Analyzing Standardized Inverse Time-Current Curve Types of Overcurrent Relays for Efficient Overcurrent Protection in Distribution Networks

The selection of the appropriate curve type of overcurrent relay function is significant for achieving optimal coordination of overcurrent protection in distribution networks. In this study, we conducted a comprehensive analysis of the overcurrent relays performance regarding their different inverse time-current curve types. Additionally, different fault locations were taken into consideration. To investigate the impact of curve types on overcurrent relays coordination, we employed a uniform curve type for all overcurrent relays in two representative power systems. The results, encompassing three standardized IEC curve types, are presented, and analyzed to illustrate the efficacy of our proposed approach. Therefore, this study underscores the critical role that curve type selection has in determining the feasibility of attaining reasonably low overcurrent relay trip times.