摘要
海上风电场汇集线路发生单相接地故障时,线路两侧短路电流分别由风电机组换流器和柔直换流器提供,由于正序、负序与零序网络串联,在传统大电网存在场景下不受控制影响的零序电流也将像正序和负序电流一样呈现幅值受限、相位受控特性,柔直侧距离保护无法正确识别单相接地故障。该文建立海上风电场汇集线路单相接地故障时的复合序网,分析汇集线路两侧故障特性,在不借助线路双端通信的前提下,利用柔直侧负序和零序电流准确求取风机侧零序电流。基于此,构建关于故障距离的方程,提出柔直侧新型距离保护方案,解决了双端均为逆变型电源的线路中零序电流受控导致距离保护性能下降的问题。此外,所提保护方案受风电场无功支撑策略、过渡电阻大小及性质影响小。测试结果表明,该保护方案可以准确识别海上风电场汇集线路区内外单相接地故障。
When a single-phase grounding(SPG)fault occurs in the offshore wind farm collection line,the short-circuit current on both sides of the collection line is provided by the wind turbine inverter(WTI)and the modular multilevel converter(MMC),respectively.Since the positive-,negative-,and zero-sequence networks are connected in series,the positive-,negative-,and zero-sequence currents show the characteristics of limited amplitude and controlled phase.The MMC-side distance protection cannot identify the SPG fault.This paper establishes the composite sequence network,and analyzes the fault characteristics when the SPG fault occurs in the collection line.Then the zero-sequence current at WTI-side is calculated through the negative-and zero-sequence currents at MMC-side without communication.Based on this,the equation about the fault distance is constructed,and a novel MMC-side distance protection scheme is proposed,effectively addressing the issue of the performance degradation of distance protection of line with inverter-based sources on both ends.The proposed protection scheme is less affected by the reactive power support strategy and the fault resistance.And the test results show that the proposed protection scheme can accurately identify internal and external SPG faults.
作者
晁晨栩
郑晓冬
叶海
刘中平
刘虎林
韩俊
张怀宇
邰能灵
CHAO Chenxu;ZHENG Xiaodong;YE Hai;LIU Zhongping;LIU Huin;HAN Jun;ZHANG Huaiyu;TAI Nenging(Key Laboratory of Control of Power Transmission and Conversion,Ministry of Education(Shanghai Jiao Tong University),Minhang District,Shanghai 200240,China;State Grid Company East China Division,Pudong New District,Shanghai 200120,China;State Grid Company Southwest Division,Chengdu 610095,Sichuan Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2024年第15期5899-5907,I0005,共10页
Proceedings of the CSEE
关键词
海上风电场
柔性直流换流站
汇集线路
距离保护
单相接地故障
过渡电阻
offshore wind farm
flexible DC converter station
collection line
distance protection
single-phase grounding fault
fault resistance
