Study on unified control of grid-connected generation and harmonic compensation in dual-stage high-capacity PV system

In this paper, a novel high-capacity grid-connected photovoltaic (PV) system based on Boost converter + dual-level four-leg inverter is proposed, which can perform both grid-connected system and active power filter (APF). Comparing with single-stage three-phase three-wire PV system, the proposed system not only allows a wide range of input voltage, but also can compensate unbalance loads current. This paper explains the control principle of unified control strategy of combination of PV grid-connected injection and active power filtering in detail. And the key of unified control is the current reference generation. Simulation results on MATLAB/Simulink are presented to demonstrate practicability of the unified control strategy. Applying proposed topology and control method to a 100 kVA grid-connected PV system based on FPGA+DSP controller, the experimental results are given to verify correctness of the whole system and unified control strategy.