Research On Control Strategy Of Multi-function Grid-connected Inverter Based On Microgrid

The integration of distributed generation units,power electronic devices and various complex loads into the power grid has a great impact on the stable operation of the power grid.For traditional methods of reactive power and active power compensation,it is necessary to increase equipment to compensate for harmonics and reactive power in power quality problems,which undoubtedly increases the investment cost of the system.The use of existing equipment for power quality control of the system has undoubtedly become a research focus.The grid-connected inverter in the micro grid is an important device of the micro grid system and is the core of realizing the power conversion.Analysis of its main circuit topology finds that it has the same main circuit structure as the power quality control device.Based on different control strategies,the control strategy for grid-connected inverters was redesigned to have the function of grid-connected generation and active management of power quality.The main content of this paper is based on the grid-connected inverter in the micro grid,and it has the same main circuit topology as the active power filter in the energy management device.It can be used without changing the hardware devices.Its control strategy was redesigned so that it can carry out grid-connected power generation and active power quality management on the basis of the original equipment.Firstly,the research background and control strategy of the multi-function grid-connected inverter are described,and the problems in the research of multi-function grid-connected inverter are understood.A variety of harmonic detection methods in the power quality control device are analyzed,and the command current is analyzed.The command current generation has a great influence on the control accuracy of the following control strategy.Detailed instruction current generation is performed here.analysis.Then the mathematical model of the LCL type multi-function grid-connected inverter is analyzed,and the coupling problem caused by the coordinate transformation is analyzed,and the LCL filter parameters are designed in detail.Then,the control strategy of the multi-function grid-connected inverter is redesigned.The effect of adding the LCL filter on the system stability is analyzed in detail here,and the inherent resonance problem of the LCL filter is analyzed.The resonance suppression method was analyzed and a more cost-effective active damping method was selected for resonance suppression.After analyzing the control strategy,the capacitive current feedback and grid-connected command current dual closed-loop control strategies that can perform active damping are selected to control the system.Finally,on the basis of previous analysis,the system hardware and software are designed.The TMS320F28335 digital signal processor is used as the controller of the system,and its peripheral circuits,sampling circuits and software system programs are designed.Finally,the MATLAB/Simulink was used to simulate the system control strategy,and the experimental circuit designed above was used to verify it.