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A voltage phase differential protection method for half-wavelength transmission lines

A transmission line, half-wavelength technology, applied in the direction of automatic disconnection of emergency protection devices, circuit devices, emergency protection circuit devices, etc. clear selective effect

Active Publication Date: 2020-12-08
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the 1940s, it was proposed and conducted preliminary research by Soviet experts [1] , but due to the limitation of actual conditions, there is no half-wavelength transmission line actually put into operation
[0003] In summary, there are few protection principles for half-wavelength AC transmission lines at present, and it is necessary to conduct in-depth excavation and research

Method used

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  • A voltage phase differential protection method for half-wavelength transmission lines
  • A voltage phase differential protection method for half-wavelength transmission lines
  • A voltage phase differential protection method for half-wavelength transmission lines

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Embodiment Construction

[0039] When the length of the transmission line cannot be ignored compared with the wavelength of the electromagnetic wave, the distribution of voltage and current along the line will fluctuate regularly. Therefore, the half-wavelength transmission line cannot be analyzed by the centralized parameter model, and the distributed parameter model must be used. figure 1 The double-sided power system of the is the equivalent system potential on both sides, Z m ,Z n is the equivalent system impedance on both sides. The transmission line adopts the distributed parameter model and is considered to be a uniform transmission line, then the following equation is satisfied under the steady state of power frequency

[0040]

[0041] In the formula, are the voltage and current at the m-side of the line head end, Take the bus flow direction line as positive; is the voltage and current at x km away from the m side; the line propagation constant α and β are attenuation factor and...

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Abstract

The invention relates to a voltage fault component phase differential protection method for a half-wavelength transmission line. The method comprises the steps that a symmetrical component method is utilized to calculate sampling values of negative sequence voltage; similarly, sampling values of N-side negative sequence voltage are calculated; the size of each data block is set, a data block before a moment t is subtracted from each data block collected at an M side after the moment t, a series of voltage break-variable sampling values are obtained, and the symmetrical component method is utilized to calculate sampling values of positive sequence voltage break-variables; similarly, sampling values of N-side positive sequence voltage break-variables are calculated; a Full-wave Fourier algorithm is utilized to calculate phase angles of u<M2>(k) and u<N2>(k), and a phase angle difference theta<2> between u<M2>(k) and u<N2>(k) is solved; the Full-wave Fourier algorithm is utilized to calculate phase angles of delta(u<M1>(k)) and delta(u<N1>(k)), and a phase angle difference delta(theta<1>) between delta(u<M1>(k)) and delta(u<N1>(k)) is solved; and fault judgment and protection are performed.

Description

technical field [0001] The invention relates to the field of power system protection, in particular to a voltage phase differential protection method for a half-wavelength transmission line. Background technique [0002] Half-wavelength AC transmission technology (half-wavelength AC transmission, HWACT) refers to the ultra-long-distance three-phase AC transmission technology whose electrical distance is close to one power frequency half-wave, ie 3000km (50Hz) or 2500km (60Hz). In the 1940s, it was proposed and carried out preliminary research by Soviet experts [1] , but due to the limitation of practical conditions, there is no half-wavelength transmission line actually put into operation. Half-wavelength AC transmission technology has the advantages of large transmission capacity, no need for reactive power compensation, and no need to set up intermediate switching stations. The interconnection with the Internet can also be applied to the construction of the global energy...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26H02H3/26
Inventor 张艳霞林志海
Owner TIANJIN UNIV