Study on a Novel Method of Distance Protection in Transmission Line with STATCOM

With the development of FACTS technology, STATCOM is more widely applied in the transmission system and it plays the role of reactive power compensation and making the voltage stability. However, it will inevitably have a negative impact on the relay protection. In this paper, it theoretically analyses the impact of the distance protection with STATCOM., getting a result that it will produce a additional impedance with STATCOM. This phenomenon will make the distance relay under-reaching or over-reaching. It installed a two-generator protect system model with STATCOM and have proved these effects. It proposes a new method of distance protection-According to the fault voltage information in the protect installation we can judge that whether the fault circuit contains STATCOM, if it contains STATCOM, the actual fault impedance the original measured impedance minus a additional impedance; on the contrary, the actual impedance is just the impedance, therefore, we can get the correct measured impedance in order to eliminate the effects of the impedance relay. It has made simulations to verify the correctness and the feasibility of this new method.