MMC (Modular Multi-level Converter) converter valve submodule device based on thyristor device and controlling method of submodule device

Abstract

The invention relates to the field of power systems and power electronics and in particular relates to an MMC (Modular Multi-level Converter) converter valve submodule device based on a thyristor device and a controlling method of the submodule device. The MMC converter valve submodule device comprises a main circuit and two forced commutation circuits which are connected in parallel with two ends of the main circuit, wherein the main circuit comprises a thyristor unit I, a thyristor unit II and a capacitor C, and the thyristor unit I and the thyristor unit II are both formed by a thyristor and a diode which is connected in inverse parallel with the thyristor. The method comprises the following steps that: (1) a capacitor C1 and a capacitor C2 in the two forced commutation circuits are respectively precharged; and (2) the submodule works and outputs a voltage. According to the MMC converter valve submodule structure based on the thyristor device disclosed by the invention, the thyristor device is utilized to replace an IGBT (Insulated Gate Bipolar Translator) device, thus lowering the switching loss of the device and the controlling complexity and improving the switching efficiency of the submodule.

Description

technical field [0001] The present invention relates to the field of power system and power electronics, in particular to a thyristor device-based MMC converter valve sub-module device and its control method, in particular to a thyristor-based MMC converter valve sub-module topology device and its control method. Background technique [0002] Due to the shortage of energy and the deterioration of the environment, vigorously developing new energy has become the main direction of my country's development, and flexible direct current transmission technology is the main means of grid-connected new energy. The core equipment of the flexible DC transmission technology, the voltage source control (VSC) converter valve, currently mainly adopts a modular multilevel (MMC) structure, which firstly consists of sub-modules that can be turned off, and then multiple sub-modules are connected in series. [0003] The structure of the sub-module is very important to the performance and contr...

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Problems solved by technology

Compared with thyristor devices, IGBT devices have larger switching losses and complex control. The rated voltage and current of a single device is lower. With the continuous increase of voltage level, the number of sub-modules in series increases, and it is difficult to balance the voltage between sub-modules. , which is not conducive to the development of converter valves in the direction of high pressure and large capacity

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