Research On Condition Based Opportunistic Maintenance Strategy For Double-fed Wind Turbine Under Failure Interaction

Scientific and efficient management of wind farm has become a new topic.The purpose of the maintenance of wind turbines is to improve the maximum utilization hours and the reliability of power supply,and to ensure the quality of electric power to satisfy the conditions as prescribed by the States.The wind turbine is a kind of large-scale electromechanical equipment which integrates many kinds of technologies and has a complex structure.The reliability of the system is closely connected with the reliability of each subsystem and the fault transmission between them.The traditional reliability modeling assumes that failures are independent between subsystems.It must necessarily result in the inaccuracy of the model,and unable to reasonably arrange the maintenance plan of wind turbines.This will cause an increase in operating cost.Therefore,it is of great significance to optimize the operation and reduce the cost of wind farms by considering the fault correlation and researching on condition based opportunistic maintenance strategy.A double-fed wind turbine is selected as the research object,and the maintenance strategy is studied under the condition of fault correlation.A practical example is given to verify the advantages of the maintenance model in cost saving.Firstly,the basic principle of condition based opportunistic maintenance is introduced.The condition based opportunistic maintenance model of double-fed wind turbine is defined by the proportional failure model proposed by the Cox,and the solution to the model parameter is given.Then,according to a Gansu wind farm fault record information and monitoring data,fault directed graph theory is used to analyze the direction of fault transmission between subsystems.Through the matrix processing,the influence degree of the fault is transformed into the network node importance and solved by the Pagerank algorithm.The relationship between the three subsystems,namely,the comprehensive reliability,the inherent reliability and the related factors,is derived from the full probability formula.Compared with the inherent reliability model,the comprehensive reliability model is closer to the actual operation state.Finally,the comprehensive reliability model is introduced into the research of the optimal maintenance strategy of wind farm,and the condition based opportunistic maintenance model of wind turbine is established under the condition of fault correlation.The model parameters are solved with the minimum maintenance cost,and the effectiveness of the model is verified by an example.The results show that the reliability model of wind turbine under fault correlation is more close to the actual operation of wind turbine,which has certain theoretical significance to the design and manufacture of wind turbine.The maintenance model has some advantages in saving the operation cost and improving the availability of the wind farm.