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Intelligent neutral point harmonic elimination apparatus

A neutral point and harmonic elimination technology, applied in the field of power grid harmonic elimination, can solve problems such as poor product protection effect, and achieve the effect of eliminating malfunction and suppressing resonance overvoltage

Inactive Publication Date: 2009-11-25
曲娜
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to invent a method to reliably eliminate resonance overvoltage for the problems of existing harmonic and arc elimination methods and poor product protection effects

Method used

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  • Intelligent neutral point harmonic elimination apparatus

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Experimental program
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Effect test

Embodiment 1

[0012] Referring to the accompanying drawings, at first the system resonance detector 2 analyzes the voltage signal collected by the voltage collector 4, when 1 / 3 harmonic, 1 / 2 harmonic, fundamental wave, second harmonic, third harmonic appear in the system, When the fifth harmonic overvoltage occurs, the system resonance detector 2 sends out a signal, triggers the triac 1 to turn on, connects the damping resistor 3, stops after 10 milliseconds, and the system resonance detector 2 triggers the thyristor 1 to turn off broken. If there is still a resonant overvoltage condition, trigger the thyristor 1 to turn on again after 15 milliseconds. until the resonance disappears.

Embodiment 2

[0014] Referring to the accompanying drawings, at first the system resonance detector 2 analyzes the voltage signal collected by the voltage collector 4, when 1 / 3 harmonic, 1 / 2 harmonic, fundamental wave, second harmonic, third harmonic appear in the system, When the fifth harmonic overvoltage occurs, the system resonance detector 2 sends out a signal, triggers the triac 1 to conduct, connects the damping resistor 3, and measures the current flowing through the damping resistor 3 at the same time, if the current at the neutral point exceeds The overcurrent setting value of the neutral point of the system (this value is set by the user referring to the relay protection quick determination value of the outgoing line of the system), the system resonance detector 2 triggers the thyristor 1 to shut down, if there is no neutral point overcurrent situation, until the resonance overvoltage disappears, the system resonance detector 2 triggers the thyristor 1 to turn off, and the damping...

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Abstract

The invention belongs to the technical field of power system, relating to a system resonance detector for monitoring resonant overvoltage in power system and a switched damping resistor mounted in the neutral point of the system. The technical proposal is that: an intelligent harmonic elimination apparatus is composed of a system resonance detector and a switched damping resistor mounted in the neutral point; the switched damping resistor is disposed between the neutral point and the earth by connecting with the fast thyristor switch in series; the value range of the damping resistance is between 1 to 1500 ohm; the dimension of the resistance value is selected according to the severity degree of the resonant overvoltage in specific power transmission and distribution system; if the resonant degree is more serious, the resistance is less. The system resonance detector can monitor resonant overvoltage caused by 1 / 3 harmonic, 1 / 2 harmonics, fundamental wave, second harmonic, triple-frequency harmonic and quintuple harmonic; simultaneously, according to the features that the line voltage is unbalanced when the fundamental wave is resonant, the invention exactly differentiates the fundamental wave resonant overvoltage or system single-phase grounding. When the system is normal, the fast thyristor switch is cut off; when the system resonant overvoltage is detected, the thyristor switch is closed; the neutral point is earthed through the damping resistor, thereby eliminating resonant overvoltage. Various damages caused by resonant overvoltage are prevented.

Description

technical field [0001] The invention relates to the field of power grid harmonic elimination, and is suitable for neutral point non-effectively grounded power grids of electric power systems, in particular a method for neutral point non-effectively grounded power grids. Background technique [0002] In the power system, resonant overvoltage occurs frequently in normal operation, which is very harmful. Once the overvoltage occurs, it often causes damage to electrical equipment and large-scale power outages. Many operating experiences show that most of the overvoltage accidents in medium and low voltage power grids are It is caused by resonance phenomenon. Due to the long time of resonance overvoltage action, it is difficult to choose protection. At present, most of my country's 35KV and below power grids still operate with neutral point ungrounded. Operation experience shows that the neutral point ungrounded system has more ferromagnetic resonance overvoltage caused by the sat...

Claims

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Application Information

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IPC IPC(8): H02H9/08
Inventor 曲娜
Owner 曲娜
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