Leakage current compensator circuit

A method for compensating a leakage current in a grid-connected device, the grid-connected device being electrically connected to a plurality of current carrying wires and a protective earth conductor, the method comprising:

• measuring a first leakage current in the plurality of current carrying wires based on the output of an open loop measurement circuit;
• injecting a compensation current into the protective earth conductor based on the measured first leakage current to provide an open loop leakage current reduction;
• measuring a second leakage current in the plurality of current carrying wires based on the output of a closed loop measurement circuit;
• and
• modifying the compensation current based on the measured second leakage current to provide a closed loop leakage current reduction, wherein:
• the compensation current is generated based on the measured first leakage current from the open loop measurement circuit, and
• the compensation current is modified based on the measured second leakage current from the closed loop measurement circuit according to a closed loop control function.

A system for compensating for a leakage current, the system comprising:

• a measurement circuit configured to measure a leakage current in a plurality of current carrying wires that are electrically connected between a power supply and an electrical load, wherein the measurement circuit includes:
• an open loop measurement coil configured to measure the leakage current in the plurality of current carrying wires and configured to provide a first output signal representing the measured leakage current,
• a closed loop measurement coil configured to measure a compensated leakage current in the plurality of current carrying wires after application of a compensation current and configured to provide a second output signal representing the compensated leakage current;
• a current injector configured to apply the compensation current to a protective earth conductor that is electrically connected between the power supply and the electrical load;
• and
• a processor electrically connected to the open loop measurement coil of the measurement circuit, the closed loop measurement coil of the measurement circuit, and the current injector, the processor being configured to determine the compensation current according to:
• an open loop gain function based on the first output signal from the open loop measurement coil, and
• a closed loop gain function based on the second output signal from the closed loop measurement coil,
• the processor being further configured to cause the current injector to generate the compensation current based on the first output signal from the open loop measurement coil and modify the compensation current based on the second output signal from the closed loop measurement coil according to a closed loop control function, wherein the processor is further configured to cause the current injector to apply the compensation current to the protective earth conductor to reduce the leakage current.