基于电流变化率的多级直流配电馈线保护研究

摘要

The imperfection of line protection technology is one of factors restricting the develop-ment of DC distribution network.This paper proposes a line protection scheme and its setting method which can be used in DC distribution network with multiple lines.Under the different fault locations leading to different DC capacitor current rate increase the operating conditions of line protection are formed.The process of DC fault occurs in DC lines is divided into three stages and analyzed in detail.For each stage,the equivalent circuit of the system and the calculation method of DC fault current are set and the action threshold is determined according to the result of fault analysis.Finally,a series of performance tests of the proposed line protection scheme is carried out by RT-LAB experimental platform.The simulation results show that the proposed protection method can cooperate with a converter protection.It can distinguish whether the fault occurred in protected zone,and ensure the selectivity of DC circuit breaker to protect the DC dis-tribution line effectively.%线路保护技术不完善是目前制约直流配电网发展的重要因素之一。本文提出了一种可用于具有多级馈线的直流配电系统线路保护方案及其整定方法。利用不同故障位置下，直流电容放电电流变化率不同构成了保护判据，并且在时序上将直流故障的发展过程分为了三个阶段，根据每一阶段的等效电路及故障电流的计算结果对保护进行整定。在 RT-LAB 实验平台上对该线路保护方案做了一系列性能测试。仿真结果表明，所提出的保护方案能够与换流器保护形成配合，分辨故障是否发生在本级线路，保证直流断路器的动作具有选择性，有效地保护直流配电线路。