| 引用本文: | 张琦雪,司雨欣,桂林,李华忠,王凯.大型同步发电机定子分支电势对位移电压的影响[J].电力自动化设备,2025,45(7):212-217 |
| ZHANG Qixue,SI Yuxin,GUI Lin,LI Huazhong,WANG Kai.Impact of stator winding branch potentials of large synchronous generator on displacement voltage[J].Electric Power Automation Equipment,2025,45(7):212-217 |
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| 摘要: |
| 大型同步发电机正常运行时如果有明显的位移电压，则会扩大基波零序电压保护的死区，不利于发电机安全，同时也影响定子接地故障的准确定位。通过分析稳态的分布电容电流，引出电势不对称度的定义，三相分支电势不对称或者三相对地电容不均匀、不相等是产生位移电压的根本原因。从单根线棒出发，研究单个线圈及1个分支的电容电流，推导出π型等值电路的准分布电容参数模型。针对JH电厂350 MW发电机进行分析，三相分支电势不对称导致了位移电压；对比理论计算值和现场实测值，显示各电压基波有效值相对误差不超过5 %，相位误差不超过5°，验证了理论分析及等值电路的有效性。 |
| 关键词: 大型同步发电机 中性点位移电压 准分布电容参数模型 定子单相接地故障 定子分支电势 π型等值电路 |
| DOI：10.16081/j.epae.202503022 |
| 分类号:TM31 |
| 基金项目:国家自然科学基金资助项目(52077115) |
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| Impact of stator winding branch potentials of large synchronous generator on displacement voltage |
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ZHANG Qixue1, SI Yuxin2, GUI Lin3, LI Huazhong1, WANG Kai1
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1.NR Electric Co.,Ltd.,Nanjing 211102, China;2.Hangzhou Power Supply Company of State Grid Zhejiang Electric Power Co.,Ltd.,Hangzhou 310016, China;3.State Key Laboratory of Power System Operation and Control, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
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| Abstract: |
| If there is significant displacement voltage during the normal operation of a large synchronous generator, it will expand the dead zone of the fundamental zero sequence voltage protection, which is adverse to the safety of the generator and also affects the accurate of grounding fault location. By analyzing the steady-state distributed capacitance current, the definition of potential asymmetry is derived. The asymmetry three-phase stator winding branch potentials, the uneven distribution or the inequality of the three-phase capacitance-to-ground are the fundamental reasons for displacement voltage. Based on a single stator bar, the capacitance currents of both a single coil and a branch are studied, and the quasi-distributed capacitance parameter model of π-type equivalent circuit is derived. For the analysis of the 350 MW generator at JH Power Plant, the asymmetry of three-phase branch potentials leads to displacement voltage. Comparing the theoretical calculation value with the field measurement value, it shows that the root-mean-square value relative error of the fundamental voltage is no more than 5%,and the phase angle error is within 5°,which verifies the effectiveness of the theoretical analysis and equivalent circuit model. |
| Key words: large synchronous generator neutral point displacement voltage quasi-distributed capacitance parameter model stator single-phase grounding fault stator winding branch potential π-type equivalent circuit |
