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Fault Diagnosis and Prognosis Capabilities for Wind Turbine Hydraulic Pitch Systems

Alessio Dallabona, Mogens Blanke, Henrik C. Pedersen, Dimitrios Papageorgiou

Abstract

Wind energy is the leading non-hydro renewable technology. Increasing reliability is a key factor in reducing the downtime of high-power wind turbines installed in remote off-shore places, where maintenance is costly and less reactive. Defects in the pitch system are responsible for up to 20% of a wind turbine downtime.Thus, monitoring such defects is essential for avoiding it. This paper presents a generic assessment of the diagnosis capabilities in hydraulic pitch systems, which are used in high-power wind turbines. A mathematical model of the non-linear system dynamics is presented along with a description of the most frequent faults that occur. Structural analysis is used to assess which defects can be detected in the pitch system. The structural properties are furthermore explored to investigate the possibility of reducing the amount of sensors without compromising the fault diagnosis capabilities. Robustness to model uncertainty is finally addressed and generic principles for estimating the detectable magnitude of wear and tear are presented.

Fault Diagnosis and Prognosis Capabilities for Wind Turbine Hydraulic Pitch Systems

Abstract

Wind energy is the leading non-hydro renewable technology. Increasing reliability is a key factor in reducing the downtime of high-power wind turbines installed in remote off-shore places, where maintenance is costly and less reactive. Defects in the pitch system are responsible for up to 20% of a wind turbine downtime.Thus, monitoring such defects is essential for avoiding it. This paper presents a generic assessment of the diagnosis capabilities in hydraulic pitch systems, which are used in high-power wind turbines. A mathematical model of the non-linear system dynamics is presented along with a description of the most frequent faults that occur. Structural analysis is used to assess which defects can be detected in the pitch system. The structural properties are furthermore explored to investigate the possibility of reducing the amount of sensors without compromising the fault diagnosis capabilities. Robustness to model uncertainty is finally addressed and generic principles for estimating the detectable magnitude of wear and tear are presented.
Paper Structure (17 sections, 31 equations, 7 figures, 4 tables)

This paper contains 17 sections, 31 equations, 7 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Pitch System Topology and Modeling
  3. Hydraulic Cylinder
  4. Valves
  5. Supply Circuit
  6. Sensors
  7. Fault Description
  8. Structural Analysis of the Benchmark Model
  9. Analysis based on system's structure
  10. Full Model Analysis
  11. Distinct Operation Regions
  12. Sensor placement for topology improvement
  13. Robustness to model uncertainty
  14. Model uncertainty
  15. Example
  16. ...and 2 more sections

Figures (7)

  • Figure 1: Hydraulic pitch system components pedersenInvestigationLoadReduction2016.
  • Figure 2: Diagram of most relevant fault modes and their causes.
  • Figure 3: DM Decomposition for the full plant.
  • Figure 4: DM Decomposition for the full plant, measurement of $F_{ext}$.
  • Figure 5: Structural Analysis for plant with single cylinder: (a) DM Decomposition. (b) Isolability Matrix: $f_{Fr,c}$ is not detectable, faults $f_{Q_{rel}}, f_{Q_{ru}}, f_{acc}$ and $f_{F_{r,u}}, f_{wv,v}$ are group-wise isolable and all the other faults are isolable.
  • ...and 2 more figures