Design of UPFC fuzzy controller and its application in power market

The applications of UPFC (Unified Power Flow Controller) in mitigating congestion and optimizing power flow are studied. The functions of UPFC, such as series voltage adjustment, line parameters series compensation, phase shift control and so on, can be used, on one hand, to improve the usage efficiency of electric components and increase system transmission capability for transmission congestion mitigation, on the other hand, to force power flow direction and change power flow distribution for power flow optimization. Based on the detailed analysis of UPFC equivalent circuit, a new reference coordinates system is built to realize the decoupling control of serial and shunt sides. Fuzzy controller with self-adjustable factor is used to enhance the robustness of UPFC, which changes control strategy according to real conditions to adapt the strong nonlinearity of power system. Simulation results show that, UPFC can not only improve the transmission capability and solve congestion effectively, but also adjust power flow quickly and smoothly when needed to realize power flow optimization and lower transmission cost.