A Dual-Function Power Decoupling Circuit for Single-Stage Grid-Connected PV Inverter

Photovoltaic energy is one of the most widespread renewable sources of electrical energy. At the heart of the power conversion system is the grid-connected interface converter based on power electronics. Single-stage systems offer higher efficiency and lower cost and size. However, they suffer from a reduced operating range due to the effects of irradiation and temperature. In addition, especially for low-power single-phase systems, pulsating power is an additional handicap. A dual-function decoupling circuit is proposed to mitigate these drawbacks. It compensates for the pulsating power and increases the lifetime of the system. In addition, the proposed low-power interface compensates for the voltage drop due to low irradiation and increases the operating range. A 1 kW test bench is designed, and experimental results show that when injecting power into the grid, the compensator attenuates 85% of the power oscillations and perfectly compensates up to 20% of the voltage drop due to low.