PSS/E Tutorial

ECE 422, EECS, UTK

April 21, 2020

Instructor: Dr. Kevin Tomsovic

Guest Lecturer: Dr. Hantao Cui

Remote Desktop Access to PSS/E2Connect to the EECS Remote Desktop2User Interface Overview2Workspace2Open / Save Data3Power Flow Study8Run the Solver8Contingency Analysis11Create Description Files11Run ACCC (AC Contingency Calculation)14Generate and Browse Report14Time Domain Simulation17Simulation Setup17Apply Disturbances20Plot Simulation Results22

1. Remote Desktop Access to PSS/Ea. Connect to the EECS Remote Desktop

Server addresses:

RD0.eecs.utk.edu

RD1.eecs.utk.edu

RD2.eecs.utk.edu

RD3.eecs.utk.edu

RD4.eecs.utk.edu

Use a remote desktop tool to connect to one of the servers. Remote desktop tools are Remote Desktop Connection on Windows, Microsoft Remote Desktop on macOS, or Remmina on Linux. Use the same server every time you perform studies, as data is not shared across servers.

Tip:

You will need to use the UTK VPN before connecting. Check the OIT documentation for a complete setup guide at https://help.utk.edu/kb/index.php?func=show&e=2712.

It is the EECS policy that data is not permanently stored on the servers. You can either copy the working data to local or save it to H:\, the T-Storage Drive.

2. User Interface Overviewa. Workspace

Siemens Power System Simulator for Engineering (PSS/E) can be found on the desktop. There are two icons, one with Parallel ACCC and the other one without. Use the one named “PSSE 33” as shown in the following.

Right-click on the icon, select “Open” and wait, as the software could take a moment to open. It is not necessary to double click for many times, as it will end up opening many Windows.

You might be greeted by a message for your first run.

The main window of PSS/E looks like the following

There are several areas, such as the menu, toolbar, tree view, and output box as marked above.

There are lots of buttons in the toolbar. All buttons can be found on the menu, so there is no need to memorize all buttons. The tutorial will use menu options for most examples.

b. Open / Save Data

All studies start with loading data files. Use “File - Open” to open file “WECC_noWind.raw”. It is likely that the file extension is hidden, and the file is associated with another application. This will not affect studies in PSS/E, as long as the file is opened with it.

There could be two or more PSS/E files in the folder. The file with the extension of “.raw” (“the RAW file” hereafter) is the power flow data file. The file ending with “.dyr” (“the DYR file” hereafter) is the dynamic data file. You might also find a file with “.sld” ending for the single line diagram among others.

PSS/E works with many different files because it is composed of many so-called subroutines. Each subroutine reads one or more files, does the number crunching, and spit out the results as files. The user interface is just a shell for invoking the subroutines with the correct inputs. Therefore, the essence of using PSS/E is to find the subroutine you need from the menu, specify the correct inputs, and let it run. Of course, all these are based on your understanding of power system analysis as an engineer.

After opening the file, you can see a spreadsheet of network data open in the main window. Notice the name tab, “Network data”, at the top, as well as the model tabs at the bottom (Bus, Plant, …). Cells in light colors are modifiable from the model tab, and cells in dark colors are not.

Let’s open the DYR file. You will be prompted a dialog like the following, which contains advanced tuning of the data. Click on OK to continue.

A new spreadsheet labeled “Dynamics Data” will load as follows. First, notice that if you switch between “Dynamics Data” and “Network Data”, the bottom tabs will change accordingly. Second, there are lots of yellow cells, which is an indication of suspect parameter issues by the program. Engineers need to check the parameters carefully to avoid errors. However, it does not guarantee issues. For models like our WECC system, which contains highly aggregated dynamic data, these alarms can be carefully ignored.

Data can be modified by double-clicking on a cell. You will be allowed to either edit the value or be prompted for a dialog for editing.

Warning:

Data being edited with a pencil to the left of the row has not been saved. Press Enter to save the change, and the pencil will disappear. Data change will be confirmed in the output window.

Before saving

Confirmation after saving

Clicking on a column header and then right-clicking on the selection can open the context menu, where you can find or filter values.

To save data into files, select from the top the data to save (Network data or Dynamics data), and open “File - Save”. The Save dialog will be different, depending on the data.

Important:

Always save Network data in the “Power Flow Raw Data” format and Dynamics data in the “Dynamics Model Data” format. These two formats are plain text-based, which are easy to edit, and are the most commonly used.

Also, check carefully that you are saving to a data file, not outputting to the report window.

Tip:

Save your work regularly, as the program might become unresponsive.

Exercise:

· Load the WECC_noWind.raw file and apply a filter to Voltage (pu) for values greater than 1.15 or less than 0.85. There should be six buses that satisfy this condition.

· Repeat the above filtering but for values greater than 1.2 and 0.8. You should see an empty sheet.

3.

3. Power Flow Studya. Run the Solver

To perform a power flow study, switch to Network data. In the menu bar, find “Power Flow” and open “Power Flow - Solution - Solve (NSOL/FNSL/FDNS/SOLV/MSLV)”.

In the dialog, you will be asked to choose the method and configure the solver. We choose Newton and perform a full Newton-Raphson solution with the following parameters. Click on “Solve” once.

In about a second, you will find the output in the output bar. The values in the spreadsheet have been updated to reflect the solution. Depending on the initial values, the new values could be different or the same as the input.

Exercise:

· Set the angle of Bus #1 (CORONADO) to 0 deg and attempt the solution. Notice the spreadsheet update after the solution.

· In the “Fixed Shunt” model tab, switch out the shunt on bus #103 GATES by unchecking the “In Service” box and run the power flow. Notice the voltage change on bus #103. Note: make sure your change is saved before solving power flow.

· Switch in the fixed shunt on bus #103 and adjust the value to -100 (Mvar). Solve the power flow again and observe the voltage change.

· Add a Fixed Shunt on bus #164 with a B-Shunt capacity of -10 and solve the power flow. You will need to scroll to the bottom of the Fixed Shunt spreadsheet to add an entry. Observe the voltage change on bus #164.

· Save the solved Network data to a new RAW file.

4. Contingency Analysisa. Create Description Files

In the menu “Power Flow”, open “Power Flow - Linear Network - Create/modify SUB, MON and CON configuration files”. These files will define the subsystem and contingency types for screening.

A dialog will open as follows. In section “Subsystem Description Data file”, click “Select…” on the subsystem selector window. Click to highlight the area on which contingency analysis will be performed, for example, “38 CNTCOAST”, and click on “>” to add it to selected areas. You can also use the tabs to select by the owner, zone, voltage level, or bus. Click OK to close the “Bus Subsystem Selector” window.

Notice that the number of buses in the Network data spreadsheet has been filtered to the selected area.

Tip:

If you want to switch back to unfiltered view (all buses displayed), select all zones with “>>” and apply. This is useful when you are done with contingency analysis.

Next, back to the Configuration File Builder. In the “Subsystem Description Data file” section, come up with a name and type in the “Subsystem name” box. Here, the example uses the same name as the selected zone.

Then, in the “Monitored Element Data File” section, adjust the bus voltage range based on the base case voltages of your selected zone, since some areas have high initial voltages.

In the “Contingency Description Data file” section, select the types of contingencies for screening. The example here only selects “Single contingency” (N-1) and “Include tie-lines”.

Finally, for each section in the dialog, deselect the “Append … to existing file”. For each section, click on the “...” button to specify the path for saving the corresponding file. You will need to provide a file name for each of them. You can use the same name for all three because the file extensions are different.

The configured builder should look like the following. Click on “Go” to create config files. Do not close the dialog yet.

Click on “DFAX..” to open the Build Distribution Factor Data File dialog. It should have all three input files prefilled. Click on the lower-right “...” to create a file for the distribution factor data, and click “Save”. The completed window should look like the following. Click OK to generate the dfx file and close the Build Distribution Factor Data File dialog.

Back to the Configuration File Builder. Click “Close”. Now, we have generated files for contingency analysis.

b. Run ACCC (AC Contingency Calculation)

From the menu “Power Flow”, open “Power Flow - Contingency, Reliability, PV/QV analysis - AC contingency solution (ACCC)” to open up the AC Contingency Solution dialog. You will find the Distribution factor data file preloaded. Click on the “...” button next to the “Contingency solution output file” to create the file (.acc). The resulting dialog should look like the following. Click “Solve” to run. Do not close the window yet.

Depending on the size of the zone and the selected contingency types, the analysis may take a few to several minutes to complete. The progress will be printed to the output window.

Once the calculation is done, the output window should look like the following.

c. Generate and Browse Report

Click “Reports…” from the AC Contingency Solution dialog to open the “AC Contingency Reports” window. Use all default settings and click “Go”. It might as well take a few minutes to process.

When done, click “Browser…” to open the Accc Post-Processor program. This is a tool that displays the ACCC report, and it takes a couple of minutes to load.

The front page of the Browser is a summary of the result file, including the options, result filtering criteria, and performance.

Here, we can see two voltage deviation violations are detected, which means two contingencies have larger voltage deviations than the defined value.

At the bottom, you can find Network, Flow Elements, and Voltage Elements reports. Pay attention to the user flow of the user interface. For example, when looking at the Networks tab, you will need to select a contingency scenario, from the “Performance Summary” in order to browse the corresponding Flow report and Voltage report.

Exercise:

· Find out the two voltage deviations.

· Hint: start from Voltage Elements, find the contingencies that cause the deviation violation.

· Locate and select the corresponding contingency in Networks - Performance Summary, and look at the voltage report, column “Violation”.

5. Time Domain Simulationa. Simulation Setup

Load a clean system by opening the RAW and DYR files in sequence. Loading a clean system helps to clear the internal states and reduces the chance of a program crash. Solve the power flow to obtain the steady-state condition.

In the menu “Dynamics”, open “Dynamics - Simulation - Perform simulation (STRT/RUN)”.

You will be asked to convert loads from constant power to ZIP based on the percentage. Use the default values, namely, 100% constant current for active power load, and 100% constant admittance for reactive power. Click “OK” to continue. The output should print the following.

Warning:

Once you convert loads, you will not be allowed to perform power flow calculation for the loaded system. If you need to start over, reload the RAW and DYR files.

A Perform Dynamic Simulation dialog will open. We will need to set up the “Channel” file to which variable outputs will be saved. In the menu “Dynamics”, open “Dynamics - Channel Setup Wizard” to open the wizard, shown as follows.

Most commonly used variables have been selected, such as generator angle, speed, and bus voltages. In the bottom “Select” section, you can select subsystems as we did in contingency screening, or use the default “All buses”. Click “Finish” to set up.

The output window will print a series of messages, ending like the following.

Back to the Perform Dynamic Simulation window. Click “...” to specify a file name for the channel outputs. Next, adjust the “Print every 1 time steps” to 100 to reduce the printing overhead. The dialog should look like the following.

Notice that the initial simulation time is “-0.0167”. It means that no prior simulation was run. To start, we need to initialize dynamic models. Initialization is the process for calculating the initial values for numerical integration, as power system simulations start from a steady state.

Click “Initialize”. The initialization output will be printed and should look like the following.

Make sure that it says “INITIAL CONDITION CHECK O.K.”. Otherwise, initialization has failed and the simulation result will be invalid.

b. Apply Disturbances

We usually apply disturbances a short while after t=0 to check the correctness of the initialization. Curves should be exactly flat before any disturbance.

Let’s run to 1 sec before applying our disturbance. Note that the 0.0083 secs is the step size throughout the simulation. Change “Run to -0.0167” to 1 (as follows) and click “Run”. The output window will start printing until the simulation runs to 1sec.

Next, the example will show a Bus Fault on Bus 80 BURNS at t=1, following by a line trip between Bus80 BURNS to 98 BURNS1, Circuit ID #1 to clear the fault.

In the menu “Disturbance”, open “Disturbance - Bus Fault” to open dialog Apply a Bus Fault. Click “Select…” to select Bus 80. Then, enter “1e+10” in the Admittance X box. This puts a large susceptance at the bus (effectively adding a short-circuit).

In the output window, you will find the message of an added shunt. You can also find the added shunt in the “Fixed Shunt” tab of Network data.

Back to the Perform Dynamic Simulation dialog, run to 1.1 seconds.

Next, clear the disturbance from the menu “Disturbance - Clear Fault”. Select the existing fault and click “Go”.

The output should say shunt deleted.

At the same time, to represent a realistic fault clearing, we also need to remove the line between Bus80 BURNS to 98 BURNS1, Circuit ID #1. In the menu “Disturbance - Trip Line”, use “Select” to select the line as follows.

After clicking on “OK”, the output should say the removal of a line.

Run the simulation until 10 seconds. This might take a while to complete. When done, close the dialog.

c. Plot Simulation Results

The simulation outputs have been saved to the Channel Output file (.outx or .out). To plot the results, we will use “Plot Book”. Use “File - New” or click on the first button in the toolbar

and select Plot Book to create a new book. An empty Channel Plot page will show up.

Use “File - Open” to open the channel output file (.outx). It might take a moment to load, and PSS/E could appear frozen. After loading, switch to the “Plot Tree View”, the last one in the Tree tabs.

In the Plot Tree View, you will find the Channel Files by expanding the folder. Locate the variable to plot and drag it to the plot book. You can drag multiple variables to the same book to compare.

In the plot, verify that the curves are flat until 1 second. Otherwise, the initialization was not successful and the results cannot be trusted.

A Plot Book can have multiple pages. Right-click on any empty areas in the book to insert a new page.

Exercise:

· When converting load at the beginning, use 100% constant power for both active and reactive power and repeat the example. Can the simulation finish? Are there differences in the generator speed response?

· Apply a Bus fault at t=1 on Bus #107. After 0.1 seconds, clear the fault and trip the line 107-108, Circuit Id 1. Observe the bus voltages on 108. What is the largest deviation?

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