lab4 – ac contingency calculation report · lab 4 – create ac contingency calculation report -...

LAB4 – AC CONTINGENCY CALCULATION REPORT

WESTERN AREA POWER ADMINISTRATION

Lab 4 – Create AC Contingency Calculation Report

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PURPOSE: The purpose of this lab is to introduce the contingency file, monitor file, and the subsystem files. This lab will explain how the three files are utilized by the AC Contingency Calculation (ACCC) feature of PSS/E to perform a power flow study on a particular zone. This lab will introduce the following aspects:

Introduction to power flow study Contingency file (*.con) Monitor file (*.mon) Subsystem file (*.sub) ACCC Using the *.con, *.mon, and *.sub to create an ACCC report

To properly perform this lab, start PSS/E and open the sample.sav file. Refer to Lab 1 on how to do this. Introduction to power flow study The power flow study that will be conducted in this lab will be based on the sample.sav file. The base case, or system intact, is a fully operational system in which everything is working the way it was intended to. However, in a real world scenario the system is not always functioning within its operating limits. In addition, if a change to the system is required, it is desired to have a way to predict the positive and negative effects that may arise with the change. In lab 3, lines were manually switched out of service to simulate how the grid reacts due to the contingency. The slider file that was manipulated is just a piece of the whole system. It would be very hard to grow the whole system into a slider file to see all the overloads that may occur when a contingency is taken. This lab will explain how to automatically take contingencies and view all the overloads due to the outages. Contingency file (*.con) The contingency file is programmed to remove equipment, one piece at a time from service; this is referred to as a contingency. When the system is fully operational, it has no outages, and is referred to as system intact or (N-0). When a single line is taken out of service, the case is then referred to as an (N-1). The easiest way to program how to do this is to see a portion of the code used in the *.con file and understand what everything does. Here is a portion of a contingency file. COM COM Contingency Description File for SAMPLE Study, Outages COM TRACE CONTINGENCY NUC-MD5 TRIP LINE FROM BUS 151 TO BUS 152 END CONTINGENCY NUC-HYDR TRIP LINE FROM BUS 151 TO BUS 201 END END


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Trace starts the program. The next line names the (N-1) contingency. The third line describes which line will be removed. The next line ends the contingency. Then the process is repeated for all (N-1) contingencies that are desired. Monitor file (*.mon) The monitor file tells the power flow simulator which branches to be supervised during the (N-1) contingencies. A sample of the monitor file will now be given: COM COM Monitored Element Description File for SAMPLE Study, Outage COM MONITOR BRANCHES IN SUBSYSTEM OVERAL MONITOR VOLTAGE RANGE SUBSYSTEM OVERAL 0.90 1.10 MONITOR VOLTAGE DEVIATION SUBSYSTEM OVERAL 0.5 0.5 MONITOR INTERFACE ZONE6H RATING 500 MW 152 3004 3002 3004 END END The first line after the comments informs which branches to monitor in the subsystem named ‘OVERAL’. The second line sets a per unit voltage range for that subsystem. The third line gives a +/- deviation from the prescribed values in line two. The fourth line indicates the power rating for a defined set of lines. The following two lines tell exactly which branches to monitor (from bus # to bus #). The first END ends that particular zone to be monitored. This is repeated for each additional zone that may be of interest, and this file is completed with a final END to stop the monitor file. Subsystem file (*.sub) The subsystem file informs the power flow analysis to only look at a prescribed section, or zone, of the overall network. A sample of the subsystem file will now be given: COM COM System description file for SAMPLE FLOW STUDY COM SUBSYSTEM OVERAL BUS 101 BUS 102 BUS 151 BUS 152 BUS 153 BUS 154 BUS 155 END END The first line after the comments names the subsystem ‘OVERAL’ as indicated in the monitor file. The seven bus number lines indicate which busses are to be included in the subsystem. The first end stops the subsystem and the final end concludes the file.


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ACCC The contingency, monitor, and subsystem files are utilized by the AC Contingency Calculation (ACCC) feature of PSS/E to perform a power flow study on a prescribed zone. The ACCC produces an analysis of the power system. Using the *.con, *.mon, and *.sub to create an ACCC report For the purpose of this lab a sample.con, sample.mon and sample.sub file are provided as examples to perform an ACCC analysis. Start PSS/E and load the sample.sav file. To perform an ACCC analysis click on the “Power Flow” drop down menu and select “Solution” “AC contingency solution (ACCC)”. The AC Contingency Solution window will be displayed:


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A Distribution Factor Data File (DFAX) needs to be created by loading the provided sample.con, sample.mon and sample.sub files. Click on the “Create DFAX” button, and the “Build Distribution Factor Data File” window will be displayed: Click on the three dots next to the “Subsystem description data” text field to load the sample.sub file. Locate the directory containing the sample files to select the sample.sub file and click “Open”. The sample.sub file will be loaded in the Subsystem description data text field in the Build Distribution Factor Data File window.


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Next, click on the three dots next to the “Monitored element data” text field to load the sample.mon file. Select the Sample.mon file and click “Open”. The sample.mon file will be loaded in the Subsystem description data text field in the Build Distribution Factor Data File window. Now, click on the three dots next to the “Contingency description data” text field to load the sample.con file. Select the Sample.con file and click “Open”. The sample.con file will be loaded in the Subsystem description data text field.


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Next, a location for the DFAX output file needs to be assigned. This is done by clicking on the three dots next to the “Distribution factor data output file” text field. Select the File name text field, type “sample.dfx” to name the DFAX output file, and click “Open”. This will create the output file in the directory listed in the window and can be created in a different directory if needed. The sample.dfx file will be loaded in the Distribution factor data output file text field in the Build Distribution Factor Data File window. The Build Distribution Factor Data File window will look like the one below after all the sample files and Distribution factor data output file have been specified. Click “OK” to return to the AC Contingency Solutions window, with the sample.dfx file loaded in the Distribution factor data output file text field.


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Finally, a location for the ACCC output file needs to be assigned. This is done by clicking on the three dots next to the “Contingency solution output file” text field. Select the File name text field, type sample.acc to name the ACCC output file, and click “Open”. This will create the output file in the directory listed in the window and can be created in a different directory if needed. The sample.acc file will be loaded in the Contingency output file text field in the AC Contingency Solution window as shown below: Click “Solve” to solve the system with the loaded sample files. Now, click “Reports” to load the AC Contingency Reports window:


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Leave everything set to the default values and click the “Go” button to run the ACCC report. Click “close” to exit the AC Contingency Reports window, click “close” again to exit the AC Contingency Solutions and return to the terminal window. Click on the report tab to view the completed ACCC Report.


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The monitored branch section shows all the branches that were overloaded due to a contingency. The contingency section shows which branch was automatically taken out of service by the ACCC, which resulted in an overload. The base case contingencies show the system intact overloads before any branches were removed from service. Scroll to the right on the report window to view the rating of the line in MWs, the power flow of the line in MWs, and the percent overload. At the bottom of the report the Monitored voltage report & Contingency legend can be seen, but is not of significant importance for this lab.


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Questions The “sample.sav” data file must be open to perform this section of the lab. Using the “sample.con” contingency file, the “sample.mon” monitor file and the “sample.sub” subsystem file that have been provided, create a “sample.dfx” DFAX and a “sample.acc” AC contingency file. Solve the system with the loaded sample files and run the ACCC report as shown above. View the report generated by PSS/E and print out the report, this print out will need to be included in the lab report. It will also be helpful in answering the following questions. 1) Which six branches suffer from overloads during the “BASE CASE” contingency

and what is their percentage of overload? Branch Percentage overload

2) Looking at the “NUC-HYDRO” contingency, which branches suffer from

overloads that did not suffer from overloads during the “Base Case”, and what is their percentage of overload?

Branch Percentage Overload

3) Of the branches suffering from overloads during the “Base Case”, which one(s) got worse during this contingency (NUC-HYDRO), and by how much?

Branch Percentage Overload Increase

4) Did any of these branches actually see a reduction in overload, if so, which ones and by how much were they reduced? ________ __ ____ __ ____

5) Which of the contingencies created the highest number of overloaded branches?

___ ____ __ __ Which branch was taken out of commission in this contingency? __ _ ____ __ __ __ __


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4) Find the “DNTN-CAD” contingency. What is the rating of the branch between bus #202 and #203 (in MW) and what is the actual power flow (in MW) on this branch? __ __ __ What is the rating of the branch between bus #204 and #205 (in MW) and what is the actual power flow (in MW) on this branch? _ _ __ _ _ Assuming a power factor of 0.9, how much actual power (in MVA) must the power company provide to each of these overloaded branches?_______________ _________________________________________________________________ How much actual power (in MVA) must the power company provide to each of these overloaded branches if the power factor was at 0.8, just 10% lower?

lab4 – ac contingency calculation report · lab 4 – create ac contingency calculation report -...

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