ADAPTIVE RELAY FOR MICRO GRID PROTECTION AT PCC
Abstract - Microgrids are the potential solution to cater the rapidly increasing energy demands globally. They offer a local generation and consumption model, improving reliability, energy efficiency and reduced emissions. They involve Distributed Energy Resources(DERs) encouraging maximum utilisation of the renewable energy sources. The conventional protection technique involves use of a dedicated protective relay for each issue. The complexity, maintenance and coordination requirement in the system is more for conventional technique. The report proposes an interface relay for integration of a DER. The protection issues concerning integration of DER at Point of Common Coupling PCC was studied. An Over current relay logic with its characteristics independent for different fault direction was developed. Dual Second Order Generalized Integrator(DSOGI) based Phase Locked Loop for synchronisation, with immunity for grid harmonics and voltage unbalance, and unintentional islanding detection was designed. These logics were included as a part of Interface relay logic. A microgrid test system with DER at PCC and the interface relay were modelled on the MATLAB/SIMULINK platform. The system was simulated and analysed for different test scenarios.
Keywords – Micro Grids; Distributed Energy Resources; Point of Common Coupling; Bi-Directionality; Over Current Relay; Synchronization