| With the energy crisis getting worse,people attach more and more importance to the micro-grid system,which has flexible power generation methods and use clean energy.As the interface of energy interchange between the micro-grid and the grid,the inverter has vital importance in the micro-grid system.The micro-grid inverter has two operation modes,including island and grid-connected mode,which is decided by the operating characteristics of the inverter.According to the practical demands,the inverter should work in the proper operation mode.Thus,it has great significance in the study on control strategy of micro-grid operation smooth switch between grid-connected and island mode.Firstly,traditional micro-grid control schemes are introduced in this paper,the typical control strategy based on the master-slave structure is analyzed in detail and the corresponding simulation is carried out to realize the transfer between two modes.Secondly,the control strategy of micro-grid operation smooth switch based on indirect current control is studied,including the derivation of mathematical model,the parameters design of the control loop and the design of phase-locked loop.Simulations in Matlab/Simulink are given to validate the control strategy and designed parameters.Thirdly,in order to further reduce the switch impact and improve the rapidity of modes transfer,a unified feed-forward control is added to the control strategy of indirect current control.The mathematical model and parameters design of the proposed strategy are depicted as well.Simulations based on this strategy are given to verify its effectiveness.Finally,a digital control based experimental prototype of 10 kVA three-phase grid-connected inverter is designed and built according to the system requirements,the hardware and software design of the prototype are introduced.The experimental results validat the feasibility and effectiveness of the control strategy based on indirect current control and unified feed-forward control. |
PDF Full Text Request