Research On Reactive Control Method For Wind Farm

Wind power as a kind of widely used new energy.The development of wind power will be the trend of future development.But,the scale of wind farm expansion has also brought many challenges.Challenges are brought to the grid because of the integration of large-scale wind power.Reactive power and voltage control is one of the challenges.Because of the volatility and randomness of wind energy resources.The main cause of voltage fluctuation by the fluctuation of wind power.Responses of reactive power compensation device regulation characteristics and time scales increases the difficulty of reactive power and voltage regulator.The thesis makes a study of reactive power and voltage control of large scale wind farms in the above background.Firstly,the theoretical study of the structure and characteristics of the wide use of several types of wind turbines.These include:cage asynchronous motor and doubly-fed induction motor.And establish the equivalent mathematical model of these two wind turbine.And also introduced three common reactive power compensation equipment:capacitor group?SVG and SVC.Introduced each device advantages and disadvantages from their characteristics in the application.Secondly,the main study of the wind farm normal work influence of the voltage and the power loss.Research wind field with different wind motor integration on power loss and static voltage influence.To establish the evaluation index of voltage.Research on of wind power access to the grid voltage quality impact assessment.Finally,wind power fluctuations caused by voltage fluctuations.And different reactive power compensation device responsive,reactive power regulation characteristics increase the difficulty of the problem of voltage regulation.Make wind farm access to the grid reactive power voltage control strategy and structure.The reactive power optimization strategy is divided into multi-stage two time scales reactive voltage regulator.Assigned to different devices for reactive power compensation.First to all day time reactive power compensation.One day in the future for short-time forecast by BP neural network.According to the prediction of wind power,the capacitor group is optimized by internal point method.In advance of the wind farm reactive power compensation.The doubly fed induction generator and static var generator reactive leaving much reactive power.After all day time reactive power compensation.Using doubly fed induction wind turbine output limit of reactive power compensation distribution.If the reactive power compensation is not enough.Using differential evolution algorithm for reactive power optimization calculation.For static var generator fast continuous reactive compensation.Make wind farm voltage and the set value of the minimum deviation.And establishing simulation model,verification of the reliability of the method.