DC fault reclosing strategy for flexible DC power transmission system

A technology for DC faults and power transmission systems, applied in electrical components, circuit devices, emergency protection circuit devices, etc., can solve the problems of low current hazard, secondary current overcurrent hazard, etc. The effect of discharge

Inactive Publication Date: 2016-10-12
TIANJIN UNIV
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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 strategy of the flexible DC transmission system, which realizes the SBSM-MMC flexible DC transmission system with low DC Fault Reclosing Method Based on Current Hazard

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  • DC fault reclosing strategy for flexible DC power transmission system
  • DC fault reclosing strategy for flexible DC power transmission system
  • DC fault reclosing strategy for flexible DC power transmission system

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Embodiment Construction

[0017] Aiming at the characteristics of the two topological structures of SBSM, 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 recloser with low current hazard strategies, including:

[0018] Aiming at the characteristics of SBSM topological structure, a corresponding new sub-module operation mode is proposed, which is called half-bridge-like blocking mode in the present invention. Such as figure 1 (a) shows the implementation method 1 of the half-bridge-like locking mode, which turns on IGBT T3 and locks T1-T2. At this time, the fault current can only flow through the freewheeling diode D2 and IGBT T3, and its physical characteristics are the same as those of the half-bridge module in the locked state, so it is named as the half-bridge-like blocking mode. Such as figure 1 (b) shows the second implementation of the half-bridge-like lockin...

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Abstract

The invention discloses a DC fault reclosing strategy of a flexible direct current transmission system, which clears the DC fault current through a blocking converter and completes deionization; after that, puts all SBSMs into a similar half-bridge blocking mode; uses the SBSM-like half-bridge blocking mode realizes the operation mode of SBSM‑MMC uncontrolled rectifier bridge; if the DC line no longer has current, it is judged that the fault has disappeared, enters the system restart operation mode, and resumes normal operation under the restart control strategy; if the DC line appears current again, then Indicates that the fault still exists, it is judged as a permanent fault, and the converter is blocked immediately. Compared with the prior art, the present invention can realize reclosing judgment only by judging whether the current exists or not. When the reclosing is a permanent fault, the converter can be quickly re-blocked under the condition of a small line current, effectively avoiding It prevents the secondary overcurrent impact caused by reclosing to the system, and has the positive effect of low current hazard.

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 enhanced self-blocking sub-module (SBSM) MMC (SBSM-MMC) to replace the traditional half-bridge MMC can achieve 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. At present, the existing fault reclosing strategy unlocks the converter station in zero power mode after a period of system de-ionization process, and judges whether the DC voltage can be established to realize the interpretation of the fault. Voltage to judge...

Claims

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Application Information

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