Multi-terminal MMC-HVDC (modular multi-level converter high voltage direct current) bipolar short-circuit fault current calculation method

A technology of MMC-HVDC and fault current, applied in the direction of power transmission AC network, etc., can solve the problem of slow simulation and achieve the effect of high calculation accuracy and fast calculation speed

Active Publication Date: 2017-08-18
STATE GRID CORP OF CHINA +2
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Problems solved by technology

At the present stage, the flexible direct current transmission project is developing towards the direction of multi-terminal high-voltage and large-capacity, involving many sub-modules, and the simulation is slow

Method used

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  • Multi-terminal MMC-HVDC (modular multi-level converter high voltage direct current) bipolar short-circuit fault current calculation method
  • Multi-terminal MMC-HVDC (modular multi-level converter high voltage direct current) bipolar short-circuit fault current calculation method
  • Multi-terminal MMC-HVDC (modular multi-level converter high voltage direct current) bipolar short-circuit fault current calculation method

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Embodiment Construction

[0040] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

[0041] The invention provides a multi-terminal MMC-HVDC bipolar short-circuit fault current calculation method, comprising the following steps:

[0042] 1) Analyze the DC side fault of the single-ended MMC-HVDC system based on HBSM (half-bridge sub-module, HBSM), that is, carry out the equivalent value of the discharge circuit before the blockage of the converter station, and obtain the The equivalent capacitance C of the fault equivalent circuit eq , Equivalent reactance L eq and equivalent resistance R eq .

[0043] Such as figure 1 Shown is a schematic diagram of the three-phase topology of the MMC in the HBSM-based single-ended MMC-HVDC system. The MMC is composed of three-phase six bridge arms, each bridge arm includes a current-limiting reactance and n sub-modules, and the current-limiting reactance is connected in cascade with the n sub-mo...

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Abstract

The invention relates to a multi-terminal MMC-HVDC (modular multi-level converter high voltage direct current) bipolar short-circuit fault current calculation method. The method includes the following steps that: 1) the equivalent capacitance, equivalent reactance and equivalent resistance of the fault equivalent circuit of a single-terminal MMC-HVDC system converter station are calculated; 2) the discharge current of the converter station which appears after the converter station is latched is calculated; 3) the initial solution of the discharge current of each converter station in a multi-terminal MMC-HVDC system under a condition that the discharge current of the converter station is not affected by other converter stations is calculated; 4) fault current actually passing through each direct-current line in the multi-terminal MMC-HVDC system is calculated; 5) the equivalent resistance and equivalent reactance of the actual fault equivalent circuit of the converter station at each terminal in the multi-terminal MMC-HVDC system are calculated; 6) the discharge current of the converter station at each terminal of the multi-terminal MMC-HVDC system is re-calculated; and 7) the step 4) to step 6) are repeated, and the discharge current value of the outlet of the converter station at each terminal of the multi-terminal MMC-HVDC system is calculated. The multi-terminal MMC-HVDC bipolar short-circuit fault current calculation method has high precision and speed and is of a certain guiding significance for direct current power grid planning and direct current circuit breaker selection.

Description

technical field [0001] The invention relates to a calculation method of a power system fault current, in particular to a calculation method of a multi-terminal MMC-HVDC bipolar short-circuit fault current. Background technique [0002] In recent years, with the development of power electronics technology, the flexible DC transmission system (voltage source converter HVDC, VSC-HVDC) based on turn-off devices has the advantages of no commutation failure, independent control of active and reactive power, and easy construction of multi-terminal power grids. , are becoming more and more popular. Flexible DC transmission systems are mainly divided into two technical routes: two-level and three-level converters and modular multi-level converters (MMC). Among them, the modular multilevel converter has become the mainstream trend in the development of voltage source converters due to its advantages such as low switching frequency, good output waveform quality, low requirements for s...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36
CPCH02J3/36Y02E60/60
Inventor 陈东梅念李高望程炜赵峥刘思源魏争李探陈钊祝全乐谭静刘崇茹谢国超王宇徐东旭王洁聪凌博文
Owner STATE GRID CORP OF CHINA
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