Research Of Voltage Stability Of Gird-connected Wind Power Generation

Since1980s, renewable energy is considered to be the best and the most effective method to solve the serious energy consumption and worsening environment pollution problems. Among renewable energy, wind energy, large-scale and industrialization, is drew much attention as a new clean energy. Because wind farm is of randomness, intermittency and instability, its power output dynamic changes, which restricts grid-connected wind farm, which is the main reason to hinder the wind field expansion. As a result, the grid instability problem which is caused by grid-connected wind farm needs to make a deep research in order to rational use of wind power generation, to protect the environment and benefit mankind.Although the wind power technology has developed rapidly, the wind turbines have made a large progress, and the influence of wind farm to the system has become smaller, the asynchronous generators have been adopted by most of wind farm. The paper studies a problem about voltage stability influenced by the characteristic of asynchronous generators at the time of grid-connected of wind farm. The paper also studies voltage deviation, voltage fluctuation and voltage instability which are caused after large wind farm connects to the power system. Based on studying the possible reasons that cause voltage instability, the paper provides the reliable data or the feasible solution to program wind farms. It also provides conclusion to serve for the built wind farms.The contents of the paper are as following: Firstly, the paper introduces the present of wind generation, and studies the voltage stability in grid-connected of large-scale wind farm system.Secondly, the paper introduces the basic principle of VSCF doubly fed induction generator and analyses the reasons which cause voltage instability. Combining with the methods to control voltage stability in traditional system, a new method is given to fit for use in the large-scale wind farms. Thirdly, the paper studies and analyses the static voltage stability of wind farms, and obtains the voltage static instability indices. The paper analyses transient voltage stability, and establishes the example of calculation system simulation model using Matlab/Simulink and PSASP.Finally, in the case of the influence of wind and the fault line, the paper analyses the static voltage stability of wind farms, and studies the effects which improves voltage stability in large-scale wind farm system caused by static var compensator SVC and doubly fed induction generator respectively.