Impact of unified power flow controllers on power system reliability

This paper examines the impact of a unified power flow controller (UPFC) on power system reliability. The UPFC is employed in the system to adjust the natural power sharing of two different parallel transmission lines and therefore enable the maximum transmission capacity to be utilized. The results of the investigations show a significant improvement in the system reliability by utilizing the UPFC. The improvement is measured using three reliability risk indices, namely, the loss of load expectation (LOLE), the loss of energy expectation (LOEE), and the system minutes (SM). The paper also presents a comparison between the effects of the UPFC and a thyristor controlled series capacitor on the system reliability.