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A kind of mmc-mtdc system startup control method

A sub-module and pre-charging technology, applied in the direction of output power conversion devices, electrical components, etc., can solve problems such as unfavorable operation control, DC voltage increase, system failure, etc., and achieve the effect of avoiding unstable charging

Active Publication Date: 2018-05-04
XUJI GRP +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The purpose of the present invention is to provide a start-up control method for the MMC-MTDC system to solve the above problem 3. If a converter station is unlocked and operated before the constant DC voltage control station, its injection or extraction of active power into the DC line will cause The increase or decrease of the DC voltage is not conducive to the operation control, and even causes the problem of system failure

Method used

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  • A kind of mmc-mtdc system startup control method
  • A kind of mmc-mtdc system startup control method
  • A kind of mmc-mtdc system startup control method

Examples

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Effect test

Embodiment 1

[0051] A method for starting a modularized multi-level flexible direct current transmission converter, including the following steps:

[0052] A. The DC side poles of each converter station are connected, the sub-modules of each station are locked, and the AC switch of the active station is closed at the same time, entering the uncontrolled charging stage;

[0053] B. After the sub-module voltage of each converter station is higher than the corresponding charging threshold voltage, the controllable voltage equalization charging method is respectively used to enter the controllable charging stage. At the same time, the active station cuts off the soft-start resistance of the AC side;

[0054] C. When the station control method is constant DC voltage control, after the AC and DC side voltages of the converter station are stable, the station is put into closed-loop voltage equalization charging method; when the sub-module voltage reaches the rated and stable, the station unlocks t...

Embodiment 2

[0095] A method for starting a modularized multi-level flexible direct current transmission converter, including the following steps:

[0096] A. Entering the stage of uncontrolled charging: the uncontrolled charging process adopts the uncontrolled charging method of the prior art, that is, different charging modes are not set according to the difference of the AC and DC side power sources of the converter.

[0097] B. When a certain voltage threshold voltage is reached, the controllable voltage equalization charging method is used to enter the controllable charging stage. For each sub-module, the above voltage threshold voltage value is the same.

[0098] C. When the sub-module voltage of the converter sub-module controlled by the station control mode is constant DC voltage reaches the rated and stable, it first enters the unlocking operation stage; when the sub-module voltage of the other stations reaches the rated and stable voltage, they are respectively unlocked and enter...

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Abstract

The invention relates an MMC-MTDC system starting control method comprising the following steps that A. the DC side poles of all converter stations are connected, the submodules of all the stations are locked, and the AC switch of an active station is closed so as to enter an uncontrollable charging stage; B. after voltage of the submodules of all the converter stations is higher than respectively corresponding charging threshold voltage, a controllable voltage equalizing charging method is switched on by the converter stations respectively and a controllable charging stage is initiated, and the AC side soft starting resistor of the active station is removed simultaneously; and C. when the station control mode is that voltage of the submodule of the constant DC voltage controlled converter station is rated and stable, the converter station enters an unlock operation stage firstly; and when voltage of the submodules of the rest stations is rated and stable, the stations are unlocked respectively and enter the unlock operation stage. The constant DC voltage controlled station is unlocked firstly so that voltage of a DC bus can be stabilized and thus stable operation of a multi-terminal system can be ensured.

Description

technical field [0001] The invention relates to a start-up control method of an MMC-MTDC system. Background technique [0002] Multi-terminal flexible DC transmission can realize multi-source power supply and multi-drop power receiving, which is a flexible, reliable and fast power transmission method in the power system. The modular multilevel converter has gradually become the development trend of multi-terminal flexible DC transmission due to its advantages of high output voltage waveform quality, low switching loss, easy expansion and strong fault ride-through capability. [0003] The successful completion of the start-up process is the premise and basis for the normal operation of the multi-terminal system. A suitable start-up strategy should be able to coordinate and configure the start-up sequence of each converter in the multi-terminal system, suppress the electrical shock caused by their mutual influence, and avoid start-up failure. However, the MMC-MTDC DC capacito...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M1/36
CPCH02M1/36
Inventor 杨美娟吴金龙王先为肖世杰刘欣和张浩李道洋
Owner XUJI GRP
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