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MMC-HVDC system single-ended fault identification method based on HHT energy entropy

A MMC-HVDC, fault identification technology, applied in the fault location, detecting faults according to conductor type, measuring electricity and other directions, can solve the problem of inability to realize single-pole grounding fault and disconnection fault detection, slow current longitudinal differential protection action, Sampling rate requirements are high, and the effect is conducive to system protection

Active Publication Date: 2020-03-24
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Traveling wave protection and differential undervoltage protection require high equipment sampling rate and poor anti-interference ability; DC overcurrent protection cannot realize single-pole ground fault and disconnection fault detection; current longitudinal differential protection operates slowly and only serves as backup protection; Voltage unbalance protection and overvoltage protection are affected by capacitive voltage transformers, making it difficult to quickly detect DC line faults

Method used

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  • MMC-HVDC system single-ended fault identification method based on HHT energy entropy
  • MMC-HVDC system single-ended fault identification method based on HHT energy entropy
  • MMC-HVDC system single-ended fault identification method based on HHT energy entropy

Examples

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Embodiment 1

[0042] Example 1: The simulation model of a 320kV bipolar MMC-HVDC system grounded through the ground electrode lead wire is as follows figure 1 shown. The circuit parameters are as follows: the total length of the line is 400km, the capacity of the simulation system is 100MW, the bridge arms of the converter are connected in series with 76 sub-modules, and the sampling frequency is 6.4kHz. Fault location: The line is 200km away from the M terminal, and the transition resistance is 0Ω.

[0043] The specific implementation steps are as follows:

[0044] (1) Obtain the initial voltage signal and the IMF component obtained through EMD decomposition according to Step 1 in the manual. At this time, the correlation coefficient between the initial signal and IMF1 is the largest, so IMF1 is used as the sensitive IMF component for extracting fault characteristic information.

[0045] (2) According to Step2 and Step3 in the manual, the value of HHT energy entropy in each operating sta...

Embodiment 2

[0048] Example 2: The simulation model of a 320kV bipolar MMC-HVDC system grounded through the ground electrode lead wire is as follows figure 1 shown. The line parameters are as follows: the total length of the line is 400km, the capacity of the simulation system is 100MW, the bridge arms of the converter are connected in series with 76 sub-modules, and the sampling frequency is 6.4kHz. Fault location: The line is 100km away from the M terminal, and the transition resistance is 100Ω.

[0049] The specific implementation steps are as follows:

[0050] (1) Obtain the initial voltage signal and the IMF component obtained through EMD decomposition according to Step 1 in the manual. At this time, the correlation coefficient between the initial signal and IMF1 is the largest, so IMF1 is used as the sensitive IMF component for extracting fault feature information.

[0051] (2) According to Step2 and Step3 in the manual, the value of HHT energy entropy in each operating state can b...

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Abstract

The invention relates to an MMC-HVDC system single-ended fault identification method based on HHT energy entropy, and belongs to the technical field of power system relay protection. The method comprises the following steps: reading a voltage signal acquired by a measuring end high-speed acquisition device; secondly, carrying out empirical mode decomposition on the obtained voltage signal, decomposing 6 intrinsic mode function components, selecting an IMF1 component as a sensitive component for extracting fault feature information to perform HHT conversion, substituting a conversion result into an HHT energy entropy formula, using normalized HHT energy entropy to construct criteria to identify internal and external faults, and selecting a fault electrode on the basis. The method is based on a single-ended quantity, is not affected by communication, and is suitable for different transition resistances and fault distances.

Description

technical field [0001] The invention relates to a single-end fault identification method of an MMC-HVDC system based on HHT energy entropy, and belongs to the technical field of electric power system relay protection. Background technique [0002] Compared with the traditional two-level and three-level VSC-HVDC systems, the converter, DC transmission line and fault branch in the MMC-HVDC system area form a unique fault loop, because the modular multilevel converter ( MMC) DC side does not have a large capacitor in parallel, resulting in a significant reduction in the identifiable boundary characteristics of the flexible DC transmission system based on MMC, and its fault characteristics are significantly different from traditional VSC-HVDC, so it is necessary to protect the MMC-HVDC DC transmission system principle for further study. [0003] At present, the protection configuration of the flexible DC transmission system is mainly protected by traveling wave protection and d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08
CPCG01R31/085G01R31/088
Inventor 束洪春王广雪田鑫萃安娜琚夏阳
Owner KUNMING UNIV OF SCI & TECH