Unified power flow controller and control method thereof

The invention discloses a unified power flow controller. The unified power flow controller comprises a plurality of series side converters, a plurality of transformers connected in series, a plurality of primary side winding by-pass switches, a parallel side converter, a parallel transformer and a wire incoming switch. The alternating-current ends of all the series side converters are connected with corresponding secondary side windings of the transformers connected in series, primary side windings of the transformers connected in series are connected with the corresponding primary side winding by-pass switches in parallel, and the primary side winding by-pass switches are connected into corresponding circuits in series. The direct-current ends of all the series side converters are connected in parallel and jointly connected with the direct-current end of the parallel side converter, the alternating-current end of the parallel side converter is connected with one end of the parallel transformer, and the other end of the parallel transformer is connected with an alternating-current bus of a multi-loop circuit through the wire incoming switch. The topological structure can achieve multiple operation modes and save a plurality of parallel side converters and transformers, has good economical efficiency and flexibility. The invention further discloses a control method of the unified power flow controller.