Joint Optimization Of Maintenance And Spare Parts Inventory Policy For Wind Turbines

The use of fossil energy is an important source of global warming and the deterioration of ecological environment,threatening the sustainable development of humankind.In recent years,renewable energy has aroused common concern of countries around the world.With the development of wind power technology,wind energy has become promising renewable energy.Installed capacity of wind power in China have ranked first around the world in these years.Nevertheless,the domestic wind power industry still faces various challenges.Wind turbines are the core equipments of wind power system.Maintenance management and spare parts management of wind turbines are important contents of operation and maintenance(O&M)of wind farm.In order to improve the economic efficiency and reduce the costs of O&M management of wind farm,it is necessary to formulate reasonable maintenance and spare parts inventory strategies of wind turbines.With wind turbine as the object,the joint decision and optimization of maintenance and spare parts inventory is studied in this thesis.The major work is as follows:(1)Study on condition-based maintenance and group opportunistic maintenance of key components of wind turbines.The deterioration process of the wind turbines is modeled with Gamma process,where the state of deterioration is detected by periodic inspections.By considering maintenance time,a condition-based maintenance policy is proposed for a single component system,where preventive maintenance and corrective maintenance are considered simultaneously.Based on the economic correlation between components,a condition-based opportunity maintenance strategy for multicomponent system is proposed considering imperfect maintenance.A simulation-optimization model of cost rate is established,where optimal cycle of inspections and maintenance plan are obtained by genetic algorithm.The economical efficiency of group maintenance and opportunistic maintenance are studied and compared.(2)Study on joint decision and optimization of maintenance and spare parts inventory for single component system of wind turbines based on condition-based maintenance policy.By considering the delay of spare parts,a joint condition-based maintenance and spare parts policy is proposed,where preventive maintenance,corrective maintenance,normal order and emergent order of spare parts are considered simultaneously.By simulating the process of degradation,inspection,maintenance and spare parts inventory,costs including inspection cost,maintenance cost,cost for spare parts inventory and loss of downtime are taken into account and an optimization model of cost rate is established.Taking the main bearing of wind turbines as an example,the optimal cycle of inspections,maintenance and spare parts inventory plan are obtained by genetic algorithm.Sensitivity analysis is conducted to verify the validity of the proposed model.The research shows that spare part is an important factor for decision making of maintenance.(3)Study on joint decision and optimization of maintenance and spare parts inventory for multicomponent system of wind turbines.Considering the economic correlation between components,a joint group maintenance and spare parts policy is proposed.A simulation-optimization model of cost rate containing diverse elements of cost is established and solved.Sensitivity analysis is conducted to verify the validity of joint optimization.This thesis models the degradation of system with a random process.Based on condition-based maintenance and group opportunistic maintenance,the maintenance optimization model and joint optimization model of maintenance and spare parts inventory are proposed,where the delay of spare parts is considered.The advantages of joint decision and optimization of maintenance and spare parts inventory are verified by cases,which can provide guide for the management of maintenance and spare parts for wind farm.