Impacts and Mitigation Techniques of the Protection Scheme with the Integration of Renewable Energy Sources into the Grid

Integrating renewable energy sources into electricity systems has increased the cost and prevalence. Due to the radial design of the conventional grid, connecting DGs to it causes problems with traditional network's protection configuration which is the main focus of this research. Bidirectional power flow that results from integrating DGs influences the network's protection configurations negatively. Relays coordination with high DGs penetration at optimal locations eliminate these challenges, improves network availability and reliability during abnormal operation situations. Analytical method is adopted for the efficient sizing and placement of DGs with grid and also developed Protection Coordination Index techniques for utility grid in the presence of DGs, the relay coordination eliminates false, sympathetic, and blinding of protection by analyzing fault current at PCC. This paper considered the protection coordination index technique to monitor the characteristic of OCR and DOCR functionality, re-coordinate the protection system of the grid with DGs connected, and examine the sensitivity of DGs under normal and abnormal situation on grid protection. Incorporation of distributed generators (DGs) increases the activity of grid, influencing fault currents and power flows, which can lead to an imbalance in the overcurrent relay system. The simulation result of three phase fault at 1km and 3km are 10.076 kA and 8.657 kA with a DGs connected, but 1.442 kA and 1.436 kA without DGs respectively. The result concluded that the closer is DGs to load, the higher fault current flow in the grid which calls for relay coordination of the grid at PCC.