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Coherent Design of Wind Turbine Controllers Considering Transitions between Operating Regions using Fuzzy Membership Functions

Horst Schulte

TL;DR

The paper addresses seamless wind-turbine control during transitions between partial-load torque control and full-load pitch control. It proposes a Takagi-Sugeno fuzzy framework with sector nonlinearity to fuse region controllers into a single coherent, bumpless control law. The approach uses a convex fuzzy blending with a coupling filter to combine two region laws into a dual-output controller, enabling tracking of the $c_P$–$\lambda$ curve in partial-load and regulation of rotor speed to $\omega_{r,rated}$ in full-load. Simulation on a 5 MW reference turbine shows smooth transitions without perturbing states such as rotor speed $\omega_r$, generator torque $T_g$, and tower motion $x_T$, with DEL-based fatigue analysis proposed for future work.

Abstract

This paper presents a coherent design of wind turbine controllers with explicit consideration of transitions between operating regions by fuzzy membership functions. In improving the design process of wind turbines, the transitions between partial-load operation by torque control and full-load operation by pitch control need to be systematically considered. From the first view, fuzzy methods for blending separately designed control laws are an obvious choice. However, valid design rules must be developed to ensure stability and performance during the transition. A model-based control design procedure in the Takagi-Sugeno fuzzy framework using the sector nonlinearity method is proposed to achieve the above control design objectives. In addition to a detailed mathematical analysis of the design, the method's applicability is verified by simulation studies using a high-fidelity reference wind turbine model.

Coherent Design of Wind Turbine Controllers Considering Transitions between Operating Regions using Fuzzy Membership Functions

TL;DR

The paper addresses seamless wind-turbine control during transitions between partial-load torque control and full-load pitch control. It proposes a Takagi-Sugeno fuzzy framework with sector nonlinearity to fuse region controllers into a single coherent, bumpless control law. The approach uses a convex fuzzy blending with a coupling filter to combine two region laws into a dual-output controller, enabling tracking of the – curve in partial-load and regulation of rotor speed to in full-load. Simulation on a 5 MW reference turbine shows smooth transitions without perturbing states such as rotor speed , generator torque , and tower motion , with DEL-based fatigue analysis proposed for future work.

Abstract

This paper presents a coherent design of wind turbine controllers with explicit consideration of transitions between operating regions by fuzzy membership functions. In improving the design process of wind turbines, the transitions between partial-load operation by torque control and full-load operation by pitch control need to be systematically considered. From the first view, fuzzy methods for blending separately designed control laws are an obvious choice. However, valid design rules must be developed to ensure stability and performance during the transition. A model-based control design procedure in the Takagi-Sugeno fuzzy framework using the sector nonlinearity method is proposed to achieve the above control design objectives. In addition to a detailed mathematical analysis of the design, the method's applicability is verified by simulation studies using a high-fidelity reference wind turbine model.
Paper Structure (8 sections, 17 equations, 9 figures)

This paper contains 8 sections, 17 equations, 9 figures.

Table of Contents

  1. Introduction
  2. Problem Formulation
  3. Essentials of State of the Art Wind Turbine Control
  4. Control scheme in the Partial-load Region
  5. Control scheme in the Full-load Region
  6. Fuzzy-Blending of Control Regions
  7. Simulation Results and Discussion
  8. Conclusion

Figures (9)

  • Figure 1: $T_g$ as a function of the generator speed $\omega_g$
  • Figure 2: $c_P$-$\lambda$ curve with labeled $c_{P,max}$ point and related $\lambda_{opt}$ value
  • Figure 3: Partial-load region control scheme with integral state-feedback PDC model-based TS fuzzy control law \ref{['eq:cntrl_law_R2']} and TS wind speed observer GauterinKammerer.2015
  • Figure 4: Full-load region control scheme with integral state-feedback PDC model-based TS fuzzy control law \ref{['eq:cntrl_law_R3']} and TS wind speed observer GauterinKammerer.2015
  • Figure 5: Weighting functions $w_{i1}(\omega_r)$ with the overlapping factor $\epsilon_\omega$
  • ...and 4 more figures