Single-ended fault ranging method of alternating-current line for flexible direct-current feeding

A flexible direct current, fault location technology, applied in the direction of fault location, fault detection according to conductor type, measurement device, etc., can solve problems such as failure of fault location methods, achieve wide applicability, solve inapplicability, and high ranging accuracy Effect

Inactive Publication Date: 2019-01-04
TIANJIN UNIV
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  • Application Information

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Problems solved by technology

Once a serious short-circuit fault occurs near the converter, and the voltage drop exceeds the adjustment capability of the fault ride-through control strategy, the converter will be blocked to isolate the DC side feed, making the fault location method based on double-terminal electrical quantities invalid

Method used

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  • Single-ended fault ranging method of alternating-current line for flexible direct-current feeding
  • Single-ended fault ranging method of alternating-current line for flexible direct-current feeding
  • Single-ended fault ranging method of alternating-current line for flexible direct-current feeding

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Embodiment Construction

[0020] The present invention will be described in further detail below in conjunction with accompanying drawing and example. figure 1 The figure shows a typical flexible DC infeed AC-DC hybrid transmission system, and a single-phase ground fault occurs on the AC transmission line.

[0021] The fault location method of the present invention for locating single-phase ground faults of AC lines fed by flexible DC mainly includes three parts: decoupling of single-ended electrical quantities, calculation of sequence component distribution of fault voltage and fault current along the line, and distance measurement criteria.

[0022] 1. Single-ended electrical quantity decoupling

[0023] There is electromagnetic induction between the three-phase transmission lines, which will affect the accuracy of calculating the voltage and current distribution along the line. Therefore, it is necessary to convert the electrical quantities on the traditional AC power supply side into mutually indep...

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Abstract

The invention, which belongs to the field of relay protection of a power system, particularly relates to a single-ended fault ranging method of an alternating-current line for flexible direct-currentfeeding. The method comprises the following steps that: after a power transmission system detects a single-phase ground fault, a single-ended electrical quantity of a conventional alternating-currentpower supply side is collected; discrete Fourier transform is carried out on an electrical quantity in a sampled data window and a fundamental frequency component is extracted; with a symmetrical component method, phase-mode transformation is carried out on the fundamental frequency component in a frequency domain to obtain sequence components of a fault voltage and a fault current; on the basis of a distributed parameter model, fault voltage and negative-sequence fault current distribution of a fault phase along a line is calculated; a data group formed by fault voltages and negative-sequencefault currents of fault phases at different distances at different times along the line is obtained in a time domain and fault ranging is carried out by using unary linear regression according to thecharacteristic of meeting a direct proportional linear relationship by the data group only at a fault point. Therefore, a problem that the traditional fault location method has low applicability is solved; and the single-ended fault ranging method has advantages of high ranging accuracy and wide applicability.

Description

technical field [0001] The invention belongs to the field of relay protection of electric power systems, and in particular relates to a fault location method for an AC line fed by flexible DC in an AC-DC hybrid power transmission system. Background technique [0002] AC transmission lines are prone to unipolar ground faults, and their short-circuit currents will seriously affect the safe and stable operation of the system. Therefore, it is of great significance to quickly locate the fault point and clear the fault to improve the economy and reliability of the system operation. Due to the absence of commutation failure and its outstanding advantages in flexible control and power quality, flexible DC transmission plays an important role in the fields of new energy grid integration and regional grid interconnection. In the AC-DC networking mode based on flexible DC transmission, the fault characteristic quantity in the AC system is affected by the control strategy of the conve...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08G01B21/02
CPCG01B21/02G01R31/086
Inventor 薛士敏陆俊弛刘冲范勃旸赵杨竹雨刘白冰
Owner TIANJIN UNIV
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