Detection of phase loss Fault in a Three-Phase Transformer Based Grid-Feeding PV Inverter

A delta-star transformer is popularly used to interface the photovoltaic (PV) inverter with the grid. The transformer connectors are prone to disconnection primarily because of wear and tear. To ensure the safe and reliable operation of the system, the fast detection of the fault is important. The phase loss or open circuit fault at the star side of the transformer is very common and it is difficult to detect. The conventional detection methods use additional current or voltage sensors or current injection circuits incurring additional operational cost. This paper presents a cost effective phase loss fault detection technique for the phase loss fault using the delta side voltage measurements. Therefore, the proposed technique does not require additional current or voltage sensors. thereby provides cost effective solution.