Guided power transformer-free inverter for grid-connected photovoltaic system, has regulating device controlling shift operations of switch device dependent on detected voltages such that direct current component in network is reduced

摘要

The inverter (10) has an output circuit (14) for coupling the inverter to an energy network. Measuring devices (15) e.g. measuring taps, to detect direct voltage (VDC) falling at impedance of the output circuit and another direct voltage resting against terminals of an output interface (12) of the output circuit. A regulating device (16) controls shift operations of a controllable switch device (13) dependent on the direct voltages detected with the measuring devices such that direct current component in a power supply network is reduced. The regulating device comprises an offset controller, proportional action controller, proportional plus reset controller, a proportional-derivative-controller or an integral action controller. Independent claims are also included for the following: (1) a method for operating a guided power transformer-free inverter (2) a grid-connected photovoltaic system comprising a photovoltaic generator.