Improved Differential Based Protection Scheme for Renewable Energy Based Microgrids with Low Communication Burden

Due to prevalence of distributed energy resources, especially inverter interfaced ones, conventional protection systems meet substantial challenges for fault detection. Differential protection is the most reliable protection method for current networks; however, the conventional method leads to high communication burden. We propose a new differential protection based on disturbance detection and positive phase angle differences. The disturbance detection method is proposed based on Mathematical Morphology which has high speed and accuracy. Instead of transmitting the instantaneous values or the phasor of the currents which impose high communication burden on the network, the phase angle of the current is the only data which is transmitted when a sudden change is detected. The proposed method reduces the communication burden significantly and increases the resiliency of the protection scheme. The effectiveness of the proposed method is verified in modified IEEE 9 bus 3 machine network with three distributed energy resources. PSCAD is used to simulate the microgrid and the proposed method is implemented in MATLAB. It is proved that this method works properly in both islanded and grid connected modes and despite significant changes in the grid. The robustness of method in presence of noise and its high reliability and dependability is verified through various simulation case studies.