Improved Distance Relaying for Double-Circuit Lines Using Adaptive Neuro-Fuzzy Inference System

Utilizing double-circuit lines may represent a challenge for distance relaying functions owing to the significant impacts of the mutual coupling among the adjacent conductors. This paper proposes a new adaptive distance relaying scheme for double-circuit transmission lines using fuzzy logic tuning. The scheme depends on two basic steps. First, the impacts of the mutual coupling of the adjacent conductors on the accuracy of the distance relaying core are minimized based on the decoupling feature of modal transformation. Then, a dedicated online intelligent tuning mechanism is utilized to precisely improve the relay reach. The adaptive neuro-fuzzy inference system is employed to realize an optimum design of the aimed tuning mechanism. A thorough investigation of the proposed scheme is performed utilizing a detailed modeling of a typical 400-kV interconnection system with both single- and double-circuit line segments. The electromagnetic transient program (ATP-EMTP) is employed for modeling the considered power system, whereas the protection scheme is constructed and tested using MATLAB. Finally, the performance of the proposed relaying scheme is investigated under different load conditions, various fault types and fault locations to visualize its efficacy precisely. As compared with conventional distance relaying core, the proposed adaptive distance scheme has a precise fault distance estimation with a reach error less than 6% of the total line length. Accordingly, a corrected declaration of the faulted zone is realized along the entire range of the protected line despite the added fault resistance, loading condition and fault type.