Reliability Evaluation And Optimization Measures Of Offshore Wind Power Integration System Considering The Influence Of Typhoon

With the rapid development of economy,the demand for energy is increasing.While as the non-renewable energy,fossil energy is facing the dilemma of gradual depletion.Meanwhile,offshore wind power,as the clean,abundant but underutilized energy,is of great significance for China to achieve "carbon peak" and "carbon neutralization”.However,with the offshore wind power capacity increasing,the security and stability of power system is facing unprecedented challenges.Meanwhile,the operation environment of offshore wind farm is severe and its deterioration process is greatly affected by typhoon weather.What’s more,its maintenance accessibility is low,resulting in high maintenance cost and long maintenance downtime,which further reduces the reliability level of power system.Therefore,it is necessary to further study the generation reliability of offshore wind farm considering the influence of typhoon,the influence on power system reliability after being connected to power grid and the maintenance optimization strategy of offshore wind farm.In this paper,the reliability of offshore wind farm grid connected system considering the influence of typhoon is studied.The specific research contents are as follows:Firstly,the reliability model of offshore wind farm grid connected system considering the influence of typhoon is established.Based on the time series prediction of wind speed distribution,the multiple states model of offshore wind farm is established by using state space diagram and Markov process.Based on the typhoon model and the distribution model of typhoon key parameters,the multiple states model of offshore wind farm is modified by considering the wind speed reconstruction and the influence on the failure rate of wind turbine during the process of typhoon.In addition,considering the failure states of wind turbines,cables and switches in offshore wind power collection system,the reliability models of collection system with different topologies and switch configurations are established.What’s more,according to the structure and electrical composition,the reliability model of offshore wind power converter station is established.Secondly,for the reliability evaluation of offshore wind power integration system considering the influence of typhoon,the double-layer system state transition sampling method is used to sample the system state,and the state analysis is carried out based on the optimal load shedding of DC power flow.Through the reliability indexes,the reliability level of the whole system is reflected qualitatively and quantitatively in a reasonable and objective way.When it comes to several offshore wind farms,a multivariate ARMA time series wind speed model considering wind speed correlations is established,which is based on Copula.Taking Modified IEEE RTS79 as an example,the influence of different capacities,access locations,collector system topologies and switch configurations,load models,wind speed correlations and typhoon on system reliability level is evaluated quantitatively.Finally,for the optimized maintenance strategy of offshore wind turbines considering the influence of typhoon,the optimization model of regular maintenance plan based on minimum system operation cost,maintenance cost and load loss expectation is established.Meanwhile,the optimal model of opportunity maintenance with the purpose of minimum operation cost of single offshore wind turbine is established.Based on the optimization strategy of regular maintenance plan,considering the influence of typhoon on the deterioration process of the single wind turbine,the opportunistic maintenance plan is added to establish a two-level optimization model.The maintenance costs,wind turbine reliability levels and system reliability levels under different maintenance strategies are compared and analyzed,which can provide suggestions and references for the maintenance plan of offshore wind turbines.