含分布式电源和电动汽车的城市电网半不变量故障分析方法

Cumulant Failure Analysis of Urban Power Grid With Distributed Generation and Electric Vehicles

故障分析是城市电网保护配置的基础,现有方法大多基于某一运行点,并未计及分布式电源出力与电动汽车放电的随机性。基于此,提出一种含分布式电源和电动汽车的城市电网半不变量故障分析方法。该方法在建立分布式电源与电动汽车随机出力模型的基础上,将已知出力的概率分布转化为半不变量,通过线性化后的PQ控制策略下故障计算模型,得到功率与电压电流之间的关系,进而计算得到故障电压、短路电流的半不变量,然后利用Gram-Charlier级数展开得到故障电压、短路电流的概率分布。最后,基于改进的IEEE 33节点算例模型对所提方法进行验证,证明该方法的准确性与有效性。该方法适用于考虑分布式电源出力与电动汽车放电随机性的城市电网故障分析,可为保护装置整定值的选择提供依据。

Fault analysis is the basis of urban power grid protection configuration. The existing methods are mostly based on one operating point without taking into account the randomness of distributed generation and electric vehicle output. Therefore, a cumulant fault analysis method for urban power grids with distributed generation and electric vehicle is proposed. Based on the establishment of the distributed generation and electric vehicle random output model, the method converts the probability distribution of the known output into a cumulant. The relationship between the power and the voltage current is obtained by the fault calculation model under the linearized PQ control strategy, and then the cumulant of the fault voltage and the short-circuit current is calculated. The cumulant is then exploited using the Gram-Charlier series to obtain the probability distribution of the fault voltage and short-circuit current. Finally, the proposed method is validated based on the improved IEEE33 node model, which proves the accuracy and effectiveness of the proposed method. The method can be applied to the urban power grid fault analysis considering distributed generation and electric vehicle output, and can provide a basis for the selection of protection device setting values.