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Method and system for AC low voltage protection of DC transmission system

A technology for DC transmission system and low voltage protection, applied in emergency protection circuit devices, electrical components, etc., can solve the problems of grid-side voltage measurement drop to zero, DC false blocking, etc., to reduce risks, improve reliability and stability Sex, to eliminate the effect of stealth jumping

Active Publication Date: 2019-09-20
ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Judging by taking the maximum value of the three-phase voltage of the incoming line of the rheology transformer, however, the AC low voltage protection of the prior art is not associated with the open position of the terminal box of the voltage transformer on the grid side and the network voltage measurement board of the protection device (protection screen cabinet) When the three-phase ground fault does not occur on the AC busbar or AC line, the circuit breaker of the voltage transformer terminal box on the grid side or the circuit breaker of the protection device network voltage measurement board will cause the network The measurement of side voltage drops to zero, that is, a measurement failure occurs
At this time, both CPUs meet the AC low-voltage protection action conditions, and the protection system of the DC transmission will trip the outlet, resulting in DC false blocking

Method used

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  • Method and system for AC low voltage protection of DC transmission system
  • Method and system for AC low voltage protection of DC transmission system
  • Method and system for AC low voltage protection of DC transmission system

Examples

Experimental program
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Embodiment 1

[0041] see figure 1 , figure 1 It is a flow chart of an AC low-voltage protection method for a DC transmission system provided by an embodiment of the present invention; including:

[0042] S1. Setting the parameters of the protection control word, the protection exit state, the protection pressure plate exit state and the fault state of the merging unit of the DC transmission system;

[0043] S2. Judging whether the grid-side voltage of the converter transformer in the direct current transmission system satisfies a preset condition; the preset condition includes that the maximum value of the grid-side voltage is greater than the set value of the operating voltage, and within the first preset time The maximum value of the grid-side voltage is greater than the set value of the operating voltage;

[0044] S3. Determine whether the open position of the terminal box of the voltage transformer on the grid side and the open position of the voltage measurement board on the grid sid...

Embodiment 2

[0061] see Figure 4 , Figure 4 It is a structural block diagram of an AC low-voltage protection system of a DC transmission system 10 provided by an embodiment of the present invention; it includes:

[0062] The parameter setting unit 1 is used to set the parameters of the protection control word of the direct current transmission system, the protection exit state, the protection pressure plate exit state and the failure state of the merging unit;

[0063] The grid-side voltage judging unit 2 is used to judge whether the grid-side voltage of the converter transformer in the direct current transmission system satisfies a preset condition; the preset condition includes that the maximum value of the grid-side voltage is greater than the operating voltage setting, and The maximum value of the grid-side voltage within the first preset time is greater than the set value of the action voltage;

[0064] The voltage transformer judging unit 3 is used to judge whether the open posit...

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Abstract

The invention discloses an alternating-current low-voltage protection method for a direct-current transmission system. The method comprises: a protection control word parameter, a protection exit state, a protection pressing plate exit state and a combination unit failure state of a direct-current transmission system are set; whether a grid-side voltage of a converter transformer in the direct-current transmission system meets a preset condition is determined; whether an air switch position of a terminal box of a grid-side voltage transformer and an air switch position of a grid-side voltage measuring panel card of a protection screen cabinet are in a closing state is determined; when the grid-side voltage meets the preset condition and the air switch position of the terminal box of the grid-side voltage transformer and the air switch position of the grid-side voltage measuring panel card of the protection screen cabinet are in a closing state, alternating-current low-voltage protection is triggered. In addition, the invention also discloses an alternating-current low-voltage protection system for a direct-current transmission system. Therefore, the potential safety hazard of the false operation of alternating-current low-voltage protection is eliminated; a problem that the operation box is damaged because the protection exit can not return is solved; and the reliability and stability of the operation of the direct-current transmission system are improved.

Description

technical field [0001] The invention relates to the technical field of power system control, in particular to an AC low voltage protection method and system for a direct current transmission system. Background technique [0002] In the protection system of DC power transmission, AC low-voltage protection is usually configured. Its function is: when a three-phase ground fault occurs on the AC busbar or AC line, if the relevant AC protection refuses to operate and the fault cannot be removed, the DC The AC low voltage protection action outlet in protection trips the incoming circuit breaker of the converter transformer on the fault side, and blocks the valve trigger pulses on the rectifier side and inverter side of the DC system. [0003] In the prior art, the protection device of the DC transmission system usually has two CPUs. In order to ensure the reliability of the AC low voltage protection action, the AC low voltage protection will only operate after the two CPUs meet th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
Inventor 朱煜昆郭琦黄立滨李书勇
Owner ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD