A new hybrid islanding detection method combination of NJSMS and Q-f for islanding detection of microgrids

Microgrids can provide economic and environmental benefits, but their performance poses great technical challenges in control, protection and energy management. Microgrids can be operated either grid-connected or islanded mode. Such dual configuration capability produces challenges on the design of the protection system. Fault current magnitudes will change depending on the microgrid operating mode. this paper proposes a novel hybrid method for islanding detection of microgrids. The proposed method which is a combination of nonlinear jumping Slip mode frequency shift (NJSMS) and reactive power versus frequency (Q-f) as active methods, detects the islanding phenomena by forcing the DG lose its stable operation and drift the frequency out of the normal range of the system frequency. A simple passive islanding detection scheme that relies on system frequency such as under/over frequency protection (UFP/OFP) would be sufficient to detect the moment of islanding. The effectiveness of proposed method is demonstrated and discussed through a comprehensive set of simulation studies conducted in the Matlab/Simulink environment.