Ground fault and insulation degradation detection and localization in PV plants

Ground faults are a major hazard in PV networks. Early detection as well as location of these ground faults can provide higher plant availability as well as protection for personnel and equipment. Since the occurrence of a ground fault or even insulation degradation changes the equivalent ac impedance (RLC) of the distribution network, transient analysis of the currents at string or array combiners can be used to detect and locate the fault or the beginning of insulation degradation. In this paper, the analysis of ground faults and insulation degradation and their effect on the transient waveforms is presented for grounded and floating PV networks. The current spectral analysis can clearly distinguish, identify and locate faults in the plant.