With the request of renewable energy also the size of the wind turbines is growing. The converters used to connect them to the grid have to transfer a big amount of captured power. Since they handle high power, the switching devices work with a low switching frequency. This results in a high harmonic distortion of the injected currents and the need of big passive filters on ac side. In order to improve the Power Quality of the transferred wind energy, an inverter system made up of interlaced Active front-ends is proposed. Its mathematical model is also developed in order to analyze harmonic distortion. It can be introduced in the existing models of wind turbines and grid. The numerical results prove the benefits of the proposed system.@en

Improved and extended DG capability in voltage regulation by reactive and active power Triggianese, M.; Morren, J.; de Haan, S.W.H.; Marino, P.; Power Engineering, Energy and Electrical Drives, 2007. POWERENG 2007. International Conference on 12-14 April 2007 Page(s):583 - 588 Abstract: Distributed Generation (DG) units are fluctuating power sources that may cause a fluctuating voltage at the point of common coupling (PCC) with the grid. Their connection to distribution networks makes the voltage regulation important since the voltage fluctuations can generate flickers problems. Wind Generation is considered as example of DG. The power electronic converters that connect wind turbines to the grid can contribute to voltage regulation. Reactive power compensation is mostly adopted. Moreover since distribution networks are much more resistive than transmission ones, the conventional technique of voltage regulation by reactive power compensation shows its limits. Therefore new techniques are needed. In this contribution the active power curtailment is investigated and a new controller for voltage control by reactive power compensation is proposed. This controller concerns a new technique in the voltage control loop which improves the dynamical response of the voltage control. It is given by a combination of a feed-back and a feed-forward action.@en