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Multi-terminal flexible DC grid longitudinal protection method and system based on current-limiting inductor voltage polarity

A current-limiting inductance and voltage polarity technology, which is applied in the direction of power transmission AC network, emergency protection circuit device, information technology support system, etc., can solve the difficulty of implementing additional protection methods, high sensitivity and reliability, and no easy implementation, etc. problem, to achieve the effect of shortening the protection time, simple principle and algorithm, and easy engineering implementation

Active Publication Date: 2019-10-29
SHANDONG UNIV +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This protection method has a fast protection speed, however, it needs wavelet transform to extract the specific frequency band of the voltage, which increases the difficulty of implementing the protection method
[0008] It can be seen that the existing protection methods for DC lines in DC power grids have their own advantages and disadvantages, and there is no method that is easy to implement, fast in action, high in sensitivity and reliability

Method used

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  • Multi-terminal flexible DC grid longitudinal protection method and system based on current-limiting inductor voltage polarity
  • Multi-terminal flexible DC grid longitudinal protection method and system based on current-limiting inductor voltage polarity
  • Multi-terminal flexible DC grid longitudinal protection method and system based on current-limiting inductor voltage polarity

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Embodiment 1

[0045] In some implementations, a method for longitudinal protection of DC lines in a multi-terminal flexible DC grid based on the voltage polarity of a current-limiting inductor is disclosed, such as Figure 13 shown, including the following steps:

[0046] (1) Let the two ends of the line be the M terminal and the N terminal respectively, and collect the voltage value v of the current-limiting inductor at both ends of the DC line in real time Li(i represents the positive pole p or negative pole n at one end of the DC line);

[0047] (2) Using the voltage gradient algorithm to v Li To process, and then detect whether there is a fault;

[0048] The fault detection criterion and calculation expression are shown in the following formula,

[0049] |▽v L (k)|>Δ 1 (1)

[0050]

[0051] In the formula, v L (k),▽v L (k) are the voltage value and voltage gradient value of the kth sampling point on the current-limiting inductor; Δ 1 is the starting threshold; k and j are s...

Embodiment 2

[0130] In some embodiments, a multi-terminal flexible direct current grid pilot protection system based on the voltage polarity of the current-limiting inductor is disclosed, including a server, the server includes a memory, a processor, and a memory stored on the memory and can run on the processor A computer program, the processor implements the multi-terminal flexible DC grid longitudinal protection method based on the voltage polarity of the current-limiting inductor described in Embodiment 1 when executing the program.

Embodiment 3

[0132]In some implementations, a computer-readable storage medium is disclosed, on which a computer program is stored. When the program is executed by a processor, the multi-terminal flexible DC grid based on the voltage polarity of the current-limiting inductor described in Embodiment 1 is implemented. Pilot protection method.

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Abstract

The invention discloses a multi-terminal flexible DC network longitudinal protection method and system based on current limiting inductor voltage polarity, which comprises the following steps: collecting voltage values of current limiting inductor at both ends of a DC line in real time; detecting voltage values of current limiting inductor at both ends of the DC line in real time; Voltage gradientalgorithm is used to deal with the voltage, and then to detect whether there is a fault; After the protection is started, the current-limiting inductor voltage in the sampling data window is integrated, and the current-limiting inductor voltage polarity is judged by comparing the integrated value S with the set threshold value. The current limiting inductor voltage polarity R at both ends of theline is compared, and if both polarities are positive, the fault is judged to be in-area fault, otherwise, the fault is judged to be out-of-area fault. The protection principle and algorithm of the invention are simple, and do not need mathematical tools such as fast Fourier transform, wavelet transform and the like for frequency division or traveling wave capture, and also do not need data synchronization at both ends of the line, and are easy to realize. The data window of the protection criterion is short, and no additional fault pole identification step is needed, so the protection criterion is fast.

Description

technical field [0001] The invention relates to the technical field of DC power grid line fault protection, in particular to a multi-terminal flexible DC power grid longitudinal protection method and system based on the voltage polarity of a current-limiting inductance. Background technique [0002] At present, the protection strategy of the DC line in the flexible HVDC project is based on the protection strategy of the traditional high-voltage DC line, and the traveling wave protection and the differential undervoltage protection are used as the main protection of the DC line. For the protection of the multi-terminal flexible DC grid, in addition to improving the existing methods, scholars have also proposed some effective fast protection methods based on single-ended quantities, such as using the boundary effect of the current-limiting inductance at the end of the DC line. Voltage change rate, current change rate, etc. to identify internal and external faults; use paramete...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26H02H7/28G01R31/08H02J3/36
CPCG01R31/086H02H7/263H02H7/265H02H7/268H02H7/28H02J3/36Y02E60/60Y04S10/52
Inventor 邹贵彬黄强魏秀燕张烁张洁孙辰军
Owner SHANDONG UNIV
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