Control Strategy Research Of Grid-Connected Voltage Of Photovoltaic DC Microgrid Based On Flywheel Energy Storage

The large-scale use of new energy sources has become a top priority for national energy development at present.Based on the traditional AC grid with many commutation links,complex control structures and problems with frequency and phase synchronisation,the DC grid has become an important direction for future grid development because it is easy to control,it does not necessitate the consideration of reactive current balancing and is therefore more favorable to the availability and stable operation of fresh sources of energy.However,the participation of a high number of power semiconductor converter components isolates the electrical part of the grid and the mechanical transmission section,culminating in a tiny inertia,affecting the system’s DC bus voltage stability to unexpected load changes and variations in the new energy production.A new type of elastic virtual inertia control is offered to address the issue of poor voltage regulation in the optoelectronic storage DC microgrid.The control strategy aims to maximize the energy of the microgrid and maintain the stability of the bus voltage.Firstly,to address the problem of low inertia in a DC microgrid with flywheel energy storage,a virtual inertia control strategy based on an adaptive inertia controller is proposed.Based on an analysis of the inertia principle of the virtual DC system,a correlation was established between the values of the inverter output power and the DC capacity on the virtual grid side,which theoretically shows the possibility of using inertial energy storage to maintain the inertia of the DC microgrid.This strategy for the control of flywheel energy storage systems is then improved using a method of adjusting the sag curve intercept and the control function is then using a power function with nested hyperbolic tangent functions.The sensitivity of the flywheel energy storage power change when the system is disturbed is improved to provide suitable inertia support for the system and maintain the bus voltage stability.Secondly,to address the problem of large fluctuations in grid-side voltage due to sudden load changes,an improved whale optimization algorithm is proposed to improve the optimization of control parameters for grid-side and storage side mitigate the obsession with assortment and to rally the command tracking capability of the system so that the DC voltage overshoot is within the tolerance range during start-up and in the face of fluctuations.The overall good steady-state performance of the DC microgrid system is achieved.Finally,a simulation model of a DC microgrid consisting of photovoltaic elements,an energy storage flywheel,load cells and an AC grid was developed in Matlab/Simulink modelling software.The simulation results verify the effectiveness and feasibility of the proposed control strategy under the effect of the proposed control strategy on the energy storage side converter,in the face of different operating conditions,compared with the traditional control.