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A single-ended directional protection scheme suitable for UHV multi-terminal hybrid DC transmission lines

A technology of hybrid DC and transmission lines, applied in emergency protection circuit devices, current-only measurement, electrical components, etc., can solve problems such as the reduction of mutation amplitude, the impact of transition resistance, and the damage of DC equipment, so as to prevent protection malfunctions , The effect of strong resistance to transition resistance

Active Publication Date: 2022-06-24
KUNMING UNIV OF SCI & TECH
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  • Abstract
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  • Claims
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AI Technical Summary

Problems solved by technology

[0003] At present, the line protection of UHV multi-terminal hybrid DC transmission system generally refers to the protection of traditional DC transmission and flexible DC transmission lines. The main protection mainly adopts traveling wave protection, such as voltage mutation protection, current mutation protection, etc. The transition resistance has a great influence. When a high-impedance grounding fault occurs on the line or the fault location is far away from the protection installation location, the mutation amplitude of this type of protection is greatly reduced. At this time, this type of protection is easy to refuse to operate. It will cause great harm and seriously threaten the safe and stable operation of the DC system

Method used

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  • A single-ended directional protection scheme suitable for UHV multi-terminal hybrid DC transmission lines
  • A single-ended directional protection scheme suitable for UHV multi-terminal hybrid DC transmission lines
  • A single-ended directional protection scheme suitable for UHV multi-terminal hybrid DC transmission lines

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Embodiment 1

[0026] Embodiment 1: as Figure 1-Figure 2 As shown, a single-ended directional protection scheme suitable for UHV multi-terminal hybrid DC transmission lines, the specific application is as follows:

[0027] S01: When the DC system fails, collect the fault transient current signal at the end of the line L1 and the fault transient current signal at the head end of the line L2, the sampling frequency is 20kHz, and decouple their phase-mode transformation respectively to obtain the line-mode component of the fault current, The phase mode transformation formula is:

[0028]

[0029] In the formula, i 0 is the zero-mode component of the current, i 1 is the line-mode component of the current, i n is the line negative current, i p is the line positive current;

[0030] S02: Carry out 8-scale wavelet decomposition on the fault current line-mode components of the lines on both sides of the T area. The wavelet base function adopts db4 wavelet function, and use db4 wavelet to pe...

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Abstract

The invention discloses a single-end direction protection scheme suitable for UHV multi-terminal hybrid direct current transmission lines. The invention obtains the fault transient current at the end of the line L1 and the fault transient current at the head end of the line L2, and then based on the measured fault transient current Perform phase-mode transformation decoupling, use wavelet decomposition to decompose the fault current line-mode components of line L1 and line L2 to 8 scales, calculate the wavelet energy at each scale, and use the wavelet energy difference at the 8th scale of the fault current line-mode components of line L1 and line L2 Distinguishing the direction of the fault can effectively prevent the protection malfunction caused by the reverse out-of-area fault; use the ratio of the wavelet energy under the first scale of the fault current line mode component of the fault line to the wavelet energy under the sixth scale to determine the inside and outside of the area Fault discrimination can effectively determine the fault location, the protection range covers the entire length of the line, and has a strong ability to withstand transition resistance.

Description

technical field [0001] The invention relates to a single-end directional protection scheme suitable for UHV multi-terminal hybrid DC transmission lines, and belongs to the technical field of relay protection. Background technique [0002] UHV multi-terminal hybrid direct current transmission adopts LCC converter station (grid commutation converter) at the sending end, and MMC converter station (modular multi-level converter) at the receiving end. LCC converter station and MMC converter station are connected The advantages are combined to make up for their respective shortcomings, solve the problem of continuous commutation failure caused by the centralized feed-in of multiple DC circuits, and improve the safe and stable operation of the power grid. [0003] At present, the line protection of UHV multi-terminal hybrid DC transmission system generally refers to the protection of traditional DC transmission and flexible DC transmission lines. The main protection mainly adopts t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26G01R19/00G01R23/16
CPCH02H7/268G01R19/0092G01R23/16
Inventor 陈仕龙王龙毕贵红蔡旺高敬业李朋松邓健张梓航陈俊澔
Owner KUNMING UNIV OF SCI & TECH
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