Abstract

When wind speeds are above the rated speed of variable speed variable pitch wind turbines, pitch angles are changed to keep output powers and rotor speeds at their rated values. For wind turbines with nonlinear and complex structure, conventional PID variable pitch controller is difficult to achieve precise control. In this paper, a variable pitch controller combining back-propagation(BP) neural network with PID (BP-PID) is proposed. By real-time detecting the deviation of the rotor speeds, the BP neural network with self-learning and weighting coefficient correction capability is used to adjust the PID parameters online and further to achieve the optimal combination of the PID parameters. Considering various uncertain disturbances and parameter changes on the mechanical components of the wind turbines, an active disturbance rejection pitch controller of the wind turbines is designed based on BP-PID algorithm. Combined with a tracking differentiator, an extended state observer (ESO) is employed to observe the state and disturbance of the system. In addition, in order to compensate the BP-PID variable pitch controller, nonlinear state error feedback control laws are designed by configuring nonlinear structures according to the state deviation between the extended state observer and the tracking differentiator. The simulation results show that the variable pitch active disturbance rejection control (ADRC) based on BP-PID can effectively estimate the system states and disturbances. And the proposed controller has good dynamic performance and strong robustness.

Highlights

  • With the rapid advancement of wind power technology, wind power has become one of the fastest growing power industries all over the world [1]

  • SIMULATION RESULTS AND ANALYSIS A 3MW wind turbine pitch control system was simulated by MATLAB/Simulink software to verify the effectiveness of the proposed control algorithm

  • The research in this paper is mainly for the area above the rated wind speed, whose goal is to minimize the fluctuation of the rotor speed and keep the output power at the rated value

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Summary

Introduction

With the rapid advancement of wind power technology, wind power has become one of the fastest growing power industries all over the world [1]. Wind turbines have evolved from the initial fixed pitch to the variable pitch and further from the variable pitch with fixed speed to the current variable speed variable pitch. The power generation efficiency is significantly improved. Variable speed variable pitch wind turbines extract the maximum power by increasing wind power coefficient at low wind speeds and variable pitch control strategies are used at high wind speeds to keep output powers at the rated value [2]–[6]. The operating regions of the wind turbine are generally divided into four parts. In region 1, the actual wind speed is

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