Power Control Of Wind Farm Based On Doubly-fed Generators

Conventional energy sources, power shortages and environmental pollution problems have become increasingly prominent, and the use of renewable energy such as wind, as the next most important, one clean and alternative energy sources, to alleviate the energy shortage has great significance. Therefore, in recent years, wind power in the world had rapidly developed, also in China. But with the installed capacity of wind power continues to increase, wind power's effect on the power system becomes increasingly prominent. The output of conventional power plants can be highly controllable, and the power output of wind power depends on the wind speed changes, volatility, and less controllable. This brought to the power system scheduling difficulties, but also limits the development of wind power. So people do amount of research in the wind power impact on the power system and the optimal control of wind turbine and have made great progress. However, wind power and wind power output control to optimize operation of the internal electric field has yet to be further study. So this master's thesis studies the output control and optimizes operation of wind farm based on the good performance of AC-excited doubly-fed wind turbine.At present, the new wind farm mainly use large capacity of AC-excited doubly-fed wind turbine as the main model. Compared to normally wind turbine, doubly-fed wind turbine's rotor using AC excitation operation mode, it has fan speed range, the largest wind energy effective tracking. And configuration of the inverter unit in the rotor circuit, only to deal with the poor two-way flow of power, not only has the converter small size, light weight and low cost characteristics, and electro-mechanical systems to achieve a flexible connection. Because of their great advantages in comparison of conventional units, so this type of wind turbine is used widely.First of all, this master's thesis summarizes the development of wind power's control technology and the impact of wind power on grid network. And the thesis analyzes the control technology of doubly-fed generator and wind farm deeply. On the basis of the existed doubly-fed generator's mathematical model, this thesis analyzes the characteristics of the doubly-fed generator's output and the control factor. On the basis of doubly-fed generator's operation region, the thesis comparatives the control technology and methods in different operational regions of the unit. The thesis finds wind farm has a controllable output power to complete certain power scheduling tasks, to reduce the adverse effects on the power grid. Second the thesis analyzes the active and reactive power output of wind farm based on the doubly-fed induction generator. According to the actual operating conditions of each wind turbine and separately control of active and reactive power's idea, the thesis assorts the wind turbines in the wind farm respectively. Active and reactive power control methods of wind farm are given separately. According to the control order, the thesis assorts the wind turbines and gives power allocation strategy of the similar units. In this way, wind power can meet the scheduling requirements of the power system and the use of units of a reasonable distribution of output power has been optimized to work. Last the thesis use MATLAB to simulate the control strategy, the results show that the method has a certain degree of practicality and feasibility.In summary, based on the research status of doubly-fed generator at home and aboard, the dynamic modeling and operation characteristics of doubly-fed generator are fully analyzed in this dissertation. Completed reach active power and reactive power output control of wind farm based on doubly-fed generator when participating in the composition of grid scheduling. This master's thesis makes classification method of wind farm based on active control and reactive of wind power. And the wind farm monitoring system for wind farm power reference value of the unit's settings. To enable the completion of wind power system scheduling tasks at the same time, the internal unit has been optimized to work.