Method and system for protecting direct current transmission line

A technology for DC transmission lines and protection systems, applied in emergency protection circuit devices, short-circuit tests, electrical components, etc., can solve problems such as long time to judge faults, unreliable fault distinction, and inability to protect the full length of the line, so as to save protection time , short protection time, reliable detection effect

Active Publication Date: 2022-06-28
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a DC transmission line protection method and system, which solves the problem of unreliability in distinguishing whether the fault occurs in the area or outside the area when the high-resistance fault of the existing DC transmission line occurs, judging the fault time is too long and single-ended protection The problem of not being able to protect the full length of the line

Method used

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  • Method and system for protecting direct current transmission line
  • Method and system for protecting direct current transmission line
  • Method and system for protecting direct current transmission line

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] Example 1: First, build a DC transmission line model in PSCAD / EMTDC. The line length is 1500km, the voltage level is ±800kV, and the sampling frequency is 1MHz. The rectifier side external faults are set respectively, and the high-resistance (500Ω) ground fault at 5km is 1495km. There are four cases of high-resistance (500Ω) ground fault and high-resistance (500Ω) ground fault outside the inverter side area.

[0062] like figure 1 As shown, a DC transmission line protection method, the specific steps are:

[0063] Step1: Collect the traveling wave signal at the single end of the line to obtain the variation of the traveling wave signal, and use it to construct the start signal.

[0064] like figure 2 As shown, the specific steps of Step1 are:

[0065] Step1.1: Collect the traveling wave signal of the single end of the line, and the traveling wave signal is the collected voltage traveling wave u or current traveling wave i. The single end is the first end or the sec...

Embodiment 2

[0098] Example 2: First, build a DC transmission line model in PSCAD / EMTDC. The line length is 1500km, the voltage level is ±800kV, and the sampling frequency is 200kHz. Set the metal grounding fault outside the rectifier side and the metal grounding outside the inverter side. Fault, high resistance (500Ω) ground fault outside the rectifier side, high resistance (500Ω) ground fault outside the inverter side, high resistance (500Ω) ground fault at 5km, high resistance (500Ω) fault at 1200km, high resistance (500Ω) at 1495km There are eight cases of high resistance (500Ω) fault between poles and high resistance (500Ω) ground fault at 1495km.

[0099] The specific implementation steps are:

[0100] Step1: Collect the traveling wave signal at the single end of the line to obtain the variation of the traveling wave signal, and use it to construct the start signal.

[0101] Step1 The specific steps are:

[0102] Step1.1: Collect the traveling wave signal of the single end of the l...

Embodiment 3

[0128] like Figure 9 As shown, a DC transmission line protection system includes:

[0129] The numerical calculation module is used to obtain the variation of the traveling wave signal and construct the start signal. Calculate the short-window energy of the start signal within the set short-window I. Calculate the absolute value of the short-window energy. Computes the power transform of the absolute value of the short-window energy. Calculate the maximum value of the change rate of the absolute value of the short-window energy within the set short-window II, and construct the fault section identification signal.

[0130] The logic judgment module is used to judge whether the absolute value of the short-window energy is greater than the set startup threshold. If not, continue to execute the short-window energy; if so, judge whether the absolute value of the short-window energy is greater than 1; The absolute value of the energy is multiplied by a coefficient to make its v...

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Abstract

The invention relates to a DC transmission line protection method and system, belonging to the technical field of electric power system relay protection. Collect the single-ended traveling wave signal of the line to obtain the variation of the traveling wave signal, and use it to construct the start signal; calculate the short window energy of the start signal within the set short window; judge whether the short window energy is greater than the set start threshold, If not, then return to continue to calculate the short window energy, if so, calculate the maximum value of the rate of change in the set short window after the power transformation of the short window energy, and construct the fault section identification signal; judge whether the fault section identification signal is greater than If the section threshold is set, if it is not, then it is not the fault of the own line, if it is, then it is the fault of the own line, and a protection action command is issued. The invention only utilizes single-ended quantity, does not need synchronous time adjustment, can realize fast and reliable detection and identification of faults, and takes into account the selectivity, quickness, sensitivity and reliability of protection.

Description

technical field [0001] The invention relates to a direct current transmission line protection method and system, belonging to the technical field of power system relay protection. Background technique [0002] my country's energy and load distribution is uneven from east to west, energy is more distributed in the central and western regions, and loads are more distributed in the eastern region. Most of the clean energy such as wind power, photovoltaic power generation in the northwest and hydropower in the southwest is transmitted to the eastern load center. HVDC transmission has unique advantages such as large transmission capacity and long transmission distance; simple structure of transmission towers, narrow transmission corridors, few transmission lines, and low transmission loss, etc. Especially in clean energy transmission, DC transmission can realize asynchronous networking and other advantages, which are widely used. application. In the process of HVDC transmission...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26G01R31/52
CPCH02H7/262G01R31/52
Inventor 束洪春李文龙杨竞及唐玉涛王锐薄志谦
Owner KUNMING UNIV OF SCI & TECH
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