Multi-module series converter self-powered circuit with self-voltage-sharing capability and control method thereof

Abstract

The invention discloses a multi-module series converter self-powered circuit with a self-voltage-sharing capability and a control method thereof. The self-powered circuit is connected in parallel witha voltage-sharing circuit at the low-voltage output side of a power-taking power supply, and the voltage-sharing circuit is formed by connecting a switching device and a low-voltage load resistor inseries. The control method comprises the steps of during the pre-charging period of a sub-module direct-current capacitor of the converter, the sub-module controller or the uniform controller automatically controls the power of a load resistor at the output side of the power-taking power supply according to the capacitor voltage to adjust the direct-current capacitor voltage of each sub-module, sothat the balance of the direct-current capacitor voltage of the sub-module during the pre-charging period is realized, and the successful pre-charging of the system is ensured. The voltage-sharing circuit is configured on the low-voltage output side of the power-taking power supply, and is simple in circuit, convenient to control, low in cost, free of participation of a master controller and wider in application range. After the sub-modules are pre-charged and enter an operation state, the voltage-sharing circuit stops working, so that the loss is reduced.

Description

Technical field[0001]The invention belongs to the technical field of power electronic control, and specifically relates to a self-powered circuit of a multi-module series converter with self-voltage equalization capability and a control method thereof.Background technique[0002]Compared with traditional two-level and three-level converters, a new generation of multi-module series-parallel circuits is more suitable for high-voltage, high-power, large transformation ratio and other power conversion occasions, such as modular multi-level converters ( MMC) has become one of the preferred topologies in the fields of HVDC transmission, new energy grid connection, and island power supply due to its advantages such as direct series connection without devices, good output waveform quality, low switching frequency of devices, and high degree of modularity. Due to the large number of sub-modules of multi-module series converters, high voltage levels, high insulation requirements, and black star...

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Problems solved by technology

[0004] Aiming at the problem that the voltage equalizing resistor in the voltage equalizing circuit of the prior art consumes a lot of power, and it completely depends on the central controller to be powered on first, and then the central controller controls the voltage equalizing circuit, which is not suitable for black start occasions. The present invention proposes a multi-module serial converter self-supply circuit with self-equalizing capability and its control method

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