An improved reduced-order model of an electric pitch drive system for wind turbine control system design and simulation

• An improved reduced-order transfer-function model of an electric pitch drive system for a wind turbine is proposed.
• Frequency characteristics analysis, simulation, and experimental test are carried out to validate the improved model.
• The improved model is superior to a first-order model for the performance analysis of a wind turbine pitch angle controller.
• The improved model can meet the requirements of large-scale simulations on the loading characteristics of a wind turbine.

To obtain satisfactory dynamic characteristics and enhance numerical simulation efficiency, an improved reduced-order transfer-function model of an electric pitch drive system (EPDS) for a wind turbine is proposed. First, a detailed transfer-function model of an EPDS is developed on the basis of its mathematical model. Thereafter, the improved reduced-order transfer-function model for an EPDS is derived from the detailed model by transfer-function approximation, sensitivity analysis, and block diagram reduction. The frequency-domain characteristics of the proposed model and their effects on the stability of the pitch angle control system are also analyzed and compared with that of a first-order transfer-function model. Finally, the dynamic characteristics of an EDPS using the improved model are analyzed and verified by a practical EPDS test platform. Furthermore, based on the FAST–MATLAB/Simulink co-simulation tool, simulation comparisons are performed on the loading characteristics of a wind turbine to further validate its availability in it. Results show that the improved model is superior to the first-order model for the performance analysis of a wind turbine pitch angle controller, and it also can meet the requirements of large-scale loading simulations for wind turbines both in terms of the precision and the time efficiency.