A New Method for Multiple Open-Transistor Fault Diagnosis in Photovoltaic micro-grid inverter by disposing the output current

Two-level inverter is extensively used in photovoltaic micro-grid power generation system. The transistor in the two-level inverter works under high stress and is prone to failure. In order to increase the practicability and reliability of photovoltaic micro-grid system inverters, it is necessary to study a fast and accurate fault diagnosis method for inverters. Therefore, this paper proposes a new open-circuit fault diagnosis method for photovoltaic micro-grid inverter. The proposed method has a simple calculation process and only needs to analyze the output current without the use of additional sensors, so the diagnosis cost is low. According to the different changes of output current, the diagnostic variables and adaptive thresholds are calculated for fault diagnosis and location. It can be seen from the simulation report that this method can diagnose the fault of transistor quickly and accurately, and it is robust to load disturbance.