Direct current monopole grounding fault ride-through method for multi-port flexible high-voltage direct current power transmission system

A high-voltage direct current and power transmission system technology, which is applied in the direction of converting AC power input into DC power output, output power conversion device, emergency protection circuit device for limiting overcurrent/overvoltage, etc. Continue to maintain the fault power transmission and other problems to achieve the effect of eliminating the fault transient overvoltage, improving the active defense force, and the fault restarting speed.

Active Publication Date: 2017-05-10
HUAZHONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It aims to solve the technical problem that the existing fault ride-through method applied to the multi-terminal flexible HVDC transmission system can only eliminate the transient overvoltage and cannot continue to maintain power transmission during the fault

Method used

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  • Direct current monopole grounding fault ride-through method for multi-port flexible high-voltage direct current power transmission system
  • Direct current monopole grounding fault ride-through method for multi-port flexible high-voltage direct current power transmission system
  • Direct current monopole grounding fault ride-through method for multi-port flexible high-voltage direct current power transmission system

Examples

Experimental program
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Effect test

example 1

[0132] The overhead line is used as the DC transmission line of the multi-terminal flexible HVDC transmission system. After detecting a single-pole ground fault, the MMC converter switches to the fault ride-through control mode: adjust the common mode command of the bridge arm reference signal of the faulty pole to be zero, the DC voltage command to be half of the rated value, and the active power command to be half of the rated value half. At the same time, by introducing the misphase angle γ between the differential mode component of the reference voltage of the upper bridge arm and the differential mode component of the reference voltage of the lower bridge arm, the balance of the capacitor voltage of the upper bridge arm sub-module and the balance of the capacitor voltage of the lower bridge arm sub-module are maintained, and The first additional reference voltage signal v is superimposed on the reference voltage of the faulty pole bridge arm zn1 , superimpose the second ...

example 2

[0145] The cable is used as the direct current transmission line of the multi-terminal flexible high voltage direct current transmission system. After detecting a single-pole ground fault, the MMC converter switches to the fault ride-through control mode: adjust the common mode command of the bridge arm reference signal of the faulty pole to be zero, the DC voltage command to be half of the rated value, and the active power command to be half of the rated value half. At the same time, the balance of the sub-module capacitor voltage between the upper and lower bridge arms is maintained by introducing the phase misalignment angle γ between the differential mode components of the upper and lower bridge arm reference voltages, and the first additional reference voltage is superimposed on the faulty pole bridge arm reference voltage signal v zn1 , superimpose the second additional reference signal v on the reference voltage of the sound pole arm zp1 . During the fault ride-throu...

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Abstract

The invention provides a direct current monopole grounding fault ride-through method for a multi-port flexible high-voltage direct current power transmission system. The fault ride-through method is realized through coordination matching between an MMC (modular multilevel converter) based on low-resistance grounding and having negative electric level output capability and a mechanical direct current isolation switch; in a fault period, by regulating common-mode component of a reference voltage of each MMC bridge arm, fault transient state overvoltage can be eliminated under the premise of not sacrificing the controllability of the converter; meanwhile, by overlaying a fault pole bridge arm reference voltage with a first reference voltage signal and by controlling a fault pole bridge arm current to be zero, the mechanical direct current isolation switch can isolate direct current fault in a zero current condition, so that foundation is laid for the application of the mechanical direct current isolation switch in the multi-port flexible direct current power transmission system; and in the fault period, the MMC forms a loop through sound direct current bus-alternating current side low-impedance grounding pole-ground, so that transmission of half rated active power can be maintained.

Description

technical field [0001] The invention belongs to the field of DC fault protection of a multi-terminal flexible high-voltage direct current transmission system, and more specifically relates to a fault ride-through method for DC unipolar grounding of a multi-terminal flexible high-voltage direct current transmission system. Background technique [0002] With the continuous improvement of the country's demand for energy sustainable development, my country's coal-based energy structure will gradually change to a structure in which hydropower, nuclear power, wind power, solar energy and other new energy coexist in the next few decades. The development of large-capacity long-distance advanced networking and transmission technology will help the cross-regional and complementary consumption of renewable energy, and at the same time provide strong support for promoting the construction of transmission channels from large energy bases to large power consumption areas. [0003] Under t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36H02H9/04
CPCH02H9/047H02J3/36H02M7/5388H02M7/4835
Inventor 林磊何震胡家兵
Owner HUAZHONG UNIV OF SCI & TECH
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