Analysis on false action of main transformer differential protection responding outside area fault caused by twopoint grounding of secondary current circuit

Abstract

Abstract: Abstract:An 110kV line is one of output lines of the 330kV main transformer. When a ground fault of the 110kV line occurred, the differential protection of the main transformer tripped incorrectly. The fault record figure was investigated, and it was found that when the differential protection device tripped due to the outside area fault, the phase B current increased abnormally. The CT secondary circuit site was inspected, and it was found that there was two points ground phenomenon in the secondary circuit phase B. It was analyzed that when the CT secondary circuit phase B grounded through two points, why the outside area fault can cause the differential protection of the main transformer to trip incorrectly. The preventive measures were proposed.

Key words: Keywords:main transformer, differential protection, outside area fault, phase B current, two points ground of CT

LIAO Hongtao. Analysis on false action of main transformer differential protection responding outside area fault caused by twopoint grounding of secondary current circuit[J]. Huadian Technology, 2015, 37(1): 55-57.

[1]	FENG Guangjie，WANG Zhiyong，YAN Zhihui，HU Shasha，WANG Zhiwei，XIAO Feng. An improvement scheme for busbar differential protection logic applied in singlesectionalized doublebusbar connection mode [J]. Huadian Technology, 2020, 42(1): 45-49.
[2]	ZHANG Yonggang1, 2，WANG Yue3，YAO Liang1, 2，CHEN Qi1, 2. Research on a differential current protection device for Tconnection lines [J]. Huadian Technology, 2019, 41(2): 18-21.
[3]	DU Xilai. Ground point principle and case analysis of current transformer [J]. Huadian Technology, 2018, 40(8): 31-33.
[4]	QI Jie. Fault analysis of a 600MW hydrogenerator stator winding damage [J]. Huadian Technology, 2018, 40(12): 16-19.
[5]	XUE Mingjun1,2, WANG Yuting1,2, CHEN Fufeng1,2, ZOU Lei1,2, ZHANG Xiang1,2, CHEN Shi1,2. Influence of series compensated double circuits on the same tower zerosequence component to relay protection [J]. Huadian Technology, 2017, 39(9): 6-9.
[6]	KANG Feng，WANG Runyi，ZHANG Wei，LIU Qinghai，YANG Qingsong. The design and implementation of differential protection based on current differential harmonic content [J]. Huadian Technology, 2017, 39(7): 32-35.
[7]	TANG Zhiguo,ZHOU Xiaobo,CHEN Qi,WANG Yongxu,CHEN Hongyan. Busbar abnormal great number detection method based on virtual difference current technology [J]. Huadian Technology, 2017, 39(4): 1-3.
[8]	ZHANG Yanlin, WANG Peng, HAN Yingjie, FAN Yusheng, LIU Zheng. A study of differential protection of variablefrequency motor and its applications [J]. Huadian Technology, 2017, 39(4): 8-10.
[9]	HU Bing, GUO Xiao, CHEN Shi, XING Wu, WANG Zhe. Differential protection research of voltage regulating transformer of rectifier unit and its application [J]. Huadian Technology, 2017, 39(1): 14-17.
[10]	WANG Jiqing. GIS AC withstanding voltage test by main transformer induction booster [J]. Huadian Technology, 2016, 38(3): 17-20.
[11]	WANG Song1, WU Pengyue2, SUN Ganghu2, WANG Zhigao1, GAN Jianghua3. Analysis on fault of loose connection of terminals in secondary circuit of current transformer [J]. Huadian Technology, 2015, 37(4): 19-21.
[12]	WEN Tao. Test program of differential protection for generator and transformer of AP1000 nuclear power unit [J]. Huadian Technology, 2014, 36(4): 73-76.
[13]	LIN Xiguo. Application of soft starter in reformation project of merging of induced draft fan and boost fan into one [J]. Huadian Technology, 2014, 36(3): 37-39.
[14]	YANG Yuzhu. Analysis on reason of incorrect trip of differential protection of electrostatic precipitator transformer and improvement measures [J]. Huadian Technology, 2014, 36(3): 41-42.
[15]	ZHOU Huanrong, XU Yongsheng, HU Liangsheng. Application scheme of differential protection of noninteger points phaseshift transformer [J]. Huadian Technology, 2014, 36(10): 43-45.

Analysis on false action of main transformer differential protection responding outside area fault caused by twopoint grounding of secondary current circuit

Knowledge

Abstract

Cite this article

share this article

References

Related Articles 15

Recommended Articles

Metrics

Comments