两种多端直流拓扑故障下的仿真比较与分析

Simulation Analysis of Two Kinds of Multi-terminal DC Topology Under Fault Condition

国内外关于直流输电控制理论的分析已有很多,但关于多端直流输电的直流故障仿真分析较少。针对2种多端直流拓扑,分析其应对直流故障的反应能力,从而分析2种拓扑结构的优劣性。在仿真分析中,对比分析的故障类型采用直流母线正极接地故障,并用新型全控混合式高压直流断路器进行故障的切除。2种模型的风电场侧换流站都采用定有功功率的控制方法实现解耦,受端换流站均采用下垂控制方法。仿真实验结果表明:一般环形拓扑比中心环星型拓扑具有更好的稳定性,其中对稳定性的分析主要包括故障时的直流母线电压跌落的幅值、故障时直流线路的短路电流冲击大小及对其他换流站的影响程度,仿真实验的方法及结果可作为相关理论的参考。

There are a lot of researches on control theory for HVDC power transmission at home and abroad, but there are less simulation analysis on the DC fault of MTDC. According to the two multi-terminal DC topologies, their response capability for dealing with the DC fault is analyzed, and then the advantages and disadvantages of these topologies are analyzed. In the simulation analysis, the fault type is DC bus positive grounding, and the new full-controlled hybrid HVDC circuit breakers are used to clear the fault. Constant active power control method is used by the wind farm side converter stations to realize decoupling, and the droop control method is adopted by the receiving end converter stations. The simulation results show that the general ring topology has better stability than the star with central switching ring topology. Stability analysis mainly includes the amplitude of DC bus voltage drop during a fault, short-circuit current shock of DC line during a fault and its influence upon other converter stations. The method and results of the simulation experiment can be used as references for the relevant theory.