Fault Detection of Grid-Connected Looped Microgrid based on Estimated Energy Difference Signal

Due to the integration of distributed generation (DG), fault level of the microgrid changes significantly. The fault current behaves dynamically and inhibits the activities of conventional protection algorithms. To address this serious issue for protection, a simple and fast protection algorithm, based on Empirical Mode Decomposition (EMD) and Hilbert Transform (HT) is proposed in this paper for the protection of grid-connected 14 BUS looped microgrid system. This scheme estimates the energy difference of current signals retrieved from both ends of the feeder. Further, the fault detection signal is generated from the Hilbert spectral energy difference. Nonetheless, for the comparative analysis of the performance of proposed EMD based fault detection technique, Variational Mode Decomposition (VMD) is also performed. Further high resistance fault cases are also examined to verify effectiveness of this proposed scheme. As this technique is essentially reckoning on the energy difference of current signals, it does not suffer from the difficulties associated with dynamic current behaviour of a microgrid. This proposed system is simulated in PSCAD simulation software and the programming for signal analysis is performed in MATLAB.