Strong Robust Control Method for LCL-Type APF Under Weak Grid
The existence of delay in the digital controller in active damping causes the control system to be highly susceptible to instability when the resonant frequency of the filter is shifted due to changes in the grid impedance under a weak grid.A strong robust control method of the LCL-type active power filter under the weak grid is proposed,which is based on the traditional capacitor-current-feedback active damping,and the feed-forward point is moved forward to the input of the current controller,and the structure of the current controller is improved based on which the active damping controller and the current-loop controller are combined to obtain a composite controller.On the basis of this method,the structure of the current controller is improved,and a composite control-ler is obtained by combining the active damping controller and the current loop controller.The stability constraints of the system are deduced based on the Juli's criterion and the Nyquist's stability criterion,in order to realize the parameter design of the composite controller and guarantee the strong robustness of the system under the weak power grid.Simulation experiments show that the LCL-type active power filter designed according to the proposed method can effectively compensate the harmonic currents in the grid and can guarantee the strong robustness of the control system to the grid impedance changes of the grid.
active power filtersweak power gridactive dampingcomposite controllerrobustness
万方数据
维普
