A valve-level control method for flexible direct current transmission system

A power transmission system, flexible DC technology, applied in the direction of DC network circuit devices, AC network circuits, electrical components, etc., can solve problems such as processing a large amount of data, and achieve the effects of reducing losses, reducing time occupied, and low harmonic content

Active Publication Date: 2016-08-24
XUJI GRP +2
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Problems solved by technology

[0004] The purpose of the present invention is to provide a valve-level control method of a flexible direct current transmission system to solve the problem that the current valve-level control process needs to process a large amount of data in a short time when the number of levels is very high

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  • A valve-level control method for flexible direct current transmission system
  • A valve-level control method for flexible direct current transmission system
  • A valve-level control method for flexible direct current transmission system

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Embodiment Construction

[0027] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0028] The flexible direct current transmission system of the present invention is composed of three-phase six bridge arms, and each bridge arm is composed of coupled or uncoupled inductors and N identical sub-modules cascaded. Each sub-module consists of two IGBTs, two reverse diodes and a DC capacitor, the structure is as follows figure 1 As shown, the DC current and the current flow direction of the upper and lower arms are as follows figure 1 As shown, the valve-level control method of the flexible DC transmission system is composed of modulation algorithm, sorting algorithm and selection algorithm. The specific principle is shown in figure 2 , the valve-level control method of the flexible direct current transmission system includes the following steps:

[0029] 1 According to the signal issued by the extreme control of the valve-lev...

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Abstract

The invention relates to a valve level control method for a flexible DC power transmission system and belongs to the technical field of power electronics and custom power. The method comprises the steps that correlation operation is performed on a three-phase modulation signal received by valve level equipment to obtain the number of sub-modules which should be input by upper and lower bridge arms; afterwards, capacitor voltage values of the collected sub-modules are sequenced from small to large; finally, the direction of bridge arm current is judged, the sub-modules with lower capacitor voltages are input if the direction of the bridge arm current is the same as that of charging current, and the sub-modules with higher capacitor voltages are input if the direction of the bridge arm current is the same as that of discharging current. According to the valve level control method, the balance of the capacitor voltages can be maintained while the time consumed by a sorting algorithm is shortened remarkably, and the capacitor voltages of all the bridge arm sub-modules can be effectively maintained to be on the same level on the basis of guaranteeing that the valve level control cycle reaches the microsecond level below; in addition, the harmonic content of AC output voltage is low, reduction of system loss is facilitated, and the construction cost is also lowered.

Description

technical field [0001] The invention relates to a valve level control method of a flexible direct current transmission system, which belongs to the technical field of power electronics and user electric power. Background technique [0002] Compared with the traditional flexible DC transmission system (based on IGBT series technology), the flexible DC transmission system based on modular multilevel converter (MMC) has attracted a lot of attention in recent years because of its simple structure and easy engineering implementation. wide attention of foreign experts and scholars. [0003] An important feature of the MMC topology is that the energy storage capacitors are placed in series sub-modules. This brings a series of problems. For example, due to the existence of the bridge arm current, the capacitor voltage of each sub-module changes all the time. How to keep the capacitor voltage of each sub-module stable becomes a technical difficulty. , the traditional high-voltage D...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J1/00
CPCH02J3/36H02J2003/365
Inventor 张群郝俊芳严兵赵倩陈朋张爱玲
Owner XUJI GRP
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