Simulation And Analysis Of Multi-voltage Grade AC-DC Hybrid Microgrid

As a technology widely focused by the power workers in the world,microgrid technology has experienced a lot of breakthroughs within the less than 20 years from being created till now.The reason responsible for its receiving much attention lies in that it is an efficient path to exploit scattered distributed power source,plus its ability to improve quality of electric power and power distribution reliability.The world today is confronting unprecedented opportunities and challenges,which are caused by rapidly developing social productive forces and looming drain of traditional energy.Against this backdrop,the advantages of microgrid technology can both meet the energy demands in the course of productivity growth and make the most of clean and reproducible new energy,hence its important significance for social development.This paper designs an AC-DC hybrid microgrid and simulates it for analysis by dint of MATLAB/simulink.Firstly,the structure of microgrid is designed,which is characterized by three buses within microgrid:800V DC bus,48V DC bus and 380V(line voltage)AC bus,and distributed power source,DC load and AC load are respectively connected to three different buses.This structure isolates the electrical equipment on different buses in microgrid,hence the change of electric parameters on one bus produces little influence on the electrical equipment of another two buses,thereby improving power distribution reliability and quality of electric power of microgrid.Secondly,the control strategy of multi-voltage grade AD-DC hybrid microgrid is established according to microgrid structure and control standards.According to system structure,the key to control strategy of microgrid is the control strategy of energy storage element in microgrid.The control modes of energy storage unit are different depending on two running statuses of microgrid-connected operation and island operation,to realize the objective of controlling microgrid.Lastly,in MATLAB/simulink software,the simulation model of multi-voltage grade AC-DC hybrid microgrid is built,and a simulative analysis on the system is conducted in two running modes of grid-connected and island respectively.Thereinto for the grid-connected operation,two conditions are considered:one is the microgrid being suddenly connected into fan;the second is the load in microgrid suddenly changing.The performance of designed microgrid is verified through simulation.The research in this paper serves as a discussion on the application mode of microgrid technology,with main emphasis on structure and control strategy of microgrid.The research verifies that the multi-bus grid structure is provided with good electric isolation effect to improve quality of electric power and power distribution reliability of microgrid.To sum up,multi-voltage grade AC-DC hybrid microgrid can absorb distributed power source,improve quality of electric power and power distribution reliability.Able to supply electricity to AC load and DC load,microgrid has a wide application scope.With simple grid structure and flexible control,it is a relatively ideal microgrid structure.