A Novel Approach Based on Line Inequality Concept and Sine–Cosine Algorithm for Estimating Optimal Reach Setting of Quadrilateral Relays

Quadrilateral characteristics of distance relays are widely used in modern power systems because of its lesser sensitivity to the variation in operating scenarios and fault parameters. The performance of quadrilateral relay is heavily dependent on the proper selection of reach settings. The reach accuracy of distance relays with settings estimated using conventional techniques deteriorates during stressed conditions such as load variation, power swings and remote end infeed/outfeed variations. A proper setting in addition to avoiding overreach and underreach cases should also posses higher loadability limit. In this regard, the relay reach setting has been mathematically formulated as a constrained optimization problem in the present work, with the aim of maintaining the trade-off between the reach accuracy and the loadability limit in terms of area enclosed by the relay characteristics. Sine–cosine algorithm has been adopted to solve the multiobjective optimization problem and hence obtain the reach setting of the quadrilateral relay. The performance of the proposed scheme in terms of providing optimal reach setting has been extensively examined against wide variation in fault parameters and operating scenarios. Further, in order to test the effectiveness of the proposed scheme for real-time applications, the suitability of the quadrilateral relay has also been validated by performing real-time simulations using OPAL-RT digital simulator.