Flexible multi-state switch and control method

Abstract

The invention provides a flexible multi-state switch and a control method. The flexible multi-state switch comprises two chain type current converters. The chain type current converter comprises three multi-level current conversion chains, the three multi-level current conversion chains are mutually connected end to end to form an angle type connection method, and the end parts are led out to be connected with an alternating current power grid; the multi-level current conversion chain comprises N four-port power modules and at least one damping unit, and N is an integer greater than or equal to 1; the four-port power module is composed of a direct current capacitor, a power assembly, a first switch unit and a second switch unit. The direct-current capacitor is connected with the power assembly, the power assembly comprises four groups of power semiconductor devices which form two bridge arms in a full-bridge connection mode, and midpoints of the two bridge arms are led out to be defined as alternating-current ends of the four-port power module; one end of the first switch unit is connected with a positive electrode or a negative electrode of the direct current capacitor, the other end is connected with one end of the second switch unit, and a connection point of the first switch unit and the second switch unit is led out and defined as a first direct current port; and the other end of the second switch unit is defined as a second direct current 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 becoming more and more difficult for traditional power supply networks to meet users' power supply needs. When one of the lines in the existing power supply and distribution network is overloaded or fails, it often leads to a large-scale power outage. In the case of dual 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 using power electronic technology, the reliability of power supply can be improved. , can also achieve active power balance. At the same time, in the AC and DC distribution network, the application range 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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