Influence of the Combination-Type Grounding Scheme on Voltage-Injected Stator Ground Fault Protection

doi:10.11930/j.issn.1004-9649.201805084

Abstract

Abstract: By drawing upon the advantages of the resonant grounding method, a combination-type grounding scheme is adopted for large-sized generator to reduce the ground fault current, in which the inductor is installed in parallel with the load resistor on the LV-side of the neutral grounding transformer (NGT). In the paper, a numerical simulation model is established by using Matlab Simulink. The quasi-distributed capacitance model is used to simulate the stator ground fault protection, and the algorithm used for the protection devices is adopted to calculate the voltage-injected stator ground fault protection. A conventional high-resistance grounding scheme and three combination-type grounding schemes are designed, and simulations are carried out for the large-sized generator of Baihetan hydropower station in China. By comparing the simulation results, a study is made on the influence of the combination-type grounding scheme on the voltage-injected grounding protection. The results show that adding parallel inductor will worsen the calculation results of the ground fault resistance; the parallel inductor installed on the high voltage side of the NGT is most favorable to the voltage-injected stator ground fault protection, but the equipment cost will be increased; within the limited amount of compensation current by the parallel inductor, the greater the degree of detuning is, the better the measurement of the ground fault resistance is.

Key words: large-sized generator, single-phase-to-ground fault, high-resistance ground, resonant ground, stator ground fault protection, voltage-injected

CLC Number:

TM772

ZHANG Qixue, WANG Xiangheng, CHEN Jiasheng, XU Tianle, LI Huazhong, WANG Guang, CHEN Jun. Influence of the Combination-Type Grounding Scheme on Voltage-Injected Stator Ground Fault Protection[J]. Electric Power, 2018, 51(11): 96-103.

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URL: https://www.electricpower.com.cn/EN/10.11930/j.issn.1004-9649.201805084

https://www.electricpower.com.cn/EN/Y2018/V51/I11/96

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