No-load cutting-in control of the doubly fed induction generator based on grey prediction PI control

The traditional method of stator flux oriented PI control of the doubly fed induction wind generator (DFIG) no-load cutting-in is easy to implement under ideal conditions, but in the actual project with high frequency of wind speed change, the feedback hysteresis of the traditional closed-loop control system leads to the inaccurate feedback current value of DFIG, which makes the stator voltage and grid voltage have certain errors, so it is difficult to realize the grid connection without impulse current. Therefore, a control method combining grey prediction and traditional PI is proposed. Firstly, to sample the rotor current data fed back from DFIG, then to process the data by zero point transformation method. After that, to establish the model of GM(1,1) by using the principle of constant maintenance innovation. Finally, to predict the rotor current value of the next step feedback, and put the difference between the feedback current value and set current value into PI controller in advance to control the motor. When the actual wind speed fluctuates with high frequency, the disadvantages of poor control accuracy and slow dynamic response are improved. The simulation results show that under the influence of actual wind speed, the traditional PI control reaches steady state in 0.07s, and the error between stator voltage and grid voltage is about 30V after stabilization, while the grey prediction PI control reaches steady state in 0.02s, and the error between stator voltage and grid voltage is only about 0.3V after stabilization. Further, it shows the superiority of the grey prediction PI control in DFIG no-load cutting-in. (C) 2021 The Author(s). Published by Elsevier Ltd.