Research On Control Strategy Of Hybrid Microgrids Based On Virtual Synchronous Generator

Power electronics devices play an increasingly important role in the power system.One of the important reasons is to make efficient use of a variety of cleaner,endless renewable energy sources.However,power electronics as the power source of the power system will bring several new challenges to the power grid than traditional synchronous generators,one of which is low inertia and low system inductance.In order to introduce rotor inertia and large inductance of synchronous generators in new energy-based power systems,virtual synchronous generator technology has been proposed and has received increasing attention.This paper proposes a virtual synchronous machine technology for a two-stage inverter—virtual synchronous machine technology based on DC voltage.This technique significantly reduces the circulating power between two-stage inverter energy storage devices,thereby reducing losses and reducing the design capacity of the energy storage device.At the same time,compared with the traditional virtual synchronous machine technology,the virtual synchronous machine technology based on DC voltage and the synchronous generator have better analogy,and the correspondence between their parts is stronger,which is convenient for traditional power system theory to be applied in applications in the future power grid.At the same time,as more and more DC loads emerge,many regions begin to build hybrid AC-DC power grids,in which AC-DC interface converters are the core components.The traditional interface converter control will bring a lot of instability factors to the hybrid microgrid.So this paper presents a virtual synchronous machine control method for AC-DC microgrid interface converter.Compared with the traditional method,the method of this paper not only maintains the distributional power of the traditional method,but also effectively suppresses the fluctuation,thereby increasing the inertia of the hybrid microgrid.The main contents of the study are as follows:(1)Analyzing the application of inverter power generation system and summarizing the research of virtual synchronous generator.(2)Reviewing the status of virtual synchronous generator of two-stage inverter,analyzing its power flow and loss,and proposing a virtual synchronous machine control method based on DC voltage.(3)The control method of the AC/DC hybrid microgrid interface converter is studied,and its defects are analyzed.The virtual synchronous machine control strategy of the AC/DC hybrid microgrid interface converter is proposed.