Location

This example model can be found in the Software Example model library: Protection → Distance_21_POTT → bank → hnk → Distance_Relay_POTT.ecf.

User can select a location for this example to be stored. Afterwards, a folder with the TestView project will be created at the selected location. The folder can be seen in the following picture with the name DISTANCE_21_POTT. 

Description

The model includes a 300 km, 500 kV transmission line for the demonstration of the 21 MHO Distance Relay. More information about the distance relay can be found on MHO Distance Relay page. 

Both relays, 'Local relay' and 'Remote Relay' are configured with Zone 1 to protect the first 80% of the line with a time delay of ½ cycle to avoid overreaching, and Zone 2 to protect 120% of the line with a time delay of 200 ms. Two different test cases: POTT disabled and POTT enabled on local relay are used to explain the operation of 21MHO Distance relay. 

Following are the parameters set for both the relays. 

Simulation and Results

Test 1: Fault in Zone 2 for Local Relay and POTT is disabled

In this test, a single-line-to-ground fault is applied in Zone 2 of the local relay and Zone 1 of the remote relay. POTT is disabled.

• The relay settings are in the previous section. Go the ‘Settings’ tab in the parameter form of the 21MHO1 and 21MHO2, uncheck ‘Enable permissive tripping’ to disable the permissive tripping scheme if it is selected. 

• Open the parameter form of L1, change the ‘Distance of fault from (+) side’ to 270 km, so that the fault occurs in Zone 2 of 21MHO1. In the ‘Timing’ tab, configure the fault to occur at t=0.2s. Select ‘Phase operated’ to be Phase A and Ground in order to simulate a single-line-to-ground fault.

• Start the simulation. You can run it at localhost and offline as target settings or on a simulator in real time. The results won't be different from what is shown in this page.

• Launch ScopeView and open template: ‘Distance_Relay_POTT.svt.’ from the project folder shown in the picture below.

• Check Sync and Trig, and start data acquisition.

From Page ‘Relay1’ as shown in below figure, it can be seen that Phase A fault current reaches a peak value of 3720A and Relay 1 is asserted at t=0.4112s, which is 0.2112s after the fault occurs. The breaker receives the trip command and opens the three phases to isolate the fault.

Relay1 trips 211.2ms after the fault occurs because the fault is in its Zone 2, which features a time delay setting of 200ms. Since POTT scheme is not enabled, Relay1 Zone 2 only trips when the fault is detected in Zone 2 and remains in Zone 2 for a duration longer than the time delay.

Below figure shows Page ‘Relay2’ in the template, it can be seen that Relay 2 trips at t=0.2166s, which is 0.0166s after the fault occurs. This is because the fault falls in the Zone 1 of Relay 2.

Below figure shows the measured impedance locus seen by Relay 1. The circles in red and blue represent the protection zones. It can be seen that the measured Phase A impedance (in green) enters and stays in the Zone 2 circle.

Test 2: Fault in Zone 2 for Local Relay with POTT enabled

In this test, the same single-line-to-ground fault is applied in Zone 2 of the local relay and Zone 1 of the remote relay. POTT is enabled.

• To enable POTT scheme, check ‘Enable permissive tripping’ block in ‘Settings’ tab of 21MHO1 and 21MHO2 parameter form. It is seen in the picture below.

• Do not change the fault settings and let it be as before. 

• Run the simulation (if it has been stopped), open ScopeView template and do an acquisition with Sync and Trig on.

When POTT scheme is enabled, Relay 1 receives the permissive tripping signal from Relay 2 and detects the fault in its Zone 2, thus Relay 1 trips at t=0.2112s and opens the breaker, as shown in below figure. 

Relay 2 acts in the same way as before. It detects the fault in Zone 1 and when the ½ cycle time delay is satisfied, the trip signal is asserted at t=0.2112s.

Below figure shows the measured impedance locus of Relay 1. Since the fault is closer to Relay 2, Relay 2 detects the fault first and sends a transfer trip to Relay 1. As soon as Relay 1 detects the fault in Zone 2, it trips. The impedance locus also shows that Relay 1 trips immediately after the Phase A impedance enters the Zone 2 circle.

The above results shows that for the two different test cases: Zone-2 fault with and without POTT (Permissive Overreach Transfer Trip), 21MHO-distance relay can pick up faults in different zones with corresponding time delay settings. POTT function can be enabled to accelerate the operation upon faults in Zone-2.

TestView Project

Introduction

A project in TestView, which is the automated testing tool in HYPERSIM, has been made to perform tests on the model in three cases which include 10 tests each: no POTT called POTT_DISABLED, POTT is enabled in relay 1 called POTT_ON_RELAY1, and POTT is enabled on both relays called POTT_ON_RELAY1&2. 

In each test, a different type of fault is injected at a different location on the line. The table below shows the parameters for each test. 

The following sections will describe how to set up the test cases and run them, and also shows the results. For more information about TestView in general and how to create different examples with it , please refer to TestView on Confluence.

Step-by-Step Guide

This guide shows you how to open the project in TestView, set it up successfully, and run one test case POTT_DISABLED. By following the guide and running the test case, you should be able to run the other two without any problems.

• Open Distance_Relay_POTT.ecf model from the folder DISTANCE_21_POTT\bank\hnk of the folder in which you've saved the example model.

• 

  Open TestView by clicking on the TestView button in the HYPERSIM tab at the top left side of the screen under Tools. If it asks to do an analysis, answer "Yes".

• 

  In TestView, choose Open Project from File. When the window opens, find DISTANCE_21_POTT.prj from the folder in which the model is saved.

• Expand DISTANCE_21_POTT from the "project" panel on the left to open three tests. Double-click on the "POTT_DISABLED" test.

• 

  In the panel that will open on the right, double-click on the "Table: [Export operate time to Excel report]" tree node.

• 

  Under "Excel export options", specify your Excel File Path by pointing to DISTANCE_21_POTT.xlsx which you can find in the model directory. Press "Apply" or "Unlock and Apply" to close the dialog. If you get a notification about unlocking the test, press Yes.

• Double-click on the "HypExcel_1" tree node.

• 

  In the next window, click on "..." next to Excel File Path.

• 

  On the next window, choose the same exact excel file in the model directory as before. Press Select HYPERSIM Excel File and afterwards, press Apply.

• 

  Double-click on the "HyperWorks Test" tree node.

• Update your session ID by changing your user name in the string. The string's format should be:  /Hypersim/%WINDOWS_USER%/HyWorks-1, where %WINDOWS_USER% is your Windows user name. Press Apply.

• Double click on In the second toolbar 'HyperWorks Settings' as shown below.

• Click on the "HYPERSIM Connections ..." button which is the two computers icon as highlighted below.

• In the next window, make sure the "Current design" section has your name and the name of the .ecf file from the folder DISTANCE_21_POTT\bank\hnk.

Otherwise, you need to Disconnect the current host, change the Current design to the model name and Connect again. Once the correct file is selected, press Close.

• Back in "HyperWorks Settings" menu, find the Sensors selection. If there is no sensor file selected and it is showing "none", click on the "..." next to it. If there is already a sensor file DISTANCE_Relay_POTT selected. Or if it shows in the drop down menu, then you can skip to the Load Preferences step.

• The next window is to choose the sensor file for the project. Click on Files of type at the bottom and choose "All files".

• 

  Move to the model folder and find the sensor file "Distance_Relay_POTT.csv" from DISTANCE_21_PIOTT\bank\hnk folder. Find the file and click on Select Sensor-IO.

• The file will be loaded and in the Sensors selection of HyperWorks Settings menu.

• 

  In the HyperWorks settings menu, click on "Load Preferences from HYPERSIM" and press "Apply". Now you can close the HyperWorks menu.

• On the testview window, right-click on the "POTT_DISABLED" test in the "project" panel on the left and click Save.

• 

  In the middle panel, under "View" tab, choose how to process the results. If you press Show under Processing, once you run the test sequence, for each test, ScopeView opens with the specified diagrams (from relay 1 and relay 2) and you have to press OK to move the test to the next one. If you don't choose this option, the test sequence will go through the 10 tests without showing the ScopeView graphs.

• In the middle panel, under the "Runner" tab, click the purple play button.

NOTE: If the test does not run successfully, the window 'Stdout' displays the error message. Debug the model accordingly and re-run the test again to automate the results. 

• While the test is running, you can check out Stdout to see the test parameters.

• If Show is enabled in the View → Processing option, after passing each test, you will see a ScopeView template with two pages. Page 1 shows the results for Relay 1 and Page 2 shows the results for Relay 2.
  The graphs that are shown at each page from top to bottom are: Voltage input to the relay, Current input to the relay, and the output Trip signal of the relay.

• You can press OK to move to the next test.

NOTE: If you don't wish to view any more results, simply disable Show from View → Processing and press OK on the ScopeView template.

• After the tests are done, you can see its notification in stdout.

• Try and run the two other tests: POTT_ON_RELAY1 and POTT_ON_RELAY1&2 by following the same steps.

Test Results

The test results are stored in the excel sheet DISTANCE_21_POTT.xlsx in the project folder. Find it and open it.

The file contains multiple sheets:

• General Information: Diagram and information about the example model

• Input: Parameters for each test such as Fault location and its operating phases. 

• Output: Test results for each test. They include the relay clearing and operating times for both relay 1 and relay 2.

• Plot: Plots of relay 1 and 2 operating times.

The picture below shows the Output sheet. The results of each test are placed in their respective section: POTT disabled, POTT enabled on one relay, and POTT enabled on both relays.

• The results can be analyzed, saved, copied, etc.
  very time the tests are run, the results are overwritten with new values and updated date.