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Method for judging high-voltage polar wire short out of low voltage polar wire in back-to-back DC engineering

A medium-high-voltage, pole-line technology, applied in the direction of overcurrent protection, automatic disconnection emergency protection device, circuit device, etc., can solve the problem of slow action speed, small short-circuit current, and fast section of overcurrent protection. Reliable action and other issues

Active Publication Date: 2008-08-27
NR ELECTRIC CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] The shortcomings of the existing methods for identifying the short circuit of the high-voltage pole line and the fault of the low-voltage pole line of the back-to-back DC system: conventional back-to-back differential protection (greater than 500 milliseconds), low-voltage protection (second level), and the action speed is very slow
For the fault after the smoothing reactor of forward power transmission (from T1 side to T2 side), or the fault before the smoothing reactor of power reverse transmission (from T2 side to T1 side), since the short-circuit current is relatively small, the overcurrent protection The fast segment may not be able to operate reliably

Method used

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  • Method for judging high-voltage polar wire short out of low voltage polar wire in back-to-back DC engineering
  • Method for judging high-voltage polar wire short out of low voltage polar wire in back-to-back DC engineering

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Embodiment Construction

[0031] Read the sampling value, calculate (5)-(8) formula, use figure 2 The implementation block diagram of the back-to-back DC system realizes the fast and reliable protection of the short circuit of the high voltage pole line and the fault of the low voltage pole line. The delay here is the condition (5)-(8) directly plus the delay action, without any other processing in the middle.

[0032] Setting value selection reference: setting value 4 is about 0.133±0.05 times the DC rated current, setting value 5 is about 0.65±0.2 times the DC rated current. The delay is about 40±10ms. It is better to take the intermediate value to complete the present invention.

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Abstract

This invention relates to a method for judging that the high voltage polar short circuit on low voltage polar fault in the back to back DC project, in which, IDL-|IVY1| is greater than constant value 4 and |IVY1| is less than constant 5(5), IDL-|IVD1| is greater than constant 4 and the |IVD1| is less than constant 5 (6), IDL+IDGND-|IVY2| is greater than constant 4 and |IVY2| is less than constant 5 (7), IDL+IDGND-|IVD2| is greatr than constant 4 and |IVD2| is less than constant 5 (8), after the condition of 5,6,7 or 8 and the time delay are met, the protection operation is done and the satisfaction of the time delay means that adding time delay action directly on conditions (5)-(8), selection of forward current direction: IDL is the direction of ordinary work of current and IDGND is the direction flowing to the earth point.

Description

1. Technical field [0001] The invention relates to a method for judging that a high-voltage pole line is short-circuited to a low-voltage pole line in a back-to-back DC project, and a related relay protection device. 2. Background technology [0002] HVDC back-to-back transmission system is more and more widely used because of its good and stable connection characteristics of large AC power grid. The core of HVDC back-to-back transmission system is HVDC back-to-back transmission control and protection system, which includes control system and protection system. [0003] There are many kinds of high voltage pole line short circuit faults. Among them, the short-circuit fault between the high-voltage pole line and the low-voltage pole line will not generate grounding point current. [0004] Existing identification of pole-to-ground faults in back-to-back DC systems ( figure 1 In the F2 fault) method, the main protection uses the grounding point current criterion (IDGND). Ho...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H3/08H02H3/087H02H3/093
Inventor 王俊生李海英卢宇
Owner NR ELECTRIC CO LTD