An Adaptive Relay Based on Curve Fitting Technique for Micro-grid Protection

The micro-grid should operate in a well controlled manner both during grid connected and islanded mode. Also, microgrids have protection issues during faults due to the difference in fault currents when microgrids operation changes from one mode to the other. The conventional relay which works with fixed relay settings has protection challenges such as relay miscoordination and delay in operation of primary relays. This paper proposes suitable relaying scheme based on curve fitting technique for microgrids and performs well without using any extensive communication facility. The fitness of curve is accessed by measuring the value of coefficient R
²
to determine the suitable degree of curve polynomial. Efficiency of the proposed method is evaluated by comparing it with conventional over current relay. The comparison of the results show that the proposed method is efficient for detection of faults in microgrids. Suitable relay logic has been proposed to take care of all types of faults. To make the relay adaptive, appropriate synchronization logic has been applied and the details of the adaptive relaying scheme has been presented in this paper.