Frequency-domain modeling of nonlinear power system devices: The quasi-sinusoidal volterra approach

Studying the impact of nonlinear devices on harmonic pollution represents a very important task, especially in modern distribution grids. In this case, harmonics are produced by the large amount of power electronic devices, which is going to further increase because of the growing penetration of diffuse generation and the expected diffusion of plug-in electrical vehicles. Suitable nonlinear frequency-domain models are required for the purpose, and the frequency transfer matrixes approach is typically employed. A possible alternative approach comes out from a suitable simplification of the Volterra series. The derived models are defined by a reduced set of coefficients and they allow reaching good accuracy for a wide range of input values. The performance of this approach is evaluated through numerical simulations by predicting the input current of a bridge rectifier operating in continuous conduction mode.