| Although distributed generation brings great advantages,there are many factors that restrict its development.The technology of microgrid can effectively solve the uncontrollable problem and take full advantage of distributed generation.In this paper,the microgrid inverter has been analyzed.The control strategy of the microgrid based on the droop control and the harmonic suppression method have been studied.Firstly,the characteristics of the power transmission of the power supply are analyzed,and the system of microgrid is modeled by the principle of droop control.The parameters and droop coefficient of the voltage and current double closed loop controller are designed in detail.Matlab/Simulink simulation software is used to simulate two operating modes of islanded mode and grid-connected mode.The effectiveness of the control strategy is verified by simulation analysis.Secondly,the role of virtual impedance in improving the output characteristics of microgrid inverter is studied.The virtual impedance is used to suppress the harmonic pollution of microgrid.The voltage amplitude and frequency recovery control is applied to solve the problem of voltage and frequency variation under the islanding mode of microgrid with load variation.Then,the basic principle of the synchronization is analyzed.A simple and reliable presynchronous control algorithm is adopted in this paper.And the seamless switching between the islanded mode and the grid-connection mode is achieved.The effectiveness of the control strategy is verified by simulation analysis.Finally,the experimental analysis and verification are carried out.The experiment platform is built,and the design of hardware and software are carried out. |
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