考虑瞬时功率的柔性直流配电线路保护方法  

Flexible DC Distribution Line Protection M ethod Considering Instantaneous Power

作　　者：王沥泽 WANG Lize(State Grid Tongchuan Power Supply Company,Tongchuan 727031,Shaanxi Provine,China)

机构地区：[1]国网铜川供电公司,陕西铜川727031

出　　处：《电力与能源》2024年第2期160-163,168,共5页Power & Energy

摘　　要：为了避免在柔性直流配电线路保护过程中出现误动作,需要准确识别故障位置。针对直流配电线路的故障特征较难把握,定位故障位置困难的现状,探讨了考虑瞬时功率的柔性直流配电线路保护方法。使用模块化多电平换流器(MMC)对端口进行换流,通过计算得到在三相静止坐标系下的配电线路动态模型。根据电压阶跃信号中的频域信息,将时域中的故障信息进行转换,并运用小波变换的方式对故障特征进行提取。考虑瞬时功率特性,在柔性直流电网线路端口处安装保护装置,根据端点的瞬时功率变化,判断直流输电线路中故障发生的位置。利用故障电压特征,设计故障选极判据,对电流突变量进行方向性判断,实现柔性直流配电线路保护。试验结果表明:所提方法的保护动作正确,该方法下区外故障直流电压变化率与区内故障直流电压变化率几乎一致,使得保护动作可靠,实现了考虑瞬时功率的柔性直流配电线路保护方法的良好应用。In order to avoid misoperation during the protection of flexible DC distribution lines,it is necessary to accurately identify the fault location.However,it is difficult to grasp the fault characteristics of DC distribution lines and locate the fault.The protection method of flexible DC distribution line considering instantaneous power is studied.A modular multilevel converter(MMC)is used to commutate the ports,and the dynamic model of distribution line in three-phase static coordinate system is obtained by calculation.According to the frequency domain information in the voltage step signal,the fault information in the time domain is converted,and the fault features are extracted by wavelet transform.Considering the instantaneous power characteristics,the protection device is installed at the port of the flexible DC power network line.According to the instantaneous power change of the end point,the fault location in the DC transmission line is determined.Based on the fault voltage characteristics,the fault pole selection criterion is designed to judge the direction of the current mutation,and the flexible DC distribution line protection is realized.The experimental results show that the protection action of the proposed method is correct,and the DC voltage change rate of the fault outside the area is almost the same as that of the fault inside the area,which makes the protection action reliable and realizes the good application of the flexible DC distribution line protection method considering instantaneous power.

关 键 词：瞬时功率 柔性直流 配电线路保护 小波变换 

分 类 号：TM773[电气工程—电力系统及自动化]