Application of decision tree and discrete wavelet transform for an optimized intelligent-based islanding detection method in distributed systems with distributed generations

In this paper, a method for islanding detection based on analysis of transient state signals is provided. Decision tree (DT) is trained for classifying the transient events. The required features for classifying are extracted through discrete wavelet transform (DWT) of signals. The proposed method is then simulated on a medium voltage distribution system of CIGRE with two kinds of distributed generations (DGs) using DIgSILENT, MATLAB and WEKA softwares. By analysis performed on type of input signal, type of mother wavelet and required transform level, among 162 relay designs, an optimum relay is selected for distributed generations (DGs) based on accuracy, speed, simplicity and cost parameters. By evaluation, it is determined that using only one input (voltage) signal not only improves speed and simplicity and reduces costs, also makes accuracy of the proposed relay better than other intelligent and passive methods. The final selected relay for each DG is V-db4-D3 which has accuracy equal 98%.