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A backup protection method for HVDC transmission line based on DC control system

A DC control system, high-voltage DC technology, applied in the direction of emergency protection circuit devices, information technology support systems, electrical components, etc., can solve the complex geographical environment, the influence of the safety and stability level of the AC-DC hybrid power system, protection composition principles, The calculation basis of the setting is not disclosed, etc.

Active Publication Date: 2019-02-05
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the high voltage level of the DC transmission line and the complex geographical environment along the line, the probability of failure is also high, which seriously affects the safety and stability of the DC transmission system.
[0003] At present, the main protection schemes of DC transmission lines include traveling wave protection, differential undervoltage protection, DC differential protection, etc. [5] , but its core technology is mainly in the hands of a small number of foreign manufacturers, and the protection composition principle and setting calculation basis have not yet been made public. The safety and stability level of my country's AC-DC hybrid power system has caused a great degree of impact
[0004] HVDC transmission systems generally use differential undervoltage protection and longitudinal differential protection as backup protection, but the operating characteristics of differential undervoltage protection undervoltage criteria are closely related to factors such as transition resistance and DC control system parameters; longitudinal differential protection It is greatly affected by the control system and in order to avoid out-of-area faults, its action delay is as long as 1.1s

Method used

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  • A backup protection method for HVDC transmission line based on DC control system
  • A backup protection method for HVDC transmission line based on DC control system
  • A backup protection method for HVDC transmission line based on DC control system

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Experimental program
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Embodiment 1

[0061] Embodiment 1: A backup protection method for HVDC transmission lines based on a DC control system, the specific steps are:

[0062] (1) In the DC system, the area from the rectifier side DC outlet to the inverter side DC outlet is a high-voltage DC transmission line. The faults that occur in this area are internal faults, and the protection operates. The rest of the faults are external faults, and the protection does not operate. ;

[0063] (2) Real-time monitoring of the differential current signal on the rectification side and the inverter side. The differential current signal on the rectification side is the difference between the current at the rectification valve and the current at the DC outlet of the rectification side, which is recorded as ΔI re ; The differential current signal on the inverter side is the difference between the current at the inverter valve and the current at the DC outlet of the inverter side, which is recorded as ΔI inv ;Use these two differ...

Embodiment 2

[0078] Embodiment 2: as figure 1As shown, the ±800kV UHVDC transmission model. In this model, the rated power of the DC transmission is 5000MW, the rated current is 3125A, the rectification side: the voltage of the AC system is 525kV, the short-circuit ratio SCR=2.5 / 840, the reactive power compensation capacity is 3000Mvar, and the DC filter is 12 / 24 / 36 triple-tuned filters, each pole commutation unit is composed of two 12-pulse converters connected in series, and the voltage in series is distributed according to ±(400+400)kV. The reactive power compensation capacity of the inverter side is 3040Mvar, and other parameters are consistent with the rectification side. The total length of the direct current transmission line is 1500km (the actual project is 1418km), and the control system is established according to the test system of the direct current transmission standard of the International Conference on Large Power Grids (CIGRE).

[0079] Such as figure 1 As shown, after ...

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Abstract

The present invention relates to a DC control system-based high-voltage DC power transmission line backup protection method and belongs to the technical field of power system relay protection. In a high-voltage DC system, when faults occur in different areas, a DC control side generates different responses. Based on the trigger angle alpha of a current converter, the turn-off angle gamma of an inverter, and the change features of differential currents delta Ire and delta Iinv between two end value sides and a DC outlet area during the fault occurrence stage, internal and external faults can be accurately distinguished. Based on the response of the trigger angle alpha of the current converter, rectifier-side AC system faults and antipode circuit faults can be identified. Based on the turn-off angle gamma of the inverter, inverter-side AC system faults can be identified. Based on differential current signals delta Ire and delta Iinv between two end value sides and the DC outlet area, faults from the end value sides to the outlet area can be identified. The method is high in action reliability, fast in operation speed and strong in anti-transition-resistance capability. The protection requirement of far-end faults can be met. The method has an important reference significance on the backup protection configuration of an actual high-voltage DC transmission engineering line.

Description

technical field [0001] The invention relates to a backup protection method for a high-voltage direct current transmission line based on a direct current control system, and belongs to the technical field of electric power system relay protection. Background technique [0002] At present, my country's power system has realized national networking, long-distance, large-capacity power transmission. It is estimated that by 2020, there will be more than 50 direct current transmission projects in my country, of which UHV direct current transmission projects account for about 60%. Due to the high voltage level of the DC transmission line and the complex geographical environment along the line, the probability of failure is also high, which seriously affects the safety and stability of the DC transmission system. [0003] At present, the main protection schemes of DC transmission lines include traveling wave protection, differential undervoltage protection, DC differential protecti...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26G01R31/08
CPCG01R31/085H02H7/268Y04S10/52
Inventor 刘可真张凌跃周帆张灿袁宝辉杜峥卢佳杨浩
Owner KUNMING UNIV OF SCI & TECH