Application Note
System-based Testing of Busbar Protection Author Florian Fink |
[email protected] Date May 12, 2017 Related OMICRON Product CMC – RelaySimTest – CMGPS 588 Application Area Busbar differential protection Keywords RelaySimTest, System Testing, Busbar protection, PTP Version v 1.0 Document ID ANS_17003_ENU Abstract Due to the high short-circuit power on a busbar system and to guarantee the continuity of power supply, it is necessary to switch off appearing faults selectively and in a short time. Busbar differential protection systems can provide these functionality for many different busbar topologies. To test such a protection system thoroughly, an application oriented approach with multiple test sets can be utilized. This application note describes how this could be done in an easy and comfortable way using the OMICRON RelaySimTest software. To perform a test a fault scenario is calculated based on the simulation of the power system network. The resulting voltages and currents for the different relay locations can be used to test the correct behavior of the differential protection system. Additionally RelaySimTest offers the possibility to control several distributed and time synchronized CMC test sets.
© OMICRON
Page 1 of 35
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. All rights including translation reserved. Reproduction of any kind, for example, photocopying, microfilming, optical character recognition and/or storage in electronic data processing systems, requires the explicit consent of OMICRON. Reprinting, wholly or partly, is not permitted. © OMICRON 2017. All rights reserved. This application note is a publication of OMICRON.
© OMICRON 2017
Page 2 of 35
Content 1
Safety instructions ................................................................................................................................5
2
About this application note ..................................................................................................................6
3
4
5
2.1
General requirements .....................................................................................................................6
2.2
What this application note describes ..............................................................................................6
2.3
Templates .......................................................................................................................................6
Numerical busbar protection................................................................................................................7 3.1
Considerations ................................................................................................................................7
3.2
Differential Measurement................................................................................................................7
3.3
Technical realization .......................................................................................................................8
3.4
System configuration ......................................................................................................................8
3.5
Tripping ...........................................................................................................................................9 3.5.1
Busbar selective measurement ......................................................................................................... 9
3.5.2
Check zone ....................................................................................................................................... 9
3.6
Breaker failure function ...................................................................................................................9
3.7
Short circuit in the dead zone of the coupling feeder .................................................................. 10 3.7.1
Coupling with one CT only .............................................................................................................. 10
3.7.2
Coupling with two CTs .................................................................................................................... 10
System under Test ............................................................................................................................. 11 4.1
Application example – Protected Area ........................................................................................ 11
4.2
Modelling the Busbar Topology in RelaySimTest ........................................................................ 11 4.2.1
Drawing the Topology ..................................................................................................................... 12
4.2.2
Enter Element Names ..................................................................................................................... 12
4.2.3
Configuration of Current and Voltage Transformers ....................................................................... 13
4.2.4
Configuration of Infeed Data ........................................................................................................... 13
4.2.5
Configuration of Circuit Breaker ...................................................................................................... 13
4.2.6
System verification .......................................................................................................................... 14
4.2.7
Configuration of Field Units and Central Unit .................................................................................. 15
Test sets configuration ...................................................................................................................... 17 5.1
5.2
Test setup .................................................................................................................................... 17 5.1.1
Test setup overview ........................................................................................................................ 17
5.1.2
Time synchronization and communication to test sets .................................................................... 18
5.1.3
Wiring check at bays with QuickCMC ............................................................................................. 19
5.1.4
Naming the CMC test sets .............................................................................................................. 19
Test sets configuration in RelaySimTest ..................................................................................... 20 The analog and binary signals must be connected to the corresponding CMC in- and outputs. ................. 21
© OMICRON 2017
Page 3 of 35
6
Test cases ........................................................................................................................................... 22 6.1
7
Suitable test cases ....................................................................................................................... 22 6.1.1
Test case 1 – Wiring and CT ratio check ........................................................................................ 23
6.1.2
Test case 2 – Stable load flow ........................................................................................................ 24
6.1.3
Test case 3 – Fault outside of bay A ............................................................................................... 25
6.1.4
Test case 4 – Fault outside of bay A – External Breaker Failure .................................................... 26
6.1.5
Test case 5 – Fault on busbar B ..................................................................................................... 27
6.1.6
Test Case 6 – Fault on busbar B – Breaker Failure Bay B ............................................................. 29
6.1.7
Test Case 7 – End Zone Fault ........................................................................................................ 30
6.1.8
Test Case 8 – Fault in the dead zone ............................................................................................. 30
6.1.9
Test Case 9 – Fault on busbar A – Rigid coupling .......................................................................... 32
List of Literature ................................................................................................................................. 34
© OMICRON 2017
Page 4 of 35
1
Safety instructions This application note may only be used in conjunction 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 with. Carefully read and understand the contents of this application note (as well as the manuals of the systems involved) before you start to work with it. Please contact OMICRON Support if you have any questions or doubts regarding the safety or operating instructions. Follow each instruction listed in the manuals particularly the safety instructions, since this is the only way to avoid danger that can occur when working at high-voltage or high current systems. Only use the equipment according to its intended purpose to guarantee safe operation. Existing national safety standards for accident prevention and environmental protection may supplement the equipment’s manual.
Only experienced and competent professionals who are trained for working in high-voltage or high current environments may perform the applications in this document. In addition 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 CMC test sets, CMGPS 588.
© OMICRON 2017
Page 5 of 35
2
About this application note
2.1 General requirements Before you get started with this application note, read the “Getting Started” manual [1] of RelaySimTest. Please make sure that you also have a good knowledge about the CMC test system.
2.2 What this application note describes This application note describes how busbar protection systems could be tested using RelaySimTest. Therefore it shows the following content: 1. 2. 3. 4. 5.
Numerical Busbar Protection (general information) Defining the System under Test Overview about the hardware test setup Defining the Test sets configuration Defining Test cases
This application note does not describe parameter tests. To test the protection thoroughly such tests are also recommended.
2.3 Templates For this application note a corresponding template is installed with setup of RelaySimTest. The template Busbar Protection double Busbar with Isolators.rstt contains the same system under test and test cases described in the application note. In addition the following templates for busbar protection are available:
Busbar Protection Breaker and a Half Busbar Protection double Busbar with bypass transfer Mode Busbar protection double Busbar with double Breaker Busbar Protection Ring Bus Topology Busbar Protection Single Busbar and Tie Breaker Busbar Protection with Reverse Blocking
© OMICRON 2017
Page 6 of 35
3
Numerical busbar protection
3.1 Considerations Due to the high short circuit power on a busbar system and to guarantee the continuity of power supply, it is necessary to switch off appearing faults selectively and in a short time. Busbar
I2
I1
I3 ...
In
Figure 1: Single busbar with n feeders
The current difference, which is the actual protection criterion in this case, is based on Kirchhoff's current law. This law says that the signed sum of all currents in a closed area must be zero. 𝐼1 + 𝐼2 + 𝐼3 + ⋯ + 𝐼𝑛 = 0 The occurrence of a busbar short circuit causes a differential current, which is the criterion for the protection.
3.2 Differential Measurement The differential current is calculated as follows: 𝐼𝑑𝑖𝑓𝑓 = |𝐼1 + 𝐼2 + 𝐼3 + ⋯ + 𝐼𝑛 | Due to CT measurement errors and in case of CT saturation on high-current faults located outside, differential currents can occur. This is the reason why a restraint characteristic is used. The limit of the differential current depends on the restraint quantity IRT (stabilization quantity IStab) as show in Figure 2 below. 𝐼𝑅𝑇 = |𝐼1 | + |𝐼2 | + |𝐼3 | + ⋯ + |𝐼𝑛 | IDiff
k
Operating Region
87P or IDiff>
Restraining or Stabilization Region
IRT or IStab Figure 2: Restraint Characteristic
© OMICRON 2017
Page 7 of 35
3.3 Technical realization One variant is the decentralized busbar protection. The system consists of field units that are connected by optical fiber to the central unit.
BB A
Bay A
Bay Unit A
Bay B Bay Unit B
Bay n Bay Unit n
Central Unit
Figure 3: Principle of a decentralized busbar protection (e.g. Siemens 7SS52, ABB REB500, AREVA P740)
For the centralized busbar protection, all isolator positions are sent directly to the central unit. CTs in each bay are also connected to the corresponding input at the central unit.
BB A
Bay A
Bay B
Bay n Central Unit
Figure 4: Principle of a centralized busbar protection (e.g. Siemens 7SS50, ABB RED670)
3.4 System configuration The selectivity of the busbar protection can only be guaranteed if the protection does have the correct positions of all isolator at any time. This is the reason why the protection must be configured very carefully. The assignment of a feeder to a busbar section is done via the isolator replica, where the status is evaluated for each isolator.
© OMICRON 2017
Page 8 of 35
3.5 Tripping There are two independent criteria for tripping: busbar selective measurement and check zone measurement. 3.5.1 Busbar selective measurement Depending on the isolator positions, the currents of a single busbar section are used for calculating the differential and stabilization current. BB A BB B i1
i2
i3
DIFF-ZONE busbar A
i5 = i 3 + i4
i4
DIFF-ZONE busbar B
Figure 5: Busbar selective measurement
3.5.2 Check zone In opposite to busbar selective measurement, the check zone method uses the current sum of all feeders without considering the isolator positions. Coupling feeders are not taken into account. In order to avoid over-stabilization through load currents, two current sums are calculated; the sum of the absolute values of currents flowing towards the busbar and the sum of the absolute currents flowing away from the busbar. Double Busbar
Single Busbar
BB A BB B
BB A
i1
i2
i3
i3 + i4
i4
DIFF-ZONE busbar A
DIFF-ZONE busbar B
i1
i2
CHECKZONE
Figure 6: Establishing the stabilization factor
∑|𝐼𝑝 | = |𝐼1 | + |𝐼2 | + |𝐼3 | + |𝐼4 | ∑|𝐼𝑛 | = |𝐼3 + 𝐼4 | The lower of these two sums is used as the stabilization current for the check zone.
3.6 Breaker failure function The integrated breaker failure function in the busbar protection clears the affected busbar section when a circuit breaker failure occurs. When a busbar short circuit occurs, the affected section is switched off. If this results in a breaker failure, a transfer trip command must be sent to the opposite side in order to interrupt the current feeding the faulty busbar.
© OMICRON 2017
Page 9 of 35
Busbar
I2
I1
I3
I4
Figure 7: Breaker failure in feeder 4 in case of a busbar short circuit
3.7 Short circuit in the dead zone of the coupling feeder 3.7.1 Coupling with one CT only If there is only one CT in the coupling bay, the area between the CB and the CT is described as "dead zone". If a short circuit occurs in the dead zone, busbar A is switched off first. After opening the coupling breaker there is still a short circuit current which is supplied by busbar B. BB A BB B
ICoupling
I1
I2
Figure 8: Short circuit in the dead zone
Busbar B is switched off after the circuit breaker failure time has expired, which is started by the current criterion. If auxiliary contacts of the circuit breaker are used, busbar B is switched off in a shorter time. 3.7.2 Coupling with two CTs If two CTs are used in the coupling bay, the protection areas overlap. Compared to the solution with only one current transformer, both busbars are switched off immediately when a short circuit occurs in the area between the coupling breaker and the coupling feeder CT. With two CTs the correct busbar can be switched off when a fault between CB and CT occurs. BB A BB B
I1
IBB A
IBB B
I2
Figure 9: Bus coupler with two current transformers
© OMICRON 2017
Page 10 of 35
4
System under Test
4.1 Application example – Protected Area Figure 10 shows a busbar with its differential protection system, which is used as an example:
Figure 10: Example of protected area (CT: Current Transformer, VT: Voltage Transformer CB: Circuit Breaker, BB: Busbar)
4.2 Modelling the Busbar Topology in RelaySimTest RelaySimTest provides for busbar protection testing templates. You find them when you select Create new document on the RelaySimTest start page.
Figure 11: Create new document menu with OMICRON templates
Of course every busbar protection is different, the number of bays, positions of CTs and breakers can very. Therefore our template must be adapted. In the next chapters we show how edit power system topology and test cases. For this application note we use the template “Busbar Protection double Busbar with Isolators”. © OMICRON 2017
Page 11 of 35
4.2.1 Drawing the Topology To draw the topology according to the application example, use the single line editor like described in the Getting started. After drawing the first bay, you can easily duplicate the bay completely:
Figure 12: Duplicate bays
4.2.2 Enter Element Names Assign a name to each element and node. This eases using widgets later on:
Figure 13: Element naming
© OMICRON 2017
Page 12 of 35
4.2.3 Configuration of Current and Voltage Transformers CT and VT settings of the example: CT A: 2000/1 A CT B: 1500/1 A CT C: 2500/1 A CT D: 4000/1 A VT D: 110 kV / 100 V 4.2.4 Configuration of Infeed Data The next step is to enter the infeeds parameters which are the main elements for busbar protection because they are defining load and fault currents.
Figure 14: Infeed parameters
4.2.5 Configuration of Circuit Breaker Enter trip and close time of the circuit breaker (CB). With this information the simulation in RelaySimTest and the binary outputs of the CMC can simulate the behavior of the CB.
Figure 15: Configuration of CB settings © OMICRON 2017
Page 13 of 35
CB settings: Type: 3-pole Trip time: 20 ms Close time: 50 ms To set up the standard isolator and CB positions, double-click the breaker and switches:
Figure 16: Standard isolator and CB position
4.2.6 System verification To check your entered values, pin widgets to the dashboard. Place faults on busbars or nodes to check the fault currents.
Figure 17: System verification by checking fault currents with labels © OMICRON 2017
Page 14 of 35
4.2.7 Configuration of Field Units and Central Unit In our example we have a decentralized busbar protection with four bay units and a central unit. We add the devices corresponding. Connect each bay unit to its corresponding CBs and CTs. At Bay A we use in addition an external breaker failure signal. Therefore add also a simulated protection device to the Power system and define a User-defined binary output.
Figure 18: Power system with simulated protection device for external breaker failure protection
Connect Field Unit A in addition to CB and CT to the External Protection device. Now you are able to simulate in test cases an external breaker failure signal.
Figure 19: Device connection for bay units © OMICRON 2017
Page 15 of 35
The central unit is only used for recording of binary signals. Therefore use User-defined binary outputs. In the test case we will use this signals for measurements and assessments.
Figure 20: User defined binaries at central unit
© OMICRON 2017
Page 16 of 35
5
Test sets configuration
5.1 Test setup 5.1.1 Test setup overview For the busbar protection test with RelaySimTest, the following components are needed:
CMC test sets – analog outputs and binary in- and outputs corresponding to the number of bays in use (Each with a valid RelaySimTest license). PTP transparent switch CMGPS 588 – PTP grandmaster clock PC with RelaySimTest software Test leads If needed a possibility to simulate isolator and CB positions
Figure 21: Exemplary of a busbar protection test setup for medium distances up to 100 m
© OMICRON 2017
Page 17 of 35
Figure 22: Exemplary of a busbar protection test setup without PTP switch infrastructure
5.1.2 Time synchronization and communication to test sets Synchronized test current injection is necessary to perform a busbar protection test for a differential protection system. The synchronization ensures that all test sets start the test at the same time. This is very important since any inaccuracy can result in an unwanted differential current and thus in an unexpected relay behavior. For this reason, RelaySimTest supports the use of CMGPS 588, an antenna-integrated GPS controlled time reference to synchronize the starting point of the CMC test process. It delivers a time signal using PTP (Precision Time Protocol). For more information about PTP, see [4]. All devices are connected via Ethernet (Figure 21). You must use a PTP transparent switch (according to standard IEEE 1588 PTP). The switch provides control traffic from the PC; the time signal from the CMPGS 588 to all CMC test sets (see Figure 21). You can use, for example, the Hirschman RSP20 switch. The following application note describes how to configure this switch to the correct PTP setting: CMC-AppNoteConfigure-PTP-Transparent-Switch-from-Hirschmann-2014 [5].
© OMICRON 2017
Page 18 of 35
You may, alternatively, build a setup with distributed test sets. For synchronization every CMC test set is connected to a CMGPS 588. Control of the CMC test sets is done with an Ethernet connection and a dump switch. (
Figure 22). 5.1.3 Wiring check at bays with QuickCMC You should practice a wiring check at every bay. A practical way is to use Test Universe QuickCMC. By injecting secondary currents from single CMCs to the field units, the currents can be checked on the field unit’s display. 5.1.4 Naming the CMC test sets You should provide a certain name to every CMC. Therefore, use the Test Universe Test Set Association tool. From the toolbar menu, click Extras > Set Name
© OMICRON 2017
Page 19 of 35
Figure 23: Naming a CMC test set using the Test Set Association and Configuration tool
5.2 Test sets configuration in RelaySimTest When all CMC test sets are connected to the PC and the wiring checks are done, you can proceed to the Test sets configurations in RelaySimTest. Configured CMC name
Figure 24: CMC Test set overview
© OMICRON 2017
Page 20 of 35
The analog and binary signals must be connected to the corresponding CMC in- and outputs.
Figure 25: Configuration of analog and binary signals
© OMICRON 2017
Page 21 of 35
6
Test cases
6.1 Suitable test cases This chapter describes test scenarios that fit the application.
Figure 26 gives an overview of the different test cases, while the following chapters describe them in detail. Because each busbar protection scheme is very individual, these test cases are just examples for tests. They should explain testing methods with RelaySimTest in general. Suitable test cases are: Stability Tests: 1. Wiring and CT ratio check 2. Stable load flow 3. Outside faults Faults in Protected Area: 4. Faults on busbars 5. End zone fault 6. Faults in the dead zone
© OMICRON 2017
Page 22 of 35
4 1
5 1
3
6 1
1
Figure 26: Suitable test cases
For the faults in the different test cases at least the following Fault types should be used: L1-N L2-L3 L1-L2-L3 Depending on the relays under test, on the relay’s parameter, and on the grid where the protection system is used, you may need to add more fault types. The nominal trip time of the differential protection is 0 s, therefore the simulation time after a fault or switching event is at least 0.5 s. Hence, the protection system has enough time to show its reaction on the event. Sometimes the behavior of the protection system depends on the prefault condition e.g. load current. However, for this example, this distinction is not considered. 6.1.1 Test case 1 – Wiring and CT ratio check This test case is an advanced wiring check. The injection is carried out for a long duration. On every bay load current is injected and you have the possibility to check these currents at the field and central unit. Furthermore, it’s a first check if the protection system is stable.
© OMICRON 2017
Page 23 of 35
To generate a load flow thought the protected area you can adjust the phase angle of the infeeds. This is also possible in the widgets (Figure 27).
Figure 27: Test case 1 – Wiring and CT ratio check
The measurements are defined to the following signals of the central unit: Trip busbar A, Trip busbar B, Breaker failure. In this test case, the current flows through the protected area. There is no differential current. Therefore, the differential protection is not allowed to trip. Because of this, the assessment for all measurements is that no stop event occurs. If the protection system trips, it can have the following causes:
Wiring of test setup or protection system is incorrect. CT ratio or direction does not correspond between protection system and simulation. Parameters of protection system do not work as expected.
6.1.2 Test case 2 – Stable load flow This test case shows that the differential protection does not trip if a load current flows through the protected area. In contrast to test case 1 different load flow situations are simulated. Order of steps to generate test case 2: 1. Duplicate test case 1. 2. Reduce the simulation duration e.g. to 2s. 3. Vary the phase angle of the infeeds to get different load flow situations. Measurements and assessments are defined like in test step 1.
© OMICRON 2017
Page 24 of 35
Figure 28: Varied infeed phase angles
6.1.3 Test case 3 – Fault outside of bay A This test case shows that the differential protection does not trip in case a fault occurs outside of the protected area. Simulated is a fault outside at the feeder of bay A. Inception angle is 0° to get highest DC offset. We very fault type to get three test steps.
Figure 29: Test case 4 - Fault outside of bay A
The fault leads to high currents flowing through the protected area. There is also no differential current. Therefore, the differential protection is not allowed to trip. So measurement and assessment are the same as in test case 1 & 2.
© OMICRON 2017
Page 25 of 35
Figure 30: High currents flowing through the protected area
6.1.4 Test case 4 – Fault outside of bay A – External Breaker Failure This test case shows that the breaker failure protection of the busbar protection can be triggered by an external protection relay. Like in test case 2 an external fault at the feeder of bay A occurs. But in addition an external breaker failure signal appears.
Figure 31: External breaker failure signal appears after fault entry
In this case the breaker failure function in the busbar protection will operate and trip the effected bay. To adapt the binary slope of the simulated breaker failure signal you must click on the slope and afterwards you can configure the slopes in the ribbon menu. For this test case, the assessment is: Signal Trip time min. Trip time max. Trip busbar A No trip - start but no stop event occurs. Trip busbar B No trip - start but no stop event occurs. Breaker Failure No trip - start but no stop event occurs. Trip Bay A 200 ms 250 ms
© OMICRON 2017
Page 26 of 35
6.1.5 Test case 5 – Fault on busbar B Test cases 4 and 5 should show that a fault on the protected busbar leads to a trip of the differential protection.
Figure 32: Test cases 4 & 5 – Fault on busbar B
A fault on busbar leads to a differential current. Therefore, the protection system has to trip. The measurement is defined to start from fault rising until the signals of the “Central Unit: Trip busbar A, “Trip busbar B”, and “Breaker Failure”.
Figure 33: Defining measurements
© OMICRON 2017
Page 27 of 35
To get a selective trip commands from the protection system, select Enable Iterative Closed-Loop.
Figure 34: Enabling Iterative-Closed-Loop feature
With this feature enabled, RelaySimTest remembers the relay’s initial selective trips. RelaySimTest calculates the signals so as to repeat the previous test step with the correct simulation of the breaker operations. Now the protection clears the fault selectively.
Figure 35: Selective trip when fault appears on busbar B © OMICRON 2017
Page 28 of 35
For this test case, the assessment is: Signal Trip time min. Trip time max. Trip busbar A No trip - start but no stop event occurs. Trip busbar B 0 ms 50 ms Breaker Failure No trip - start but no stop event occurs. Only bays connected to busbar B will be tripped. The rest of the protection system should be stable. 6.1.6 Test Case 6 – Fault on busbar B – Breaker Failure Bay B This test case test the breaker failure protection function. Duplicate the previous test case and select the breaker failure tool in the ribbon. Place the breaker failure on CB B.
Figure 36: Fault on busbar B and breaker failure at CB B
Iterative-Closed-Loop of RelaySimTest will now ignore the trip command for CB B. After the first iteration the fault current will still be present. Therefore the busbar protection send the breaker failure protection signal to trip the bay on the other end of the line at infeed B.
Figure 37: Breaker Failure command when fault on busbar persist © OMICRON 2017
Page 29 of 35
For this test case, the assessment is: Signal Trip time min. Trip time max. Trip busbar A No trip - start but no stop event occurs. Trip busbar B 0 ms 50 ms Breaker Failure 200 ms 250 ms First, only busbar B trips. When the Central Unit detects that currents persist, breaker failure protection operates. 6.1.7 Test Case 7 – End Zone Fault In this test case a fault appears between the CB and the CT in bay A, called end zone fault.
Figure 38: Test Case 7 – End Zone Fault
The busbar protection first trips the busbar A and when it recognized that the fault current is still present it operates the breaker failure protection to trip the breaker on the other end of the line at infeed A. For this test case, the assessment is: Signal Trip time min. Trip time max. Trip busbar A 0 ms 50 ms Trip busbar B No trip - start but no stop event occurs. Breaker Failure 200 ms 250 ms 6.1.8 Test Case 8 – Fault in the dead zone This test case verifies that the busbar protection trips correctly when a fault occurs in the dead zone between CB and CT in the coupling field bay D.
© OMICRON 2017
Page 30 of 35
Figure 39: Test Case 8 - Fault in the dead zone
Therefore, also the Iterative Closed-Loop function should be enabled to get the correct behavior of the protection system. When the fault appears, the protection system detect it on busbar A. So also the Iterative Closed-Loop function is in use, the differential current persist, and the central unit will trip the breaker failure.
Figure 40: Protection system will operate breaker failure when a fault in the dead zone appears © OMICRON 2017
Page 31 of 35
For this test case, the assessment is: Signal Trip time min. Trip busbar A 0 ms Trip busbar B 200 ms Breaker Failure 200 ms
Trip time max. 50 ms 250 ms 250 ms
6.1.9 Test Case 9 – Fault on busbar A – Rigid coupling This test case shows that the differential protection does trip correctly in case a fault occurs when both busbars are linked by a rigid coupling with two isolators.
Figure 41: Fault on busbar A – Rigid coupling
For this test case, you have to change the isolator topology. To change the initial position, double-click the isolator. To verify that the isolator, the breaker positions of the simulation and the protection are the same, you can add an instruction commands before the test case to get a reminder before you start a test.
Figure 42: Instruction command for breaker and isolater positions © OMICRON 2017
Page 32 of 35
When both busbars are linked by a rigid coupling, the central unit will merge the two protection zones by one zone (Busbar A). Therefore, when a fault now appears in the protected area, the protection system will trip all bays instantaneously.
Figure 43: Instantaneous trip command at all bays when the busbars are linked to one protection zone
For this test case, the assessment is: Signal Trip time min. Trip time max. Trip busbar A 0 ms 50 ms Trip busbar B 0 ms 50 ms Breaker Failure No trip - start but no stop event occurs.
These were a couple of exemplary tests for a busbar protection. Every protection system is very individual. Tests must be prepared according to corresponding logic and scheme of the system under test.
© OMICRON 2017
Page 33 of 35
7
List of Literature [1] Getting started with RelaySimTest; OMICRON electronics GmbH; 2017 [2] “Numerical Differential Protection: Principles and Applications”; second edition; Gerhard Ziegler; Publicis MCD; 2012 [3] „SIPROTEC Dezentraler Sammelschienen- / Schalterversagerschutz 7SS522 V4.7, 7SS523 V3.3, 7SS525 V3.3 “, SIEMENS [4] “Implementation and Transition Concepts for IEEE 1588 Precision Timing in IEC 61850 Substation Environments”; B. Baumgartner, C. Riesch, M. Rudigier; OMICRON electronics GmbH [5] CMC AppNote Configure PTP Transparent Switch from Hirschmann; OMICRON electronics GmbH; 2014
© OMICRON 2017
Page 34 of 35
Support When you are working with our products we want to provide you with the greatest possible benefits. If you need any support, we are here to assist you.
24/7 Technical Support – Get Support www.omicronenergy.com/support At our technical support hotline, you can reach well-educated technicians for all of your questions. Around the clock – competent and free of charge. Make use of our 24/7 international technical support hotline: Europe / Middle East / Africa Americas Asia-Pacific
+43 59495 4444 +1 713 830-4660 +1 800-OMICRON +852 3767 5500
Additionally, on our website you can find our Service Center or Sales Partner closest to you.
Customer Area – Stay Informed www.omicronenergy.com/customer The Customer Area on our website is an international knowledge exchange platform. Download the latest software updates for all our products and share your own experiences in our user forum. Browse through the knowledge library and find application notes, conference papers, articles about daily working experiences, user manuals and much more.
OMICRON Academy – Learn More www.omicronenergy.com/academy Learn more about your product in one of the training courses offered by the OMICRON Academy.
