Assessment of an Overcurrent Protection Strategy Based on Thermal Stress Curves in Distribution Networks Under Reconfiguration Scenarios

Network reconfiguration enables the restoration of power supply in interrupted areas after faults or planned maintenance events. However, changes in network topology can often lead to alteration in the direction and magnitude of fault currents, undermining the coordination of overcurrent relays. In response to this challenge, adaptive protection systems have been developed that utilise system-wide communication to recalibrate relays dynamically. However, implementing system-wide communication comes with significant economic burdens, data integrity concerns and infrastructure limitations, especially in underdeveloped communities. In this study, the analysis of the overcurrent protection strategy based on thermal stress curves is conducted, to validate the appropriateness of the relay settings for a reconfigurable distribution network. The methodology was demonstrated on a test distribution system utilising directional overcurrent relays. The results demonstrate that the proposed protection strategy offers a simple and cost-effective means to enhance the effectiveness of power system protection within a reconfigurable grid. Consequently, this method presents an alternative to the concept of adaptive protection.