Single-phase grounding selection for small-current system

A technology of single-phase grounding and line selection method, which is applied in the fault location and other directions, can solve the problem of low line selection accuracy, and achieve the effect of improving line selection accuracy, eliminating the influence of capacitive current, and implementing simple implementation.

Inactive Publication Date: 2005-02-23
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Through the practical application of the above methods, each has its own advantages, but there is a disadvantage of low line selection accuracy

Method used

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  • Single-phase grounding selection for small-current system
  • Single-phase grounding selection for small-current system
  • Single-phase grounding selection for small-current system

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Embodiment Construction

[0014] exist figure 1 In the schematic diagram of the working principle shown, the zero-sequence winding voltage of the line voltage transformer PT 4 is preprocessed by the zero-sequence winding voltage or the zero-sequence voltage preprocessing unit 17, and then converted by the A / D converter 27 and then sent to the DSP or microcontroller 28. Determine whether grounding occurs. When a grounding occurs, the DSP or microcontroller 28 issues a command to start the specific current signal generator 2 and close the switch 3. The specific current signal is injected into the PT along the L point, the PT zero-sequence winding and the N point, and the magnitude and The currents 7A, 7B and 7C in the same direction are respectively I SA , I SB and I SC , the current is injected into each branch circuit through the bus A phase 11A, B phase 11B and C phase 11C, and flows back to the ground in the form of ground point G or leakage current, forming a loop with the ground 8 of the PT prim...

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Abstract

A method for selecting out single phase earthing in small current system includes injecting a current signal with specific frequency intermittently to three phase circuit; carrying out voltage preprocessing, synchronous sampling and digital filtering to detect the current signal comparing resistive current size of the current signal in each subcircuit and confirming that subcircuit with the largerst resistive current is earthing subcircuit.

Description

(1) Technical field [0001] The invention relates to a single-phase grounding line selection method for a small current system, which is suitable for the single-phase grounding line selection and positioning of 6KV, 10KV and 35KV systems of power system substations. (2) Background technology [0002] At present, the single-phase grounding line selection methods of small current systems can be technically divided into fundamental wave method, harmonic method, transient signal method and injection method. Both the fundamental wave method and the harmonic method use the characteristic that the zero-sequence current of the grounding branch is equal to the sum of the zero-sequence currents of all other branches, and select lines by comparing the amplitude and phase, but the fundamental wave method is only suitable for ungrounded systems . The transient signal method is to select the line by capturing the transient signal when grounding. "S injection method" is a representative i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08
Inventor 王广柱
Owner SHANDONG UNIV
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