This chapter discusses grid integration issues. It provides a thorough description of the grid integration issues of wind generator systems. Wind power as a generation source has specific characteristics, which include variability and geographical distribution. Due to random wind speed variation, wind generator output power, frequency, and terminal voltage fluctuate. In other words, power quality of the wind generator deteriorates. With the rapid increase in installation of wind generators in the power system, it becomes necessary to require wind farms to behave as much as possible like conventional power plants to support the network voltage and frequency not only during steady-state conditions but also during grid disturbances. Introducing wind generation can increase the regulation burden and need for reserves, due to its natural intermittency. The impact of the wind plant variability may range from negligible to significant depending on the level of penetration and intermittency of the wind resource.