This chapter reviews power electronics for control and grid integration of various wind and photovoltaic (PV) power systems. Power electronics plays an important role in wind and PV power systems. The generator converts mechanical power to electrical power, which is fed into a power grid or used to supply local loads through optional power electronic converters and a power transformer with circuit breakers. The use of power electronic converters enables the wind turbine generator to operate at variable speed to generate the maximum power and to have many other operational benefits, such as reactive power and power factor control, reduced mechanical stresses of the drive-train system, and enhanced grid fault ride through capability. Power electronic converters are commonly employed to convert the electrical power from the form generated by the wind turbine generator into the form required by the power grid or load.