Nonlinear Quadratic Regulator Design With a Hybrid Switching Scheme for Wind Turbine Generators

Ton Duc Do, Hoach The Nguyen, Ameena Saad Al-Sumaiti, Khalifa Al Hosani, Duy Dinh Nguyen

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


This article proposes a new control scheme with a nonlinear quadratic regulator (NQR) associated with a hybrid switching stage for permanent magnet synchronous generator-based wind turbines (WTs). The proposed method shows a new approach combining a nonlinear optimal control method with a hybrid switching stage for WT generations (WTGs). As the WTG is a nonlinear system, NQR control design is directly employed to deal with the nonlinearity while a hybrid switching scheme can deal with constrained control inputs as discrete nonlinear characteristics of switch-mode power converters. A polynomial-based dynamic model is derived for the new NQR design. Unlike the previous state-dependent Riccatti equation (SDRE) technique where the solution of the nonlinear optimal controller is approximated, this technique finds the exact online solution of SDRE with nonlinear feedback gains flexibly depending on the tracking error. Then, the optimal control laws are implemented via a hybrid switching stage ensuring a smooth current regulation under a reduced switching frequency while avoiding any complicated modulator or finite state search. The proposed control design is investigated via comparative studies with linear quadratic regulator (LQR), direct switching, and space-vector pulse-width-modulation stages (SV-PWMs) implemented in both platforms of MATLAB/Simulink and real-time OPAL-RT. Comparative results exhibit flexible optimal performances via online hyper-parameter tuning to reduce the speed tracking error and low current ripples under a reduced switching frequency.

Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalIEEE Transactions on Systems, Man, and Cybernetics: Systems
Publication statusAccepted/In press - 2023


  • Behavioral sciences
  • Control systems
  • Direct switching
  • disturbance observer (DOB)
  • Modulation
  • nonlinear optimal control
  • Optimal control
  • Power electronics
  • state-dependent Riccatti equation (SDRE)
  • Switches
  • Wind speed
  • wind turbine (WT)

ASJC Scopus subject areas

  • Software
  • Control and Systems Engineering
  • Human-Computer Interaction
  • Computer Science Applications
  • Electrical and Electronic Engineering


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