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MMC-based pseudo-random code fault location method and system

A technology of fault distance measurement and pseudo-random code, which is applied in the direction of fault location, fault detection according to conductor type, fault detection by pulse reflection method, etc., to achieve the effect of eliminating power and pulse width, large time-bandwidth product, and excellent autocorrelation characteristics

Active Publication Date: 2021-10-01
CHINA UNIV OF MINING & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Since the common noise signal is a typical random signal, it is unavoidable in signal processing. At present, there is no method to completely remove the noise, but to minimize the influence of the noise, and the pseudo-random signal has a noise-like Excellent characteristics, it obtains the distance information of the target by calculating the cross-correlation between the transmitted signal and the received signal. The noise signal cannot be cross-correlated with the transmitted signal. Even if the reflected signal contains a noise signal, the noise signal cannot be corrected. At the same time, the pseudo-random signal also has excellent characteristics such as excellent autocorrelation characteristics, large time-bandwidth product, easy generation and replication, etc., so it has been widely used in ground penetrating radar, ultrasonic ranging and other fields

Method used

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  • MMC-based pseudo-random code fault location method and system
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Embodiment 1

[0049] figure 2 It is a schematic diagram of the topology structure of the modular multilevel converter (MMC), including the positive pole P and the negative pole N of the DC bus. There are upper and lower bridge arms between the DC buses. The arm is connected to the negative pole N of the busbar, the junction of the upper and lower bridge arms is node a, and the node a is connected to the upper and lower bridge arms respectively through inductance; point O is the equivalent neutral point, u vais the output voltage on the AC side of phase A. Both the upper and lower bridge arms are equipped with a number of series-connected half-bridge sub-modules (Half Bridge SM, HBSM). The sub-modules include two series-connected IGBTs (T1, T2), and T1 and T2 are respectively equipped with anti-parallel diodes D1, D2, T1, T2 are connected in parallel with capacitor C after being connected in series. The first output terminal of the sub-module is located on the line connecting the emitter ...

Embodiment 2

[0083] Such as figure 1 As shown, a pseudo-random code fault ranging system based on MMC includes a pseudo-random sequence generation module, a modulation control module, a delay time calculation module, and a ranging module;

[0084] The pseudo-random sequence generation module generates m-sequence signals; the modulation control module receives the m-sequence signals and controls the MMC DC side voltage to follow the m-sequence signals to switch between two levels; the delay time calculation module receives the MMC DC side voltage signals and reflected wave signals And calculate the delay time between the MMC DC side voltage signal and the reflected wave signal; the ranging module receives the delay time signal and calculates the distance between the fault point and the MMC terminal.

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Abstract

The invention discloses an MMC-based pseudo-random code fault location method and system. The method comprises the following steps that: m sequence signals formed by 0 and 1 are generated; MMC modulation control is carried out through the m sequence signals, the code elements 0 and 1 are corresponding to the different quantities of switched-in MMC phase unit sub-modules respectively, so that MMC direct-current side voltage is controlled to be switched between two levels along with the m sequence signals; the MMC direct-current side voltage is propagated along a direct-current line, when the MMC direct-current side voltage encounters a fault point,refraction and reflection of traveling waves occur, generated reflected waves return to an MMC end, and delay time of the MMC direct-current side voltage signals and reflected wave signals is calculated through a cross-correlation function; and the distance between the fault point and the MMC end is calculated according to the delay time. With the method adopted, the contradiction between the power of transmitted signals and pulse width when a pulse reflection method is used for fault detection and positioning is eliminated, and the fault positioning precision is improved.

Description

technical field [0001] The invention relates to the technical field of line fault distance measurement, in particular to an MMC-based pseudo-random code fault distance measurement method and system. Background technique [0002] Modular multilevel converter (MMC) is a new type of converter topology developed by scholars R.Marquart and A.Lesnicar. It has the advantages of modularity, redundancy, easy expansion, and controllability. Realizing large-scale production and integrated design, while having the advantages of low harmonic content and low loss, it has received extensive attention since it was proposed. The emergence of modular multilevel converters not only improves the operation performance and scalability of the transmission system, but also lays the foundation for the future development of multi-terminal and networked DC transmission technology. [0003] There are many fault location methods for DC transmission lines, and the pulse reflection method is one of the m...

Claims

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Application Information

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IPC IPC(8): G01R31/08G01R31/11
CPCG01R31/085G01R31/11
Inventor 王颖杰刘海媛侯贺港毕琪文余储胜王亚娟
Owner CHINA UNIV OF MINING & TECH
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