Precise Hybrid Method for Solving the Selectivity Problem of Overcurrent Relays due to PV Uncertainty

Photovoltaic (PV) power plants include several parallel and series units. PV uncertainty due to scheduled or forced outages of these units affects the coordination of overcurrent relays (OCRs) and may violate the optimization constraint. This paper proposes a novel hybrid method to solve the selectivity problem of overcurrent relays due to photovoltaic power plant uncertainty. The proposed technique exploits K-medoids and interval linear programming (ILP) to provide setting groups (SGs). The recommended method not only maintains relay coordination for all PV generation scenarios, but also optimizes their operating time. In addition, this method can also be applied to the uncertainties caused by the synchronous distribution generation (DG) unit, which is verified in the studied networks. This research has been tested on the IEEE 8-bus and IEEE 30-bus distribution systems and the superiority of the proposed method in solving the selectivity problem and relay trip time optimization is demonstrated by the simulation results.