Modeling And Operation Analysis Of A Doubly-Fed Induction Generator With Stator Winding Inter-turn Short Circuit

With the people's concerns about energy and environmental issues, wind power develops rapidly. Comparing with solar energy, nuclear energy and other new energy generation, wind power is the power generation which has great potential, great condition for large-scale development and commercial prospects.VSCF unit, based on doubly-fed induction generator(DFIG), become the mainstream of the international wind turbine, with its smaller capacity required excitation frequency converter, wide speed range, active and reactive power decoupling control and so on. Due to complex operating conditions, the probability of failure in DFIG is high. Stator winding inter-turn short circuit(SWITSC) fault is the general internal fault of DFIG, which often leads to the phase- phase or single-phase ground short circuit and has serious harm. Some data indicates that after SWITSC fault occurs, an induction motor still continues to run hundreds of hours under full pressure. It means that induction motors, including DFIGs, can be sick running with SWITSC fault. This paper focuses on the modeling and operation analysis of DFIG with SWITSC fault. The main work and results achieved is following:Firstly, based on the theory of multi-loop, the paper builds the mathematical model of DFIG with SWITSC fault in ABC three-phase static coordinate and dq0 synchronous rotating coordinate system.Then the paper establishes its healthy and fault model in Matlab/Simulink environment. Comparing with the simulation of the model based on a Matlab typical system, the correctness of the model has verified.Secondly, in the condition of different degrees of SWITSC fault, when the wind speed changes, the paper analyzes its ability to achieve maximum wind energy tracking. The results show that DFIG with SWITSC fault can't achieve the maximum wind power tracking. With the deepening of the fault, the ability of DFIG with SWITSC fault to achieve the maximum wind energy tracking becomes weak er.Finally, contrasting the dynamic response of DFIG at different degree of SWITSC fault and grid voltage dip, the paper analyzes its ability to achieve low voltage ride through(LVRT). In the case of SWITSC fault, the active power and rotational speed of DFIG reduce. Neither does the ability of providing reactive power to the grid and its stability. With increasing degree of SWITSC fault and grid voltage dip, the above consequences become more obvious.