DC fault judgment method for flexible multi-terminal DC transmission system and control method

A DC power transmission system, DC fault technology, applied in emergency protection circuit devices for limiting overcurrent/overvoltage, measuring electricity, electrical components, etc. Achieve the effect of improving the speed of power recovery, improving the reliability of system power supply, and reducing the risk of overcurrent

Inactive Publication Date: 2016-04-13
STATE GRID HUBEI ELECTRIC POWER COMPANY +2
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Problems solved by technology

Due to the need to compare the physical quantities on both sides of the line, the conventional fault judgment method needs to rely on the communication system, and the communication system will bri

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  • DC fault judgment method for flexible multi-terminal DC transmission system and control method
  • DC fault judgment method for flexible multi-terminal DC transmission system and control method
  • DC fault judgment method for flexible multi-terminal DC transmission system and control method

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[0043] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] The DC fault control method of the multi-terminal flexible DC power transmission system of the present invention is used for processing DC faults in the DC power transmission system based on modular multi-level converters to improve the speed of power supply recovery after the fault is cleared. This method is to block the bridge arm current of the modular multilevel converter by reducing it or p...

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Abstract

The invention discloses a DC fault judgment method for a flexible multi-terminal DC transmission system. The DC rise rate in a DC fault is lowered by increasing a DC inductance value to prevent an MMC from being locked; or an AC instruction value of the MMC is set to be zero during the DC fault, so that a bridge arm current is lowered to prevent the MMC from being locked; or the MMC is locked during the DC fault, but an AC breaker of the MMC is not cut off, so that the power restoration speed after the fault is cleared is improved. The invention further discloses the DC fault judgment method for the flexible multi-terminal DC transmission system. The DC voltage mutation rate on a DC inductance line side is measured, so that the DC fault is judged when an absolute value of the mutation rate exceeds a certain threshold. The AC breaker of the MMC can be prevented from being cut off in the DC fault; the power restoration speed of the MMC employing an overhead line after the DC fault is cleared is greatly improved; meanwhile, a rapid and accurate judgment can be made for the DC fault; and timely fault treatment and control are facilitated, so that the risk that the MMC bears an over-current is reduced.

Description

technical field [0001] The invention belongs to the technical field of power transmission and distribution in power systems, and more specifically relates to a DC fault judgment method and control method for a multi-terminal flexible DC power transmission system. Background technique [0002] With the development of Modular Multilevel Converter (MMC), Modular Multilevel Converter has been more and more used in DC-DC transmission. Most of the existing MMCs use half-bridge sub-modules. When a DC fault occurs, it is necessary to block the trigger pulse of the IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) to prevent the sub-module capacitor from discharging through the IGBT and destroying the IGBT due to overcurrent. After the IGBT is locked, the MMC works in an uncontrolled rectification state. The AC system connected to the MMC continuously provides fault current to the DC fault point through the diode. Breaking the AC circuit breaker of the MMC ...

Claims

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Application Information

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IPC IPC(8): H02H9/02H02H7/26G01R31/00
CPCG01R31/00H02H7/226H02H7/268H02H9/02
Inventor 蒋霖胡济州程杰陶芬文劲宇谢竹君张峻榤
Owner STATE GRID HUBEI ELECTRIC POWER COMPANY
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