Electrical System Load Modeling and its Impact on Harmonic Analysis of a Wind Power Plant

In the current context, due to the increasing insertion of nonlinear elements in the electric system,harmonic analysis becomes necessary and has been highlighted in the international scenario. Regarding the modelling of the linear load of the electric system, it is relevant to note that, due to the impact on the frequency response of the grid and, in principle, to increase damping for the harmonic currents generated by wind farms, it is important to verify the impact caused by the different forms of representation of the load or its disregard. In this sense, this article presents the criteria adopted by the Brazilian National Electric System Operator (ONS) to perform the harmonic distortion studies for the access to the HV (High Voltage) transmission system or to their frontier buses, aiming to compare three types of linear load modelling: in series, in parallel and open circuit, in relation to the harmonic distortion indexes and the frequency response of the electrical system. This comparison is carried out in a real study case of a wind farm, using the locus method, with data obtained through simulation in the HarmZs program. The results show that, when the electric system loads are represented, lower voltage harmonic distortions are found when compared to the simulations without considering the external load of the system.