环形直流微网短路故障分析及保护方法

以环形风电直流微网为研究对象,深入分析直流母线发生双极短路故障时电压源变流器(VSC)的故障特性,并据此提出以电流差动保护为主保护、欠电压保护为后备保护的环形直流微网故障定位与保护方案。该方案通过检测直流线路的输入、输出电流及其差动电流来定位和隔离故障线路,并配备欠电压后备保护以确保故障下直流微网系统的安全运行。基于MATLAB/Simulink对环形直流微网进行仿真研究以验证所提保护策略的可行性。仿真结果表明,在线路发生双极短路故障时,保护系统能够根据线路差动电流值做出快速响应,从而实现了直流微网系统短路故障的定位和隔离。

Short circuit fault analysis and protection scheme for looped DC microgrid

With the looped DC microgrid with wind turbines as the research object, the transient characteristics of VSC(Voltage Source Converter) during the pole-to-pole short circuit fault of DC buses are analyzed, based on which, its fault location and protection scheme with current differential protection as main protection and under-voltage protection as backup protection is proposed. The currents and differential currents of DC input and output are detected to locate and isolate the faulty lines and the under-voltage backup protection is applied to ensure the safe operation of DC microgrid with faults. MATLAB/Simulink-based simulation is carried out for the looped DC microgrid to verify the feasibility of the proposed protection strategy and results show that the designed protection system responses rapidly to the pole-to-pole short circuit fault according to the differential current to realize short circuit fault location and isolation of the DC microgrid.