A five-level sub-module capacitor voltage balance control method for a modular multilevel converter

A modular multi-level, capacitor voltage technology, applied in the field of power system, can solve problems such as difficulty, increased cost and uncertain factors, achieve wide application, effective and reliable capacitor voltage balance control, reduce circulating current and unbalance effect of current

CN105763086BInactive Publication Date: 2019-02-05UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2019-02-05
Estimated Expiration
Not applicable · inactive patent

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Abstract

The present invention provides a five-stage sub-module capacitor voltage balance control method of a modular multilevel converter, which superimposes an additional energy balance control component between bridge arms on the existing control method, and balances with the existing bridge arm internal voltage The combination of control methods is applicable to half-bridge sub-modules, full-bridge sub-modules and hybrid sub-module multilevel circuits. The five-level sub-module capacitor voltage balance control methods include the first-level single sub-module capacitor voltage closed-loop feedback control, the second-level half-bridge arm capacitor voltage closed-loop feedback control, the third-level full-bridge arm capacitor voltage closed-loop feedback control, and the fourth-level Closed-loop feedback control of capacitor voltage between two bridge arms and closed-loop feedback control of capacitor voltage between five-stage three-phase three-bridge arms. The invented control method is helpful to improve the stability of the system under different load conditions, improve the power quality of the capacitor voltage of the direct current transmission system, reduce the investment cost of the modularized multi-level power transmission system, and improve the stability and reliability.
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Description

technical field

[0001] The invention relates to a five-level sub-module capacitor voltage balance control method of a modular multilevel converter in the field of power systems. Background technique

[0002] In recent years, with the increasingly serious problems of energy crisis and environmental pollution, countries around the world are vigorously developing and utilizing clean energy. However, in view of the large population expansion and limited power supply and transmission lines, there is an urgent need for more flexible, economical and environmentally friendly power transmission methods Realize more stable and efficient power transmission. Modular multilevel converter (Module Multilevel Converter, MMC) technology effectively provides power supply mode and quality, and solves the withstand voltage problem of switching devices. At the same time, because this converter adopts a highly modular structure and has strong scalability, it is widely used to implement flexible ...

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Embodiment Construction

[0029] Below in conjunction with accompanying drawing, the implementation method of the present invention is described in detail: this implementation method is carried out under the condition taking the technical scheme of the present invention as a premise, has provided detailed implementation mode and concrete operation process, but protection scope of the present invention does not Limited to the following examples.

[0030] Such as figure 1 Shown is the topology of the power conversion transmission circuit of the modular multilevel converter. The power transmission system connects the modular multilevel converter and the load to the common connection point PCC through the LCL filter. The modular multilevel converter is composed of three-phase bridge arms, and each bridge arm has 2n sub-modules in series. , there is an inductor in series at the voltage and current output position of the converter. There are 6n sub-modules corresponding to the capacitor voltage, and corres...