The Steady-State Interaction of a Grid-Connected Doubly-Fed Induction Generator and the Wind Turbine

The generic expressions for the steady-state stability profile of a doubly-fed induction generator operating in maximum power tracking (MPT), power regulation, and rated output power modes are derived in this paper. This paper considers both mechanical and electrical dynamics in the derivation of the stability criterion. The contour plots using these expressions reveal a reduced stability region than previously reported in literature for both MPT and rated power modes. The paper further explores the sensitivity of the steady-state stability region to changes in rotor speed, wind speed, and blade pitch angle as to guarantee a good prediction of the steady-state stability region. Specifically, the simulations show that when operating in the sub-synchronous region, the effect of the pitch angle on the stability region is more prominent than its corresponding super-synchronous region when the mechanical dynamics are accounted for.