主从控制孤岛微电网的优化故障控制策略

Optimal Fault Control Strategy of Master-slave Controlled Islanding Microgrid

中压等级的主从控制孤岛微电网中,通常仅依据并网点电压跌落程度来进行无功支撑,可能会导致采用V/f控制方式的主控电源无法正常消纳无功电流,并迫使其有功电流输出减少,进而导致微电网系统失稳。该文根据典型逆变型分布式电源(inverter interfaced distributed generator,IIDG)的控制模型,分析了故障情况下PQ控制IIDG低电压穿越时引起的无功倒送问题,并阐述了无功倒送对中压孤岛微电网稳定运行可能造成的不利影响。针对该问题,根据IIDG故障时的输出特性,提出了协调主控电源和从属电源的优化故障控制策略。最后,通过PSCAD的仿真算例,验证了所提推论及优化策略的准确性和有效性。

In medium voltage islanding microgrid,V/f controlled DG(V/f-DG)may produce the fluctuation and collapse of voltage when the support of reactive power only based on the extent of voltage dips.Not only the additional reactive power cannot be absorbed by V/f-DG,but also the active current of V/f-DG is forced to reduce.Eventually,it is possible to bring about the power disequilibrium within network.Thus,according to the typical IIDG control model,this paper analyzed the problem of reactive power reverse caused by the PQ control IIDGs during low voltage ride-through in the case of fault,and revealed the possible adverse effects of this problem on the stability of islanding microgrid.Then,according to the fault characteristics of IIDG,the optimization strategy of master and slave control IIDGs is put forward.Finally,examples are simulated in PSCAD and the results verify the accuracy and effectiveness of the proposed inference and optimization strategies.