Control method of AC-DC interconnected bidirectionally-supported isolated two-stage DC/AC converter

Abstract

The invention relates to the field of power electronics, and aims to provide a control method of an AC-DC interconnected bidirectionally-supported isolated two-stage DC / AC converter. According to theinvention, an isolated two-stage DC / AC converter is adopted to realize connection between an AC sub-network and a DC sub-network, a bidirectional DC / AC converter module is used for realizing active power sharing of an AC side and a DC side and can realize bidirectional voltage support, and a bidirectional resonance DC converter module is used for realizing voltage matching and current isolation ofthe AC side and the DC side. According to a proposed control strategy, two pieces of heterogeneous information, namely alternating-current frequency and direct-current voltage, are normalized in a bidirectional DC / AC system, and that the normalized values of the alternating-current frequency and the direct-current voltage are equal is taken as a control target. According to the invention, bidirectional power support and inter-network seamless connection between alternating current and direct current sub-networks of different voltage levels are realized without switching a control strategy, sothe plug-and-play control characteristic of an alternating current and direct current hybrid sub-network is improved, the voltage requirement of the alternating current sub-network on direct currentsub-network connection is reduced, and good control performance is achieved.

Description

technical field [0001] The invention relates to a control method of an isolated two-stage DC / AC converter supported by AC and DC interconnection bidirectionally, belonging to the field of power electronics. Background technique [0002] The AC-DC hybrid microgrid connects the DC subnet and the AC subnet through the converter, makes full use of the advantages of AC power supply and DC power supply, reasonably regulates the AC-DC distributed power supply and load, minimizes the intermediate conversion links, and improves the system efficiency. At present, there are mainly two types of connecting AC subnet and DC subnet: non-isolated DC / AC converter and DC / AC converter with AC power frequency transformer. Among them, the non-isolated single-stage DC / AC converter has poor safety, the DC / AC converter with AC power frequency transformer has low overall efficiency and occupies a large area, and the bidirectional full-bridge DC / DC converter has a high degree of modularization , can...

AI Technical Summary

Problems solved by technology

Traditional isolated two-stage DC / AC converters mostly use AC power frequency transformers to step down the AC voltage to match the requirements for DC voltage levels, and use droop control for DC / AC converters to realize the interconnection of AC and DC sub-networks. The control method is less flexible for voltage matching and it is difficult to achieve two-way support

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