Research On Condition Assessment And Maintenance Strategy Of Wind Turbines

Wind turbine is a complex multi-component repairable system, which is composed of transmission system, electrical system, yaw system, hydraulic system, control system, etc. Wind turbine usually works in remote outdoor, and the critical components run in the altitude nearly one hundred meters. It is heavily influenced by wind, rain, frost, snow and other meteorological factors. The complexity of the mechanical structure and the uniqueness of the operating environment result in frequent failures, reduce the availability and cause the expensive maintenance cost and high downtime loss. Therefore, assessing the operating condition and formulating reasonable maintenance strategy play an important role in improving the reliability and economy of wind turbine. In order to solve this problem, based on condition monitoring information and historical fault data, the Weibull proportional intensity model is built to assess the condition of critical components, and condition based opportunistic maintenance is utilized to optimize maintenance strategy. In this paper, the feasibility and effectiveness of the maintenance strategy is verified by the simulation analysis in reducing the maintenance cost and improving the availability, which offers a new way for optimization maintenance of wind turbine.For the situation that condition maintenance models are mostly maximum or minimum maintenance, this paper puts forward imperfect maintenance model, which is accordant with the practical situation, namely maintenance makes the component return to a certain condition between “as new” and “as old”. The paper studies the concept and modeling process of imperfect maintenance model based on the Weibull proportional intensity function, and proposes the condition assessment approach for critical components of wind turbine. Firstly, we use the maximum likelihood method to estimate the model parameters and get the mathematical expression of the model; Secondly, we define the condition observer and apply minimum maintenance cost method to determine the condition maintenance threshold function; Then, the condition maintenance threshold function is drawn and condition monitoring data is plotted; Finally, we compare the values of condition observer and condition maintenance threshold function to determine the operating condition of each component.On the basis of condition assessment of critical components, this paper puts forward the condition based opportunistic maintenance of wind turbine. It adopts condition based maintenance, opportunistic maintenance and non-maintenance to describe the maintenance action, define condition based maintenance threshold function and opportunistic maintenance threshold function and determine when and how to implement maintenance according to the relations between condition observer and condition maintenance threshold functions. Condition based opportunistic maintenance is a kind of optimization maintenance strategy for multi-component system, which combines the advantages of condition based maintenance and opportunistic maintenance respectively corresponding to single component and multiple components. By the concept of opportunistic maintenance, the components in different condition can be repaired at the same time, which achieves the goal of saving maintenance cost and improving availability.