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Improvement of power swing blocking scheme in distance protection relay

Distance relay is a protective device in electrical power system. It detects faults in transmission system and isolates abnormal or fault conditions by sending a trip signals to the circuit breaker. Power swing is caused by the large disturbances in the power system that if not blocked, could caus...

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Main Author: Ya'u, Mohammed Sani
Format: Thesis
Language:English
Published: 2015
Online Access:http://psasir.upm.edu.my/id/eprint/65499/1/FK%202015%20181IR.pdf
http://psasir.upm.edu.my/id/eprint/65499/
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spelling my.upm.eprints.654992018-09-24T03:28:59Z http://psasir.upm.edu.my/id/eprint/65499/ Improvement of power swing blocking scheme in distance protection relay Ya'u, Mohammed Sani Distance relay is a protective device in electrical power system. It detects faults in transmission system and isolates abnormal or fault conditions by sending a trip signals to the circuit breaker. Power swing is caused by the large disturbances in the power system that if not blocked, could cause wrong operation of the distance relay and can generate wrong or undesired tripping of the transmission line circuit breaker. Due to the characteristics of distance relay that can trip during power swings, a Power Swing Blocking (PSB) unit is developed to prevent unwanted distance relay operation during power swings. The main purpose of the PSB unit is to differentiate between faults and power swings and block distance or other relay elements from operating during a power swing. The problem with the originally available PSB in PSCAD/EMTDC is that it does not follow the exact shape of the operation characteristics of the available quadrilateral distance relay element. The PSB band may get too close to maximum load region, thus making load encroachment possible. This can create false fault or power swing pick up. Power swing blocking must be an immediate decision, immediately before allowing or disallowing the distance relay operations. Thus, PSB band must be attached back-to-back to the characteristic of the distance relay. Otherwise there will be an inaccuracy in measurement of impedance trajectory time interval from outer boundary to the inner boundary of the PSB band. This is the main problem when dealing with the current original PSB element in PSCAD/EMTDC. Therefore an improvement must be made to improve the power swing detection and thus make the quadrilateral distance relay element in the PSCAD/EMTDC to operate more efficiently. This improvement strategy will involve modelling an improved version of the original PSB and also introducing a new phasor comparator PSB scheme. These two techniques shall provide results that can validate the anticipated improvement in power swing detection over the original algorithm inherent in PSCAD/EMTDC. The original PSB problems are addressed in the newly improved FORTRAN and phasor comparator PSB schemes proposed in this research. In the original PSB available in PSCAD, the power swing detection time is close to the distance relay pick up time with a difference of only 0.01 second. This may cause wrong operation of distance relay if the relay picks up earlier and subsequently leading to a tripping of transmission line circuit breaker. However, the short seperation between the original PSB and the distance relay is addressed using the improved and phasor comparator PSB created in this research. In both cases, power swing detection is improved by 0.04 seconds. That gives sufficient time interval (0.04 seconds) between the PSB detection time and distance relay pick up time thus preventing the distance relay from sending a wrong tripping signal to the circuit breaker. With the modified PSB in the PSCAD/EMTDC, the problems related to the unmatched shapes of the PSB band and the quadrilateral distance relay operation characteristics have been addressed successfully. 2015-04 Thesis NonPeerReviewed text en http://psasir.upm.edu.my/id/eprint/65499/1/FK%202015%20181IR.pdf Ya'u, Mohammed Sani (2015) Improvement of power swing blocking scheme in distance protection relay. Masters thesis, Universiti Putra Malaysia.
institution Universiti Putra Malaysia
building UPM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Putra Malaysia
content_source UPM Institutional Repository
url_provider http://psasir.upm.edu.my/
language English
description Distance relay is a protective device in electrical power system. It detects faults in transmission system and isolates abnormal or fault conditions by sending a trip signals to the circuit breaker. Power swing is caused by the large disturbances in the power system that if not blocked, could cause wrong operation of the distance relay and can generate wrong or undesired tripping of the transmission line circuit breaker. Due to the characteristics of distance relay that can trip during power swings, a Power Swing Blocking (PSB) unit is developed to prevent unwanted distance relay operation during power swings. The main purpose of the PSB unit is to differentiate between faults and power swings and block distance or other relay elements from operating during a power swing. The problem with the originally available PSB in PSCAD/EMTDC is that it does not follow the exact shape of the operation characteristics of the available quadrilateral distance relay element. The PSB band may get too close to maximum load region, thus making load encroachment possible. This can create false fault or power swing pick up. Power swing blocking must be an immediate decision, immediately before allowing or disallowing the distance relay operations. Thus, PSB band must be attached back-to-back to the characteristic of the distance relay. Otherwise there will be an inaccuracy in measurement of impedance trajectory time interval from outer boundary to the inner boundary of the PSB band. This is the main problem when dealing with the current original PSB element in PSCAD/EMTDC. Therefore an improvement must be made to improve the power swing detection and thus make the quadrilateral distance relay element in the PSCAD/EMTDC to operate more efficiently. This improvement strategy will involve modelling an improved version of the original PSB and also introducing a new phasor comparator PSB scheme. These two techniques shall provide results that can validate the anticipated improvement in power swing detection over the original algorithm inherent in PSCAD/EMTDC. The original PSB problems are addressed in the newly improved FORTRAN and phasor comparator PSB schemes proposed in this research. In the original PSB available in PSCAD, the power swing detection time is close to the distance relay pick up time with a difference of only 0.01 second. This may cause wrong operation of distance relay if the relay picks up earlier and subsequently leading to a tripping of transmission line circuit breaker. However, the short seperation between the original PSB and the distance relay is addressed using the improved and phasor comparator PSB created in this research. In both cases, power swing detection is improved by 0.04 seconds. That gives sufficient time interval (0.04 seconds) between the PSB detection time and distance relay pick up time thus preventing the distance relay from sending a wrong tripping signal to the circuit breaker. With the modified PSB in the PSCAD/EMTDC, the problems related to the unmatched shapes of the PSB band and the quadrilateral distance relay operation characteristics have been addressed successfully.
format Thesis
author Ya'u, Mohammed Sani
spellingShingle Ya'u, Mohammed Sani
Improvement of power swing blocking scheme in distance protection relay
author_facet Ya'u, Mohammed Sani
author_sort Ya'u, Mohammed Sani
title Improvement of power swing blocking scheme in distance protection relay
title_short Improvement of power swing blocking scheme in distance protection relay
title_full Improvement of power swing blocking scheme in distance protection relay
title_fullStr Improvement of power swing blocking scheme in distance protection relay
title_full_unstemmed Improvement of power swing blocking scheme in distance protection relay
title_sort improvement of power swing blocking scheme in distance protection relay
publishDate 2015
url http://psasir.upm.edu.my/id/eprint/65499/1/FK%202015%20181IR.pdf
http://psasir.upm.edu.my/id/eprint/65499/
_version_ 1643838332822618112
score 13.211869

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