LINEAR TIME PERIODIC MODELLING OF POWER ELECTRONIC DEVICES FOR POWER SYSTEM HARMONIC ANALYSIS AND SIMULATION

This paper presents an analytical frequency-domain method for harmonic estimation able to assess harmonics and interharmonics levels and to capture the coupling between frequencies. It is based on the linear time – periodic system theory as a result of the periodic behaviour of the state variables in steady state operation. It consists of describing the considered system with a set of differential equations, presenting them in a matrix form in the frequency domain by decomposition of the converter state variables into Fourier series and finally solving the matrix equations in order to calculate the current and the voltage harmonics. The method is applied to a single phase full wave rectifier and to an association rectifier- inverter, the results are verified by simulation