Control system of doubly fed induction generators based wind turbines with production limits

Doubly fed induction generators based wind turbines are today one of the most widely used generation systems in wind farms due to the ability of variable speed operation and with decoupled control of active and reactive power. Nowadays these wind turbines are operating without generation limits, but the increasing wind power penetration in power systems must lead to that the wind farms have to operate with production limits imposed by the electrical system operators to maintain the stability of the electrical network. In this paper, a new control system of doubly fed induction generators based wind turbines is proposed for the control of active and reactive powers according to the imposed power limitations. This control system presents an active power controller, reactive power controller and pitch angle controller, in order to operate the wind turbine with optimum power efficiency or with limited active power and the demanded reactive power. This generation control provides a better grid integration of doubly fed induction generators

I. Introduction

Wind energy is the way of electrical generation from renewable sources which uses wind turbines, concentrated in wind farms, to convert the energy contained in flowing air into electrical energy. Wind power is the world's fastest growing energy source with a growing at an annual rate in excess of 30% and a foreseeable penetration equal to 12% of global electricity demand by 2020 [1].