Secondary Harmonic Emission in Wind Power Plants

The harmonic emission of wind power plants into the public grid is an important part of studies for connecting such plants to the power system. However, the transfer of emission between individual wind turbines within the collection grid is normally not considered. Neither are different grid impedance scenarios considered. This transfer is one of the types of secondary emission that needs to be considered for a complete picture of harmonics in wind power plants. In this paper, a study after the importance of the secondary emission in wind power plants is presented. The impact of the grid impedance on this emission is also considered. For this, the current transfer and the transfer admittance functions were used in two wind power plants, with five and 42 wind turbines each. From the results, it was possible to estimate the secondary emission contribution from the wind turbines and estimate the impact of the grid impedance. The grid impedance has shown to have an important impact on the secondary emission for wind turbines. The harmonic transfer between wind turbines is shown to be considerable. It can vary from 15% to 70%, for the wind power plant with five wind turbines. For the 42 wind turbines case, it can vary from 2% to 14%, assuming current emission, and, from 0.48% to 3.32%, assuming a voltage source for the emission.