Method and apparatus for ground fault detection

An apparatus for determining a ground fault impedance, comprising:

• a voltage divider;
• and
• and a controller comprising at least one processor and a memory, the memory coupled to the at least one processor and having stored therein a ground fault detection module comprising computer executable code that, when executed by the at least one processor, (i) determines a first voltage based on at least one voltage measurement of the voltage divider while the voltage divider is coupled between a first AC line on an AC side of an inverter and a DC line on a DC side of the inverter;
• (ii) determines a second voltage based on at least one voltage measurement of the voltage divider while the voltage divider is coupled, subsequent to being uncoupled from the first AC line, between a second AC line on the AC side of the inverter and the DC line;
• (iii) determines a differential voltage based on at least one voltage measurement between the first AC line and the second AC line;
• and (iv) computes the ground fault impedance based on the first voltage, the second voltage, and the differential voltage.

A system for determining a ground fault impedance, comprising:

• a DC power source;
• and
• an inverter, coupled to the DC power source and to an AC grid, wherein the inverter comprises a voltage divider and a controller comprising at least one processor and a memory, the memory coupled to the at least one processor and having stored therein a ground fault detection module comprising computer executable code that, when executed by the at least one processor, (i) determines a first voltage based on at least one voltage measurement of the voltage divider while the voltage divider is coupled between a first AC line on an AC side of an inverter and a DC line on a DC side of the inverter;
• (ii) determines a second voltage based on at least one voltage measurement of the voltage divider while the voltage divider is coupled, subsequent to being uncoupled from the first AC line, between a second AC line on the AC side of the inverter and the DC line;
• (iii) determines a differential voltage based on at least one voltage measurement between the first AC line and the second AC line;
• and (iv) computes the ground fault impedance based on the first voltage, the second voltage, and the differential voltage.