Optimal selection of excitation capacitor for dual stator-winding induction generator wind power system

In the dual stator-winding induction generator (DWIG) wind power system, the optimal selection of excitation capacitor is very important for minimizing the capacity of static excitation controller (SEC). The optimal excitation capacitor is not only related to the generator parameters and speed range, but also affected by the wind turbine power curve and the types of load. Based on the analysis of the change of excitation reactive power in DWIG, the optimal rule of excitation capacitor is investigated to minimize the capacity of SEC. The graphic and iterative methods are employed to achieve the optimal excitation capacitor with the resistance load. Considering the nonlinear influence of rectifier load, this capacitor is modified properly by simulation. Experiments are carried on the prototype of 18 kW DWIG system with the rectifier load. The results illustrate that the system has good performance over a wide speed range, and the capacity of SEC accounts for about one third of the rated power. The implementation of minimizing the capacity of SEC is obtained.