Implementation of a new high-power current-source single-stage PV grid-connected system with reactive power compensation

In view of the shortcoming of voltage source converter in the application of high-power photovoltaic (PV) grid-connected system, this study designs a new single-stage current source PV grid-connected system based on dc current reinjection conversion. The system can freely control the dc current in a wide range, so only one stage of conversion is needed to achieve wide range control of the dc side maximum power point tracking. The amplitude and phase angle of the ac output current can be freely regulated, so it is able to realise grid-connected power generation under unit power factor and supply a certain amount of reactive power according to the control order while grid-connected power generation. Meanwhile, the new current source converter topology eliminates the ac capacitors which are arranged between the converter and the power grid, and gets approximately sinusoidal ac currents without setting filters. This study describes the circuit structure and control of the PV grid-connected system, and builds an experimental prototype. The simulation and experimental results will be shown to demonstrate the feasibility of the converter topology, and the effectiveness of the control strategy.