01_SEP674_RET670_Exercise_1_Differential_protection.pdf

Transformer protection RET670 Exercise 1 – Differential protection Engineering 1MRG004956

Exercise 1 – Engineering

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Trademarks ABB is a registered trademark of ABB Group. All other brand or product names mentioned in this document may be trademarks or registered trademarks of their respective holders.

ABB AB Substation Automation Products SE-721 59 Västerås Sweden Telephone: +46 (0) 21 34 20 00 Facsimile: +46 (0) 21 14 69 18

www.abb.com/substationautomation

Transformer protection RET670 1MRG004956

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Transformer differential protection engineering

On completion of this exercise you should be able to understand ·

normal steps in the engineering process of an IED

·

transformer differential characteristics and main settings

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Transformer differential protection This exercise is based on the configuration in figure 1, i.e., a three winding transformer protection.

Transformer Data: 80 / 80 / 30 MVA 145±9*1,67% / 22 / 11 kV 318 / 2099 / 1574 A YNd5d11 140 kV Bus

RET670 140kV/110V

Meter. CV MMXU

500/1

Meter. C MMXU

300/1

84

Meter.

49

Ith

TR PTTR

C MSQI

↑↓

TCM YLTC

11 kV Bus

W1 W3

87N

IdN/I

87T

REF PDIF

W2

3Id/I

T3W PDIF

1500/1

2000/1

Meter.

22kV/110V

C MMXU

Meter. C MSQI

49

Ith

24

TR PTTR

U/f>

OEX PVPH

Y Y

Mont.

Meter.

DRP RDRE

CV MMXU

Function configured

22 kV Bus

ANSI

IEC

IEC61850

Function not configured ANSI

IEC

IEC61850

Figure 1: A protection application for a three winding transformer in single breaker arrangement

Figure 1 shows all included functionality in the configuration. Function blocks in black are configured and the rest indicate possible additions.


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Start PCM600 and open project 1. Start PCM600

PCM600 is the tool to be used to engineer the IED i.e. to do all necessary changes when it comes to configuration, settings etc.

There is a project prepared to be used in this exercise. The project is named RET670_Exercise. It is saved in the PCM600 database. The project contains all configured data for the IED. Figure 2: The File Menu

2. Open the Project Manager

The Project Manager is used to handle projects and now we will open the project. Figure 3: Open Project

3. Open Project RET670_1p2_Training_Ex1 When the project has been opened, PCM600 will return to the Plant Structure and here you can expand the structure. Check the connected IED if version 1p1 or 1p2 should be used (use the local HMI).

Below the IED-level there are two levels - IED configuration - Application Configuration Figure 4: The Plant Structure

4. Expand the tree structure by clicking on the plussign

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The Plant Structure Below IED Configuration you will find general information for the IED regarding the hardware, setting group, identification, monitoring etc.

Figure 5: The Plant Structure – IED Configuration

5. Expand the structure below IED Configuration Below Application Configuration you can expand the structure down to function level.

Figure 6: The Plant Structure – Application Configuration

6. Expand the structure below Application Configuration


Compare the Application Configuration structure in the figure to the left and function blocks in the configuration (figure 1). You will find a direct match between the function blocks, i.e., T3WPDIF.

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IED Properties Open the Object Properties window.

Figure 7: IED Properties

7. Open Properties Here you will find some important information regarding the IED. For instance: IP Address and Terminal version. This information must match the IED.

IED factory settings Front port: 10.1.150.3 Rear port AB: 192.168.1.10

Product identifiers you will find on the local HMI under Main menu/Diagnostics/IED status/Product identifiers

Figure 8: Parameter Setting

8. Compare included the properties in PCM600 and corresponding information in the IED (use the local HMI)

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Hardware Configuration The transformer protection in the IED has specific hardware. Use the Hardware Configuration tool to check the hardware.

Figure 9: Hardware Configuration

9. Open the hardware configuration BIM: Binary Input Module BOM: Binary Output Module IOM: Combined In- and Output Module MIM: mA input Module TRM: Analog input module, 12 currents TRM: Analog input module, 6 currents, 6 voltages LDCM: Line Data Communication Module (normally not included in a RET 670)

Figure 10: Parameter Setting

10. Compare hardware in PCM600 and in the IED (use the local HMI and/or indentify the modules from rear view)


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License update tool The License update tool is used to synchronize a PCM600 IED object with the physical IED capabilities when it comes to functions and hardware. Use the tool when you are connected to an IED for the first time. Figure 11: License Update Tool

11. Start License Update Tool and follow the instructions

Application configuration You do not have to do any configuration but it could be useful to start the ACT-tool and get to know the configuration

Figure 121211:

Application configuration

12. Application configuration

Parameter setting The transformer protection is configured but the settings are default values. So we need to do some adjustments to be able to use the transformer protection in our application.

Figure 131312:

Parameter Setting

13. Open the parameter setting

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Analog inputs You will find the settings related to the current and voltage transformers in TRM_12I and TRM_6I_6U.

Figure 141413: Parameter settings for current transformers

14. Move to TRM_6I_6U

Settings for winding 1 Current transformer rated values, primary and secondary. The channel names are defined in Application configuration (ACT). The names are updated in PST after reading the settings in the IED. Use information in figure 1 and update the settings.

Figure 151514: TRM current parameter settings for winding 1

15. Set CTStarPoint to ToObject (all three phases) 16. Set CTSec to 1 A (all three phases)

The CT secondary is earthed towards the transformer i.e. to object.

17. Set CTPrim to 500 A (all three phases)


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Settings for winding 2 Current transformer rated values, primary and secondary.


18. Set CTStarPoint to ToObject (all three phases) 19. Set CTSec to 1 A (all three phases)

The CT secondary is earthed towards the transformer, i.e., ToObject.

20. Set CTPrim to 2000 A (all three phases) Settings for high voltage side Voltage transformer rated values, primary and secondary.

Figure 171716: TRM parameter settings for voltage transformers, high voltage

21. Set VTSec to 110 V (all three phases) 22. Set VTPrim to 140 kV (all three phases)

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Settings for medium voltage side Voltage transformer rated values, primary and secondary.

Figure 181817: TRM parameter settings for voltage transformers, medium voltage

23. Set VTSec to 110 V (all three phases) 24. Set VTPrim to 22 kV (all three phases) Setting for winding 3 Current transformer rated values, primary and secondary.


25. Move to TRM_12I 26. Set CTStarPoint to FromObject (all three phases)

The CT secondary is earthed towards the busbar, i.e., FromObject.

27. Set CTSec to 1 A (all three phases) 28. Set CTPrim to 1500 A (all three phases)


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Pre-processor (SMAI) function block settings The Pre-processor (SMAI) function block is the interface between the configuration (ACT) and the signal matrix (SMT). The function-block could be used both for voltage and current measurement. This is not defined in the configuration.

Figure 202019:

SMAI function block

29. Move to Analog modules in the Plant structure

Figure 212120: 3PhaseAnalogGroup

30. Move to 3PhaseAnalogGroup

The selection voltage or current is a setting parameter per SMAI function block. These settings are very important. Voltage: Type 1 Current: Type 2 Figure 222221:

Analog Modules

31. Check that all SMAI TYPE-settings are correct (1: Voltage and 2: Current)

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Phase reference angle and LED settings A reference PhaseAngleRef can be defined to facilitate service values reading (does not influence protection functions). This analog channels phase angle will always be fixed to zero degree and all other angle information will be shown in relation to this analog input.

Figure 232319:

Analog Modules

32. Move to AISBAS:1

Select a voltage input to be used as angle reference channel. TRM41-Ch7 corresponds to TRM_6I_6U_32 Channel 7 (UL1 HV). Figure 242420: angle

Phase reference

33. Set PhaseAngleRef to TRM41-Ch7 The LED indication module comprising 15 LEDs is standard. Alarm LEDs can be configured in PCM600.

Figure 252521:

Analog Modules

The module must be taken into operation in PST. 34. Move to HMI and LEDGEN 35. Set Operation to On


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Disturbance recorder settings, general Disturbance report is always included in the IED and acquires sampled data of all selected analog input and binary signals connected to the function block. Maximum 40 analog and 96 binary signals.

Figure 262622: IED Conf – Disturbance Report

36. Move to Monitoring and DisturbanceReport

Disturbance report functionality is a common name for several functions: • Event list • Indications • Event recorder • Trip value recorder • Disturbance recorder

The disturbance recorder will affect the yellow and red LEDs on the local HMI. Yellow: Disturbance recorder have started Red: A selected binary input has been activated (Trip signal) Figure 272723: – general

Disturbance recorder

37. Set Operation to On

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Disturbance recorder settings, specific It’s also necessary to do some settings regarding the binary and analog inputs.

Figure 282824: Application Conf – Disturbance Report

38. Move to Monitoring and DisturbanceReport Binary inputs

The channel names are defined in Application configuration (ACT). The names are updated in PST after reading the settings in the IED. Operation: On The signal will start a recording Triglevel: Start on positive or negative flank Indication: Show (hide) the signal in the indication list (or not) Set LED: Activate the 3rd red LED on the HMI at operation

Figure 292925: – binary signals


39. Check the configuration and do proper settings per channel


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Analog inputs

The channel names are defined in Application configuration (ACT). The names are updated in PST after reading the settings in the IED. Operation On The signal is included in the recording It is possible to have analog level trigging of the disturbance recorder but beware the risk of having vast number of recordings due to bad level setting. Enormous number of recordings will shorten the life of the flash memory.

Figure 303026: Application Conf – Disturbance Report

Analog level trigging should only be used in very special situations and carefully prepared settings.

40. Check the configuration and take all analog channels into operation

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Service value functions Measurement functions is used for power system measurement, supervision and reporting to the local HMI, monitoring tool within PCM600 or to station level for example, via IEC 61850.

Figure 313127: IED Conf – Disturbance Report

41. Move to Measure – Monitoring

ServiceValues (MMXN), CurrentPhasors (MMXU) and CurrentSequenceComponents (MSQI) are configured and should be taken into operation.

We will just transfer measured values to the Control Screen (single line diagram) thus it’s not necessary to set IBase, UBase and SBase.

Figure 323228: – general


42. All Monitoring functions: Set Operation to On


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Calculating settings for transformer differential protection The transformer differential protection is a unit protection. It serves as the main protection of transformers in case of winding failure. The protective zone of a differential protection includes the transformer itself, the buswork or cables between the current transformers and the power transformer. When bushing current transformers are used for the differential IED, the protective zone does not include the bus-work or cables between the circuit breaker and the power transformer. A transformer differential protection compares the current flowing into the transformer with the current leaving the transformer. A correct analysis of fault conditions by the differential protection must take into consideration changes due to voltages, currents and phase angle changes caused by protected transformer. Traditional transformer differential protection functions required auxiliary transformers. Differential protection algorithm as implemented in the IED compensate for both the turns-ratio and the phase shift internally in the software. The differential current should theoretically be zero during normal load or external faults if the turn-ratio and the phase shift are correctly compensated. However, there are several different phenomena other than internal faults that will cause unwanted and false differential currents. The main reasons for unwanted differential currents are: • Mismatch due to varying tap changer positions • Different characteristics, loads and operating conditions of the current transformers • Zero sequence currents that only flow on one side of the power transformer • Normal magnetizing currents • Magnetizing inrush currents • Over excitation magnetizing currents The internal / external fault discriminator is a very powerful and reliable supplementary criterion to the traditional differential protection. It is recommended that this feature shall be always used (enabled) when protecting three-phase power transformers. The internal / external fault discriminator detects even minor faults, with a high sensitivity and a high speed, and at the same time discriminates with a high degree of dependability between internal and external faults.

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Differential protection settings The differential protection has two groups of settings: - General settings related to the transformer data - Specific settings for the differential protection (Setting Group 1-6) In the first group you will find fundamental settings for the differential protection such as, ratings, vector group and clock number. Figure 333329: settings

43. Move to T3WPDIF


Differential protection

In the second group you will find specific protection settings such as, the operate characteristic.

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Differential protection general settings Compare the settings and figure 1. Winding 1 is the phase angle reference (Y) and magnitude reference.

Figure 343430:

General setting

44. See Figure 1. Set rated values for W1, W2 and W3.

45. Set connectTypeW1 to WYE

The transformer is solidly earthed at the 145 kV side. In case of earth-fault in the 145 kV system residual current flows from the transformer. This residual current is seen as a differential current even if there is no internal transformer fault. To prevent unwanted trip at external earth-fault there is a function where the zero sequence current is eliminated from the measured transformer current. This elimination is only needed for winding 1 in this application.

46. Set connectTypeW2 and W3 to Delta 47. Set ClockNumberW2 to 5 (150 deg lag) 48. Set ClockNumberW3 to 11 (30 deg lead) 49. Set ZsCurrSubtrW1 to On 50. Set ZsCurrSubtrW2 and W3 to Off

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In multi-breaker arrangement there is a risk of overbiasing, if the CT ratings are much higher than the rated current of the transformer. This will result in de-sensitize the differential protection. To prevent this situation there is a possibility to reduce the bias by a factor (RatedCurrentWx/CTyRatingWx).

Figure 353531: arrangement

Multi-breaker

Our application is a single breaker application i.e. TconfigWx = No.

51. Set TconfigForW for W1, W2 and W3 to No. It is possible to adapt the differential protection according to tap-changer position. Initially we do not use the feature in this exercise.

Figure 363632:

General setting

52. Set LocationOLTC1 and 2 to Not Used.


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Differential protection specific settings IdMin During normal operation there is a ”false” differential current measured by the protection due to the following: - Deviation tap changer position compared to the nominal transformer ratio - Difference in current transformer error

Figure 373733: Pick up and tripping characteristics settings

53. Set Operation to On 54. Set SOTFMode Off (temporary, we will focus on the differential function initially)

55. Check that IDiffAlarm is 0.20 (default) 56. Check that tAlarmDelay is 10.0 s (default) 57. Set Idmin to 0.25 IB 58. Check that Endsection1 is 1.25 IB (default) 59. Check that Endsection2 is 3.0 IB (default) 60. Check that SlopSection2 is 40% (default)

At the tap position giving the lowest LV voltage the transformer ratio is 166.8/22 kV. At 1.25 times the rated power (EndSection1) the 145 kV current is: 1.25 × 80 I HV = = 346 A 3 × 166.8 This corresponds to 1.09 times the rated current. The low voltage side current is 1.25 times the rated current and thus the differential current is about 0.16 times the rated transformer current. At the tap position giving the highest LV voltage the transformer ratio is 123.2/22 kV. At 1.25 times the rated power (EndSection1) the 145 kV current is: 1.25 × 80 I HV = = 469 A 3 × 123.2 This corresponds to 1.47 times the rated current. The low voltage side current is 1.25 times the rated current and thus the differential current is about 0.22 times the rated transformer current. The current transformers class is 5P giving a maximum amplitude error of 1 % and maximum phase displacement of 60 minutes. To assure that the load current does not cause unwanted operation IdMin is set to 0.25 times the rated transformer current.

61. Check that Slop Section3 is 80% (default)

62. Set IdUnre to 5.0 IB

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IdUnre The unrestrained differential protection function is operated without any stabilization. The setting principle is that the unrestrained function shall only be able to detect internal faults. This means that the current setting shall be larger than the largest current through the transformer at external faults. The fault level for external fault is calculated to be 1.48 kA. This corresponds to 4.6 transformer rated current. In the setting there should also be consideration to the influence from fault current DC component and inrush current.



2nd and 5th harmonic The classical way to avoid tripping due to inrush currents or overexcitation is checking the amount of 2 nd and 5th harmonics in relation to the fundamental frequency.

Figure 383834: Negative sequence diff protection settings

IMinNegSeq The transformer differential protection also has external/internal fault discrimination, based on negative sequence current. The default settings of NegSeqDiffEn, IMinNegSeq and NegSeqROA are recommended.

63. Check that I2/I1Ratio is 15% (default) 64. Check that I5/I1Ratio is 25% (default) 65. Check that CrossBlockEn is On (default) 66. Set NegSeqDiffEn is OFF (temporary, we will test the feature separately)

This feature we will test later.

67. Check that IMinNegSeq is 0.04 IB (default) 68. Check that NegSeqROA is 60 Deg (default) Open CT detection It is possible to detect and avoid tripping due to an open current circuit (one phase out of three). This function is only active after a certain time (1 min after energization) during normal load (10-110% IBias). Figure 393935: Negative sequence diff protection settings

This feature we will test later.

69. Check that OpenCTEnable is On (default) 70. Check that tOCTAlarmDelay is 3.0 s 71. Check that tOCTResetDelay is 0.25 s 72. Check that tOCTUnrstDelay is 10.0 s


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Trip function block settings A function block for protection tripping is normally provided for each circuit breaker involved in the tripping of the fault. It provides the pulse prolongation to ensure a trip pulse of sufficient length. In this exercise we only use one trip function block. (Normally we are using the trip matrix function (TMAGGIO) to route trip signals and/or other logical output signals to different output contacts on the IED.)

Figure 404036: Differential protection settings

73. Set Operation On

The signal matrix tool

Figure 414137:

Differential protection settings

The graphical signal matrix of PCM600 allows the user to efficiently connect CTs, VTs, binary input and output signals to the configuration. The tool can also be used for connecting the LEDs on the IED as well as for connection of the GOOSE (IEC 61850) signals between the IEDs.

74. Start the Signal Matrix Tool

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Signal Matrix Binary information

Figure 424238:

Binary input mapping

75. Check the mapping binary inputs

Figure 434339:

Binary output mapping

76. Check the mapping for binary outputs

Figure 444440:

LED mapping

77. Check the mapping for the LEDs


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Signal Matrix Analog Inputs

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Figure 454541: winding 1

Analog input mapping

78. Check the mapping for winding 1








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Graphical Display – supplementary exercise Page 1 - Service values

Figure 484844: Graphical Display Editor presenting service values

81. Use the GDE and create a information screen to be written into the IED

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Write to IED All data engineered will be read or written. Some tools support separately read/write. Communication management (CMT), Graphical display editor (GDE) and Parameter setting (PST) can read/write.

Figure 494945:

Write to IED

82. Write information to the IED


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ABB AB Substation Automation Products SE-721 59 Västerås, Sweden Phone +46 (0) 21 34 20 00 Fax +46 (0) 21 14 69 18

www.abb.com/substationautomation

01_SEP674_RET670_Exercise_1_Differential_protection.pdf

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