大容量逆变型分布式电源接入对配电网单相接地检测的影响

Analysis of the impact of large capacity IIDGs on single-phase grounding detection of distribution networks

大容量IIDG(逆变型分布式电源)接入配电网之中会影响单相接地的检测,危害配电网的安全稳定运行。根据IIDG特性和序网理论,给出小电流接地系统中发生单相接地时故障电流和线路零序电流的理论计算方法,得出IIDG的基波和谐波分量会影响故障点电流以及线路零序电流的结论。通过仿真分析了零序电流采样谐波含量高对单相接地判断的影响以及小波包算法对高谐波采样的适应性,说明了含大容量IIDG的配电网中接地选线校核的重要性,得出了基于小波包算法的接地选线算法在IIDG渗透率更高的配电网中适应性较好的结论。

With its connection to distribution networks, the inverter-interfaced distributed generators(IIDGs) affect single-phase grounding detection and jeopardize their safe and stable operation. Based on the characteristics of IIDGs and sequence network theory, the theoretical calculation method of fault current and zero-sequence current in case of single-phase grounding in the small-current grounding system is given. It is concluded that the fundamental and harmonic components of IIDGs can influence the current at the fault point and zero-sequence current of the line.The impact of the high harmonic content of zero-sequence current sampling on single-phase grounding judgment and the adaptability of wavelet packet algorithm to high harmonic sampling are analyzed through simulation. The significance of grounding line selection and calibration in distribution networks containing large capacity IIDGs is illustrated. Moreover, the grounding line selection algorithm based on the wavelet packet algorithm shows greater adaptability in distribution networks with higher IIDG penetration.