Studies On The Stability Of Regional Power Grids With Trip-off Accidents Of Large-scale Wind Power

Now, with the rapid development of economic globalization in the world, energy crisis and environmental pollution are two urgent issues facing society today. The wind power is a kind of renewable green power resources, its development and utilization is necessary. Doubly Fed Induction Generator (DFIG) is the world’s major wind turbine products with large market share. It has the advantage of wide speed regulation range, active power and reactive power can be adjusted independently, small inverter capacity, wind energy captured ability is better and so on. With the increase of the single capacity of wind turbine and wind farm scale, interactions between wind turbine and power grid is more and more big. Therefore, the study of system stability under the condition of different penetrating after power DFIG off-grid is of great significance. In this paper, to a real power grid in Guangdong Province as the research target,the impact on the electricity system based on dyn amic simulation in the simulation software DIgSILENT/PowerFactory(DPF)environment, su ch as maximum power injection of Wind Farm and Wind Power off-grid are researched. The main research contents are as follows:(l)The international and domestic status and trends of wind Power generation background and the present situation are surveyed, and the present domestic and foreign scholars about wind power grid technology and Wind Power Off-Grid are described.(2)Based on doubly Fed induction wind turbine, the mathematical model of Wind power generation system and Wind turbine system are built, including mathematical model of wind turbine torque, transmission model, mathematical model of pitch angle control. The Stationary and synchronous reference frame to coordinate transformation relation is provided, and equation about mathematical model of doubly-fed induction generator in the Stationary and synchronous reference frame is deduced.(3)The stand-alone infinite system based on DFIG is built in the simulation software DPF environment, to study the stability of the stand-alone infinite system, and it gets that there is not electromechanical transient instability phenomenon about DFIG itself and nor is there a problem with the system out of step between synchronous generators. (4)Off-grid wind power mechanism is analyzed, and low voltage ride through is outlined, for research wind turbines due to the failure off-grid power system to the impact of power system provide a theoretical basis.(5)Through in-depth study of the major factors that can affect maximum power injection of Wind Farm, for a certain region of Guangdong Power Grid actual situation, the method which is suitable for the region’s maximum power injection of Wind Farm, is determined. Maximum power injection of Wind Farm based on dynamic simulation for the regional power grid is researched, and Maximum power injection of Wind Farm to the regional power grid is solved. Finally, the stability of the regional power grid under wind power penetration in different circumstances after the off-grid wind turbine is studied.