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Direct-current distribution network rapid direction protection method based on current/voltage high-frequency traveling-wave ratio

A directional protection, high-frequency technology, applied in the direction of emergency protection circuit devices, electrical components, circuit devices, etc., can solve problems such as irrationality, dependence on line terminal boundaries, current differential protection that cannot reliably distinguish internal faults from external faults, etc. , to reduce the difficulty of

Active Publication Date: 2021-11-26
TIANJIN UNIV
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Problems solved by technology

This means that traditional current differential protection cannot reliably distinguish between internal and external faults
Similarly, the operational reliability of directional protection based on Δi or di / dt is also severely affected by distributed capacitive currents due to the oscillatory nature
To sum up, for MVDC power distribution system, when designing DC protection, it is unreasonable to ignore the influence of distributed capacitive current and line wave impedance difference, and to rely on line terminal boundaries

Method used

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  • Direct-current distribution network rapid direction protection method based on current/voltage high-frequency traveling-wave ratio
  • Direct-current distribution network rapid direction protection method based on current/voltage high-frequency traveling-wave ratio
  • Direct-current distribution network rapid direction protection method based on current/voltage high-frequency traveling-wave ratio

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Embodiment Construction

[0022] Below in conjunction with the accompanying drawings, the framework structure, functions and effects of the present invention are described in detail as follows.

[0023] Such as figure 1 Shown is a schematic diagram of a three-terminal DC system. Such as figure 2 shown, to protect the installation position P 1 The traveling wave grid diagram of the forward fault. Such as image 3 shown, to protect the installation position P 1 Schematic diagram of the reflection and refraction characteristics of the forward fault traveling wave in the multi-terminal DC system; (a) the number of DC feeders is 2, (b) the number of DC feeders is n.

[0024] Considering the impact of line geometric parameters on wave impedance difference on protection, when a fault occurs in the DC system, the protection installation position P 1 ,P 2 A fault traveling wave is generated instantaneously and propagates along the cable. The size of a traveling wave changes during propagation and durin...

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Abstract

The invention discloses a direct current distribution network rapid direction protection method based on a current / voltage high-frequency traveling wave ratio, and the method comprises the steps of carrying out high-pass filtering on the measured voltage and current signals after protection is started, and obtaining a high-frequency component; according to the ratio of the |uSb_hf| to the |uSc_hf|, judging whether a direct current fault exists, and if max|uSb_hf| / max|uSc_hf| is greater than kset1, determining that a direct current cable fault exists; and 4, after the DC fault is determined, further distinguishing a fault cable and a non-fault cable for the condition that one DC bus is connected with a plurality of DC cables. Compared with the prior art, the method is based on an accurate line model, considers the influences of the line geometric parameters on protection, avoids the threats of larger line wave impedance differences on protection reliability, and is suitable for a direct current power distribution system, especially an MVDC power distribution system.

Description

technical field [0001] The invention relates to the field of relay protection for DC power distribution systems, in particular to a fast direction longitudinal protection method for DC power distribution networks based on the current / voltage high-frequency reverse traveling wave amplitude ratio. Background technique [0002] DC line protection is one of the key technologies in the development of DC systems, among which fast and reliable judgment of the fault direction is an indispensable key link for the rapid protection of DC lines. [0003] The existing DC distribution level longitudinal protection part considers the influence of line distribution parameters and frequency variable parameters on protection, but does not consider the influence of parameter differences of different lines on protection. In different types of transmission conductors (conductors and overhead lines), different Geometric parameters (cable inner diameter, insulation type, thickness, buried depth, a...

Claims

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Application Information

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IPC IPC(8): G01R31/08H02H7/26H02H1/00
CPCG01R31/08H02H7/268H02H7/265H02H7/261H02H7/263H02H1/0007Y02E60/60
Inventor 吕慧婕何佳伟李斌
Owner TIANJIN UNIV
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