基于相序差动电流特征差异的换流变压器匝间保护优化研究  

Research on the Optimization of Inter-turn Protection of Converter Transformers Based on the Difference of Phase Sequence Differential Current Characteristics

作　　者：杜丁香 杨国生 曹虹 吕鹏飞 梁英 高晨光 DU Dingxiang;YANG Guosheng;CAO Hong;LYU Pengfei;LIANG Ying;GAO Chenguang(State Key Laboratory for Security and Energy Saving(China Electric Power Research Institute),Haidian District,Beijing 100192,China;State Grid Corporation of China,Xicheng District,Beijing 100031,China)

机构地区：[1]电网安全与节能国家重点实验室(中国电力科学研究院有限公司),北京市海淀区100192 [2]国家电网有限公司,北京市西城区100031

出　　处：《中国电机工程学报》2023年第17期6576-6588,共13页Proceedings of the CSEE

基　　金：国家电网公司科技项目(5108-202218280A-2-360-XG)。

摘　　要：针对实际特高压换流变压器匝间短路故障时的二次谐波制动判据持续闭锁导致差动保护动作速度较慢的问题,该文详细分析特高压换流变匝间短路故障时的保护动作行为,通过理论分析换流变压器三相的相序差动电流变化量,发现匝间短路故障时具有故障相的相序差动电流变化量幅值为非故障相的两倍且相位差为180°的特定关系,在此基础上,提出相序差动电流开放判据。此外,为防止特殊涌流工况时开放判据误闭锁,增设基于涌流间断偏移特征的识别开放判据,并进一步构造整套基于相序差动电流特征差异的换流变压器匝间保护优化方案。通过现场录波及实时数字仿真(real time digital simulation system,RTDS)仿真验证,提出的保护方法在匝间短路故障且二次谐波制动判据误闭锁时具有高快速性,对于暴露问题的实际故障,保护动作时间由56ms缩短为20ms。同时,保护在各类涌流工况时可靠不误动。该保护算法具有计算量小,对数据采样率要求不高的特点。In order to solve the problem that the operation time of practical UHV converter transformer differential protection is long because of the second harmonic braking criterion continuously blocking during the inter-turn short-circuit fault,this paper analyzes the protection action results of the UHV converter transformer inter-turn short-circuit fault in detail.Through theoretical analysis of the phase sequence differential current variation of the three-phase converter transformer,it is found that the phase sequence differential current variation amplitude of the faulty phase during the inter-turn short circuit fault is twice that of the non-faulted phase and the phase angle difference is 180°,on this basis,the open criterion of phase sequence differential current is proposed.In addition,in order to prevent the opening criterion from being blocked by mistake under special inrush current conditions,an identification opening criterion based on the inrush current discontinuous offset characteristics is added,and a complete set of converter transformer inter-turn protection optimization scheme based on the difference of phase sequence differential current characteristics is further constructed.Through the field recording and real time digital simulation system(RTDS)simulation verification,the protection method proposed in this paper has high speed when the inter-turn short circuit fault and the second harmonic braking criterion is incorrectly blocked.The protection action time(20ms)is shortened to about 36%of the existing protection(56ms).Otherwise,the protection is reliable and does not malfunction under various inrush conditions.The algorithm of this protection scheme has a small amount of calculation,does not require high data sampling rate,and has strong engineering practicability.

关 键 词：换流变压器 匝间保护 二次谐波制动 涌流闭锁 相序差动电流变化量 

分 类 号：TM77[电气工程—电力系统及自动化]