Harmonic modeling of linear and nonlinear loads based on Kalman filtering algorithm

Most harmonic nonlinear load modeling techniques developed in the last two decades, assume that the load connected to the load bus has a constant admittance, inductive or capacitive, which depends on the mode of operation of the load (constant R, L, and C). This is not true, since the loads in most cases are nonlinear and they inject harmonics into the system. This paper presents a new application of Kalman filtering (KF) to nonlinear load modeling in the presence or absence of harmonics. The proposed technique uses directly available samples of the load voltage and current to estimate, and track the variation of load parameters. The proposed algorithm can be used directly on-line for harmonics load modeling, as well as, to track the load power active and reactive. The effects of the critical parameters on the behavior of the proposed algorithm are discussed. Results for different simulated examples and practical examples from field measurements are reported in the paper. The conclusion drawn from these examples is that the algorithm is successful in estimating the load parameters.