Intelligent weight function based control strategy of DC link capacitor voltage in UPFC

The voltage of DC link capacitor of a UPFC system impacts on the performance of the entire UPFC controller. To keep it constant, a feedback control loop is necessarily used to control DC bus voltage. The intelligent weight function control strategy presented in this paper can dramatically improve the dynamic performance of DC control loop, with the calculation amount close to that of PID control. The performance of intelligent weight function control strategy was studied by comprehensive software simulations with the Power System Blockset of Matlab software. By comparing it with conventional PID control strategy, the effectiveness of this kind of control strategy can be seen clearly. The results of simulations illustrated that the overshoot and transient response time are just one tenth of PID control algorithm at the same conditions, close to fuzzy control strategy. This paper also presents a kind of control structure of UPFC.