A flexible multi-state switch, flexible AC-DC interconnection system and control method

Abstract

The present application provides a flexible multi-state switch, a flexible AC-DC interconnection system and a control method: including at least two chain-type converters; the chain-type converters include three energy-balanced converter chains, and the power unit is composed of a first The DC capacitor is composed of a power component; the power component is a half bridge, a full bridge or a direct series connection; the DC equalization unit includes three ports, which are respectively defined as the first, second, and third DC ports, of which the first and second DC ports are The DC ports are cascaded, and the head end and the tail end are respectively defined as the first equalization port and the second equalization port of the commutation chain; the third DC port is connected to the positive or negative electrode of the first DC capacitor; and at least one DC interconnection is included. unit; both ends of the DC interconnection unit are respectively connected to the first DC capacitors located on any different power units of the two chain-link converters.

Description

technical field [0001] The present application relates to the technical field of power electronics, in particular to a flexible multi-state switch, a flexible AC-DC interconnection system and a control method. Background technique [0002] With the continuous improvement of users' requirements for power consumption, power quality and power supply reliability, it is increasingly difficult for traditional power supply networks to meet users' power supply needs. When one of the lines of the existing power supply and distribution network is overloaded or faulty, it often leads to large-scale power outages. In the case of double busbar power supply, one busbar is often overloaded, and the other busbar is lightly loaded, and there is an unbalanced power load. If the two busbars are interconnected by power electronic technology, the reliability of power supply can be improved. , the balance of active power can also be achieved. At the same time, in the AC and DC distribution netw...

AI Technical Summary

Problems solved by technology

At the same time, in the AC and DC distribution network, the application range of distributed power generation in the power grid is becoming more and more extensive, and it has gradually become an effective supplement to the large power grid. Distributed power sources, loads and energy storage devices constitute a micro-grid. The types of loads, loads, and energy storage devices are different, including DC or AC, and the voltage level and capacity are also different. How to economically and effectively connect the above-mentioned low-voltage units and conduct unified management is a difficult problem to solve

[0003] In the prior art, the flexible loop-closing device based on voltage source converters (voltage source converters, VSC) back-to-back with full-control devices can realize the loop-closing operation of the power distribution network, improve the reliability of power supply, and realize the mutual transmission of active power , but the cost of the above method is too high; and the interconnection method is single, which can only realize the interconnection between two medium-voltage AC power sources, and cannot provide low-voltage AC-DC system access or realize low-voltage AC-DC interconnection

cannot be an economical and effective solution

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