MMC direct current short circuit breakdown detection method and apparatus
A DC short-circuit and fault detection technology, applied in the direction of measuring devices, measuring electricity, measuring electrical variables, etc., can solve problems such as DC short-circuit faults, secondary short-circuit faults, etc.
Active Publication Date: 2017-07-04
XUJI GRP +4
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[0007] The purpose of the present invention is to provide a method and device for MMC DC short-circuit fault detection, which is used to solve the secondary short-circuit fault problem caused by raising the DC voltage when the DC short-circuit fault is not completely cleared
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[0043] The specific embodiments of the present invention will be further described below in conjunction with the drawings.
[0044] An embodiment of the MMC DC short-circuit fault detection method of the present invention:
[0045] Such as figure 1 The double-ended or multi-terminal flexible DC transmission system composed of half-bridge and full-bridge sub-module hybrid modular multi-level converters shown, the number of full-bridge and half-bridge sub-modules in the system are N and M respectively, where N≥ 2. M≥2; figure 1 Middle: u sm Is the sub-module voltage, U dc It is a DC voltage, HBSM (half-bridge sub-module) is a half-bridge sub-module, and FBSM (full-bridge sub-module) is a full-bridge sub-module. When the DC bipolar short circuit fault is detected, the full bridge sub-module can output negative voltage. Using this feature, the system can control the system DC voltage U more flexibly while maintaining the AC voltage amplitude unchanged. dc . Utilizing the ability ...
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The invention relates to an MMC direct current short circuit breakdown detection method and apparatus. According to the invention, the method includes the following steps: dividing converter stations into a main station and sub-station modes, selecting one converter station as the main station and other converter stations as sub-stations, the main station gradually boosting a DC voltage, the sub-stations tracking the DC voltage of the main station through the difference between a DC current feedback value and a DC current reference value, and if the time duration when DC voltage that is boosted by the main station is constantly smaller than a first set value is set as T1, determining that the DC short circuit breakdown is still on. According to the invention, communication among stations is not required in the entire breakdown detection process, no other detection devices are needed, and the short circuit breakdown detection is realized by means of original DC voltage and current sensors, which provides reliable guarantee for boosting the DC voltage if the DC short circuit breakdown is not completely cleared, and secondary short circuit, sub-module fast discharging and being bypassed, and lockout and tripper of converters.
Description
Technical field [0001] The invention belongs to the technical field of direct current transmission, and specifically relates to a method and device for detecting MMC direct current short-circuit faults. Background technique [0002] At present, with the development of fully-controlled power electronic devices and the application of power electronic technology in power systems, flexible DC transmission technology based on voltage source converters has received increasing attention. Modular multilevel converter (Modular multilevel converter, MMC) is one of the voltage source converters used in the flexible DC transmission system. It is composed of multiple sub-modules connected in a certain way. By controlling each sub-module IGBT group The input and removal states of the converter make the AC voltage output by the converter approach a sine wave, realizing efficient energy transmission. [0003] In traditional modular multilevel converters, half-bridge sub-modules are usually used a...
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IPC IPC(8): G01R31/02
CPCG01R31/50
Inventor 姚为正李道洋吴金龙王先为刘欣和张浩孙树敏李广磊
Owner XUJI GRP