适应于光伏电站主变压器的差动保护工作模式  

Differential Protection Working Mode Applicable to Main Transformers of Photovoltaic Power Plants

作　　者：李乐[1] 安源[1] 郝治国[2] 付泽宇 孟瑾 LI Le;AN Yuan;HAO Zhiguo;FU Zeyu;MENG Jin(School of Electrical Engineering,Xi’an University of Technology,Xi’an 710054,Shaanxi,China;School of Electrical Engineering,Xi’an Jiaotong University,Xi’an 710049,Shaanxi,China;Baoji Power Supply Company,State Grid Shaanxi Electric Power Co.,Ltd.,Baoji 721004,Shaanxi,China)

机构地区：[1]西安理工大学电气工程学院,陕西西安710054 [2]西安交通大学电气工程学院,陕西西安710049 [3]国网陕西省电力有限公司宝鸡供电公司,陕西宝鸡721004

出　　处：《电网与清洁能源》2022年第3期97-104,共8页Power System and Clean Energy

基　　金：陕西重点研发计划项目(2019ZDLGY18-04)。

摘　　要：光伏电站主变压器产生的合闸涌流,经过电流互感器(current transformer,CT)传变后,其二次谐波比会有所提高,若同时发生区内故障,光伏逆变器的短路电流会带来额外高含量的二次谐波,这将导致主变压器差动保护在涌流闭锁期间无法及时切除故障。根据主变压器差动电流基波与二次谐波的相位差变化特征,提出一种防止保护拒动的工作模式,甄别出涌流闭锁过程中的故障发生时刻,并依据涌流与区内故障时的二次谐波比差异,及时提高故障时刻定值,以避免保护闭锁。借助PSCAD/EMTDC软件,验证故障定值选取后差动电流的二次谐波比变化和保护动作情况,结果表明,所提光伏电站主变压器差动保护工作模式区分性能优异,能够可靠切除涌流过程中发生的区内故障。The closing inrush current generated by the photovoltaic power station will find its second harmonic ratio increased after it is transformed by the current transformer(CT).And when an internal fault occurs simultaneously within the area,the short-circuit current of the photovoltaic inverter will also bring an extra high content of second harmonic,which will make the differential protection of the main photovoltaic power station unable to remove faults timely during the inrush current blocking.According to the phase difference characteristics of fundamental wave and second harmonic of the differential current of the main transformer,a working mode of preventing protection maloperation to identify the fault occurrence time in the inrush current blocking process and increase the fault setting value timely to avoid protection locking based on differences of the second harmonic ratio when the inrush current and faults occur within the area.The PSCAD/EMTDC software is used to verify the second harmonic ratio change and protection action after the fault setting value is selected.The results show that the proposed differential protection working mode of the main transformer of the photovoltaic power station has excellent performance and can reliably remove the internal faults when the inrush current occurs.

关 键 词：光伏电站 变压器 合闸涌流 差动保护 二次谐波制动 

分 类 号：TM772[电气工程—电力系统及自动化]