Hybrid Unified Power Flow Controller Topology and Control Strategy Optimization

In order to reduce the cost of the electromagnetic hybrid unified power flow controller (HUPFC), the thyristor H-bridge ST topology is analyzed. This topology enables the “Sen” Transformer (ST) primary-side winding to achieve a two-stage voltage output. A simple two-stage ST switching strategy is proposed. In order to make the corresponding thyristor reliably turn off when ST is switched, the on-off characteristics and triggering conditions of the thyristor during ST switching are analyzed, and a reliable trigger signal generation circuit for thyristor is designed. The injection voltage estimation and ST switching delay are adopted, which reduces influence of control overshoot on ST switching control, optimizes the control structure of HUPFC, and analyzes the adjustment characteristics of HUPFC. Finally, the HUPFC is capacitated by the actual power flow calculation of distribution ring network, and the simulation model of HUPFC is built under PSCAD/EMTDC software. The steady-state simulation and transient simulation are carried out to verify the power flow control capability of HUPFC and the effectiveness of the control system.