逆变型分布式电源接入对小电阻接地系统馈线零序电流保护的影响

逆变型分布式电源(IIDG)的接入改变了小电阻接地系统的接地故障特性,不仅使传统零序电流的计算方法不再适用,而且对馈线零序电流保护造成了不利的影响。通过分析IIDG的故障电流特性,建立了具有低电压穿越能力的PQ控制型IIDG故障等值模型;在含IIDG小电阻接地系统接地故障分析建模的基础上,提出了零序电流迭代求解算法,并利用MATLAB编写相应的求解程序,将计算结果与电力系统实时仿真系统(RTDS)的仿真结果进行比较,验证了所提算法的有效性和准确性;基于所建立的故障分析模型,揭示了IIDG的接入对小电阻接地系统馈线零序电流保护的影响机理,利用所提零序电流迭代求解算法求解不同故障情况下的馈线零序电流值,验证了理论分析的正确性。

Influence of inverter interfaced distributed generators on zero-sequence current protection for feeder of low resistance grounding system

The access of IIDG(Inverter Interfaced Distributed Generator) changes the grounding fault characteristics of low resistance grounding system, which not only makes the traditional calculation method of zero-sequence current no longer applicable, but also has a negative impact on the zero-sequence current protection of feeder. A PQ control strategy-based IIDG fault equivalent model with low voltage ride-through capability is established by analyzing the fault current characteristics of IIDG. Based on the analysis and modeling of grounding fault in the low resistance grounding system with IIDGs, an iterative solution algorithm of zero-sequence current is proposed. The solving procedure is compiled with MATLAB, and the calculative results are compared with the simulative results of the power system RTDS(Real-Time Digital Simulator) to verify the effectiveness and accuracy of the proposed algorithm. Based on the established fault analysis model, the influence mechanism of the IIDG access on the zero-sequence current protection of low resistance grounding system feeder is revealed. The zero-sequence currents of feeder under different fault conditions are calculated using the proposed iterative solution algorithm, which verifies the validity of the theoretical analysis.