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Capacitance balancing control method for three-phase full-bridge modular multilevel converter legs

A modular multi-level, converter bridge technology, applied in the direction of converting AC power input to DC power output, irreversible DC power input converting to AC power output, electrical components, etc., can solve the problem of full-bridge modularization. The multi-level converter is not fully applicable, and the switching state of the full-bridge sub-module is complicated, which can reduce the switching frequency and cost.

Active Publication Date: 2015-05-13
STATE GRID CORP OF CHINA +2
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Problems solved by technology

The above control method optimizes the switching frequency of the half-bridge modular multilevel converter sub-module to a certain extent, but compared with the half-bridge sub-module, the switching state of the full-bridge sub-module is more complicated, and the full-bridge The lower bridge arm of the bipolar DC short-circuit fault needs to output reverse voltage, so the above control method is not completely applicable to the full-bridge modular multilevel converter

Method used

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  • Capacitance balancing control method for three-phase full-bridge modular multilevel converter legs
  • Capacitance balancing control method for three-phase full-bridge modular multilevel converter legs
  • Capacitance balancing control method for three-phase full-bridge modular multilevel converter legs

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Embodiment Construction

[0036] The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0037] Aiming at the internal capacitor balance control of the bridge arm of the full-bridge modular level converter, the invention provides a general balance control method for the capacitor voltage of the sub-modules in the bridge arm. In the present invention, by comparing the capacitance voltage of each switch state submodule of the bridge arm capacitance, and according to the current direction of the bridge arm current and the upper layer control instruction, the switch state of the relevant submodule in the bridge arm is adjusted to realize the response to the upper layer control instruction. At the same time, it is ensured that the capacitor voltage of the sub-modules in the bridge arm is relatively consistent. According to the designed balance control method, each switching device of the sub-module has the same s...

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Abstract

A method for controlling capacitance balance of legs of a three-phase full-bridge Modular Multilevel Converter (MMC). Based on an on / off state of a current sub-module, a leg current, and a sub-module inputting instruction to determine sub-modules that are to be input in positive or negative direction at the next time point, the balance of the capacitances and the voltages of the sub-modules inside the legs is controlled. By the on / off state of the full-bridge sub-module, the control method implements consistent on / off frequencies of devices in the sub-module, and reduces the on / off frequencies of the devices. The control method is applicable to control of operation of the DC-side converter in a normal state or in a failing state, and control handover is not required.

Description

technical field [0001] The invention belongs to the technical field of flexible DC power transmission in power systems, and in particular relates to a method for controlling bridge arm capacitance balance of a three-phase full-bridge modular multilevel converter. Background technique [0002] Modular Multilevel Converter (MMC) adopts a new type of multilevel topology that is currently popular in the world. Its core unit - sub-module (Sub Module, SM, figure 1 shown) can be half-bridge or full-bridge. Compared with the half-bridge modular multilevel converter, its remarkable feature is that it has the ability to ride through DC faults. The full-bridge sub-module consists of four self-turn-off power electronic switching devices with anti-parallel diodes and a capacitor. The basic topology of a three-phase full-bridge converter is as follows: figure 2 As shown, it consists of three phase units (Phase Module or Phase Unite, figure 2 1) in the composition, each phase unit c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/48
CPCH02M7/483H02M7/4835
Inventor 汤广福孔明林畅李文津马巍巍
Owner STATE GRID CORP OF CHINA
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