Propagation of Supraharmonics Generated by PMSG Wind Power Plants into Transmission Systems

This paper is focused on the propagation of supraharmonics into power transmission grids introduced by wind power plants (WPP) based on permanent magnet synchronous generator (PMSG) wind turbines. The methodology is based in steady state and time domain simulations performed by MATLAB Simulink®. As results steady state power flow and time domain voltages and currents are obtained and supraharmonic indicators are proposed for analysis. In order to simulate the electrical power system, transmission lines are modelled by Pi equivalent circuit based on distributed parameters and linear models of transformers are considered. Furthermore, wind power plants are modelled as aggregations of several wind turbines. A study case based on the west side of the Brazilian state of Rio Grande do Sul is proposed to validate the modelling and simulation methodology. Results show that the level of supraharmonics emission from WPP is straightly related to the PWM modulation of power inverters. Furthermore, the propagation of supraharmonics into transmission grids follows a linear tendency of decreasing according to the distance in transmission lines to the point of common coupling (PCC) of the wind power plants. Anyway, intrinsic characteristics at each point of the grid such as load profile, generation and presence of capacitor banks also influence the behavior of supraharmonic propagation.