Transient Voltage Stability Analysis Of Wind Power Grid Connected Based On Dpeak Equivalent Modeling

In recent years,the rapid development of society is closely related to the highspeed consumption of energy,and energy reserves have become an important chip in the competition between countries.With the decline of fossil energy reserves such as coal and oil in various countries,wind power generation has become an important part of energy utilization in various countries.Wind energy is abundant in China,and the gradual maturity of wind power technology promotes the formation of large-scale wind farm grid connection.However,the randomness and unpredictability of wind energy make the voltage stability problem of wind power grid connection limit the scale of grid connected wind farm.Therefore,this thesis studies the equivalent modeling of wind farm and the influence of transient fault on voltage stability of wind power grid connected system.Firstly,this thesis introduces the background and significance of wind power development at home and abroad,and further introduces the research results of wind power from the world and China.Through the analysis of data and icon,it shows that wind power technology has become mature.In this thesis,the research status of wind farm equivalent modeling method and wind power grid transient voltage stability analysis method is stated.Through the analysis of the advantages and disadvantages of the existing literature,the Dpeak based wind farm modeling method and the maximum Lyapunov exponent based method are introduced,The main research content and process of this thesis are given.Secondly,the wind turbine model and control model are studied in this thesis.Based on these,the wind speed,rotor speed,pitch angle and wind turbine output power are selected as the clustering indexes of wind farm modeling,and the dynamic equivalent modeling method of wind farm based on Dpeak algorithm is proposed.At the same time,the effectiveness and accuracy of the proposed wind farm equivalent model are verified by setting the variable wind speed and using the active and reactive power evaluation indexes in the case of three-phase fault in the parallel network.Finally,the proposed Dpeak equivalent model is incorporated into IEEE-39 bus system,and the transient faults of wind farm access point and grid side transmission line are set up to analyze the transient voltage stability operation state of wind farm parallel point.In addition,a transient voltage stability criterion based on the improved LLE index is proposed to identify the transient voltage stability of the wind farm parallel point when three-phase short circuit fault occurs at the grid side.The simulation results show that: whether in the case of access point fault,grid side fault,or single-phase or three-phase fault,the dynamic modeling method of wind farm based on Dpeak algorithm is more close to the detailed model after the wind farm is integrated into the power system than the other two equivalent modeling methods,which can more accurately reflect the actual state of wind farm grid connection Compared with the time domain simulation method and the traditional LLE method,the improved LLE method has more advantages in rapidity and accuracy,which has a certain guiding significance for on-line voltage stability analysis of wind farms.