Document Type : Original Research Paper

Authors

• A. Yazdaninejadi
• M. Akhavan

Power Engineering Department, Faculty of Electrical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran.

Abstract

Background and Objectives: Protection of sub-transmission systems requires maintaining selectivity in the combinatorial scheme of distance and direction overcurrent relays (DOCRs). This presents a complex challenge that renders the need for a robust solution. Thereby, the objective of the present study is to decrease the number of violations and minimize the tripping time of relays in this particular issue.
Methods: This study deals with this challenge by using numerical DOCRs which follow non-standard tripping characteristics without compromising the compatibility of the curves. In this process, the time-current characteristics of relays are described in such a manner that they can maintain selectivity among themselves and with distance relays. Therefore, in addition to the second zone timing of distance relays, time dial settings, and plug settings of overcurrent relays, the other coefficients of the inverse-time characteristics are also optimized. The optimization procedure is formulated as a nonlinear programming model and tackled using the particle swarm optimization (PSO) algorithm.
Results: This approach is verified by applying on two test systems and compared against conventional methods. The obtained results show that the proposed approach helps to yield selective protection scheme owing to the provided flexibility.
Conclusion: The research effectively enhanced selectivity in sub-transmission systems and minimizing relay tripping times through the innovative use of numerical DOCRs and PSO-based optimization.

Keywords

• Coordination Violations
• Nonlinear Programming Model
• Combinatorial Protection
• Selectivity
• Distance Protection

Main Subjects

• Power Systems

Open Access

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Publisher

Shahid Rajaee Teacher Training University