PowerWorld Simulator version 11. Manual

Run Mode Tools and Options

Directions Dialog

Directions are objects that are defined and used when computing a Power Transfer Distribution Factor using multiple

directions.

The Directions Dialog can be used to insert a new direction or to modify the information for an existing direction. This

dialog can be called by choosing Insert or Show Dialog from the Directions Display local menu.

The options that can be set from this dialog include:

Name of Direction

The name for the direction. If you are entering a new direction, you can enter a new direction name. If you are

modifying an existing direction, the name of the currently viewed direction will be displayed. A drop down list shows

a list of currently defined direction names, and choosing one from the list will display that direction's information in

the dialog. The up and down arrows next to the field also allow you to scroll through the list of defined directions.

Direction Number

If you are entering a new direction, you can put in a new direction number. If you are viewing or modifying an

existing direction, the direction's number will be displayed.

Source

Select the type of the transfer direction source. Once the type has been selected, the advanced find list will be

enabled, allowing you to search for the specific object or group of objects to set as the direction source.

Sink

Select the type of the transfer direction sink. Once the type has been selected, the advanced find list will be

enabled, allowing you to search for the specific object or group of objects to set as the direction sink.

Include in list of monitored directions

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

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Auto Insert Directions

Multiple directions can be automatically inserted for PTDF studies using the Auto Insert Directions dialog. This

option can be selected from the local menu of the Directions Display.

The layout of the dialog is as follows:

Type of Direction

There are six types of directions that can be automatically defined. Area to Slack, Zone to Slack and Injection

Group to Slack will define directions from areas, zones or injection groups to the slack bus of the system. Area to

Area, Zone to Zone and Inj. Groups to Inj. Group will define directions from areas to other areas, zones to other

zones, or injection groups to other injection groups.

Delete Existing Directions

When checked, any previously defined directions will be deleted before the new directions are automatically

inserted. If not checked, then automatically inserted directions will be added to the list of previously defined

directions. By not deleting existing directions before automatically inserting new directions, it is possible to have

more than one direction defined with the same source and sink.

Only Insert for Areas or Zones with Display Filters Set

If checked, then only Areas and Zones with their Area/Zone/Owner Filters set to Yes will be used when

automatically inserting directions.

Starting Number, Increment By

The Starting Number will be the first number used when automatically numbering the automatically inserted

directions. Each subsequent direction added will be numbered according to the Starting Number and the

Increment By value.

Insert Directions

Insert Directions will perform the automatic insertion routine for the directions, according to the defined options.

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Run Mode Tools and Options

Sensitivities

Flow and Voltage Sensitivities

The Flows and Voltages Sensitivities Dialog can be opened from the Tools > Other Sensitivities > Flows and

Voltages menu option in Run Mode.

The Flows and Voltages Sensitivities Dialog shows the effect an additional injection of real or reactive power at a bus

has on real, reactive, or complex power flow on a particular line or interface, or on the voltage of a selected bus. The

grid that occupies the bottom of the dialog lists each bus in the system, subject to the Area/Zone/Owner Filter settings.

This grid is a case information display and thus shares properties and controls common to all other case information

displays. The P Sensitivity field indicates the effect a 1 MW increase in real power at the bus has on the flow (either

MW, Mvar, or MVA flow, as dictated by the Flow Type setting) or voltage on the device identified by the Device

Identifier. Likewise, the Q Sensitivity field indicates the effect a 1 Mvar increase in reactive power at the bus has on

the flow (either MW, Mvar, or MVA flow, as dictated by the Flow Type setting) or voltage on the device identified by

the device identifier.

Use the Device Type control to indicate whether the sensitivities are to be calculated for a line/transformer, an

interface, or a bus. Use the Flow Type control to specify the type of power flow for which the sensitivities will be

calculated. Use the Device Identifier fields to identify the line/transformer, interface or bus.

Whenever you make a change to any of these settings, click Calculate Sensitivities to update the grid with the new

sensitivities.

The option labeled Set Out-Of-Service allows you to approximate the sensitivities at out-of-service buses with the

sensitivity of the closest bus. Otherwise the out-of-service buses will display sensitivities of 0 when the sensitivities

are calculated.

Click Close to close the Flows and Voltages Dialog.

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Loss Sensitivities

The Losses Dialog can be opened from the Tools > Other Sensitivities > Losses menu option.

The Bus Marginal Loss Sensitivities Dialog is used to calculate and display the sensitivity of a real power loss

function, PLosses, to bus real and reactive power injections. Stated mathematically, the display calculates d PLosses /d Pi

and d PLosses /d Qi , where Pi and Qi are the real and reactive power injections at bus i, respectively. The display is

available in the Run Mode by selecting Tools > Other Sensitivities > Losses.

Stated less formally, the display indicates how losses would change if one more MW or Mvar of power were injected at

bus i. Simulator can calculate the losses for a bus relative to losses in the bus’ island or area, to losses in a select

group of areas, or, if the bus belongs to a super area, to losses in the bus’ super area. How Simulator computes the

losses is governed by the value of the Loss Function Type option.

The Loss Function Type may assume one of the following six values:

Do Not Calculate Bus Loss Sensitivities

No Losses are calculated because a loss function is not specified.

Each Electrical Island

Losses are calculated with respect to the losses in bus’ island. If the power system consists of only one island,

losses are computed with respect to the total system losses.

Each Area

Losses are calculated with respect to the total losses for the area containing bus i. This is probably the most

common loss function because usually one is concerned with minimizing losses for a particular area rather than for

the entire case.

Each Area or Super Area

Losses are calculated with respect to the total losses for the area containing bus i if bus i does not belong to a super

area, and with respect to the total losses for the super area containing bus i if bus i does belong to a super area.

Areas Selected on Loss Sensitivity Form

Losses are calculated with respect to the total losses for a group of areas, specified in the Selected Areas table.

User-Specified

If you select User-Specified as the loss function type, the values last calculated using a different loss function type

will become fixed. Thus you can force the loss sensitivities to remain constant when used in other features and

tools of Simulator.

In steady-state power system operation, total generation must always equal total load plus losses. Therefore, the real

power injection at a single bus cannot be changed arbitrarily; it must be met by a corresponding change somewhere

else in the system so that the total power remains balanced. In other words, the change in power injection must

somehow be absorbed. How the injection is absorbed depends on the Loss Function Type. If the Loss Function Type

is Each Island, the injection is absorbed by the island slack. For the Each Area and Selected Areas loss functions,

the injection is absorbed at the area tie-lines.

The loss sensitivities are calculated by modeling an injection of power at a bus and then assuming that this injection is

absorbed by the island slack bus. The sensitivity then shows how much the losses (for the region of interest) increase

when you transfer 1 MW at the injection bus to the island slack. The "region of interest" is what was chosen as Island,

Each Area, or Selected Areas.

Therefore, the "absolute numbers" given by the loss sensitivity dialogs are not directly meaningful because we are

always assuming that the absorbing point is the island slack bus. What is meaningful is the "difference" between

sensitivity numbers.

Example:

Assume the sensitivities are calculated to be

Bus A Loss MW Sensitivity = -0.04 = Asens

Bus B Loss MW Sensitivity = -0.02 = Bsens

Bus C Loss MW Sensitivity = +0.03 = Csens

Using these we can then look at the sensitivity of generic transfers between these buses by using "superposition".

Consider the following change in injections modeling a transfer of power from Bus A to Buses B and C.

Bus A injection = +10 MW = AMW

Bus B injection = - 6 MW = BMW

Bus C injection = - 4 MW = CMW

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Run Mode Tools and Options

An estimate of the change in losses can then be calculated as

Loss Change

= (AMW)(Asens) + (BMW)(Bsens) + (CMW)(Csens)

= (+10)(-0.04) + (- 6)(-0.02) + (- 4)(+0.03)

= -0.4 MW

The Bus Marginal Loss Sensitivities Dialog houses the following controls:

Selected Areas Table

This table is used only when the Loss Function Type is set to Selected Areas; otherwise, it is ignored. Left-click

on the Include field to include or exclude areas from the loss function.

Calculate Marginal Loss Sensitivities Button

Once the loss function type has been specified, click this button to calculate the bus marginal loss sensitivities and

update the Bus Marginal Loss Sensitivities table.

Bus Marginal Loss Sensitivities Table

This table shows the bus marginal loss sensitivities for all buses with valid Area/Zone/Owner filters. The Bus

Marginal Loss Sensitivities Table is a type of Case Information Display and thus exhibits features and behavior

similar to all other case information displays. It has a local menu from which you can choose to find out more about

a particular bus. You can sort records by any of the listed fields by clicking on the column headings. The table

contains the following fields:

Number, Name

Number and name of the bus.

Area Number, Area Name

Number and name of the bus’ area.

Loss MW Sens .

Sensitivity of the loss function to an increase in the real power injection

(generated power assumed positive) at the bus.

Penalty Factors

Computed penalty factor of each bus.

MVR Sens .

Sensitivity of the loss function to an increase in the reactive power injection

(generated power assumed positive) at the bus.

Just Generators Marginal Loss Sensitivities Table

This table shows the bus marginal loss sensitivities for only the generator terminal buses with valid

Area/Zone/Owner filters. This table is otherwise identical to the displayed values and table operation as the Bus

Marginal Loss Sensitivities Table described above.

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Transmission Loading Relief Sensitivities

Transmission Loading Relief (TLR) Sensitivities may be thought of as the inverse of Power Transfer Distribution

Factors. Both TLR Sensitivities and PTDFs measure the sensitivity of the flow on a device to a transaction. To

calculate PTDFs, you specify a source group and a sink group, and Simulator determines the percentage of a single

transfer between the source and sink that flows on each of several monitored elements. For TLR sensitivities, you

specify a single device, such as a transmission line, to monitor, and a group that serves either as source or as sink.

Simulator then determines the sensitivity of the flow on the single monitored element to many different transactions

involving the group you specified as the source or sink. To summarize, PTDFs express the sensitivity of many

monitored elements to a single transaction, whereas TLR sensitivities gauge the sensitivity of a single monitored

element to many different power transfers.

"TLR" stands for "Transmission Loading Relief." TLR is an industry-wide tool for managing transmission utilization to

prevent overload situations that put the system at risk. For example, suppose a particular line is loaded beyond its

thermal limit. Its ow ner will request that a TLR program be initiated, which dictates that all transactions for which 5%

or more of the exchanged power flows on the overloaded element be curtailed. The TLR sensitivity tool in Simulator is

useful for pinpointing those transactions that would be curtailed. Suppose we use the TLR tool to determine where

area A can purchase power from while the TLR for the overloaded element is in place. We specify area A as the

buyer area, identify the overloaded line, and tell Simulator to perform the calculation. Simulator will then list the

sensitivity of the flow on the overloaded line to power exchanges between all other generators, areas, and buses to

area A. Any transaction for which the sensitivity exceeds 5% would be curtailed; anything below 5% would be allowed

to continue.

To calculate TLR Sensitivities, select Tools > Other Sensitivities > TLR Sensitivities from the main menu. This will

open the TLR Sensitivities dialog, which will allowyou to set TLR Sensitivities options and then calculate the

sensitivities.

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Run Mode Tools and Options

TLR Sensitivities Dialog

The TLR Sensitivities dialog allows you to calculate Transmission Loading Relief Sensitivities for the load flow case at

its solved load flow point.

The following describes the sections of the dialog:

Device Type

Select whether you want to calculate the sensitivities for a transmission line/transformer, for an interface, or for

multiple elements. To calculate sensitivities for an interface, you must have the interface defined in the case.

When you choose an individual line/transformer or interface, you need to specify the device by selecting it from the

list of devices. In this case you specify the From Bus, To Bus, and circuit identifier for a branch, or the interface

name or number. When you select the Multiple Elements option, the device selection area of the dialog changes to

allow you to select a TLR Multiple Device Type. The TLR results display changes accordingly in order to

accommodate TLR sensitivities for multiple elements.

Device Identifier

Specify the From Bus, To Bus, and circuit identifier for a branch, or the interface name, number, and monitored flow

direction.

For multiple elements, specify the multiple device type. Choices are: selected lines/transformers, selected

interfaces, overloaded lines/transformers in the base case, overloaded interfaces in the base, overloaded

lines/transformers during the set of contingencies, and overloaded interfaces during the set of contingencies.

Select Lines/XFMRs

Opens the case information display for lines/transformers. To include a line/transformer in the TLR study, set the

Selected? field to Yes.

Select Interfaces

Opens the case information display for interfaces. To include an interface in the TLR study, set the Selected? field

to Yes.

# Elements

Shows the total number of elements to be included in the TLR study.

Transactor Type

Specify if the sensitivities will be calculated for the transactor being the buyer or the seller.

Transactor Object

Specify what the transactor will be. The choices are Area, Zone, Super Area, Slack, Injection Group, and Bus.

TLR Sensitivities

Specify if the next set of calculated TLR sensitivities should replace the currently calculated values, or be appended

to the current values.

PTDF Calculation Method

Choose the solution method to use for calculating the sensitivities.

Include only AGCAble Generators

If checked, then only generators available for generation control will be included in the TLR sensitivity calculations.

Generator, Area and Bus Sensitivities

Displays the other devices that can be involved in a transaction with the transactor, and the resulting TLR sensitivity

for performing a transaction with that device.

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TLR Multiple Device Type

The Multiple Device Type selector allows you to specify a group of elements for which Transmission Loading Relief

(TLR) sensitivities will be calculated. The Multiple Device Type selection is accessible only when you chose the

Multiple Elements option from the Device Type in the TLR Sensitivity Dialog.

When you change the Multiple Device Type section, the # of Elements box changes to indicate how many elements of

the selected type are available for TLR calculation.

When you click the Calculate TLR Sensitivities button for multiple elements, the table will show a TLR column for each

element in the set and two additional columns:

Effective Transmission Loading Relief (ETLR)

In the same manner as the TLR represents the MW increase in an element per MW transfer, the ETLR column in

the Mult. Bus Sensitivity table represents the total MW increase in all the elements in the set per MW increase of

the transaction. Let us suppose that the set contains two transmission lines: A and B and assume that for a 1 MW

transfer from bus i to the transactor, the flow in line A increases in 0.5 MW and the flow in line B decreases in -0.3.

Then the ETLR of bus i is +0.2 since that is the total MW increase in the elements in the set. The ETLR provides a

measure of the simultaneous MW change in multiple elements, and thus the overall effect in flows on the element of

the set. The ETLR is a bus field that can be included in the bus Case Information Display, used in Contouring, etc.

Weighted Transmission Loading Relief (WTLR)

The WTLR column in the Mult. Bus Sensitivity table weights the sensitivities based on the flow or overload flow

values of the element. It is a measure of the value of a certain bus to relief transmission loading. The buses with the

highest WTLR (or lowest WTLR, depending on the transactor type) are identified as the most effective buses to

mitigate transmission loading considering multiple elements. The WTLR is a bus field that can be included in the

bus Case Information Display, used in Contouring, etc.

Selected Lines/XFMRs

Choose this option to include in the multiple element TLR calculation those transmission lines and transformers that

have been selected. To select a transmission line or transformers, toggle the Selected field in the Lines and

Transformer Case Information Display to Yes. If the Selected field is not available in the information display, add

that column to the display by right-clicking in the display and selecting Display/Column Options. The ETLR of

selected Lines/XFMRs is the algebraic sum of the TLRs of each individual element. The WTLR uses as weight the

current MW flow in the element.

Selected Interfaces

Choose this option to include in the multiple elements TLR calculation those interfaces that have been selected. To

select an interface, toggle the Selected field in the interfaces Case Information Display to Yes. If the Selected field

is not available in the information display, add that column to the display by right-clicking in the display and selecting

Display/Column Options. The ETLR of the selected interfaces is the sum of the TLRs of the interfaces that have a

limit different from zero. The WTLR uses as weight the MW flow in the interface

Overloaded Lines/XFMRs

Select this option to include in the multiple element TLR calculation those transmission lines and transformers that

are overloaded in the present case based on the Limit Monitoring Settings. The list of the overloaded lines and

transformers is available in the Limit Violations information display. It can also be sorted in the lines and

transformers Case Information Display. The ETLR of overloaded lines and transformers is the algebraic sum of the

individual TLRs. The WTLR for overloaded transmission lines and transformers uses as weight the MVA overload of

each transmission line and transformer.

Overloaded Interfaces

Select this option to include in the multiple elements TLR calculation those interfaces that are overloaded in the

present case based on the Limit Monitoring Settings. The list of the overloaded interfaces can be obtained from the

Limit Violations information display or by performing a sort in the interfaces Case Information Display. The ETLR for

overloaded interfaces is the sum of the individual TLRs. The WTLR for overloaded interfaces uses as weight the

MW overload of each interface.

CTG Overloaded Lines/XFMRs

Select this option to include in the multiple element TLR calculation those transmission lines and transformers that

were identified as overloaded by the Contingency Analysis tool. A transmission line or transformer is included in the

calculation if it has been overloaded at least for one contingency. The list of the lines and transformers identified as

overloaded can be accessed from the Lines, Buses and Interfaces Tab in the Contingency Analysis Dialog.

The ETLR of the CTG overloaded lines and transformers is the algebraic sum of the individual TLRs. The WTLR

uses as weight the Aggregate MVA Overload of each transmission line and transformer, which is defined as the

sum of the MVA overload in the line or transformer across the contingencies that caused a violation in that particular

line or transformer. The Aggregate MVA Overload and a related field, the Aggregate Percent Overload of a line or

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Run Mode Tools and Options

transformer, are measures of the weakness of that transmission line on the grid. The Aggregated MVA Overload

and the Aggregate Percent Overload are line and transformer fields that can be displayed in the Case Information

Display, used in Contouring, etc.

CTG Overloaded Interfaces

Select this option to include in the multiple element TLR calculation those interfaces that were identified as

overloaded by the Contingency Analysis tool. An interface is included in the calculation if it has been ov erloaded at

least during one contingency. The list of the interfaces identified as overloaded during contingencies can be

accessed from the Lines, Buses and Interfaces Tab in the Contingency Analysis Dialog.

The ETLR of the CTG overloaded interfaces is the algebraic sum of the individual TLRs. The WTLR uses as weight

the Aggregate MW Overload of each interface, which is defined as the sum of the MW overload of the interface

across the contingencies that caused a violation in that interface. The Aggregate MW Overload and a related field,

the Aggregate Percent Overload of an interface are measures of the weakness of the interface. These two interface

fields can be displayed in the Case Information Display, used in Contouring, etc.

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Time Step Simulation

The Time Step Simulation allows you to specify operating conditions and obtain power flow solutions for a set of points

in time. It provides the tools needed to analyze the operation of a power system hour by hour.

Time Step Simulation is available in the base Simulator package. If you own Simulator, you can start taking advantage

of this valuable tool right away. In addition, if you own Simulator OPF or SCOPF licenses, you can solve hourly OPF

and SCOPF scenarios and use the tool to evaluate the behav ior of prices and operating constraints. The tool will

obtain the optimized generation dispatch for each hour of the analysis horizon.

In order to access the Time Step Simulation, go to Tools in Run Mode and select Time Step Simulation.

Please continue reading the following topics and take full advantage of this powerful tool.

Time Step Simulation Quick Start

Time Step Simulation Dialog

Specifying and Maintaining a List of Time Points

Loading Hourly Input Data

Setting up Scheduled Input Data

Storing Input Data and Results

Running a Timed Simulation

Time Step Simulation Toolbar

Running OPF and SCOPF Time Step Simulations

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Time Step Simulation

Time Step Simulation: Quick Start

The first time you access the Time Step Simulation by selecting Tools (Run Mode) and then Time Step Simulation,

you will see the Time Step Simulation Dialog, which contains several pages. The Hourly Summary page is used to

define and control the time points you want to analyze. As an example, we will assume that you have hourly load data

for tomorrow and that you want to determine the system bus voltages for each hour. You would do the following:

Step One: Set the List of Points

In order to create a list of points, right click on the Hourly Summary page and select Insert New Timepoint(s),

which brings up the New Timepoint Dialog. In this dialog, select tomorrow’s date from the drop down calendar

component. Set the field Total Number of Timepoints to Enter to 24. Assume the other default values and click

OK. This will insert 24 timepoints one for each hour starting tomorrow at 1: 00 AM.

Step Two: Specify Input Data

Input data is specified in the Input Page . In this example your input data corresponds to hourly loads. Select the

Hourly MW Loads sub-page. In order to specify hourly load values you have to insert a column for each load. Right

Click on the grid and select Scale/Insert Load Column(s) to bring up the Insert/Scale Column Dialog. In the

selector component, select the load for which you want to specify hourly values. You can press the shift key to

select multiple elements. Then press the blue Arrow Button to pass the selected loads to the right side of the

selector. Select OK to insert the new column(s). Now you can specify the hourly MW values for those loads.

Step Three: Specify the Custom Results

Obtaining solutions for a large number of timepoints has the potential to create unnecessary burden in memory and

storage due to the large amount of data that can be generated. For this reason, the Step Simulation Tool, allows

you to explicitly specify what quantities you want to display and store. This is done in the Results Page. This page

contains grids for many devices including Generators, Lines, etc. In this example we want to analyze the bus

voltage magnitudes. We specify what quantities we want to store as results for each object by clicking the

View/Modify button, which brings up the Custom Results Selection Dialog. In this dialog select the Buses page

and in the Available Bus Fields section check the Per Unit Voltage field. Results will be saved only for those

buses that have the Time Selected field on the grid set to YES. Set this field to YES for the buses that you want to

save. Click the Save and Close button to save the custom results settings, i.e., which objects, fields and records

are to be kept during the solution; in this case bus voltages.

Step Four: Run the Simulation

The upper part of the Time Step Simulation form contains buttons used to control the simulation. To do a full run of

the 24 hours click the Do Run button. The Last Result box shows the progress of the simulation as each time point

is being solved. If you are in the Results - Buses page, you will see that a column was added for each bus set to

YES in the Custom Results Selection Dialog. Each column shows the bus per unit voltage. Recall that you can

Right Click on any Simulator grid and select Plot Column to obtain a plot of the column values. If you select cells

spanning all the bus per unit voltage c olumns, you will obtain the voltage profiles for each bus, versus time.

If you are in the Hourly Summary page, the Processed column shows that each point was in fact processed and

solved.

Step Five: Save the Results

Once you have completed the simulation, you can save the results in a Time Series Binary (tsb) file by pressing

the Save Data Binary button. This file will contain all the input data, the simulation options, the custom results

settings, and the results. You can reload this tsb file any time by pressing the Read Data Binary button.

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Setup and Control

Time Step Simulation Dialog

The Time Step Simulation Dialog is used to control and visualize the time simulation. The top section of the form

contains buttons for data input/output and buttons to control the progress of the simulation. The main part of the form

has a number of Time Step Simulation Pages that contain grids where input data can be specified and simulation

results can be examined.

Input/Output Buttons

Read Data Binary

Press this button to read a Time Series Binary File (.tsb File). This files stores hourly and scheduled input data, the

simulation options and the hourly results.

Read Load Format

Reads a .csv file containing hourly load MW and MVar values. The CSV format of this file is:

BUS_NUMBER,BUS_NAME,VST bus numbers,DPID,YrMoDay,Hr,KW,KV

446,ANAME,18803,506520,20041001,1,1970,769

446,ANAME,18803,506520,20041001,2,2005,821

Save Data Binary

Press this button to save the hourly and scheduled input data, the simulation options, and the hourly results in a

Time Series Binary File (tsb file).

Read Data From Excel

Reads hourly load and generation data from Excel: The formats for generator and load data are:

Generators:

GEN DATA

Date

Hour

BusNameGen1

BusNameGen2

Bus Numbers (s)

19306

100370

10/01/05

522

340

10/01/05

522

340

Loads:

BUS_NUMBER BUS_NAME VST bus numbers DPID YrMoDay Hr KW KV

2192

3BLUFF C

19306

100370

20050101

307

177

2192

3BLUFF C

19306

100370

20050101

311

-180

Simulation Control Buttons

During the solution, the Time Step Simulation solves each timepoint in a sequential manner. During this process, the

Simulation can be in one of three states:

1. Reset: When the simulation has not started, when it has been completed, or when it has been paused and then

reset.

2. Running: When the simulation is solving time points sequentially.

3. Paused: When the user has paused the simulation. The simulation actually waits until the present time point is

solved in order to pause. If the simulation includes a SCOPF solution, then all the contingencies are processed and

the system is optimized before the simulation is paused. Note that once a time point is solved its results are available

on the various grids.

The user controls the Time Step Simulation by means of the following control buttons:

Do Run [Pause Solution, Continue Solution]

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Time Step Simulation

Press this button to initialize the Time Step Simulation and go through all the timepoints until the last time point or a

time point with Pause field set to YES is found. As the simulation takes place, the Last Result Box will be updated

with messages. In addition, the Hourly Summary Page will change the Processed and Solv ed fields from No to Yes,

reflecting the simulation progress. The result grids will be updated once the solution for a timepoint has been found.

When the Simulation starts, the simulation status changes to Running, and the Do Run button changes its caption

to Pause Solution. Press this button to pause the Solution. The simulation will continue until the current time point

is solved entirely. Once the Simulation status is set to Paused, the Do Run button caption changes to Continue

Solution. Press this button to continue the solution.

Do Single Point

Use this button to solve the next time point. You can see the last processed point in the Last Result box. You can

also select a specific starting point by using the Start Time Point Selector.

Reset Run

Use this button to go back to the first time point and initialize the simulation. This action does not delete the results

of the time points processed so far, but it resets all the processed fields to No.

Last Result

The last result box is used to show solution progress messages. The messages indicate correct solutions or errors

in the solution of the particular time point. It also shows the progress of the contingency analysis during a SCOPF

solution.

Start Time Point

Use this selector to specify a start time point other than the first time point in the list. The simulation will disregard

the time points before the selected start time point.

End Time Point

Use this selector to specify an end time point other than the end time point in the list. The simulation w ill stop right

after the selected end time point.

609

Hourly Summary Page

The Hourly Summary Page of the Time Step Simulation Dialog is used to define the time points and to display

a summary of the simulation. Most of the commands to manage time points can be accessed form the Hourly

Summary Page Local Menu.

Once timepoints are defined, the Summary Page presents the following columns for each time point:

Date

The date of the time point. To modify the date, Right Click and select Change Timepoint Time on the Local Menu.

Hour

The time of the time point to the minute. To modify the time, Right Click and select Change Timepoint Time.

Skip

This field is set to YES to include the time point in the Simulation. If set to NO, the hourly input data and any

schedule action that occurs at this time point is not to the power system.

Processed

This field is set to yes if the simulation has processed the time point. This includes applying the hourly input data,

applying the scheduled actions and solving the power flow for that particular time point.

Solution Type

The time point can be solved using one of the following Solution Types: Single Solution, Unconstrained OPF,

optimal power flow (OPF), and security-constrained optimal power flow (SCOPF). The last three solution types

require the Simulator OPF/SCOPF add-ons.

Solved

YES if a solution was obtained for the timepoint under the specified solution type.

Num Loads

Total number of loads for which hourly input data has been specified.

Total MW Load

Total MW load specified as hourly input data for the timepoint

Total Mvar Load

Total reactive load specified as hourly input data for the timepoint

Num Gens

Total number of generators in the system for which hourly input data has been specified

Total MW Gen

Total MW of generation specified in the hourly input data.

Pre Script Cmd

The Time Step Simulation has the capability of running a pre script command before each time point. The pre script

command is run right before the time point is solved. Please check the Script Command section to learn the details

about performing Simulator actions using script commands.

Post Script Cmd

The Time Step Simulation has the capability of running a post script command right after the time point is solved.

Please check the Script Command section to learn the details about performing Simulator actions using the script

language.

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Time Step Simulation

Hourly Summar y Page: Local Menu

The Hourly Summary Page Local Menu is used to perform a number of logical actions on the timepoint grid and is, as

every Simulator local menu, accessed by right clicking anywhere on the grid. When selected from the Hourly Summary

Page, the local menu shows the following options:

Apply Time Point

Simulator applies the hourly input data of that particular time point to the power system model, without solving the

time point. Upon selection of this option, the timepoint information can be visualized in the Case Information

Displays.

Solve Time Point

This option applies the time point hourly and the scheduled input data to the power system, and solves the

timepoint after the specified solution type.

Change Time Point Time

This option allows the user to modify the date time of the selected timepoint. If the new date time belongs to an

existing point in the list, an error message is displayed. The timepoints can be specified with an accuracy of up to

one minute.

Display/Column Options

Select this option to add or remove columns to the hourly summary grid.

Select Column(s)

This option is normally used to select the entire column. You can drag the mouse across several columns in a row,

and use this option to select multiple columns. Then you can for instance copy the entire column data to the

clipboard, or plot all the selected columns.

Contour Column

Use this option to contour a column in the data grid.

Insert New Timepoint(s)

Use this option to insert new timepoints into the timepoint list. This selection brings up the New Timepoint Dialog.

Plot Column(s)

Use this option to automatically generate column plots. By default, in the Time Step Simulation grids, the column

plots display graphs of column data versus the datetime column (the combination of the date and hour columns).

Delete Entire Timepoint Record

Use this option to delete the selected timepoint and all the hourly input data and custom results of that timepoint.

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Input Page

The Time Step Simulation Input Page is used to specify hourly input data and scheduled data. This requires that the

list of timepoints have been created. Please read the Specifying and Maintaining a List of Timepoints for details on

managing the list of time points.

The Input Page contains several pages that can be grouped in two types: Hourly Input Pages and Schedule Pages.

Hourly Input Pages

The hourly input pages (Hourly MW Loads, Hourly Mvar Loads, Hourly Actual MW Generation, Hourly Maximum

Generation, Hourly Line Status, and Hourly Area Load) are Matrix Grids that are used to specify data on an hour by

hour manner. In order to tell Simulator that we want to specify hourly data for a load, generator, or line, we need to

add that particular object to the corresponding grid. For instance, suppose that you want to specify hourly MW data

for Load 1 at bus 1. Then go to the Hourly MW Loads page, right click and select Insert/Scale Load Column(s) to

bring up the Insert/Scale Column Dialog. In this dialog, you can select the load and add it as a column to the Load

grid. The corresponding values for that particular load can then be entered.

A similar process is followed to add one or multiple hourly MW generations or hourly line statuses.

Use the Hourly Area Load page to specify the hourly MW load for an entire Area. When Simulator applies the input

data to solve a timepoint, it will scale the load of the specified area to match the value entered for that hour.

Schedule Pages

The schedule pages (Schedules Page and Sched Subscriptions Page) are used to specify scheduled input data,

i.e., data that does not follow an hour by hour format. Examples of data that can be scheduled are scheduled

transactions, generator statuses, line statuses, etc. For a detailed explanation on how to set up scheduled data,

please read the Setting Up Scheduled Input Data section.

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Results: Constraints Page

This page is only available in OPF and SCOPF versions of Simulator. When the OPF solution type is used to solve a

timepoint, the status of the system during that particular hour is optimized so that the total operating cost of the system

is minimized and the normal operation constraints are enforced. In addition, the SCOPF solution type enforces

contingency constraints. The OPF and SCOPF solutions contain information about the elements that determine the

LMPs, the binding constraints, the violating contingencies, and changes in the control settings.

The information related to contingencies on thes pages is available only in the SCOPF Simulator add-on.

The pages of the Results: Constraints Page are:

Results Summary

This page is similar to the Hourly Summary Page, except that it contains additional operating information such as:

Initial Cost: The cost of operating the system given the initial generator set points and a standard power flow

solution. No controls are moved to minimize cost

Unconstrained Cost: Is the total operating cost after the controls are moved to minimize cost, without enforcing

any normal operation or contingency constraint. The result is an operating cost that corresponds to an Economic

Dispatch solution.

Unconstrained LMP: Is the average marginal price of the system under unconstrained optimization.

Final Cost: Is the total operating cost after a constrained (OPF or SCOPF) solution has been obtained.

LMP (Average, Standard Deviation, Minimum and Maximum): Metrics of the LMP values.

Binding Lines: Number of transmission lines and transformers that are binding after the OPF/SCOPF solution has

been determined.

# CTGs Unsolvable : Number of unsolvable contingencies. These are severe contingencies that would cause the

power flow solution to fail for that particular time point scenario. Unsolvability of the power flow case is related to

maximum loadability conditions.

Hourly Binding Lines

This is a Matrix Grid that shows information for transmission lines and transformers that become binding constraints

during the OPF or SCOPF solutions. A similar page is available for binding interfaces.

When transmission lines or transformer thermal ratings become binding constraints for a timepoint, a column is

automatically added forming in this manner the matrix grid. You can access the details of the binding line or

transformer by right clicking and selecting Show Binding Constraint Dialog on the Local Menu. The grid shows also

the following summary columns.

Processed: YES if the time point was correctly processed.

CTGs with Viols : Number of contingencies that presented one or more violations (violating contingencies)

# CTGs Unsolveable : Number of unsolvable contingencies

for the timepoint

BC Line Viols : Number of transmission line and transformer violations that w ere identified in the base case.

# Line Viol: Number of transmission line and transformer thermal violations.

Binding Lines: Number of binding lines in the OPF/SCOPF solution.

Line Unenforceable : Number of lines with unenforceable limits.

Hourly Binding Interfaces

This is a Matrix Grid that shows information for interfaces that become binding constraints during the OPF or

SCOPF solutions. A similar page for lines is available.

When interfaces become binding constraints for a timepoint, a column is automatically added to the matrix grid. You

can access the details of the binding interface by right clicking and selecting Show Binding Constraint Dialog on the

Local Menu The grid shows also the following summary columns.

Processed: YES if the time point was correctly processed.

CTGs with Viols : Number of contingencies that presented violations (violating contingencies)

# CTGs Unsolveable : Number of unsolvable contingencies

for the timepoint

BC Interface Viols : Number of interface violations that were identified in the base case.

# Interface Viol: Number of interface violations.

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Time Step Simulation

Binding Interface : Number of binding interfaces in the OPF/SCOPF solution

Interface Unenforceable : Number of interfaces with unenforceable limits.

Hourly Binding Contingencies

This Matrix Grid shows information similar to that found on the Hourly Binding Lines and Hourly Binding Interfaces

pages. Here though the data is organized by contingencies, which allows easy identification of the most severe

contingencies. Each column of the matrix grid corresponds to a contingency. The grid shows also the following

summary columns.

Processed: YES if the time point was correctly processed.

CTGs with Viols : Number of contingencies that presented violations (violating contingencies)

# Line V iol: Number of transmission line and transformer thermal violations.

Binding Lines: Number of binding lines in the OPF/SCOPF solution

Binding Interfaces: Number of binding interfaces in the OPF/SCOPF solution

Base Case: Shows the number of violating contingencies in the base case.

Binding Line Summary Matrix

This Matrix Grid shows the number of hours that a line has been binding due to each contingency. In this case, the

rows correspond to binding lines, and the columns to violating contingencies. You can access the details of the

binding element by right clicking and selecting Show Binding Constraint Dialog on the Local Menu The grid shows

also the following summary columns

From Number: Binding line from bus number

To Number: Binding line to bus number

Circuit: Binding line circuit ID

Total Hrs: Total number of hours the line was binding (in the overall simulation).

Total Hrs Unenforceable : Total number of hours the line constraint was unenforceable (in the overall simulation)

Basecase: Number of hours the line was binding in base case solutions.

Binding Line Summary List

Shows information similar to the Binding Line Summary Matrix but in form of a List. The same line may appear

several times under different contingencies. Besides the information on the Binding Line Summary Matrix, this

grid shows the following fields.

Contingency Name: Contingency that causes the line constraint to be binding

Avg MC: Time Average MVA Marginal Cost

Max MC: Time Maximum MVA Marginal Cost

Min MC: Time Minimum MVA Marginal Cost

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Time Step Simulation

Results Page

The results of the Time Step Simulation are presented on the grids of the Results Page . The Time Step Simulation

allows you to specify what objects (buses, lines, generators, loads, etc) and what object fields (bus voltage, bus LMP,

gen MW, etc) should be displayed on the result grids. This gives the user the flexibility needed to explore the relevant

results, avoiding at the same time the problem of storing a massive amount of results, most of which may not be

relevant. Storage is a critical aspect of the Time Step Simulation, since a set of results comparable to full a

PF/OPF/SCOPF solution is generated for each timepoint.

The Results Page has two sections: The top section is used to set up the options needed to customize the results

display. The grid section is used to display the actual results.

Results Page : Top Section

This section includes the following options:

View/Modify Result Definitions

Press this button to access the Custom Results Selection Dialog. This dialog is used to specify the objects and

object fields for which results will be stored.

Load Result Definitions

The custom result definitions set up in the Custom Results Selection Dialog can be saved in a Results File in order

to use them with different tsb files or Simulator cases. Press this button to Load the Results File and apply the

result definitions to the current Time Step Simulation.

Save Result Definitions

Press this button to save the result definitions in a Results File.

Group Results by

The Result Grids for Areas, Buses, etc are Matrix Grids that present the hourly results for each type of object. For

instance, suppose that we want to store the bus voltage magnitude and angle. The Buses grid will show columns for

the hourly values of voltage magnitude and voltage angle of each bus.

Objects : The columns will be grouped by objects, e.g., all the fields of bus 1, then all the fields of bus 2, etc.

Fields : The columns will be grouped by fields, e.g. all the bus p.u. voltages, then all the bus LMPs, etc.

Identify Results by

The Result Grids for Areas, Buses, etc. create one column for each object field specified in the Custom Results

Selection Dialog. The column header thus identifies the particular object for which hourly results are displayed. This

identification can be made based on the object Number, Name or Number + Name combination.

Results Page : Grid Section

This grid section is used to display the results of the Custom Results Grid Pages.

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Custom Results Selection Dialog

This dialog is used to specify what are the objects and object fields that will be stored during the Time Step Simulation,

and that will be displayed on the Custom Results Grid Pages.

In order to tell the Time Step Simulation that you want to store a particular field for a certain object, you need to:

Click on the page of the object type you need to store (Area, Bus, etc)

Set to YES the Time Selected field of those objects for which you want to store information.

Check the boxes corresponding to those fields you want to store (bus LMP, bus p.u. voltage, etc)

Once you are done with the selections, press the Save and Close button to apply the customization. The Custom

Results Grid Pages will be filled with the corresponding columns after the Time Step Simulation starts.

Note that the actual results and the result customization will be stored in the tsb file. For more information about saving

the Time Step Simulation results, please read the Storing Input Data and Results section.

The following object fields can be specified to be displayed on the grids and stored in the tsb file.

Areas:

Hourly Costs: Initial Cost, Final Cost, Congestion Cost, Total Generator LMP Profit

LMPs : Weighted Average LMP, Unweighted Average LMP, LMP Standard Deviation (Unweighted), Minimum LMP,

Maximum LMP.

Interchange: ACE, Actual MW Interchange, Actual Mvar Interchange

Load/Gen Summary: Total MW Load, Total Mvar Load, Total MW Generation, Total Mvar Generation. Total MW

Losses, Total Mvar Losses.

Buses:

Voltage Values: Per Unit Voltage, Actual Voltage (KV), Voltage Angle (degrees)

LMPs : Real Power LMP

Attached Devices: Total Load MW, Total Load Mvar, Total Generation MW, Total Generation Mvar

Miscellaneous : Real Power Loss Sensitivity, Reactive Power Loss Sensitivity

Generators:

Basic Values: MW Generation, Mvar Generation, PU Voltage Setpoint, Terminal Bus PU Voltage, Regulated Bus

PU Voltage.

OPF Values: Terminal Bus LMP, Intial MW Generation, Delta MW Generation, LMP Profit

Loss Sensitivity: Real Power Loss Sensitivity, Penalty Factor

Injection Groups:

LMPs : Weighted Average LMP, Unweighted Average LMP, Minimum LMP, Maximum LMP.

Interfaces:

Flow Values: MW Flow, Percent of Limit

OPF Values: Marginal Cost of Limit Enforcement

Lines:

Bus Flow Values: From Bus MW Flow, From Bus Mvar Flow, From Bus MVA Flow, To Bus MW Flow, To Bus Mvar

Flow, To Bus MVA Flow.

Maximum Flow Values: Maximum MW Flow, Maximum Mvar Flow, Maximum MVA Flow, Maximum Percentage

OPF Values: Marginal Cost of Limit.

Owners:

Hourly Cost: Total Generator LMP Profit

LMPs : Weighted Average LMP, Unweighted Average LMP, LMP Standard Deviation (Unweighted), Minimum LMP,

Maximum LMP.

Load/Gen Summary: Total MW Load, Total Mvar Load, Total MW Generation, Total Mvar Generation.

SuperAreas:

Hourly Costs : Initial Cost, Final Cost, Congestion Cost, Total Generator LMP Profit

LMPs : Average LMP, LMP Standard Deviation, Minimum LMP, Maximum LMP.

Interchange: ACE, Actual MW Interchange, Actual Mvar Interchange

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Time Step Simulation

Time Step Simulation Options

The Time Step Simulation is controlled through as set of options specified in the Options Page . The Result Options

and the Pricing Options are available on this page only in the OPF/SCOPF Simulator add-ons.

Input Area Load Values

In many practical studies, hourly data of individual MW load may not be available for all the loads in a control area.

In order to simulate load variations, Simulator allows you to specify the hourly Area Total MW Load values in the

Hourly Area MW Load page of the Input Page. Thus the Time Step Simulation load data may be a combination of:

· Areas where each individual load is specified

· Areas where only the total hourly area MW load is known.

· Areas where some individual loads and the total area load are known.

Choose the Set Area Loads After Scaling Individual Loads , if you want the area load to be set first, and then the

individual loads. The final area load will be the total value specified for the area. Choose Set Area Loads Before

Scaling Individual Loads if you want the opposite to occur. In this case the area load is set first, and then the total

area load is modified by the hourly values of individual loads. This option is chosen if the individual loads are what is

more relevant for the simulation. Note that this may result in the area having a slightly different total MW than the

value specified for the area. If you want to disregard the area load values, select the Ignore Area Load Values

option.

Solution Options

These options control the solution process.

Pause if Power Flow Does Not Solve : The Time Step Simulation is stopped at the timepoint where a power flow

solution cannot be obtained. This is an indication of wrong data or a system brought to its loadability or transfer

capability limit.

Enable Power Flow Area Interchange : This option ensures that the area interchange control, if possible, is

enforced in the case.

Use Parallel Contingency Analysis (on Dual CPU Machines): Use this option to speed up the computation of the

contingency analysis by distributing the processing time on several processors. This option is available for SCOPF.

Pricing Options

These options are available only in the OPF/SCOPF add on.

Solve Unconstrained Case: Select this option when you want an unconstrained solution to be obtained before an

OPF or SCOPF solution for each time point. When combined with the Results Options -> Save Unconstrained

Generator MW Outputs , the MW Generator outputs obtained in the unconstrained solutions are saved.

Price Hydro Generation at Marginal Cost

During OPF and SCOPF simulation, hydro generation may experience large changes in output due to its low

marginal cost. However, hydro generation is often not as cheap if limited water levels and dam restrictions are

observed. These considerations are usually taken care of in the hydro-thermal coordination solution, outside of

Simulator. In the OPF and SCOPF solutions it is important to assign a reasonable price to hydro generation to avoid

large generation output deviations. A common mechanism to do that is to f irst obtain the system marginal cost, and

then assign this cost to the hydro units.

Reset Hydro Generation Price at the End of Time Period: Choose this option to make the hydro generation price

be reset for the next time point solution.

Save Binding Cons traints : The binding constraints determined in the OPF/SCOPF are stored.

Time Step Simulation Options

The Time Step Simulation can be performed in two ways:

Continuous : In this case Simulator solves one time point after another immediately. The purpose of the simulation

is to obtain the solutions for all time points as quickly as possible.

Timed: The purpose is to simulate the solutions as they would occur in actual time. In this case, the difference in

date time between two time points in the list defines a delay to start the solution of the second point. A Time Scale

is used to set the speed of the simulation with respect to actual time. Suppose that you have 3 time points defined

at the following date times:

1/20/05 1:00 AM

1/20/05 2:00 AM

1/20/05 4:00 A M

Assume also that the Time Scale is 10 seconds per hour. If you start the Timed Simulation you would see the

conditions of the first time point applied to the power system immediately, the conditions of the second time point

623

applied 10 seconds later, and those of the third point applied 20 seconds after the second point. The delays on the

simulation allow you to see how the quantities evolve in actual time. In addition, you can animate the time

simulation while each time point is being solved. The visualization of the Timed Simulation is enhanced when you

use the Time Step Simulation Toolbar.

Auto Contouring Options

The Time Step Simulation allows you to contour quantities on the oneline diagram using Simulator Contouring at

each timepoint. Optionally, these contour diagrams can be saved in different formats.

No Auto Contouring: Contouring is not used during the Time Step Simulation. Although using the Timed

Simulation you can see the quantities change and the animation take place on the diagrams, the contouring is not

displayed.

Contour but Do not Save : Contouring takes place at each timepoint, but the diagrams are not saved.

Save in File as Bitmap: The contouring diagrams generated at each timepoint are saved in Bitmap format.

Save in File as JPEG: The contouring diagrams generated at each timepoint are saved in JPEG format.

Contour File Name Format: The Bitmap or JPEG contouring diagrams are saved using the specified format, which

includes the timepoint date time.

Auto Load TSB File Options (saved in case pwb file)

These are options that relate the power system case (.pwb File) to the time series binary file (.tsb file). These options

are saved with the .pwb case.

Automatically Load Default *.tsb File : The tsb file specified in the Default *.tsb file is loaded automatically when

opening the .pwb case. If the file cannot be found, a message will be issued.

Automatically Set Default *.tsb File to Current *.tsb File : When leaving Simulator, the current time series

information is saved in the Default *.tsb file.

Default *.tsb File: Default path and name of the *.tsb file.

624

Time Step Simulation

Specifying and Maintaining a List of Timepoints

The list of timepoints is the basis for the Time Step Simulation. Simulator will go through the list of timepoints and

solve each one of them. Results will be available only for those timepoints specified in the list.

Whether you start with an empty list or you already have time points in it, you can insert new time points by Right-

Clicking in the Hourly Summary page and selecting Insert New Timepoint(s). This will bring up the New Time Point

Dialog.

The list of timepoints will be always sorted based on the date time shown on the date and hour column in the Hourly

Summary Page. Thus, if you crate a new time point with an intermediate date time, Simulator will insert it at the

appropriate place in the list. If you need to change the date time of a timepoint you can Right-Click in the Hourly

Summary grid and select Change Timepoint Time to bring up the Change Timepoint Time Dialog. This dialog is

similar to the New Timepoint Dialog, with the exception that instead of specifying the date time for a new timepoint,

you will be modifying the date time of an existing time point. If the date time matches exactly the date time of an

existing time point up to the minute, a warning message is issued.

Each timepoint is linked to its hourly data in what is called a Timepoint Record. The Timepoint Record contains the

date and hour of the time point, all the input hourly data specified for that point, and if any, the results that have been

obtained for that timepoint. If you delete a timepoint, the entire record is deleted with it. In order to delete the timepoint

you can Right Click in the Hourly Summary grid and select Delete Entire Timepoint Record. Note that you can

vertically select cells in this grid and delete several timepoints records at a time.

Suppose that you have a 1:00 AM and a 3:00 AM timepoints that have associated with them hourly MW load data. If

you insert a 2:00 AM data, the 2:00 AM cell of the MW load will appear empty. If you run a study, no data will be

applied to the power system at 2:00 AM, but you will get a result (identical to the one of 1:00 AM). You need to fill the

2:00 AM cells with data in order for the values to be applied at that timepoint and obtain the correct results for 2:00

AM.

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New Timepoint Dialog

The New Timepoint Dialog is used to define new timepoints. One or multiple timepoints can be defined at once. Use

the date drop-down box to bring up a calendar for easy selection of the date. Note that the calendar has visual controls

that allow you to navigate through months or years, which allows you to set the desired date easily.

If this is the first timepoint you will insert in the list, then by default the dialog is populated with today’s date at 1:00 AM.

If there are other points in the list, the default is one hour after the date time of the last time point.

The other options in this dialog are:

Date

Use this control to select the date of the time point. You can use the visual controls or the up or down arrow keys to

modify the date.

Time

Use the control to enter the hour, minute and AM/PM description of the time. Once you are positioned on the hour,

minute or AM/PM values, you can use the up/down arrow buttons for easy selection without having to type. Note

that the timepoints are specified with an accuracy of up to minutes.

Total Number of Timepoints to Enter

By default this field is set to one, meaning that you will enter only one timepoint with the specified date and time. If

the value is more than one, several time points will be inserted in the list at the interval defined in the next two fields.

New Timepoint Interval: Hours

If the Total Number of Timepoints to Enter is more than one, this field is used to specify the hours of the interval

between each time point. Timepoints will be Hours+ Minutes apart. Default is one hour.

New Timepoint Interval: Minutes

If the Total Number of Timepoints to Enter is more than one, this field is used to specify the minutes of the

interval between each time point. Timepoints will be Hours+ Minutes apart. Default is zero minutes.

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Time Step Simulation

Insert/Scale Column Dialog

The Insert/Scale Column Dialog is called from the Input Page grids. These Matrix Grids are used to specify hourly

input data for Load MW, Load Mvar, Generator MW, Generator Maximum MW and Area Total MW Load. Hourly data

of each particular object is specified in columns. When no column has been added to the grid, the Insert/Scale Column

Dialog allows you only to select the new object. On the other hand, when there are existing columns on the grid, the

Dialog allows you to insert a New Column either alone or based on the values of the existing columns. This option is

available because values such as hourly load MW data tend to experience similar fluctuations in time.

Current Column: If there are exiting columns and the Insert/Scale Column Dialog is called from an hourly input data

column, this field shows the position of that column. This field tells the user what column the New Column will be

based on.

Action:

These options tell how the new column will be inserted.

Scale Entire Current Column: This option is available only when the current column corresponds to an existing

hourly data column. When applied, the new column takes the values of the current column scaled by the Scaling

Factor.

Scale Selected Rows of Current Column: The Time Step Simulation allows you to select a group of contiguous

rows of a column and scale only those rows of the New Column.

Insert New Column Derived From Current Column: This options copies the values of the Current Column to the

New Column.

Scaling Factor: Factor used to scale the new column.

Load Scaling: These options are available only when inserting Load columns and are used to scale Real and

Reactive Load, Just Real Load, or Just Reactive Load.

New Column: Use this selector to specify the ID of the object that will be added as new column to the grid.

Selector: The bottom section of the dialog is a selector that allows you to specify one or multiple objects at a time

and add columns for them by passing the objects from the left side to the right side. This selector has the following

controls:

Sort by Name: Check this option to sort the list of available objects by name

Sort by Number: Check this option to sort the list of available objects by number

Define Filter: Press this button to filter the list of available objects using an Advanced Filter.

Use Area/Zone Filter: Check this box to filter the list of available objects using the Area/Zone filters.

Search: By typing the start of the name of an object in the edit line, you can search the next object or all the objects

available which match the search pattern. You can also use wildcards to search for objects.

List of Objects: The objects in the list are selected by clicking on them. Multiple objects that are together can be

selected by clicking the mouse while holding the SHIFT key. Multiple objects that are not contiguous in the list can

be selected by clicking the mouse while holding the CONTROL key.

Select Button: Press the blue arrow button to pass the selected objects on the left to the right.

Remove Button: Press the trash can button to remove the objects from the selected list on the right side.

For more information about methods to specify hourly input data, please read the Loading Hourly Input Data section.

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Loading Hourly Input Data

The Time Step Simulation allows you to specify the operating conditions of your power system through input data. The

input data can be of two types:

Scheduled Data, which is specified for data that is not hourly by nature. To set up schedule data please read the

Setting up Schedule Input Data section.

Hourly Data, or more precisely time point-based data, is specified for each time point in the Input Pages. There are

several ways to specify hourly input data:

By entering data manually on the Input Pages.

By deriving or scaling values from another column using the Insert/Scale Column Dialog.

By loading previously formatted data from Excel or .csv files through the Read Buttons in the Time Step

Simulation Dialog.

By pasting data from Excel directly to the grid. A common way to do that is to:

o Set up the desired timepoints and data columns on the grids of the Input Pages

o Copy the template to Excel by selecting Copy on the Local Menu

o Fill the Excel sheet with the appropriate data

o Paste the data back to the data grid by selecting Paste on the Local Menu

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Time Step Simulation

Schedules

Setting up Scheduled Input Data

There area two types of input data for the Time Step Simulation:

Hourly Data, which is described in the Loading Hourly Input Data section; and,

Scheduled Data, which is specified for data that is not hourly by nature. In this section we describe how to specify this

type of input data.

Although it is possible to specify the operating conditions of a power system exclusively by hourly quantities, there are

several quantities that are not hourly by nature, and whose hourly specification would be redundant and would require

significant memory storage. Examples of such quantities are:

The status of a transmission line that is taken out of service on a particular date and time for maintenance.

The status of a generator, which follows a particular maintenance schedule.

A generator’s voltage set point that is different during the day or at night.

A scheduled transaction between to areas that has different MW set points applied at 10 am, 4 pm and 10

pm.

A capacitor connection status for a Mvar block that is used only during the day.

An industrial load that operates at different levels for different shifts.

A peaker generating unit that operates only during certain hours of the day

And many others. All these quantities can be specified by introducing the concept of Schedule . A schedule is a list of

pairs (Date Time, Value), where the value can be either numerical or Yes/No. The Schedule can have any number of

time points and can be periodic. The schedule defines the "shape" of how a quantity varies in time. In order to define a

schedule, go to the Schedules Page of the Input Page , and select Insert New Schedule to bring up the Schedule

Dialog. Please follow this link for a detailed explanation on how to define a schedule.

Once a schedule has been created, we can assign an object field, such as the status of a transmission line or the MW

output of a generator to the schedule by means of a Schedule Subscription. The object field will follow the schedule

"shape" in time. The use of Schedule and Schedule Subscription objects gives us great flexibility in specifying how

quantities should vary. In particular, it is possible to assign many fields to the same schedule. In order to define a

Schedule Subscription, go to the Sched Subscriptions Page of the Input Page , and select Insert New Subscription

to bring up the Sched Subscription Dialog. In this dialog you will encounter a detail explanation of the Schedule

Subscription use and capabilities.

An important feature of the Schedules is that their date times don’t need to match the date times of the list of

timepoints (time points listed in the Hourly Summary Page). Suppose that your list of time points are define hourly for

the next day: 1am, 2am, etc. up to 11pm. You can schedule a particular action to take place at 2:35 am and see the

results of that action in the next time point, i.e., 3 am. A special logic takes care of applying scheduled action at

appropriate time points asynchronously.

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Schedule Dialog

The Schedule Dialog is called from the Schedules Page and is used to define a schedule. A schedule is a list of time

points together with a numeric or a Yes/No value that define the "shape" of how a quantity should vary in time. The

timepoints are listed on the grid section of the dialog. The Schedule Dialog also contains a number of options that

define the schedule.

When a schedule is created, the time step Simulation inserts by default four timepoints for today’s date with a numeric

value of zero in every point. So, the list of timepoints w ill not be empty. You may want to change the date and times of

the schedule timepoints and specify different values.

Schedule Dialog Local Menu Actions

The Schedule Dialog grid, as any other Simulator Grid has a Local Menu that is accessed by right-clicking on any cell.

The most important options of this dialog are:

Insert New Point(s): Select this option to bring up the New Schedule Point Dialog. This is the same New Time Point

Dialog but is used here to insert Schedule timepoints.

Change Time(s): Select this option if you want to change the date time of a schedule timepoint. The selection brings

up the Change Time Dialog, which is the same Change Timepoint Time Dialog used here to change the date time of

a schedule time point.

Delete : Use this option to delete the current schedule time point

Select Column(s): Use this option to select an entire column. Note that you can use this option and then delete all the

timepoints.

Copy: Use this option to copy the values in the Schedule grid to the clipboard. If you are using Excel, you can modify

the values and then Paste back the new schedule points into Simulator.

Timepoint List Options

These options provide shortcuts to some of the Local Menu actions related to the maintenance of the list of Schedule

time points:

Add Time Point: Adds a new timepoints at the end of the list. By default the date time of the new timepoint is one

hour after the last time point. If there are no timepoints in the list, a timepoint is inserted with today’s data at 1:00 AM.

Delete Time Point: Deletes the selected timepoint(s).

Shift Date Time Buttons : Use these buttons to move by one week, day, hour or minute the date time of the selected

time point.

Schedule Options

The upper part of the Schedule Dialog is used to define other Schedule Options:

Schedule Name: Enter here the name you want to give to the schedule. This is how you will identify the schedule

when you set up schedule subscriptions. If the user does not specify otherwise, Simulator assigns names Sched1,

Shced2, etc. as new schedules are created.

Name Suffix: This is a string automatically generated by Simulator, which is used to display the main characteristics of

the Schedule together with the name. The Name Suffix is composed of three strings separated by points:

[Num or Y/N]: Indicates whether the schedule values are numeric or Yes/No.

[NPER or PERxdyh]: The string indicates whether the schedule is non-periodic (NPER) or periodic (PER). If it is

periodic, it indicates the days (x) and hours (y) of the period.

[Nn]: Indicates the number of timepoints (n) of the Schedule.

By looking at the Schedule suffix, the user effective avoids writing long names for the Schedule to characterize its

properties.

Value Type : Numeric or Yes/No. When you toggle this selection, the value column in the Schedule grid changes its

heading from Numerical Value to Yes/No value, and the numerical cells (blue) are changed to Yes/No cells (green),

indicating that you can toggle the cell value. Note that numeric fields, such as Load MW, Schedule Transactions MW

etc, will subscribe to a Numeric Schedule, whereas fields such as Line Status will subscribe to a Yes/No Schedule. For

more details on Schedule Subscriptions, please read the Sched Subscriptions Dialog.

Periodic Options

A schedule becomes periodic when its values are repeated every certain period specified in days and hours. A logic

condition for a schedule to be periodic is that its period be larger that the time span between the date time of the last

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Time Step Simulation

time point and the first time point in the schedule. For instance, if the schedule has three time points at 1 am, 2 am and

4 am, the span is 3 hours. Thus the schedule period must be 4 hours or more. If this condition is not hold, Simulator

issues a warning message.

Repeat Every: Check this box to make the schedule periodic. The schedule must have a period greater than 0 days

and 0 hours to be considered periodic. The schedule period is the number of days plus the number of hours specified.

Days: A positive integer that specifies the number of days of the schedule period.

Hours: A positive integer from 0 to 23 that specifies the number of hours of the schedule period.

Valid From: When checked, this option sets a validity date for the schedule, whether it is periodic or not. No schedule

actions will be applied to the power system before this date. By default, the Valid From date is set to Jan 01, 2000, at

12:00 am.

Valid Until: When checked, this option sets a validity date for the schedule, whether it is periodic or not. No schedule

actions will be applied to the power system after this date. By default, the Valid Until date is set to Dec 31, 2030, at

12:00 am.

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Schedules Page

The Schedules Page is used to display all the defined schedules and their properties. The most relevant options of

Local Menu of this page are:

Schedules Page Local Menu Actions

Insert New Schedule : This option is used to define a new schedule through the Schedule Dialog

Delete: Use this option to delete the current Schedule.

Show Dialog: Select this option to bring up the Schedule Dialog with the information of the current Schedule.

Schedule Page Fields

The Schedules Page shows the following information about schedules:

Name: Schedule Name

Suffix: Schedule Suffix. For a description on how the suffix is created, please see the Schedule Dialog section.

Periodic: Whether the schedule acts as periodic or not.

Period Days: Number of days in the schedule period.

Period Hours: Number of hours in the schedule period.

Valid From: Whether a start validity date is used for the schedule.

Period Start Date: Start validity date.

Period Start Hour: Start validity time

Valid Until: Whether an end validity date is used for the schedule

Period End Date : End validity date

Period End Hour: End validity time

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Time Step Simulation

Schedule Subscription Dialog

This dialog is used to define and display the options of a Schedule Subscription. Schedule Subscriptions tell the Time

Step Simulation that a specify object field (Gen MW, Line Status, Scheduled Transaction MW, etc) should vary

according to the "shape" specified in a Schedule.

Simulator objects have a large number of fields, which can be classif ied in numeric or Boolean. Numeric fields,

whether integer or real, can subscribe to Numeric Schedules and Boolean fields can subscribe to Yes/No Schedules.

Thus a condition for a field to subscribe to a schedule is that a schedule of its type be already defined.

The Dialog includes the following options:

Active : Indicates that the schedule subscription is active. If this box is not checked, the schedule subscription is

defined, but no schedule action will be applied to the power system.

Object Type : Use this selector to specify the object type that you want to subscribe to a schedule. Currently, Simulator

supports Generators, Loads, Line/Transformers, Shunts, Areas and Transactions. When you select an Object Type ,

three things happen:

The Object ID list is populated with the elements of the object type present in the power flow case and the

first element is displayed by default.

The Field selector is populated with the enterable fields corresponding to that particular Object Type and

the first field is displayed by default.

The type of the first field (Numeric of Yes/No) is identified and the Schedule selector is populated with the

existing schedules of that type.

Object ID: Use this selector to specify the particular object of a particular Object Type w hose field you want to

subscribe to a schedule. The Object ID has above it a string that indicates how the ID of the object is built depending

on the Object Type . For instance, when the Object Type is Generator, the Object ID is specified as the Bus Number

and then the Gen ID.

Select/View Objects : Press this button to bring up the Add Schedule Subscribers Dialog. This dialog is used to select

multiple objects of the specified type, for which a field will subscribe to the schedule. When multiple objects are

selected, the Object ID indices "Multiple Objects" followed by the number of objects that will be selected. If there are

objects whose fields are subscribed to a schedule, these objects will appear in the right side selection list, because

they are currently subscribing to the schedule.

Field: Use this selector to indicate the particular Field that you want to subscribe to a schedule. Depending on the

type, the Dialog indicates whether the Field should subscribe to a Numeric or a Yes/No schedule. Once you have

selected the Field, the Schedule selector is populated only with the schedules of that particular type.

Schedule: Use this selector to specify the schedule to which the Field should be subscribed to.

Time Shift: The time shift options can be used to delay applying the scheduled actions by the specified Delay Days

and Delay Hours. For instance, suppose that you have setup a schedule so that a new 100MW generating unit enters

online on March 10^th. The entering schedule is complex and consists of increasing the output in steps of 20MW each

hour starting at 10 am. Suppose that due to unexpected events, the connection of the unit must be put off by two days.

Instead of modifying the entire schedule, you could set a 2 day (positive) delay so that the unit enters online on March

12^th at 10 am.

Subscription Type : In addition to the time shift, the value "shape" defined by a numeric schedule can be altered by

making the subscription Relative .

Absolute : Select this option so that the field takes the exact value specified in the schedule.

Relative : The numeric values of the schedule can be altered by a Multiplier and a Value Shift. In this linear

modification, the value of the field that is applied to the power system will be equal to:

Actual Field Value = Multiplier * Schedule Value + Value Shift

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PowerWorld Simulator version 11. Manual - page 16