考虑多变量协同保护的储能变流器故障穿越策略

FAULT RIDE THROUGH STRATEGY OF POWER CONVERSION SYSTEM CONSIDERING MULTI-VARIABLE COOPERATIVE PROTECTION

电网发生不对称故障时,会导致储能变流器(PCS)运行性能不满足要求,进而影响并网系统的可靠运行。针对上述问题,提出一种PCS多变量协同保护策略。该策略在柔性控制策略的基础上,以无功支撑为首要目标,PCS运行性能为约束条件,构建无功功率关于柔性控制参数k的一元函数和有功功率安全运行区域。进一步可解得满足要求的k取值范围,随后根据系统的要求选取合适的k值和此k值对应的功率参考值进行控制。仿真结果验证了所提策略的有效性,能根据电压跌落程度向电网提供相应无功支撑,在保障系统安全的基础上充分利用了PCS容量,还能在解得的k取值范围内灵活控制PCS。

When an asymmetric fault occurs in the power grid,the performance of the power conversion system(PCS)will not meet the requirements,which will affect the reliable operation of the grid-connected system.Aiming at the above problems,a PCS multi-variable cooperative protection strategy is proposed.Based on the flexible control strategy,the proposed strategy considers reactive power support as the primary objective and PCS operational performance as the constraint condition.The unary function of reactive power with respect to the flexible control parameter k and the active power safe operating area are constructed.Furthermore,the range of k values that meet the requirements can be obtained,and then an appropriate k value and a power reference value corresponding to this k value are selected for control according to the requirements of the system.The simulation verifies the effectiveness of the proposed control strategy.Besides,the strategy can provide corresponding reactive power support to the power grid according to the degree of voltage drop,completely utilizing the PCS capacity on the basis of ensuring system security,and PCS can be flexibly controlled within the value range of k obtained.