Setting and Coordination Strategy of Over Current Relays in Medium Voltage DNs with DG Integration

Abstract

Distributed Generation (DG) embedded with Distribution Networks (DNs) has been developed because its performance has become more efficient and sustainable. This reconfiguration mode increases the short-circuit current (SCC), and subsequently heightens the complexities involved in both the setting and operation of the overcurrent protection system. Therefore, it is necessary to develop a robust protection strategy for DNs integrated with DG to prevent the electrical equipment from collapsing during abnormal conditions. This study proposed one of the most important and reliable strategies for resetting and re-coordinating overcurrent relays (OCRs) that operate in the same protection zone of the distribution feeder. This methodology restricts the main variables and elements used in the protection device (PD) setting after DG is embedded to redesign a suitable setting and coordination. However, international, and national benchmark standards are used to specify suitable equations that satisfy high-protection system characteristics to ensure the reliability of DNs according to a real case study of a medium voltage level 33kV in the electrical distribution feeder of Baghdad, Iraq.