Research On Control Method Of Doubly Fed Induction Generator

The Doubly-fed generator (DFIG)which has features of variable speed constant frequency operation, superior steady-state and transient-state operation characteristics,it is especially suitable for wind-power generation system, hydropower generation with variable water head, and pumping storage generation system。The appropriate control strategy is the key to good regulation performance operational flexibility and Reliability of DFIG。based on the detailed analysis mathematical model of DFIG and basic characteristics, this paper derive vector control method and establish simulation platform based on PSCAD/EMTDC environment;analyzed the control method of DFIG at unbalance grid voltage condition with wind turbines as an example;and finish the relate simulation verification.The main work of this dissertation is follow:Analyze the basic theory and characteristic of DFIG derive the mathematical process of Vector Transform, Set up the mathematical models of DFIG and detailed analysis the energy conversion relationship about it。Describe the basic concept of vector control, analysis basic theory of vector control based on the stator flux-oriented, derivation the generator power equation based on the stator flux-oriented vector control method, set up a control strategy based on stator flux vector control system block diagram。Describe the basic concept and working principle of double PWM converter, derive the general switching function mathematical model of network-side three-phase PWM converter, based on using power grid voltage-oriented control the AC side input current is divided into active components and reactive components, control the active and reactive components achieve unity power factor control of AC and DC link voltage control.Set up a simulation system platform In the PSCAD/EMTDC environment, complete simulation of the control strategyDescribe damage to wind turbines and generator caused by unbalance power grid voltage。added the negative feedback control in the original control strategy of DFIQ the rotor side of negative feedback objective is to prevent electromagnetic oscillation, the net side of the negative feedback control objective is to prevent unbalanced currents into the power grid...