Sensitivities > Line Outage Distribution Factors (LODFs) from the

main menu in Run Mode only.

The dialog has the following options:

Near Bus, Far Bus

Specify the line whose status modification you would like to determine sensitivities to.

Action

Check Outage Sensitivities to determine sensitivities for the outage of a line.

Check Insertion Sensitivities to determine sensitivities for the insertion of a presently outaged line.

Liner Calculation Method

Linearized AC

This calculation method is not available for LODF sensitivities.

Lossless DC

Uses the DC power flow approximation.

Lossless DC with Phase Shifters

Check this to include the impact of phase shifter controllers with the Lossless DC calculation. By checking this,

it is assumed that operating phase shifters will maintain their control requirements after the line outage.

Calculate LODFs

Click this to calculate the LODFs and update the display.

Advanced LODF Calculation

Opens the Advanced LODF Calculation dialog for setting additional options for the calculation.

LODFs Tab

This tab contains a table showing a list of the lines in the case. Since this table us 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 listing, view the information dialog of the respective element, and view the Quick Power Flow List or Bus View

Display.

The default fields for the tab are as follows

From Bus Number and Name

"From" bus number and name. 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. 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.

%LODF

The LODF value for the line.

From MW, To MW

The present MW flows on the line at the "from" bus and the "to" bus.

From CTG MW, To CTG MW

The projected MW flows after the change in line status on the line at the "from" bus and the "to" bus.

Note: LODFs are always calculated using a DC power flow technique.

592

Run Mode Tools and Options

Advanced LODF Calculation Dialog

This dialog allows you to calculate the LODFs for several different contingent lines. Go to the Contingency Analysis

Tool to define which contingent lines to use (all contingencies that contain a single branch outage will be used.) Also,

only lines that are being monitored will have their LODFs calculated. See Limit Monitoring Settings to change which

lines are monitored.

This dialog defines how to save the Advanced LODF results to a file for importing in another program.

Format to Save in

You can choose to save the advanced LODF results as "Monitored Branch, Contingency" pairs for PROMOD, or as

a matrix in a comma-delimited text file. The comma-delimited text file is useful for loading the results into a

spreadsheet program.

Only save pairs with an LODF whose absolute value is greater than

This field allows you to filter out elements whose LODF is below a certain value.

Only Include Monitored Br anches whose MW flow increases

This field allows you to filter out monitored elements whose MW flow did not increase in the LODF calculation.

Maximum Columns Per Text File

This field is important when you are saving a matrix in a comma-delimited text file. Most spreadsheet programs

have limits on the number of columns they can display. The default is 256, which happens to be the maximum

number of columns allowed in Excel.

LODF Number Format

You can choose to have the LODF values stored in either scientific notation, or as a specified length decimal

number.

File Name

You must enter a file name and location or Browse for a file for saving the LODF data.

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Directions Display

The Directions Display appears in the upper-right corner of the PTDF window when you select Multiple Directions for

the PTDF Type. The Directions Display is a case information display that allows directions to be defined for

performing multiple direction Power Transfer Distribution Factors. The Directions Display allows you to insert, delete,

and modify directions using options available from the display's local menu. When directions are modified or inserted

individually, the Directions Dialog will be displayed for entering the information. In addition to individually defining

directions, they can also be automatically inserted using the Auto Insert Directions dialog.

Each record in the display shows the following default information:

Number, Name

A unique number and name given to the defined direction.

Source Type, Source Name

The name and type of the direction source.

Sink Type, Sink Name

The name and type of the direction sink.

Include

Determines if the direction is to be analyzed when calculating the multiple direction PTDF's.

Processed

Displays if the direction has already been processed for a multiple direction PTDF analysis.

594

PowerWorld Simulator version 11. Manual - page 15