Analysis And Control Of DFIG-Based Wind Farm Inter Connected To The Grid

As the increase of the wind energy interconnected to the Power system, the influence of the wind power to the grid is also increased. With the increasing requirement of the strategy of sustainable development, the advantages of wind power and the demand for it has become increasingly prominent. However, the difference between the distribution center of wind power and load, and the wind generators running in parallel resulted from their smaller capacities. Therefore, the equivalent modeling and simulation on the large scale wind farm has great significance.First, the equivalent mathematical model is modeled. The simulation model of the 3-generators-9-buses systems was established in the PSAT, which was used to the power flow calculation. Analyzing the distribution of the load flow and the network loss comparing with the model of wind farm which ignored the collecting system,note that the significance of the collecting system in the steady-state model of wind farm and the use of the steady-state model of wind farm in the aspect of deciding the location of the wind farm and reducing the loss of the network.Then, Wind farm connected to infinite bus is established in Simulink and PSAT respectively to simulate the effect on the voltage, active power and reactive power of the grid bus caused by a three-phase short-circuit fault on the transmission line. Comparing the differences between the equivalent model and the actual model connected to infinite bus, note that the correctness and practicability of the use of the dynamic model of wind farm in the analysis of the impacts on the grid transient stability when it was connected to infinite bus.Last, based on the DFIG wind farm model, the small signal stability control method is studied. The 3 machine 9-bus WSCC system has been modeled in Simulink. Accesses the system model access equivalent wind farms. The small signal stability is analyzed trough the calculate of eigenvalues. The power system stabilizer parameters is also determined by the system analysis. The time-domain simulation result also show that proposed PSS design method is useful to improve the system damping., effectively suppress low-frequency oscillations.