摘要
区别于常规电源机组,当输电线路发生短路故障时,风电机组配置的Crowbar保护可能启动,导致风电机组转速下降,从而引起风电侧短路电流频率发生偏移,使得基于基频短路电流计算的测量阻抗出现偏差,传统距离阻抗保护方法可能拒动或误动。针对该问题,提出了计及风机短路电流偏移特性的配电网阻抗幅值差动保护方法,首先探究了风电短路电流偏移特性,建立了线路故障时,风机侧短路电流偏移误差模型,并基于阻抗平面图,研究了其对距离保护的影响机理。然后,基于差动阻抗和制动阻抗在正常运行、外部故障和内部故障之间的显著差异,提取阻抗幅值差动特征,构造了阻抗保护幅值差动判据,其不受短路电流偏移的影响。最后,基于PSCAD/EMTDC进行仿真分析,结果表明:提出的保护方法不受风电接入比例及短路电流偏移的影响,并且过渡电阻电阻可以提高内部故障时保护动作的灵敏性,以及外部故障保护不动作的可靠性。
Different from the conventional power unit,when a short-circuit fault occurs in a transmission line,the crowbar protection in the wind turbine may act,which will lead to the decrease of the wind turbine speed and the short-circuit current frequency deviation at the wind turbine side. Thus,the measured impedance calculated based on the fundamental frequency short-circuit current will deviate from the actual value,causing inaction or mis-operation of the traditional distance impedance protection. To solve this problem,this paper proposes an impedance amplitude differential protection method of distribution networks considering short-circuit current deviation characteristics. Firstly, the short-circuit current deviation characteristics of wind turbine are explored,and the short-circuit current deviation error model is established. Secondly, the influence mechanism the shortcircuit current has on the distance protection is studied based on the impedance diagrams. Thirdly, based on the significant difference between differential impedance and braking impedance in normal operation,external fault and internal fault,the impedance amplitude differential characteristics are extracted,and the impedance protection amplitude differential criterion is constructed,which is not affected by short-circuit current deviation value. Finally, the simulation analysis is carried out based on PSCAD/EMTDC. The results show that the protection method in this paper can act accurately regardless of the wind power ratio and the short-circuit current deviation,and the transition resistance can improve the sensitivity of internal fault and the reliability of external fault protection.
作者
简学之
刘子俊
霍永胜
冯康康
JIAN Xuezhi;LIU Zijun;HUO Yongsheng;FENG Kangkang(Shenzhen Power Supply Bureau Co.,Ltd.,Shenzhen 518000,Guangdong,China;NR Electric Co.,Ltd.,Nanjing 211102,Jiangsu,China)
出处
《电网与清洁能源》
北大核心
2022年第8期121-129,共9页
Power System and Clean Energy
基金
南方电网公司资助科技项目(090000KK52190103)
国家重点研发计划(2018YFB1502904)。
关键词
风电
短路电流偏移特性
阻抗差动保护
过渡电阻
wind power
short circuit current deviation characteristics
impedance differential protection
transition resistance
