Optimal location of UPFC applied to nonlinear load model

The unified power flow controller (UPFC) device is now recognized as one of the most important flexible AC transmission systems (FACTS) devices since it can provide various types of compensation: voltage regulator, phase shifting regulation, impedance compensation, and reactive compensation. It has been proved that the midpoint of a transmission line is the optimal location for some FACTS devices or reactive power support. The proof is based on the linear load, which is not valid practically. The validity of the above optimal location of Pulse Width Modulation (PWM)-based UPFC devices is investigated when the nonlinear load model is considered. In this paper the UPFC as a voltage regulator applied to a nonlinear load is modeled and analyzed. It was found that the optimum installation position for this device is at the sending end bus, where wide range of receiver terminal line voltage and active power can be controlled, while the wide range of reactive power can be controlled when the device is installed close to the receiving end bus.