Flexible DC distribution line protection method based on transient current similarity

A flexible DC power distribution and line protection technology, applied to emergency protection circuit devices, electrical components, etc., can solve the problems of traditional protection that cannot act quickly, and achieve good selectivity and fast action speed

Inactive Publication Date: 2018-10-02
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Abstract
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Problems solved by technology

[0007] Step 3. In view of the fact that the traditional protection cannot act quickly after the DC line fault of the power electronic converter system, com...

Method used

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  • Flexible DC distribution line protection method based on transient current similarity
  • Flexible DC distribution line protection method based on transient current similarity
  • Flexible DC distribution line protection method based on transient current similarity

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Embodiment Construction

[0029] The present invention proposes a method for protecting flexible DC power distribution lines based on transient current similarity; the present invention will be described in detail below in conjunction with the accompanying drawings.

[0030] figure 1 Shown is a flowchart of a method for protecting flexible DC distribution lines based on transient current similarity, including the following steps:

[0031] Step 1. According to the physical nature of the instantaneous current change of the DC line fault in the system, the analytical expression of the fault current after the DC line fault is derived for the flexible direct power distribution system containing the power electronic converter;

[0032] After a bipolar short-circuit fault occurs on the DC line, the fault current is mainly composed of the capacitor discharge current of the sub-module, and the instantaneous DC voltage U dc is the sum of the capacitor voltages input into the sub-modules of the bridge arm, and i...

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Abstract

The invention discloses a flexible DC distribution line protection method based on transient current similarity, and belongs to the DC distribution system protection technical field; the method aims at the flexible DC distribution system, and derives a mathematics expression of a fault current after a DC line fails according to current change physics nature and direction characteristics at the DCline failing moment in the system; aiming at the conditions that a conventional protection cannot fast move after the DC line fails, the invention proposes the protection determination method that uses a cosine similarity; the method is simple, reliable, fast in power swing, can accurately determine DC line zone internal and external faults, thus selecting the fault line; the method is applied toDC line fault determination in a multi-terminal flexible DC distribution system; the method is not affected by line length, communication non-synchronization and transit resistance factors, thus improving the whole system operation reliability, and providing good selectivity and adaptability; the method is easy for promotion and application.

Description

technical field [0001] The invention belongs to the technical field of DC power distribution system protection, in particular to a method for protecting flexible DC power distribution lines based on transient current similarity. Background technique [0002] The flexible DC power distribution system can not only efficiently accommodate distributed power sources and DC loads, but also has the advantages of flexible control, large power supply capacity, high power supply reliability, and good power quality. It has attracted widespread attention at home and abroad. However, the development of flexible DC power distribution systems still faces several key technical issues to be studied, among which protection technology, as the first line of defense to ensure the safe and stable operation of the system, has become one of the research hotspots. The difficulty lies in the relatively weak ability of power electronic devices to withstand transient impact currents. The protection mus...

Claims

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Application Information

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IPC IPC(8): H02H7/26
CPCH02H7/268
Inventor 贾科王聪博毕天姝宣振文朱瑞赵琪娟
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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