Additional application fields of a modern wind generator even at no-wind

A modern variable speed wind turbine generator is connected to the lines (grid) through a both sides PWM controlled DC link voltage source inverter. The fast current control of the line currents by the line-side converter makes possible to compensate the deviation of the line currents from their fundamental component. This possibility can be used to compensate the lower order current harmonics in the line currents (injected by nonlinear loads on the lines) and to balance the negative sequence current component (caused by asymmetrical load). Besides, advanced control strategies make possible to control the reactive (and also the active) power of the lines, resulting in power factor correction. Since all the mentioned subjects of compensations require at most pulsating active power with zero mean value, the listed compensations are possible even at no-wind condition. Of course, the pulsating active power affects the pulsation of the
dc
link voltage, the limits of the compensations in this sense must be investigated. All the investigated additional application fields improve the power quality of lines (grid) where the wind turbine generator is connected to. The practical aim of this paper is to attract the attention of the wind turbine makers to these additional application fields. The paper presents the advanced possible line-side converter control schemes. The physical and theoretical background of the different compensations are discussed. The issues of their implementation by the presented control methods are detailed. The methods are investigated and validated by simulations of practical examples. Design criteria are given based on the considerations.