Transverter self-removing type flexible DC power transmission system fault reclosing method

A flexible DC and power transmission system technology, applied in the direction of electrical components, circuit devices, emergency protection circuit devices, etc., can solve the problems of secondary overcurrent hazards and low current hazards, and avoid secondary overcurrent shocks and capacitors. 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 fault reclosing method for the converter self-clearing type flexible DC transmission system, and realizes the fault reclosing method for the TLSM-MMC type flexible DC Transmission system, DC fault reclosing method with low current hazard

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  • Transverter self-removing type flexible DC power transmission system fault reclosing method
  • Transverter self-removing type flexible DC power transmission system fault reclosing method
  • Transverter self-removing type flexible DC power transmission system fault reclosing method

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Embodiment Construction

[0017] Aiming at the structural characteristics of TLSM, 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 hazard, the specific content include:

[0018] Aiming at the characteristics of the TLSM topology, a corresponding new sub-module operation mode is proposed, which is called a half-bridge-like blocking mode in the present invention. Such as figure 1 (a) shows the implementation method 1 of the half-bridge-like blocking mode, conduction figure 1 IGBT T5, T6, T1~T4 in (a) keep the locked state. At this time, the fault current can only flow through the freewheeling diodes D2, D3 and IGBTT5, T6, and its physical characteristics are the same as the half-bridge sub-blocks in the locked state. , so it is named as a half-bridge-like latching mode; such as figure 1 (b) shows the implementation method 2 of the ...

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Abstract

The invention discloses a transverter self-removing type flexible DC power transmission system fault reclosing method, and the method comprises the steps: removing a DC fault current through locking TLSM-MMC, and completing the deionization; enabling all TLSM submodules to enter a TLSM half-bridge-like locking mode; achieving a TLSM-MMC no-control rectification bridge operation mode through employing the TLSM half-bridge-like locking mode; judging that a fault disappears if a DC line does not has a current, entering a system restart operation mode, and restoring the normal operation under a restart control strategy; judging that the fault still exists if the DC line has the current again, judging that the fault is a permanent fault, and instantly locking a transverter. Compared with the prior art, the method can achieve the reclosing judgment through judging whether the current exists or not. When the fault is judged to be the permanent fault, the method can quickly lock the transverter under the condition of a very small line circuit, effectively prevents reclosing from causing secondary overcurrent impact on a system, and is low in current danger.

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 three-level sub-module (TLSM) MMC (TLSM-MMC) instead of 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. 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 whether ...

Claims

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Application Information

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