Research On Hierarchical Distributed Optimization Control Of Microgrid Based On MPVCC And Event Triggering Consistency

Distributed Generators(DGs)are the major components of microgrids,continuously providing electricity to microsources and energy storage devices,therefore the control of microgrid is the control of DGs.Existing DG control methods,such as constant power control,constant voltage-frequency control and droop control,have their own defects.PQ control is only suitable for grid-connected operation;V/f control is only suitable for island operation;even though droop control is applicable to both,it cannot suppress highfrequency harmonic and circulating current while causing frequency and voltage deviation.Therefore,in this paper,a hierarchical control is applied to eliminate the deviation influence.The improved control strategy not only satisfies the proportional distribution of power and energy quality requirements,but also realize a smooth switching transition when the microgrid switches between island operation and grid-connected operation.This paper mainly studies the secondary and tertiary control systems,in which the primary control mainly adopts an improved droop control method based on model predictive voltage-current control(MPVCC)to achieve stable tracking of voltage and frequency.Replacing the traditional double closed-loop cascade MPVCC module can better track the system output voltage and current quickly.At the same time,the MPVCC combined with the adaptive virtual impedance droop loop are introduced into the DG control system of the microgrid.Through rolling optimization prediction,the accuracy of system output reactive power can be improved to obtain the optimal solution of adaptive virtual impedance resistance value,thus reducing the influence of line resistance load and improving the system’s sensitization,thus achieving the droop control target.Though the traditional droop control can maintain the voltage and frequency stability in power grid,there exist some frequency and voltage deviations in regulation.To this end,the distributed event-based coordination control theory considering communication delay is proposed,which adopts an event-trigger strategy based on the DG power status information and get the voltage and frequency compensation of the system.Moreover,it adjusts the secondary coordination signal based on the threshold to realize fast compensation of voltage and frequency when the DG operation condition changes.Consequently,the accuracy of the system is improved by considering the communication delay.Finally,the feasibility and efficiency of the proposed method is verified by the MATLAB/Simulink simulation model.