(1) DC bus over-voltage protection. The inverter continuously detects the DC bus voltage. When it detects that the DC voltage is higher than 1 000 V several times, the inverter disconnects the AC contactor and stops supplying power to the grid.

(2) AC overvoltage and undervoltage protection. The inverter continuously detects the grid voltage. When it detects that the grid voltage exceeds the specified allowable voltage range, the inverter disconnects the AC contactor; if the grid voltage falls within the allowable low voltage ride through range (20%), The low-voltage ride-through function is activated, and the inverter operates at the same time. During the low-voltage ride-through time, if the grid voltage does not recover, the inverter disconnects the AC contactor and stops power supply to the grid.

(3) AC frequency protection. The inverter continuously detects the grid frequency. When it detects that the grid frequency exceeds the specified allowable frequency range, the inverter will disconnect the AC contactor within 0.2 seconds and stop supplying power to the grid.

(4) Polarity reverse connection protection. When the DC output voltage is lower than 100 V and the program detects that the DC reverse current is greater than 40 A, the inverter prompts reverse polarity protection and operation is prohibited.

(5) Short circuit protection. The inverter continuously detects the grid current. When it detects that the grid current is greater than 1.5 times the rated current, the inverter disconnects the AC contactor and stops supplying power to the grid.