Suggestion of a New Protection Scheme for a Transmission System Equipped with a Thyristor-Controlled Series Capacitor

Abstract

A thyristor-controlled series capacitor (TCSC) is employed to a transmission line in order to enhance the usable capacity of the present as well as upgraded lines, improve system stability, reduce losses, and improve power flow control capability. However, in an abnormal situation, the TCSC may transit from the existing operation mode to the other mode according to its control system and protection strategy. There is much difference in the impedance of the TCSC between each mode. This threatens the reliability of the conventional protection system, especially the distance relay, that works based on the measurement of line impedance. In this paper, we suggest a new protection scheme for a distance relay of a transmission line equipped with a TCSC. In the suggested method, in order to mitigate the effect of the TCSC in the fault loop, the TCSC injected voltage is subtracted from the measured phase voltage before supplying the voltage signal to the distance relay. The suggested scheme was verified by a real time digital simulator (RTDS)-based closed-loop test bed of a protective relay. The effect of the TCSC in the fault loop was completely mitigated. The distance relay works properly with the suggested scheme.

Adaptive Mho Distance Protection for Interconnected Transmission Lines Compensated with Thyristor Controlled Series Capacitor

“…To focus on the distinctive features of the proposed scheme, a brief comparative assessment with some published methods [11][12][13][14][15][16][17][18][19][20], to mitigate the effect of TCSC on the distance relay, is introduced as shown in Table 4.…”

“…-Some published solutions, to compensate for the negative TCSC effect on the distance relay, are based on synchronized data transfer between the two terminal ends of the TL and TCSC such as [12,13,15,16]. -In addition, the computational intelligence techniques such as [17] or implementing the philosophy of the multi-filtering technique as in [20] exceed the computational burden of existing microprocessor relays.…”

“…The practical parameters for TCSC design are not sufficiently considered in most of the existing research, and therefore, the effectiveness of their protection schemes is significantly affected by TCSC modeling parameters, which reflected on the insufficiency of their results. -Some reported research studies have developed solutions to compensate for the TCSC effect based on the synchronized data transfer between the two terminal ends of the TL and TCSC as [12,13,15,16], and therefore, several factors should be considered such as cost, speed, redundancy, and the reliability of the communication system, as its failure leads to the complete mal-operation of the protection scheme. -…”

Metaheuristic‐based graded objective function strategy for optimal thyristor‐controlled series capacitors estimation in weak distribution systems with uncertain distributed generation

“…A protection scheme is also implemented to mitigate the adverse effects of the TCSC during fault conditions. Moreover, the configuration presented in References [48] and [49] ensures protection against overvoltage issues.…”