Fuzzy time domain and Z-transform modeling for harmonic electric loads

This paper demonstrates the application of fuzzy systems and Z-transform for electric load modeling in the presence and/or absence of harmonics. The problem is formulated as one of linear optimization, where the objective is to minimize the spread of the model parameters. A triangular membership function is chosen for each load parameter. Having identified the fuzzy load parameters, the fuzzy admittance of the load is formulated in the frequency domain. The proposed algorithm is tested using simulated and actual recorded data for nonlinear loads having different characteristics. The results obtained are reported in the paper.