Method, circuit arrangement and photovoltaic inverter with means for leakage current compensation in a photovoltaic system with multiple differential current sensors

摘要

For leakage current compensation in a photovoltaic system, a reference current flowing from at least one live current-carrying line (8, 9) is detected via a capacitance (C1, C2) flowing to earth. A compensation current with phase and frequency of the reference current and with a comparison with the reference current by a negative scaling factor -G adapted amplitude is generated. By means of a differential current sensor (16), a current sum (18) is detected, wherein the summands of the current sum (18) the currents through a complete set of current-carrying lines (L1, L2, L3 and N) and - contained therein or separately - the compensation current are. The detected current sum (18) is minimized by adjusting the scaling factor -G. The compensation current is passed through at least one other differential current sensor (5), so that the compensation current compensates for a leakage current component at a differential current monitored by the other differential current sensor (5).