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

Abstract

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.

Keywords

• iidg
• single-phase grounding fault
• sequence component
• wavelet packet