Power quality improvement of a grid-connected wind energy conversion system with harmonics reduction using FACTS device

Wind power injection into an electric grid affects the power quality due to the fluctuation nature of the wind and the comparatively new types of its generators. On the basis of measurements and norms followed according to the guidelines specified in IEC-61400 (International Electro-technical Commission) standard, the performance of the wind turbine and thereby power quality are determined. The power arising out of the wind turbine when connected to a grid system generates power quality problems. The concerned power quality measurements are: active power, reactive power, voltage sag, voltage swell, flicker, harmonics, and electrical behavior of switching operation. Normally Static Var Compensator (SVC) can be used to improve the power quality by reducing harmonics in the grid current. But it has less reactive power compensation. This is because at a low voltage limit, the reactive power drops off as the square of the voltage for the SVC. In this proposed scheme a FACTS device STATIC COMPENSATOR (STATCOM) is connected at a point of common coupling. The STATCOM will reduce the harmonics in the grid current by injecting superior reactive power in to the grid. This is because of reactive power drops off STATCOM is linear with voltage. Here a bang-bang control scheme has been implemented with the STATCOM to achieve fast dynamic response for the reduction of harmonics in grid current. Bang-bang controller is simple and reliable. A STATCOM can improve power-system performance in such areas as the following: the dynamic voltage control in transmission and distribution systems, the power-oscillation damping in power transmission systems, the transient stability, the voltage flicker control and the control of not only reactive power but also (if needed) active power in the connected line.