| With the continuous development of wind energy and the increment of the operating equipment,as well as the complicated and odious of operating environment of wind farms since they are usually situated in remote mountainous or offshore areas and apart from cities,the fault law of wind turbine equipment is becoming more and more complicated and the operation and maintenance of wind farm are facing challenges,for which,it is urgent to study the operation process of wind turbine components scientifically,and put forward and analyze more effective maintenance strategies.Therefore,in this thesis,a deterioration model based on stochastic differential equation(SDE)is established to describe the state degradation process of wind turbine components.And based on this model,the spatio-temporal evolution relationship of component states is analyzed,and preventive maintenance strategies are proposed and analyzed.The main contents of this thesis are as follows:(1)Based on the analysis and introduction of the constitutions of each subsystem and its main equipment of wind turbine,the faults and monitoring indexes of each component and their corresponding relationships are extracted.Then,in accordance with the preconditions and assumptions proposed,after randomizing the traditional degradation model based on ordinary differential equations,and analyzing and considering the influence of multifarious random perturbation on component state,a component state degradation model based on SDE is established.Moreover,the existence and uniqueness theorem of the solution to the obtained SDE model is proposed and proved to ensure the rationality of the stochastic model.(2)The state degradation model based on SDE is refined for specific conditions as condition-based maintenance(CBM)and time-based maintenance(TBM).For CBM state model,the Weibull proportional hazards model,which is used to characterize component failure and multifarious parameters in the model is estimated.An SDE solution method based on function transformation is proposed,by which the analytical solution of established model is calculated.And the state degradation characteristics of components under condition-based maintenance and time-based maintenance are compared and analyzed by taking the gear box of wind turbine in a wind farm as an example.(3)Based on the stochastic state model,the CBM strategy and TBM strategy are proposed and analyzed,the characteristics of maintenance behavior under the guidance of CBM strategy and TBM strategy are studied,which results that the implementation time of CBM is random,but the status of components can be tracked and while the improper maintenance(mainly including over-maintenance and under-maintenance)exists in the implementation of TBM,but the maintenance time is fixed,and furthermore,the asymmetric relationship between CBM and TBM is established.And on this basis,the joint maintenance strategy of TBM and CBM is proposed and analyzed,the characteristics of the joint strategy and space-time characteristics of component states under the guidance of the joint strategy are elaborated and analyzed by martingale analysis,the decision-making process of the strategy combined TBM and CBM is given,and the changes in cost and reliability is compared and analyzed.Finally,taking the component generator of wind turbine as an example,the proposed content is analyzed and verified. |
