Distributed Cooperative Control Of DC Microgrids In Different Time Protocols Based On Virtual Capacitor

In order to alleviate the problem of energy shortage,countries around the world are committed to the development and application of clean energy.Microgrids,as a direct research and application carrier of clean energy,have developed vigorously in recent years.AC microgrids have always been the core of microgrid applications,but the integration of DC power generation units such as photovoltaics and fuel cells into AC microgrids has problems such as multiple conversion links,low efficiency,and large energy consumption.But the DC microgrid can effectively overcome the above shortcomings,and is more conducive to the direct connection of large-scale DC power generation units,which can effectively reduce energy loss and higher reliability.First,this paper adopts a distributed cooperative control strategy to control the output voltage and current of the distributed generation unit in the low-voltage DC microgrid island mode.In order to achieve a constant and uniform output voltage of the distributed generation unit,the output current is distributed proportionally according to the capacity of the distributed generation unit when the operating status of the system changes.Based on this,the introduction of virtual capacitors to the distributed cooperative control strategy of DC microgrids.Virtual capacitors are an improvement of the original control algorithm,the simulation of the effect of large capacitors can be effective without occupying a large space and saving costs.Ground enhances the inertia of the system,enhances the anti-interference ability of the system,at the same time,it has been designed with characteristics not available in large capacitors to optimize the control effect.In order to enhance the fast operation of the system,the finite-time protocol and fixed-time protocol are introduced into the distributed cooperative control of the DC microgrid to improve the convergence speed of the voltage and current output of the distributed generation unit when the system operating state changes.The convergence limit of the introduced time protocol is derived and the superiority of the introduced time protocol is proved.Finally,this article builds a simulation model on the Matlab/Simulink platform.It is verified by simulation that the introduced finite time protocol and fixed time protocol can accelerate the system's convergence speed,and the introduced virtual capacitor can effectively improve the anti-interference ability of the system.