Faulted-Phase Identification in TCSC-Compensated Transmission Lines using Concordance Correlation Coefficient-Based Method

Fast fault detection in the Thyristor-controlled series capacitors "TCSC" compensated transmission line is the most challenging for many of the conventional fault detection methods. This paper proposes a new algorithm for fast fault identification in TCSC-compensated line based on concordance correlation of the current signals during the fault interval with corresponding current signals at the pre-fault interval. It is observed that the concordance correlation of the current signals at the present state with the same current signals at the previous state (just a few-cycle past) is very-strong during the health state and very weak when there is a fault state. Based on this and with the assistance of the cumulative approach, a fault detection index "Cdx" has been achieved. The proposed method has been tested through different fault circumstances including different compensation levels of TCSC device. Also, the proposed algorithm has been verified successfully with close in fault, high impedance fault, different sampling frequency, sudden load switching, load flow change and multi-machine system. The experimental results shown that the proposed method is good in terms of time response regardless of the compensation level, and therefore it is more efficient for series-compensated transmission lines protection.