SDSM-MMC type flexible DC system DC fault reclosing method with low-current characteristic

A flexible DC and DC fault technology, applied in the direction of electrical components, circuit devices, emergency protection circuit devices, etc., can solve problems such as low current characteristics, low current hazards, and current secondary overcurrent hazards, so as to avoid capacitor discharge and avoid The effect of the secondary overcurrent shock

Inactive Publication Date: 2016-08-31
TIANJIN UNIV
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  • Description
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Problems solved by technology

[0003] Aiming at the problem that the fault reclosing strategy of the current flexible DC system will cause the harm of the secondary overcurrent of the current, the present invention proposes a DC fault reclosing method of the SDSM-MMC type flexible DC system with low current characteristics, and realizes the DC fault reclosing method for the SDSM-MMC type Flexible direct current transmission system, fault reclosing method with low current hazard

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  • SDSM-MMC type flexible DC system DC fault reclosing method with low-current characteristic
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  • SDSM-MMC type flexible DC system DC fault reclosing method with low-current characteristic

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Embodiment Construction

[0017] Aiming at the characteristics of the SDSM topology, the present invention proposes a new type of sub-module operation mode and the corresponding uncontrolled rectification operation mode of the converter, and accordingly designs a fault reclosing strategy with low current hazards, specifically content include:

[0018] Aiming at the characteristics of SDSM topological structure, a corresponding new sub-module operating mode is proposed, and the present invention refers to the operating mode as a half-bridge-like blocking mode. Such as figure 1 (a) shows the implementation method 1 of the half-bridge-like blocking mode, conduction figure 1 IGBT T5, T1~T4 in (a) remain in the locked state. At this time, the fault current can only flow through the freewheeling diodes D2, D4 and IGBTT5. Its physical characteristics are the same as those of the half-bridge module in the locked state, so it is named Latching mode like half-bridge; such as figure 1 (b) shows the implemen...

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Abstract

The invention discloses an SDSM-MMC type flexible DC system DC fault reclosing method with low-current characteristics. The SDSM-MMC type flexible DC system DC fault reclosing method comprises the steps of: removing a DC fault current by locking a current converter, and completing de-ionization; then putting all SDSM submodules into a quasi-half-bridge locking mode; utilizing the SDSM quasi-half-bridge locking mode to implement an operating method of an SDSM-MMC uncontrolled rectifier bridge; indicating that a fault still exists if current occurs in a DC circuit again, judging the fault to be a permanent fault, and locking the current converter immediately. Compared with the prior art, the SDSM-MMC type flexible DC system DC fault reclosing method can realize the reclosing judgment just by judging whether the current exists or not, if the current converter is reclosed at the permanent fault, the current converter can be relocked quickly under the condition of very small circuit current, the secondary overcurrent impact of reclosing on the system is effectively avoided, and the SDSM-MMC type flexible DC system DC fault reclosing method has a positive effect of low current hazards.

Description

technical field [0001] The invention relates to the field of power system protection and control, in particular to a DC fault reclosing method for a flexible DC transmission system. Background technique [0002] Flexible DC transmission using overhead lines is one of the effective ways to realize large-capacity DC transmission in the future. In the case of overhead line transmission, the DC fault rate is greatly increased, and the use of series double sub-module (SDSM) MMC (SDSM-MMC) instead of the traditional half-bridge MMC can realize rapid fault current removal. In addition, the overhead line has a high probability of transient faults, so it is necessary to design an appropriate fault reclosing strategy. The existing reclosing strategy is mainly to unlock the converter station in zero power mode after a period of system de-ionization process, and judge whether the fault exists or not by judging whether the DC voltage can be established. However, this method uses whethe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H3/06
CPCH02H3/066H02H7/268
Inventor 李斌何佳伟
Owner TIANJIN UNIV
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