Modeling of FACTS Devices Based on SPWM VSCs

In this contribution, two voltage-source converter (VSC) models based on Fourier series and hyperbolic tangent function are proposed. The models are described in detail. The proposed models can be used for fast simulation in the time domain of power-electronic devices based on sinusoidal pulse-width modulation VSCs; the undesirable error introduced by the high rates in the commutation instants are removed; even though the harmonic distortion coming from the converter is taken into account. The switching instants in the Fourier model are approximated in a closed form, and an iterative algorithm based on the Newton-Raphson method is developed for the exact calculation of the switching instants. The hyperbolic tangent model does not need the calculation of the switching instants as in the case of the Fourier model. The proposed models are validated against the solution obtained with the power system blockset of Simulink and with PSCAD/EMTDC.