Method for controlling direct current capacitor voltage of modular multi-level converter based on circulating current decoupling

A modular multi-level, voltage control method technology, applied in the direction of converting AC power input to AC power output, electrical components, output power conversion devices, etc. control strategies of multilevel converters

Inactive Publication Date: 2012-10-17
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

These methods are only proposed for a specific application, not universal and systematic, and also have some shortcomings and deficiencies of their own
Haven't seen a good control strategy for modular multilevel converters

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  • Method for controlling direct current capacitor voltage of modular multi-level converter based on circulating current decoupling
  • Method for controlling direct current capacitor voltage of modular multi-level converter based on circulating current decoupling
  • Method for controlling direct current capacitor voltage of modular multi-level converter based on circulating current decoupling

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Embodiment Construction

[0073] Reference figure 1 , A modular multilevel converter is connected between the three-phase power supply system and the three-phase load. The main circuit structure of the hybrid multilevel converter consists of six bridge arms connected in series with six connecting reactors, and then a double star connection is formed. Each bridge arm is composed of two chopper modules in series, the DC side of the module is connected in parallel with electrolytic capacitors, and the switching devices are high-power full-control devices such as IGBT or GTO. The choice of connecting reactor parameters mainly depends on the switching frequency of the H-bridge module.

[0074] There is no upper limit on the number of modules connected in series in each bridge arm, and the value depends on the voltage level of the power supply system. For the convenience of description, in the present invention, two modules are connected in series as an example for detailed description. The three-phase volta...

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Abstract

The invention discloses a method for controlling the direct current capacitor voltage of a modular multi-level converter based on circulating current decoupling. The method is characterized by comprising the following steps of: controlling the total direct current generatrix voltage by using active current which is absorbed from a power grid by the modular multi-level converter; balancing three-phase direct current voltage by using direct current components in circulating current; controlling balance of the direct current generatrixes of upper and lower bridge arms of each phase by using decoupling fundamental wave components in the circulating current; and finely adjusting the output voltage of each module along the current direction of the bridge arms, so the direct current capacitor voltage of each module in the bridge arms is balanced. The control method has the advantages that balanced control over the direct current generatrix voltage of the upper and lower bridge arms can be well realized; by using voltage control rings in other three layers, the direct current voltage of each module can be well balanced and stabilized to be in a given value range; and the method is accurate and reliable, and provides a good reference value for engineering application.

Description

Technical field [0001] The invention relates to research fields such as a high-voltage power quality controller in a modular multilevel topology (MMC) and a high voltage direct current transmission (HVDC), and particularly relates to the DC bus voltage balance control between modular multilevel bridge arms. Background technique [0002] With social progress and industrial development, modern power systems have two major characteristics: huge power transmission and distribution systems, and increased reactive and non-linear load capacities. First of all, the demand for electricity in modern society is increasing. In order to meet the increasing demand for electricity by users, the power system has become larger and larger, and the coverage area has become wider and wider. This brings challenges to the stability of the power system. At the same time, different power systems often need to be interconnected to enhance the reliability of the entire power supply system, but there is a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M5/458
Inventor 刘进军杜思行林继亮
Owner XI AN JIAOTONG UNIV
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