Application Note
Testing a relay's power swing impedance characteristic with Advance Distance Module Author Anucha Semjan Semjan Date Oct 22, 2013 (first version: Nov 24, 2010) Related OMICRON Product CMC, Test Universe Application Area Area Protection Systems Keywords Power Swing, Advance Distance Module, Zone Characteristic Testing Version v1.1 Document ID ANS_10010_ENU ANS_10010_ENU
Abstract The power swing detection is a function which is usually used to improve the operation of distance protection. The relay has to discriminate between the fault and the power swing conditions because for both cases the impedance trajectory could enter the protected zone and cause unwanted tripping. For testing this function two procedures are normally performed. The first is to test the power swing impedance characteristic, the inner and the outer zone, and also the delay time. The second is to test the power swing blocking function. The Application Note describes these tests using the OMICRON State Sequencer Test Module.
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General information OMICRON electronics GmbH including all international branch offices is henceforth referred to as OMICRON. The product information, specifications, and technical data embodied in this application note represent the technical status at the time of writing and are subject to change without prior notice. We have done our best to ensure that the information given in this application note is useful, accurate and entirely reliable. However, OMICRON does not assume responsibility for any inaccuracies which may be present. OMICRON translates this application note from the source language English into a number of other languages. Any translation of this document is done for local requirements, and in the event of a dispute between the English and a non-English version, the English version of this note shall govern.
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Content
1
Safety instructions .......................................................................................................................... 4
2
Introduction ..................................................................................................................................... 5
3
How to Prepare and Test................................................................................................................. 6
4
3.1
Test Connection........................................................................................................................ 6
3.2
Test Object ............................................................................................................................... 6
3.3
Hardware Configuration............................................................................................................ 8
3.4
Test View.................................................................................................................................. 8
Relay List ........................................................................................................................................12
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Safety instructions This application note may only be used in combination with the relevant product manuals which contain all safety instructions. The user is fully responsibility for any application that makes use of OMICRON products. Instructions are always characterized by a symbol even if they are included to a safety instruction.
DANGER Death or severe injury caused by high voltage or current if the respective protective measures are not complied.
Carefully read and understand the content of this application note as well as the manuals of the involved systems before starting its practical application. Please contact OMICRON before you continue the process if you do not understand the safety instructions, operating instructions, or parts of it. Follow each instruction mentioned there especially the safety instructions since this is the only way to avoid danger that can occur when working at high voltage or high current systems. Furthermore, only use the involved equipment according to its intended purpose to guarantee a safe operation. Existing national safety standards for accident prevention and environmental protection may supplement the equipment’s manual.
Only experienced and competent professionals that are trained for working in high voltage or high current environments may perform this application note. Additional the following qualifications are required: •
authorized to work in environments of energy generation, transmission or distribution and familiar with the approved operating practices in such environments.
•
familiar with the five safety rules.
•
good knowledge of the OMICRON CMC Test Set and Test Universe software.
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Introduction The power swing detection is a function which is usually used to improve the operation of distance protection. The relay has to discriminate between the fault and the power swing conditions because for both cases the impedance trajectory could enter the protected zone and cause unwanted tripping.
There are various methods for detecting the power swing condition. Using two impedance zones, defined as the outer and the inner zone, with a delay timer is a method widely used (see the figure 1). When the impedance enters the outer zone, a delay timer is started. If the impedance is within the area between the outer and the inner zones longer than the time setting (delay time) the power swing detection will pick up. This signal is used to block the operation of the distance protection function.
Figure 1: Power Swing Detection Logic
According to the figure above, two procedures for testing are normally performed. The first is for testing the power swing impedance characteristic, the inner and the outer zone, and also the delay time. This test procedure is used to verify that the elements are properly set up for detecting the power swing. The OMICRON Advanced Distance Test Module is used for testing, and described in this Application Note. The second is for testing the power swing blocking function. This test procedure is used to verify that the distance relay will not send an unwanted trip command in case of a power swing condition. The Application Note "Testing a Relay's Power Swing Blocking Function with State Sequencer" describes how to test this item by using the OMICRON State Sequencer Test Module.
Remark:
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This Application Note can be used only if the relay uses a logic similar to the above description for detecting the power swing and also the alarm contact for power swing detection must be available.
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How to Prepare and Test
3.1
Test Connection Connect the voltages and currents from the CMC Test Set to the relay. It is important for this application that the output power swing detection from the relay which is usually available on site for signaling has to be connected to the binary input of the CMC Test Set as trigger condition.
The binary input 7 will be used, for instance, in this document. Any other binary input can be used as well.
Figure 2: Connection Diagram
3.2
Test Object Create the power swing zone characteristic for the inner and the outer zones according to the setting parameters in the relay and also the same characteristic as shown in the relay instruction manual. Select the Type for the inner zone as "Non tripping" and the outer zone as "Tripping".
Enter the trip time values for the outer zone at the Trip Time tap to be the same setting as the delay time which is used to detect the power swing. 200 ms will be used in this document.
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Figure 3: Test Object Setup
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3.3
Hardware Configuration Assign the binary input 7 as trigger condition.
Figure 4: Hardware Configuration Set Up
3.4
Test View >
Go to the Trigger tab, and set the trigger condition with the binary input 7 (PSB Detect).
Figure 5: Trigger Condition
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>
Enter your values at the Times group of the Settings tab. The Prefault time must be greater than the reset time of the power swing detection so that the impedance stays outside from the outer zone long enough.
Enter Max fault duration. This value must be greater than the delay time used in the logic above (see figure 1)
>
Figure 6: Fault Time Setting
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>
Select either Search Test or Check Test for testing the characteristic. Click the "Add" button to add the search line as required. Only the three phase fault type will be used for testing. The figure below shows the test result of a REYROLLE OHMEGA relay for rectangular shape.
Figure 7: Test Result by Using Search Test
Figure 8: Test Result by Using Check Test
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Select Shot Test tab for testing the delay time. Click the "Add" button to add the defined test point in the area between the outer and the inner zone. Only the three phase fault type will be used for testing.
>
The figure below shows the test result of a REYROLLE OHMEGA relay for rectangular shape.
Figure 7: Test Result by Using Shot Test
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Relay List The list below names examples of relays which can be tested using this Application Note. Other relays which not in the list but using the same concept can be tested in a similar fashion.
1. 2. 3. 4.
ABB REL511 REYROLLE OHMEGA TOSHIBA GRZ100 GE D60
The figure below shows the logic diagram of the relays for which this Application Note can be used.
Figure 8: The Power Swing Detection Logic Diagram of ABB REL511
Figure 9: The Power Swing Detection Logic Diagram of TOSHIBA GRZ100
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Figure 10: The Power Swing Detection Logic Diagram of GE D60
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