Optimal Protection of Smart Grids Using Communication-based Dual-setting Directional Overcurrent Relays Considering Different Grid Configurations

Abstract

The changes in the direction and magnitude of fault currents due to different operating modes and network configuration might affect the microgrids (MGs) and smart grids (SGs). Although designing the SGs’ protection system considering the grid-connected and islanded modes in the literature, less attention has been paid to other network configurations other operating modes in the SGs’ optimum protection schemes. This paper tries to fill this gap by proposing a protective scheme using the dual-setting directional overcurrent relays (DS-DOCR), considering all network configurations due to the outage of each distributed generation (DG), besides the grid-connected and islanded modes. The DS-DOCR acts against faults in forward and reverse directions separately with separate settings in the proposed protection scheme. The forward and reverse relay settings are activated by a signal received from other DS-DOCRs. The capabilities of the proposed communication-based scheme using the DS-DOCRs are used to find the optimal settings, considering different network configurations and corresponding constraints. The proposed method is implemented on the distribution grid of the IEEE 30-bus test system. In this study, DIgSILENT is used to perform the power system analyses, and MATLAB is utilized to implement the optimization problem solving by the genetic algorithm (GA). Comparison of the obtained results with the existing methods indicates that the coordination constraints would not be violated in different configurations, while the operating time of the protection system is desired.