An overcurrent protection method for a modular multilevel converter

A modular multi-level, over-current protection technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve problems such as increased loss of converters and other equipment, damage to switching devices and capacitors, explosions, etc., to improve operational safety performance, improve economy and safety, and reduce impact

Active Publication Date: 2018-08-28
DALIAN POWER SUPPLY COMPANY STATE GRID LIAONING ELECTRIC POWER +2
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Problems solved by technology

[0003] When the AC system connected to the modular multilevel converter fails or various faults occur inside the modular multilevel converter, it will seriously affect the normal operation of the modular multilevel converter, and may Severe overcurrent is generated on the bridge arm of the converter. If the fault cannot be removed in time and effectively, it will cause serious harm. These hazards mainly include: the faulty bridge arm and the non-faulty bridge arm may have a common connection on the AC side, making the non-faulty bridge arm The bridge arm is subjected to power frequency overvoltage, which will cause damage to switching devices and capacitors in severe cases, and even cause explosions; the faulty bridge arm will cause the DC bias of the AC side voltage of the

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  • An overcurrent protection method for a modular multilevel converter
  • An overcurrent protection method for a modular multilevel converter

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[0023] The technical solutions and beneficial effects of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0024] figure 1 It is a schematic structural diagram of a modular multilevel converter. The main body of the converter is composed of 6 bridge arms, and each phase contains 2 bridge arms, which are the upper bridge arm and the lower bridge arm. For example, the phase A bridge arm consists of the upper bridge arm The bridge arm BLua and the lower bridge arm BLda are formed. The upper bridge arm BLua and the lower bridge arm BLda are respectively connected in series with the bridge arm reactance L and connected to the AC side A at the common terminal Oa of the upper and lower bridge arms. The connection mode of the upper and lower bridge arms of phase B and phase C is the same as that of the upper and lower bridge arms of phase A. The upper bridge arm and the lower bridge arm of each phase are connected in series with ...

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Abstract

The invention discloses an overcurrent protection method for a modular multilevel converter, which independently performs overcurrent protection judgment on each bridge arm of the modular multilevel converter, and when any bridge arm overcurrent protection element operates , only immediately block the faulty bridge arm and keep the normal operation of the non-faulty bridge arm, the blocking of the faulty bridge arm is to turn off all the switching devices of all the submodules in the faulty bridge arm. This method independently judges the over-current state of the bridge arm, only blocks the over-current bridge arm and maintains the normal controlled voltage state of the non-over-current bridge arm, relatively non-selectively blocks the entire converter, and significantly reduces the failure of the docking into the AC system and the impact of the converter itself.

Description

technical field [0001] The invention belongs to the technical field of flexible direct current transmission in power systems, and in particular relates to an overcurrent protection method for a modular multilevel converter. Background technique [0002] Modular multilevel converter is the most important structure and component part of flexible direct current transmission technology. Its main feature is that it is composed of fully controlled power electronic devices. Its basic circuit unit is called sub-module, and each bridge arm passes through a certain number of The sub-modules with the same structure are connected in series with a valve reactor, and the sub-modules are generally composed of turn-off devices, anti-parallel diodes and capacitors to form a half-bridge or full-bridge structure. The modular multilevel converter can flexibly change the output voltage and power of the converter by changing the number of sub-modules put into the bridge arm, and is suitable for h...

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Application Information

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IPC IPC(8): H02H7/122
Inventor 田杰卢宇汪楠楠姜崇学王佳成王辉董云龙李钢
Owner DALIAN POWER SUPPLY COMPANY STATE GRID LIAONING ELECTRIC POWER
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