DC system insulation monitoring method based on fixed-frequency switching resistor principle

A switching resistance, DC system technology, applied in the field of measurement, can solve problems such as inability to meet real-time accurate monitoring, current measurement error, etc., achieve accurate monitoring and fault branch location, avoid the impact of measurement accuracy, and has strong applicability. Effect

Inactive Publication Date: 2017-05-31
NORTHEAST DIANLI UNIVERSITY
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

However, at this stage, the DC small current sensor can only be accurate to the milliampere level, and there is a large error in the current measurement of the microampere level, which cannot meet the needs of real-time accurate monitoring

Method used

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  • DC system insulation monitoring method based on fixed-frequency switching resistor principle
  • DC system insulation monitoring method based on fixed-frequency switching resistor principle
  • DC system insulation monitoring method based on fixed-frequency switching resistor principle

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Embodiment Construction

[0033] The DC system insulation monitoring method based on the principle of constant-frequency switching resistance of the present invention will be further described below using the drawings and embodiments.

[0034] refer to figure 1 , the DC system is composed of positive and negative 110V busbars. Since the earth is a good conductor, there is a distributed capacitance C on the positive and negative busbars to the ground. + 、C - . There are also resistances to ground on the busbars R + , R - , which are respectively connected to the ground in parallel with the corresponding distributed capacitors. The load of the DC system is directly mounted to the bus by two branch wires, and a transformer for measuring the branch current is installed at the branch port. If a ground short circuit fault occurs in the branch, a grounding resistance that can be measured R X Parallel branch distributed capacitance C X grounded.

[0035] The DC system insulation detection is divided in...

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Abstract

The invention relates to a DC system insulation monitoring method based on a fixed-frequency switching resistor principle. The method is characterized by comprising steps of low frequency switching resistor branch establishment, DC leakage current measurement carried out through utilizing an AC sensor, calculation based on a circuit equation, and error analysis on current voltage waveform formed through switching, specifically, a switching resistor is utilized to convert a current passing through a transformer into DC rectangular waves; the AC sensor is utilized to realize accurate detection on a branch ten-microamp-grade ground leakage current; a ground resistor and a distribution capacitor are measured through detection and calculation in real time; accurate DC system ground fault monitoring and fault branch positioning are realized, and influence of the distribution capacitor on measurement precision of the ground resistor can be directly avoided. The method has advantages of scientific and reasonable performance, easy realization, strong applicability, high monitoring accuracy and good effects.

Description

technical field [0001] The invention relates to the field of measurement technology, and is a DC system insulation monitoring method based on the principle of constant-frequency switching resistance, which is suitable for monitoring grounding faults of DC systems in power plants and substations to avoid large-scale power supply accidents. Background technique [0002] The most common faults in the DC system faults are the insulation drop of the DC system, direct grounding or indirect grounding, etc. In the process of power generation, transformation, transmission, etc. of the power system, the composition of the DC system and the load end are relatively complex, the probability of failure is high, and it is difficult to monitor it online. The process is more complicated. In the insulation drop fault, the most common is the unipolar grounding of the load branch, that is, the positive pole of the load branch. In recent years, power plants and substations have been shut down ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/12G01R27/20G01R27/26
CPCG01R31/12G01R27/205G01R27/2605
Inventor 周军刘毕杰李曙光张瑞兰张毅
Owner NORTHEAST DIANLI UNIVERSITY
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