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A DC circuit breaker failure protection method

A DC circuit breaker, failure protection technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the problems of long time, line current rise, lack of versatility, etc., achieve short action time, improve reliability, and protect time short window effect

Active Publication Date: 2019-10-18
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the method based on current detection takes a long time, and the length of the protection time window needs to be greater than the time for the line current to decay below the threshold
If the circuit breaker is not successfully disconnected, the line current can easily rise to a serious level within the protection time window, and even cause the blockage of the converter station in the non-fault area, reducing the reliability of the DC system
The failure protection scheme based on the internal information measurement of the circuit breaker, although the detection speed is relatively high, but this method depends on the design of the circuit breaker and the amount of internal information, and is not universal.

Method used

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  • A DC circuit breaker failure protection method
  • A DC circuit breaker failure protection method
  • A DC circuit breaker failure protection method

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Embodiment 1

[0026] A DC circuit breaker failure protection method, the flow chart of this method is as follows figure 1 Shown. In this embodiment, PSCAD / EMTDC simulation software is used to construct a DC network model, such as figure 2 As shown, the DC network is mainly composed of four converter stations, DC lines and DC circuit breakers. All converter stations adopt half-bridge type sub-module converters, using pseudo-bipolar wiring, and the rated DC voltage is ± 320kV. The DC line adopts the overhead line dependent frequency model. The inherent breaking time of the DC circuit breaker is 2ms. The schematic diagram of the voltage measurement point of the circuit breaker failure protection is as follows: image 3 As shown, the protection sampling frequency is 10kHz.

[0027] DC circuit breaker failure protection includes the following steps:

[0028] 1) DC line protection action, sending out the DC circuit breaker trip signal, and at the same time starting the circuit breaker failure pro...

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Abstract

The invention discloses a failure protection method for a DC circuit breaker. The method comprises the following steps of carrying out DC line protection action, sending out a DC circuit breaker tripping signal and simultaneously starting circuit breaker failure protection; delaying deltaT1, collecting DC bus voltage Ub and line side voltage U1 and calculating a mean value Ek of difference valuesbetween the DC bus voltage Ub and the line side voltage U1 within deltaT2; judging whether the condition that Ek is greater than Eset is met or not; if so, judging that the circuit breaker is successfully disconnected and returning protection; and if not, judging that the circuit breaker is not successfully disconnected, carrying out circuit breaker failure protection action, sending out a tripping signal to the other circuit breakers connected with a bus and sending out a blocking signal to a local converter. According to the method disclosed by the invention, whether the circuit breaker successfully acts or not can be reliably distinguished only through the bus voltage and the line side voltage of the DC circuit breaker without adopting internal information of the DC circuit breaker.

Description

Technical field [0001] The invention relates to the technical field of DC transmission relay protection, in particular to a DC circuit breaker failure protection method, which is suitable for DC circuit breaker failure protection of a DC power grid using a DC circuit breaker. Background technique [0002] New energy power generation such as wind and solar energy has the characteristics of intermittent and randomness, and its large-scale grid connection will have an impact on the traditional power network, reducing the economy and reliability of the power grid. Multi-terminal DC transmission systems and DC grids based on flexible DC transmission technology can effectively solve this problem. At the same time, with the advancement of hybrid circuit breaker technology and the increase in the reliability requirements of the DC system, the DC grid solution with DC circuit breakers on both sides of the line has become the preferred solution. In this type of DC network, it is no longer...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
Inventor 李海锋谢秋霞张坤王钢
Owner SOUTH CHINA UNIV OF TECH
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