Study On Voltage Stability Of Wind Power Integrate To Regional Power Grid

With the development of social science and technology,new type of generation is becoming much more mature,which is particularly evident in the development of wind power.And wind power has a high value of commercial and environment,that makes the wind power’s prospects are limitless.Even though,wind power has his shortcomings.The randomness and volatility of wind resources can have a big impact on their controllability.Compared to traditional power generation,there is still much room for development in wind power.As we known,it will do harm to voltage stability and other effects when wind power access to regional grid.And it is gradually becoming the popular research nowadays.The object of this paper is some actual grid A.Study the variety of its voltage stability when the wind farm is integrated to grid A.Analyze the stability of static voltage and transient voltage of the grid.Build model of grid A in PSD-BPA program and study the effect of voltage stability when wind farm access to regional grid.The specific work is as follows:(1)The object of wind turbine studied is double-fed wind turbine with a capacity of 2MW.Build the mathematical model of wind turbine,including the wind energy to the mechanical energy conversion,wind power generator in three-phase stationary coordinate system and in two-phase rotating coordinate system.And next,the control strategy of rotor side converter and grid side converter is analyzed.(2)The mechanism of voltage instability is studied,including the basis for the determination of voltage instability.Load margin is an important criterion for static voltage stability.And the impact of wind speed fluctuations and line failure on the voltage must be considered when analyze the transient voltage stability.(3)Create a model for grid A and study its static voltage stability.Measure the substation node voltage associated with the wind farm and calculate the U-Q sensitivity,when the grid is running normally and when the wind farm is connected to the grid.Then find out which will affect the substation voltage.Compare two measures to improve the static stability of the power grid: install the fixed reactive power compensation equipment and adjust the wind turbine terminal voltage.Use the two methods to simulate and compare the results between two methods.The improved load margin is only about 0.4MW,but the adjustment of the terminal voltage is more economical and flexible.(4)The transient voltage stability of power grid under two disturbances which are wind speed variation and grid short circuit fault is analyzed.And the difference of the transient stability in power grid voltage before and after the installation of SVG is also analyzed.When the three-phase short-circuit fault occurs in grid-integration,voltage drop ratio decreased by 10.06% after the installation of SVG.In conclusion,the dynamic reactive power compensation device SVG can improve the transient stability of the power system when the power system suffers from short circuit fault.