unipolar grounding and rainy day grounding faults that tend to occur in photovoltaic arrays in complex environments are investigated. In view of the ineffective detection of line-ground faults under low irradiance or high mismatch ratio
the variation patterns of key parameters based on the multi-irradiance modes are proposed
and the rightmost power peak voltage
the rightmost power peak current are determined as the feature quantities of line-ground faults. The voltage correlation between faulted and non-faulted poles is analysed by Pearson correlation coefficient to determine the feature quantity of unipolar grounding fault. In view of the mechanism of common mode current generated by rainy day grounding fault
the fault feature quantity is proposed based on wavelet transform and total harmonic distortion rate. Finally
the ground fault diagnosis model of PV array based on improved cuckoo search algorithm optimised support vector machines (ICS-SVM) is constructed
and the validity of the proposed ground fault feature
the diagnostic accuracy and convergence speed of the model are confirmed by simulation and experimental validation under different irradiance levels on sunny and rainy days.
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