Calculation of Distance Protection Settings in Mutually Coupled Transmission Lines: A Comparative Analysis

Abstract

Protection of mutually coupled transmission lines poses special challenges to protection engineers, since the general principles outlining the expected performance of the protection elements are based on simplified versions of the issues affecting them. Distance protection elements are among the most commonly accepted methods for protecting mutually coupled transmission lines, however, the calculation of settings and the validation of their performance is a complex task, involving lots of simulations and analysis of results to come up with an acceptable solution. Though various methods have been proposed to deal with the problem of calculating the optimal settings of distance protection elements, there is still room for improvement, since these methods have been formulated for the general case considering simple transmission lines. In this paper, a variation of one of these methods is introduced to enhance the computing times and reliability of the solutions for the specific application of quadrilateral distance protection to mutually coupled transmission lines, through the characterization of the expected performance of the operating characteristic, and the formulation of the optimization problem and the solution method. The obtained results show the improvements in computing times and quality of the solution provided by the proposed algorithm.

Alternative Methodology to Calculate the Directional Characteristic Settings of Directional Overcurrent Relays in Transmission and Distribution Networks

“…The results for the directional overcurrent elements of the evaluated relays located at the SE_A 220 kV end of the LT_1 transmission line are presented in Table 1 for the SIEMENS 7SA87 relay and in Table 2 for the ABB REL670 relay. A variable k means that the probability distribution taken from [13,18] was considered for the different fault types, and a fixed k means that the three fault types considered (three-phase, phase-to-phase to ground and single-phase to ground) have the same probability of occurrence, and therefore, the same weight in the objective function.…”

“…Both polarizing quantities result in different performance of the direction determination algorithm for different applications. For example, the mutual coupling of transmission lines sharing the same support structure represents major challenges when using zero sequence voltages and currents, due to the fact that the mutual coupling is stronger in this sequence than in positive and negative sequence, as it can be obtained from the comparison of the mutual impedances of the mutually coupled transmission lines, as described in [4,18]. The qualitative analysis should be performed when the results obtained from running the solution method proposed in [13], with the previously described enhancements, for both zero-sequence and negative-sequence polarizing quantities, show opposite performance of the objective function when compared with the detection rate.…”

“…Special considerations apply when the protected line is mutually coupled with another line, since, as described in [3,4,18], the different operating conditions of mutually coupled lines represent different conditions for the zero-sequence networks, given the importance of the zero-sequence mutual impedance for the equivalent fault circuit to be used as basis for the calculation of the zero-sequence reference voltage and operating current used by the direction determination algorithms, as stated in [4]. Therefore, the short-circuit sensitivity analysis must also consider the three operating states of mutually-coupled lines, as described in [18], in order to ensure that the behavior of the zero-sequence quantities is considered for the solution method proposed in [13].…”

Dynamic Quadrilateral Characteristic-Based Distance Relays for Transmission Lines Equipped with TCSC

“…Furthermore, the construction of tripping boundaries of the adaptive quadrilateral relay by the optimization technique is developed in [14][15][16][17]. By considering the probabilistic behaviour of the random variables that affect the apparent impedance seen by the relays, optimal settings of quadrilateral relay zones are developed in [14].…”

“…A genetic algorithm for determining the reach settings of the quadrilateral distance protection element of mutually coupled TLs is also illustrated in [17]. The algorithm uses different faulty system conditions affecting the measured impedance as the variable input.…”