Research On Optimal Maintenance Strategy Of Wind Turbine

Wind turbines are generally installed in remote areas and often operate at altitudes of 100 meters.Due to the factors such as weather,haze and wind speed,the working environment is very harsh.which causes frequent failure of wind turbines.The maintenance cost has been kept at a high level due to repeated maintenance,At the same time,the wind turbine is shut down during maintenance operations,which reduces the normal operating hours,Therefore,it is necessary to use a reasonable maintenance strategy to improve the economy and availability of the wind turbine.The failure of each subsystem of the traditional wind turbine affects each other,which will inevitably cause the inaccuracy of reliability modeling and the inability to evaluate the actual operating conditions of the wind turbines,and further the biased formulation of the maintenance plan.Therefore,considering the correlation between faults,it is of great practical significance for studying effective and reasonable maintenance strategies,reducing operation and maintenance costs,and improving work efficiency.In this thesis,the doubly-fed wind turbine is taken as the research object.Based on the mutual influence of faults among subsystems,reasonable and effective maintenance strategies are developed.Finally,the advantages of maintenance strategies in improving economy and availability are verified by example simulation.In addition,on the basis of comprehensive consideration of maintenance cost and availability,the establishment of a multi-objective maintenance model is of great significance to effectively address the needs of decision-makers from different aspects.The main research contents of this paper are as follows:(1)Based on the theory of fault directed graph,the thesis established the fault transfer directed graph of wind turbine,and solved the CK value of influence degree of fault by Pagerank algorithm and matrix processing.Then,the full probability formula is used to combine the influence degree with the subsystem reliability modeling,and the relationship between the inherent reliability and the comprehensive reliability of the subsystem is derived.The results show that the comprehensive reliability model can better reflect the actual operation of the wind turbine than the inherent reliability model which ignores the fault correlation.(2)The thesis first elaborates the basic principles of state opportunistic maintenance strategy,defines the state maintenance threshold function,opportunistic maintenance threshold function and opportunistic maintenance interval,The comprehensive reliability model is introduced into the research on the optimization maintenance strategy of wind turbine,and the corresponding state-opportunity maintenance model of wind turbines considering the correlation of faults is established.Then from the two perspectives of economy and availability,the optimal maintenance time and maintenance threshold of the wind turbine and the corresponding maintenance threshold function are solved,and the total maintenance cost and effective running time when implementing the strategy are detailed analysis.Finally,a simulation example proves that the state-opportunity maintenance strategy has absolute advantages in improving the economics and availability of wind turbines.(3)According to the different requirements of the decision makers in the maintenance of wind turbine,a multi-objective state maintenance optimization model was established by combining the two indexes of maintenance cost and availability,and the optimal Pareto solution was solved by the objective weighted genetic algorithm.Through the example analysis,although this model increases some maintenance costs,it effectively improves the availability of the subsystem,which is more in line with the actual maintenance situation than the single-objective optimization result,and provides a theoretical basis for the formulation of scientific maintenance strategies for the wind turbine.