Single-ended protection method for HVDC transmission line based on specific frequency voltage

A specific frequency, high-voltage direct current technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the problems of high sampling frequency and processing capacity, low signal energy, low reliability, etc., to achieve perfect protection theory and high operating speed Fast, selective effect

CN107919656BInactive Publication Date: 2020-11-06TIANJIN UNIV
5 Cites 0 Cited by

Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2020-11-06
Estimated Expiration
Not applicable · inactive patent

Smart Images

  • Figure 1
    Figure 1
  • Figure 2
    Figure 2
  • Figure 3
    Figure 3
Patent Text Reader

Abstract

The invention relates to a specific frequency voltage-based non-unit protection method for a high-voltage DC transmission line. Judgement of internal and external faults is achieved by using the magnitude of non-unit specific frequency voltage change of the high-voltage DC transmission line; and the method comprises the following steps of protecting and collecting a voltage signal of a rectifier side of a high-voltage DC transmission system in real time and extracting specific frequency voltage by using a discrete Fourier algorithm (DFT) of a sliding window, wherein a specific frequency is a parallel resonance frequency of DC filters at two ends of the DC line; calculating an average voltage value as shown in the specification within 3ms, judging whether the average voltage value meets a protection starting criterion or not, and if the average voltage value is greater than a protection starting threshold value, starting protection; calculating a specific frequency voltage change coefficient VC; setting a protection judgement threshold value VCset, comparing the voltage change coefficient with the protection judgement threshold value VCset, thereby achieving identification of the internal and external faults of the high-voltage DC transmission line.
Need to check novelty before this filing date? Find Prior Art

Description

technical field

[0001] The invention relates to the field of relay protection for super / ultra-high voltage direct current transmission in power systems, in particular to a method for single-ended protection of high voltage direct current transmission lines based on specific frequency voltages. Background technique

[0002] High voltage direct current (HVDC) transmission has been widely used in long-distance power transmission and power system interconnection due to its advantages of large transmission capacity, low loss, and flexible control. HVDC transmission lines often cross complex terrains and operate in extreme climate environments, and the probability of failure is high, which seriously threatens the safe and reliable operation of HVDC transmission systems.

[0003] Traditional HVDC transmission line protection mostly uses traveling wave protection as the main protection, undervoltage protection and current differential protection as backup protection. Traveling wave...

Examples

Embodiment Construction

[0042] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

[0043] A single-end quantity protection method for high-voltage direct current transmission lines based on specific frequency voltage, which mainly utilizes the single-end specific frequency voltage variation of high-voltage direct current transmission lines to realize the discrimination of internal and external faults. The specific steps are as follows:

[0044] (1) if figure 1 As shown, is a schematic diagram of a high-voltage direct current transmission system specifically applied in this embodiment. The protection on the rectifier side of HVDC transmission system collects the voltage signal of terminal M of the DC line in real time, and uses the discrete Fourier algorithm (DFT) of the sliding window to extract the voltage at a specific frequency of 850 Hz.

[0045] (2) Calculate the average voltage within 3ms according to the specific frequency 8...