A flexible multi-state switch and control method

Abstract

The present application provides a flexible multi-state switch and a control method: the flexible multi-state switch includes two chain converters; the chain converter includes three multi-level commutation chains, and three multi-level commutation chains The head and tail of the chain are connected to each other to form an angle connection, and the ends are drawn out and connected to the AC power grid; the multi-level commutation chain includes N four-port power modules and at least one damping unit, and N is an integer greater than or equal to 1; so The four-port power module is composed of a DC capacitor, a power component, a first switch unit and a second switch unit; the DC capacitor is connected to the power component, and the power component includes four groups of power semiconductor devices to form two bridge arms, that is, a full bridge connection In the form, the midpoint of the two bridge arms is defined as the AC end of the four-port power module; one end of the first switch unit is connected to the positive or negative electrode of the DC capacitor, and the other end is connected to one end of the second switch unit. The first switch unit is connected to The connection point of the second switch unit is defined as the first DC port; the other end of the second switch unit is defined as the second DC port.

Description

technical field [0001] The present application relates to the technical field of power electronics, in particular to a flexible multi-state switch 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 network, the application scope of distributed...

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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