Digital protection strategy of microgrid with relay time grading using particle swarm optimization

Microgrid is a callow concept to utilize distributed generation optimally at load end of the conventional distribution networks. As most of the distributed energy resources are intermittent in nature the control and protection become very critical due to varying fault levels. Because of two way energy route in microgrid during Grid Connected mode the fault level drastically changes since grid generators also contribute to fault currents. The utmost importance has been given to protective relaying schemes for the microgrid in recent years. Digitization plays crucial role in the development of protection since the evolution of numerical relays. This paper presents the digital protection methodology for the microgrid using Particle Swarm Optimization (PSO) technique. The parallel feeder protection with the directional feature is introduced and Time Multiplier Setting (TMS) and Plug Setting Multiplier (PSM) for the same are optimized using PSO. A novel time grading scheme is introduced for the faster back up protection. MATLAB/SIMULINK environment is used to simulate the results.