Aspects of common-mode leakage current suppression in single-phase PV-generation systems

Power of generation systems based on renewable sources steadily grows up. New single-phase PV power generation systems (PGS) are widely built. PGS based on PV modules can operate in two modes: autonomous mode and grid-tied mode. The important part of PGS based on PV in the grid-tied mode is transformer, which provides galvanic isolation. It is possible to remove the transformer from the PGS in order to improve the energy quality and reduce losses, size, and cost. But in this case common-mode leakage current appears. This current is reason of electric safety issues existence. There are additional negative factors connected with common-mode leakage current such as reduction quality of generated electrical energy, electromagnetic emission, increases of THD and loses, degradation and failure photovoltaic modules. It is shown, that the common-mode voltage is the main reason of the leakage currents. In this paper explores possibilities of suppression common-mode leakage current in single-phase PGS. A method of suppression leakage current based on special SV PWM is proposed. Proposed solution was verified by simulation.