Power converter and protection method for short circuit to ground on direct current side thereof

A power converter, comprising:

• a positive direct current bus, a negative direct current bus, a power conversion circuit, a relay, and a controller, wherein a direct current input terminal of the power conversion circuit is configured to be connected to a photovoltaic module or an energy storage battery through the positive direct current bus and the negative direct current bus, and an alternating current output terminal of the power conversion circuit is configured to be connected to a grid through the relay;
• and
• the controller is configured to:
• when the positive direct current bus has a short circuit to ground, and when the grid voltage is in a positive half cycle, control the relay to be switched on, and when the grid voltage is in a negative half cycle, control the relay to be switched off;
• or
• the controller is configured to:
• when the negative direct current bus has a short circuit to ground, and when the grid voltage is in the negative half cycle, control the relay to be switched on, and when the grid voltage is in the positive half cycle, control the relay to be switched off.