Research On Reactive Power Optimization Of Power System Considering Wind Power Correlation And System Dynamic Stability

As one of the most important form of clean energy generation,wind power generation grows rapidly in the total installed capacity all around the world in recent years and has become a considerable industry.However,while promoting a dramatic transformation of world's energy structure,the integration of large-scale wind farms cause a number of problems for stability and economy of power grid due to the intermittent and stochastic characteristics of the wind and the features of wind turbine itself,and power system voltage stability is one of the focus issues.To guarantee the static voltage stability and dynamic voltage stability for power systems with large-scale wind farms intergration,this paper begins with the research on the correlation of wind farm output,and uses correlation theory to establish a more accurate understanding of wind power output rules.Based on the correlation structure of regional wind farm output,this paper develops a reactive power planning strategy under steady state to ensure the stability of the system voltage under static stability constraints.And then,further strategy is developed based on voltage performance under large perturbations to obtain a reactive power planning strategy condering economy and voltage stability at the same time.The main research contents of this paper are as follows:(1)The mixed Copula is introduced to describe the wind farm output correlation structure between two geographically distributed wind farms.At the same time,a novel evaluation method of Copula model is proposed,which is used in judging the superiority of mixed Copula compared with other single Copula types in describing the wind power output correlation structure.(2)This paper analyzes the advantages and limitations of establishing correlation structure by using wind speed datasets,calculated wind power datasets and actual wind power output datasets.At the same time,to find out the reason of inaccuracy when using actual wind power dataset,this paper explores the inpacts of different wind curtailment strategy.And then,an empirical wind power output allocation strategy is proposed to correct correlation structure model based on calculated wind power dataset to obtain a more practical model.(3)The practical model of wind farm output correlation structure is applied to the probabilistic power flow calculation based on scenario division,and the reactive power compensation under steady state with capacitors as compensation equipments is proposed according to the calculation results.At the same time,this paper proposes a method to select compensation nodes and optimizes the capacity based on the selected results in order to determine the number of capacitors in different scenarios and load levels.(4)Considering the dynamic stability constraints of the system,a voltage drop degree indicator is proposed to analyze the most serious fault and the weakest node.And then,a reactive power compensation model with SVC is established and verified.