A pitch control system deterioration model considering wind speed turbulence intensity
Abstract
As a consequence of high failure rate occurring to wind turbines (WTs), more and more asset owners begin to pay attention to WT’s maintenance planning. To implement an efficient condition-based maintenance policy, the deterioration modeling is of primary importance. The inherence character of wind makes WT’s operation full of uncertainties, hence, the pitch actuator movement is random and it can be modeled by a stochastic process. Meanwhile, the deterioration of the pitch control system related to the usage of the actuator is random. When the wind speed is higher than the rated wind speed (a design WT parameter, when wind speed is higher than the rated wind speed, the pitch system begin to operate) and the wind speed turbulence intensity (TI) is very important, the deterioration rate of the pitch control system increases significantly. For instance the pitch system has more failures in a windy season. Therefore, in order to propose an appropriate maintenance policy for pitch control system, it is more sensible to take into account the influence of wind speed in deterioration modelling.
In this paper, we focus on the deterioration of hydraulic pitch control system. After studying the factors influencing the deterioration, a stochastic process considering wind speed as covariates is used to model the deterioration. A maintenance policy based on an alarm threshold is considered.