PV Array Fault Detection and Localization Using a Single Voltage Sensor and Diodes Configuration

The various international standards have defined that line-to-line (LL) and line-to-ground (LG) faults in a photovoltaic (PV) system can generally be detected by the traditional protection devices once the fault current magnitude exceeds its threshold value. In general, with a low irradiance value, the activation of the maximum power point tracker, fault location, fault mismatch at the minimum level, and the presence of a blocking diode result in a lower magnitude of fault current. This fault current persists even when the irradiance level reaches a higher value, thereby establishing reliability issues, significant power losses, and fire risks. Therefore, appropriate fault detection and localization are essential to ensure the protection of a PV system. This article presents a low-cost fault detection and localization method utilizing a single voltage sensor that measures the differential voltage, along with a diode configuration circuit in a PV array system. The proposed scheme is capable of detecting and localizing LL/LG faults in a small-scale PV array system with blocking diodes. The faults can be detected and localized based on the voltage drop value of the localization diode. Experimental results on a small-scale grid-tied PV system validate the proposed scheme.