Study On Technology For Black Start By Wind Power Generation Under The Condition Of Smart Grid

Black start is the process of entirely recover from major region-wide blackouts without assistances from the neighboring utilities through the unit with self-starting capacity driving the unit without self-starting capacity as to gradually expand the recovery area of the system. Traditionally, the power sources of high operational reliability are usually chosen as black start sources such as the pumped storage power stations or gas turbines. However, due to the constraints like the irrational water resources distribution or the high operation and maintenance requirements of gas turbines, there are several actual problems including the shortage and unreasonable distribution of black start sources in the power grid. With the promotion in operation control technology under the smart grid environment, it is a beneficial attempt to use large scale "system friendly" wind generations as the participant in black start both in theoretical research and practical application. Therefore, it's an urgent need to research on the start-up characteristics, control strategies and realizing methods of the wind generations as to effectively develop the starting capacity.Firstly, the self-starting ability of wind generations is entirely analyzed in this paper based on the scenario of wind power generations participating in black start. With the key issues about wind generation participating in black start being discussed, including the selection of wind turbines, the selection of matching small capacity supporting power supply and the start time of static var generator, the process of wind power generations participating in black start is analyzed in detail. Through the deep research on mathematical model, control strategy and the composition of auxiliary equipment of permanent magnet direct driven wind turbine, the capacity of matching supporting power supply is preliminary determined, and the model of diesel generator and static var generator is established. The corresponding system model is built in PSCAD, the start-up characteristics of wind power generations under different conditions are analyzed.Secondly, according to the frequency control problems during the black start process, the cooperative frequency control strategy based on virtual inertia is proposed in the scene of black start by wind generations. Through the research on virtual inertia principle of permanent magnet direct driven wind turbine, the adaptive analysis of the traditional virtual inertia strategy is carried out based on the scene of black start by wind generations. A new frequency control strategy is proposed base on the shortages of traditional methods, the frequency control capability of the wind power generators can be significantly enhanced by adding the improved pitch angle response control and the flexible switching control, and the system frequency stability of the wind generations is promoted in the black start process. In PSCAD simulation, a comparative analysis of the whole dynamic process of wind power generations participating in black start under different strategies is carried out, which verifies the rationality and the advanced nature of the proposed strategy.Furthermore, in view of the practical engineering application, a new method based on the load control for black start by wind generations and its platform design is proposed. Through the research on the load characteristics of wind generations and thermal power plants, the static equivalent load model and the induction motor model are constructed. On the basis of the principle of stratified division load control, a new method of black start by wind generations based on the load stratified division control is proposed, the control effect of different schemes is compared in PSCAD also with the virtual inertia corporative control strategy. At the same time, the design scheme of the black start platform of the wind generations is proposed, including the design of system frame and hardware.Finally, aiming at the areas with high-density wind power penetration, the optimum path search method of multi wind farm groups is introduced based on the dynamic clustering theory. The wind farms are dynamically clustered based on the ultra-short-term prediction data and quantified by different clustering results. An optimization model comprehensively considering the maximum power output, the shortest electrical distance and the minimum starting capacity of auxiliary system is proposed, and the optimum start-up path search of multi wind farm groups is conducted based on ant colony algorithm. In MATLAB, the results of different multi-objective solution methods are compared and verified from the view of practical engineering application requirements.