A kind of MMC DC short-circuit fault detection method and device
A DC short-circuit and fault detection technology, which is applied in the direction of measuring devices, measuring electricity, measuring electrical variables, etc., and can solve problems such as DC short-circuit faults and secondary short-circuit faults
Active Publication Date: 2019-12-10
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 accompanying drawings.
[0044] Embodiment of a kind of MMC DC short-circuit fault detection method of the present invention:
[0045] like figure 1 The double-terminal or multi-terminal flexible DC transmission system composed of half-bridge and full-bridge sub-module hybrid modular multilevel converters shown in the figure, 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 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 a DC bipolar short-circuit fault is detected, the full-bridge sub-module can output a negative voltage. By using this feature, the system can more flexibly control the system DC voltage U while maintaining the AC voltage amplitude. dc ....
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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 in particular relates to an MMC direct current short-circuit fault detection method and device. Background technique [0002] At present, with the development of fully-controlled power electronic devices and the application of power electronic technology in power systems, the flexible DC transmission technology based on voltage source converters has been paid more and more attention. Modular multilevel converter (MMC) is one of the voltage source converters used in flexible DC transmission systems. It is composed of multiple sub-modules connected in a certain way. By controlling the IGBT groups of each sub-module The input and cut-off states make the AC voltage output by the converter close to a sine wave, realizing efficient energy transmission. [0003] In traditional modular multilevel converters, half-bridge sub-modules are usually used as the basic unit to reduce the...
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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