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Single-end electrical quantity protection method suitable for hybrid bipolar direct current transmission line

A technology for faults in DC transmission lines and DC lines, which is applied to electrical components, measurement of electrical variables, emergency protection circuit devices, etc., can solve the problems of little research on the protection of hybrid DC transmission lines, and achieve quick action and sensitivity. The effect of high precision and strong resistance to transition resistance

Pending Publication Date: 2021-05-14
XIAN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] At present, the research on either pure LCC type DC or pure VSC type DC is relatively sufficient, and there is little research on the protection of hybrid HVDC transmission lines.

Method used

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  • Single-end electrical quantity protection method suitable for hybrid bipolar direct current transmission line
  • Single-end electrical quantity protection method suitable for hybrid bipolar direct current transmission line
  • Single-end electrical quantity protection method suitable for hybrid bipolar direct current transmission line

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Experimental program
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Embodiment 1

[0045] By analyzing the voltage characteristic signal at the protection installation, it is found that due to the existence of smoothing reactors on both sides of the DC line, there are obvious differences in the transient high-frequency components of the voltage characteristic signal when there is a fault inside and outside the line area, and the high-frequency component of the fault in the area is obviously higher Based on this difference, a single-ended electrical quantity protection method based on the ratio of transient energy is proposed.

[0046] Proceed as follows:

[0047] 1) Using the smoothing reactors on both sides of the line of the hybrid bipolar DC transmission system as the protection boundary, the voltage characteristic signal is extracted at the protection installation;

[0048] 2) There are obvious differences in the transient high-frequency energy of the voltage characteristic signal when analyzing the internal and external faults;

[0049] 3) The obtained...

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Abstract

The invention discloses a single-end electrical quantity protection method suitable for a hybrid bipolar direct current transmission line, and constructs a direct current line fault discrimination method based on a signal transient high and low frequency energy ratio by using a specific boundary structure of a hybrid bipolar direct current transmission system. A hybrid bipolar high-voltage direct-current power transmission system is built through a PSCAD / EMTDC simulation platform, fault conditions under different working conditions are simulated, voltage characteristic signals are extracted, wavelet packet transformation is carried out, transient energy of each node is obtained, a protection criterion is constructed by using a ratio of specific low-frequency energy to partial high-frequency energy, and thus internal and external faults of a region are identified and fault line selection is carried out. The method is high in transition resistance resistance, the protection reliability, selectivity, quickness and sensitivity are all met, high precision is achieved, and faults can be accurately recognized. According to the invention, calculation related to the wavelet packet can be realized by adopting a high-performance CPU (Central Processing Unit) or a hardware circuit such as an FPGA (Field Programmable Gate Array) or a CPLD (Complex Programmable Logic Device), so that the fault identification speed, precision and reliability are improved.

Description

technical field [0001] The invention belongs to the technical field of electric power system relay protection. Specifically, it utilizes the unique boundary structure of a hybrid bipolar direct current transmission system, and relates to a DC line fault discrimination method based on signal transient high and low frequency energy ratios. Background technique [0002] DC transmission occupies an important position in long-distance power transmission, so there has been an upsurge of research on high-voltage DC transmission at home and abroad, and DC transmission has become an inevitable move for the development of power grids. my country has a vast territory and abundant resources, and the energy distribution is uneven, making it one of the countries with the best prospects for the development of direct current transmission in the world. my country has established a large number of direct current transmission projects to carry out long-distance and large-capacity power transmi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26H02J3/36G01R31/08
CPCH02H7/26H02H7/268H02J3/36G01R31/081G01R31/088Y02E60/60
Inventor 高淑萍宋晓辰王斐徐振曦邵明星李磊叶换飞
Owner XIAN UNIV OF SCI & TECH
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