Simulation Of TCSC Influence On Transmission Line Relay Protection

Thyristor Controlled Series Compensator (TCSC) is an important member of the Flexible AC Transmission System (FACTS)'s family. It can realize large-scale smooth regulation of the TCSC impedance connected in the transmission line; thereby it can be used to increase transmission capacity, control power flow flexibly and improve transient stability of the system. Because of its potential economical efficiency, it is firstly selected in FACTS practices around the world. On the other hand, TCSC produces harmonics, fast parameter changes and fast dynamic process when it runs in the power system, The TCSC line can produce some special physical phenomenon when a fault occurs, and this differs from other common lines. All these above mentioned not only bring troubles to the setting of relay protection, but also challenge the conventional line protection relay principles. Therefore, it is necessary to study TCSC' influence on line relay protection, and review the adaptation of TCSC on the existing relay protection in order to ensure the TCSC line secure operation.At first, based on existing research achievements, this article introduced the development and current research status of FACTS, especially of TCSC. Then it gave a particular description of the structure and working principle of TCSC, introduced the controlling system of TCSC, and also analyzed the characters of the fundamental-frequency impedance of TCSC. Based on the fundamental principle of TCSC, this article deduced the relation curve between fundamental-frequency impedance and trigger angle when taking the line current as the synchronizing signal. Using the software of PSCAD, we founded a detailed model of TCSC, and did some emulation in the double-source system model. At last, based on the simulation of TCSC line, we researched the influence of TCSC on protection for the transmission line when a fault occurs, and then some improvement of advices has been proposed.