Abstract: Renewable energy sources are alternative energy sources, can bring a new challenge when it is connected to the power grid system. As a promising alternative wind and geo-thermal is one of the significant sources of generation. When the wind and geo-thermal is connected to an electric grid it affects the power quality. There are many power quality issues pertaining when wind energy and geo-thermal is connected to the grid. For example reactive power, voltage sag, voltage swell, harmonics, flickers and electrical behavior of switching operation. In order to mitigate these issues, various techniques have been explained in this paper. In this proposed scheme a FACTS devices such as SVC, STATCOM, VSC, UPQC, and UPFC are commonly used to mitigate the power quality measurements. Consequently, with the development of the wind farms and geo-thermal power sources which are integrated into the grid, power quality could be better improved in the future. Recently, the most of wind conversion systems are equipped with a variable speed DFIG and geo-thermal power generation system equipped with high performance synchronous generators. The FACTS device control scheme for the grid connected wind and geo-thermal to improve the power quality standards is simulated by using MATLAB/SIMULINK environment. Results promise, and it seems that suggested idea is competitive with other renewable energy sources. Further studies are necessary to achieve more realistic results to start actual projects.

Keywords: power quality, Wind energy generation system and Geo-thermal power, FACTS device control and protection scheme, DFIG.