Robust Control of Hydraulic Pitch System

Pedersen, Casper Strøm ; Fink, Magnus

4. term

Energy Engineering, Master

2024

2024-05-30

108 pages

Wind turbines are a huge part of the transition towards renewable energy. Studies have shown that maintenance and downtime of wind turbines are a large contributor to the Cost of Energy, where especially the wind turbine pitch system is the largest contributor to failures and downtime. This project examines the influence of subjecting a pitch system to an internal leakage fault, as studies have shown this fault has the highest Risk Priority Number. Introducing a leakage fault to the pitch system is seen to decrease the performance of the nominal pitch position controller. Therefore, a Fault Tolerant Control strategy is designed to be robust towards internal leakage faults. The FTC design includes using an Unscented Kalman Filter to estimate the internal leakage and load torque. The leakage estimate is then used to design an Active Flow Feed Forward algorithm with leakage compensation to compensate for internal leakage faults. It is in this project shown that the UKF algorithm is capable of accurately estimating internal leakage and load torque, as well as it is found to be very robust towards parameter uncertainties. Including the UKF leakage estimate as a feedback in the design of a Active FFW yields an increased controller performance compared to the nominal position controller designed for a healthy pitch system.

Hydraulics ; Robust Control ; Fault Tolerant Control ; Parameter Estimation ; State Estimation ; Unknown Load Estimation ; Unscented Kalman Filter

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