Integration of energy storage with a doubly-fed induction machine for wind power applications

The doubly-fed induction machine has been shown to be a popular choice for wind power generators, due to the desirable features of variable speed operation, reduced converter size and the ability to control the real and reactive output power. For this topology, reactive power compensation can be supplied from both the supply side and rotor side converters and thus has the potential to provide voltage support. Addition of an energy storage element on the DC link can help to improve transient stability of the system as well as enable a greater level of control over the real power output. The storage element can be used to smooth the generator´s power output by injecting real power under low wind conditions and storing energy during high wind conditions. The design of the proposed system and the control is presented and its feasibility is supported using its representation in EMTP-RV.