Wind Farm Equivalence Modeling And Sub-synchronous Oscillation Analysis Of Wind Power Transmission System

In response to the dual requirements of environmental protection and energy supply and demand,the use of wind energy as a new clean energy has gradually increased,and more and more research on wind power grid-connected systems has also increased.In this thesis,the doubly-fed wind power transmission system is used as the research object,the wind farm group equivalence modeling is analyzed,and the logistic regression method is applied to predict whether the doubly-fed wind power transmission system produces sub-synchronous oscillation,and the sub-synchronous oscillation of the doubly-fed wind power transmission system is suppressed.The main research contents and achievements are as follows:1.In order to accurately analyze the sub-synchronous oscillation of the doublyfed wind power delivery system,this thesis uses the k-means algorithm and the invasive weed algorithm to optimize the k-means algorithm to model the equivalence of large-scale and scattered wind farm groups.Through comparison,it is found that the mean squared error and average absolute error of the K-Means algorithm optimized by the invasive weed algorithm are smaller,and the output active power fitting degree of the equivalent model corresponding to the K-Means algorithm optimized by the invasive weed algorithm is higher with the detailed equivalent model,indicating that the steady-state accuracy of the doubly-fed wind power delivery system established after using the invasion weed algorithm to optimize the k-means algorithm equivalent wind farm group is higher,which can overcome the shortcomings that the k-means algorithm relies on the initial clustering center and is easy to fail to achieve the global optimality.It lays a foundation for the analysis of sub-synchronous oscillation of the subsequent doubly-fed wind power transmission system.2.Based on the two mechanisms of Induction Generator Effect(IGE)and Subsynchronous Control Interaction(SSCI)of doubly-fed wind power transmission system,the uncertainties and determinants that induce sub-synchronous oscillation of doublyfed wind power transmission system are analyzed.A logistic regression prediction model is constructed,and the four inducing factors of cascade complementarity,wind speed,and,and are set as independent variables to predict whether the doubly-fed wind power transmission system produces sub-synchronous oscillation.The simulation results show that the logistic regression prediction model can simultaneously predict whether the double-fed wind power transmission system will produce sub-synchronous oscillation under a variety of inducing factor conditions,overcoming the shortcomings of using the simulation model built in PSCAD/EMTDC to analyze whether the doublyfed wind power transmission system produces sub-synchronous oscillation under only one inducing factor condition at a time,and provide a reference for subsequent suppression of sub-synchronous oscillation.3.Aiming at the sub-synchronous frequency problem caused by disturbance under the working condition of the doubly-fed wind power transmission system,the doublefed wind power transmission system model established by the K-Means algorithm is optimized based on the invasion weed algorithm,and the band stop filter and additional damping controller are designed to suppress the sub-synchronous oscillation of the doubly-fed wind power transmission system from the aspects of blocking electrical quantity and improving system damping.The simulation results show that the bandstop filter cannot suppress the sub-synchronous frequency under high string complement condition,but the addition of additional damping controller can effectively suppress the sub-synchronization frequency under high series complement condition,and its suppression effect is better than that of band-stop filter under other conditions.