A multifunctional grid-connected converter with voltage dynamic compensation capability and its multi-mode flexible switching strategy

The parallel power quality control device based on grid-connected converter has superior performance in harmonic current suppression and reactive power compensation, but it lacks the ability to solve the transient voltage fluctuation problem. Therefore, a multi-function grid-connected converter (MF-GCC) is proposed with transient voltage active support and its multi-mode flexible switching strategy. Under the condition of normal grid voltage, MF-GCC operates in parallel compensation mode to ensure unit power factor operation on the grid side. Under the condition of grid voltage fluctuation, MF-GCC works in series compensation mode to maintain a constant voltage on the sensitive load side. In addition, the switching process of MF-GCC from parallel to series compensation mode and from series to parallel compensation mode is analyzed in detail. Further, the optimal switching sequence is proposed for active power devices. Simulation and experimental results verify the effectiveness and feasibility of the proposed topology and control strategy.