Fault experiments in a commercial-scale PV laboratory and fault detection using local outlier factor

The experiments of line-line faults in solar photovoltaic (PV) arrays are implemented in a 35kW commercial-scale PV laboratory. The paper discusses both the transient response and post-fault behavior of the PV system (DC side), including PV array, overcurrent protection devices (OCPD, i.e. fuses) and grid-connected PV inverter. The experimental results demonstrate that fault locations and the maximum power point tracking (MPPT) may significantly reduce the fault current magnitude so that the fault is not detectable by OCPD. To eliminate the protection “blind spot,” statistic outlier detection rules are applied on the PV-string monitoring system, but sometimes they may cause false alarms. To address this issue, the local outlier factor (LOF) is developed in PV installations that shows improved fault detection. In experimental results, the proposed method demonstrates several advantages over traditional PV monitoring systems, such as simplicity, quick response, easy implementation and no requirement of weather information. The limitations of the proposed method are also discussed.