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Modular multi-level flexible direct current system direct current fault overvoltage restraining method

A modular multi-level, flexible DC technology, applied in the direction of protection against overvoltage, can solve problems such as unsatisfactory overvoltage levels, reduce overvoltage levels, reduce insulation design requirements, and reduce construction costs and the effect of occupying

Active Publication Date: 2015-06-24
GLOBAL ENERGY INTERCONNECTION RES INST CO LTD +3
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  • Abstract
  • Description
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Problems solved by technology

[0009] The problem with this method is that because the charging voltage is too high, even if the arrester operates, the overvoltage level that can be suppressed is still unsatisfactory. It is extremely necessary to reduce overvoltage through more reasonable and effective measures

Method used

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Embodiment

[0041] Such as figure 2 As shown, when the modular multilevel flexible DC system is operating normally, the positive and negative DC voltages are about 0.5 times the rated voltage. When a unipolar ground fault occurs on the DC line in 0.8s, the overvoltage of the healthy pole DC line is about 2.4 times the rated voltage when traditional protection measures are adopted. At this time, the overvoltage will cause serious damage to the insulation of the DC field equipment and the converter valve. Threat; after adopting the present invention, the overvoltage of the sound pole DC line can be reduced to below 2 times of the rated voltage. Simulation results show that: for single-pole grounding faults, the invention can effectively reduce the overvoltage level of healthy DC lines, reduce the insulation design requirements for DC field equipment and converter valves, and thus reduce equipment investment. exist figure 2 Among them, ○Udc1Pmeas and □Udc1Nmeas respectively represent the...

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Abstract

The invention relates to a modular multi-level flexible direct current system direct current fault overvoltage restraining method which is characterized by comprising the following steps of (1) detecting direct current circuit faults, (2) lowering direct current voltage set parameter level after the faults are detected, (3) setting sending end station transmission power inversion, (4) locking a converter valve and (5) switching off a direct current line breaker. By means of the method, overvoltage level under a direct current line single-pole grounding fault can be effectively lowered, and therefore insulation design requirements on direct current field devices and the converter valve are lowered, system insulation manufacturing cost is effectively lowered, and system related properties are optimized.

Description

technical field [0001] The invention relates to a control method applied under a DC line fault, in particular to a method for suppressing a DC fault overvoltage of a modularized multi-level flexible DC system. Background technique [0002] Compared with conventional DC technology, flexible DC technology has low harmonic content, does not require filters, can flexibly control active and reactive power output, does not require reactive power compensation devices, and does not occur commutation failures, occupying a small area , the excellent performance in all aspects has attracted more attention. In recent years, the generation of modular multi-level technology is more flexible DC technology and a topology structure that is easier to expand is proposed. Therefore, the amount of flexible DC engineering in the world Showing explosive growth, my country's flexible DC technology has also made great progress. [0003] The modular multilevel converter is composed of 6 bridge arms, a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H3/20
Inventor 杨杰王海田赵岩孔明阎发友
Owner GLOBAL ENERGY INTERCONNECTION RES INST CO LTD
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