Coordination and Security Assessment of Distribution Feeder with Intermittent Renewable Generation

This paper presents the analysis of over-current relay coordination and the safety of the distribution system after the addition of a photovoltaic (PV) system and wind turbine generation (WTG) as intermittent distributed generation (DG). The coordination and security were assessed using ETAP simulation for 20 kV distribution network with 20 buses. In this study, power flow analysis and short circuits were conducted for relay settings and selectivity analysis. The analysis was carried out before and after the addition of a PV system and WTG. The results showed that the protective relays are coordinated appropriately, and the security of the system runs properly before the addition of the intermittent DG. However, after the addition of intermittent DG at a certain percentage of load power, the protective relays are uncoordinated and, under certain conditions, the security of the system is faulty. This condition was resolved by resetting the existing relays and by adding new relays at the intermittent DG bus. The study concludes that the addition of overcurrent relay close to DG location can improve distribution system security and make the over current relays coordinated.