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Method for identifying permanent fault of ultrahigh voltage overhead-cable hybrid transmission line

A technology for permanent faults and transmission lines, applied in emergency protection circuit devices, measuring electricity, electrical components, etc., can solve the problems of small fault phase recovery voltage and misjudgment, and achieve the effect of short judgment time and easy to meet sampling requirements.

Active Publication Date: 2016-06-08
TIANJIN UNIV
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Problems solved by technology

Since the shunt reactor compensates the line-to-ground capacitance and the phase-to-phase capacitance of the power cable section is zero, the recovery voltage of the fault phase is small, so the traditional judgment method applicable to overhead lines may be misjudged

Method used

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  • Method for identifying permanent fault of ultrahigh voltage overhead-cable hybrid transmission line
  • Method for identifying permanent fault of ultrahigh voltage overhead-cable hybrid transmission line
  • Method for identifying permanent fault of ultrahigh voltage overhead-cable hybrid transmission line

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Embodiment Construction

[0028] In order to overcome the defects of the existing technology, a permanent fault discrimination method for EHV overhead-cable hybrid transmission lines with shunt reactors is proposed. Frequency f and setting value Kf set Compare. In a certain period of time, if f has not been greater than Kf set , the fault is a permanent fault; if f is always greater than Kf set , the fault is a transient fault. If it is not a permanent fault, it will start reclosing; if it is a permanent fault, it will effectively block the reclosing switch without reclosing.

[0029] Below by specific embodiment, describe the technical scheme of this method in detail:

[0030] (1) The shunt reactor is installed at the N terminal of the hybrid line, and the single-ended overhead-cable hybrid transmission line with a shunt reactor is shown in figure 1 . In the figure, F is the fault location, J is the connection point between the overhead line and the power cable, L is the inductance of the shunt ...

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Abstract

The invention relates to a method for identifying a permanent fault of an ultrahigh voltage overhead-cable hybrid transmission line. The method is applied to a hybrid transmission line with a paralleling reactor and comprises the following steps: collecting a restoring voltage of a fault phase after a hybrid line is subjected to single-phase earth fault and the electric arc is extinguished; restoring a pole corresponding to a voltage power frequency component and a pole corresponding to a voltage attenuation periodic component; acquiring the frequency f of the attenuation periodic component; comparing the frequency f of the attenuation periodic component with a setting value Kfset, wherein K is a margin coefficient and fset is the frequency for restoring the voltage power frequency component calculated according to the parameters of the hybrid transmission line; confirming the fault as the permanent fault if f is not more than Kfset all the time within a set time period. According to the method, the identification for the permanent fault of the ultrahigh voltage overhead-cable hybrid transmission line can be reliably realized.

Description

technical field [0001] The invention relates to the field of power system transmission line protection, in particular to single-phase self-adaptive reclosing technology for transmission lines with shunt reactors. Background technique [0002] EHV overhead-cable hybrid transmission lines have the advantages of economy and reliability in the transmission to urban load centers and across rivers and seas, so they have been widely used and promoted in modern power construction and power grid transformation. Accurate line parameters are the basis for the system to perform power flow calculation, relay protection setting, fault location, etc. In the single-phase fault of hybrid transmission lines, most of the overhead line sections are transient faults, and the power cable sections are generally permanent faults. At present, for single-phase faults of hybrid transmission lines, it is generally determined whether to start reclosing according to the length relationship between the l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26G01R31/02
CPCG01R31/50H02H7/26
Inventor 李博通张云柯陈晓龙
Owner TIANJIN UNIV
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