A method for distance measurement of arc-flash ground faults in power supply lines

A technology for power supply lines and ground faults, which is applied in the field of power systems, can solve problems such as measurement process interference, unsatisfactory results, and deviations in ranging results, and achieve the effects of simple calculation procedures, fast measurement speed, and easy realization

Active Publication Date: 2018-01-26
广西电网有限责任公司河池供电局 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are still some problems in this method in practical application: 1. Under the condition of AC voltage breakdown, the impedance of the fault point is seriously non-linear, which affects the measurement accuracy; 2. The user load has a great interference to the measurement process; 3. The fault The line and the normal line are connected together, and the structure is complex, which leads to a large deviation in the distance measurement results; 4. In most cases, the ground fault is an arc flashover fault, and the fault point cannot be represented by a simple linear resistance
When this technology is applied to multi-branch lines such as fault location in distribution network systems, the effect is not ideal
The traveling wave is greatly affected by the branch of the line during the transmission process, the signal is reflected and merged multiple times, and the distortion is serious, so it is difficult to detect the wave head of the traveling wave
In addition, the traveling wave ranging equipment is complex, and it is difficult to popularize it in the medium and low voltage power supply system

Method used

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  • A method for distance measurement of arc-flash ground faults in power supply lines
  • A method for distance measurement of arc-flash ground faults in power supply lines
  • A method for distance measurement of arc-flash ground faults in power supply lines

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Effect test

Embodiment 1

[0041] Such as figure 2 Shown is the first-order fault equivalent circuit diagram of the faulty line. In the figure, L is the equivalent inductance of the line between the current injection point and the fault breakdown point, which is proportional to the fault distance; R 0 is the line equivalent resistance between the current injection point and the fault breakdown point, which is proportional to the fault distance; R 1 is the ground transition resistance after fault breakdown.

[0042] Perform Laplace transform on the first-order fault equivalent circuit to obtain its transfer function, after discretization, obtain a discrete pulse transfer function, use the dynamic system identification method to obtain the parameters of the pulse transfer function, and obtain by solving the equation The transfer function parameters of the continuous system, and then calculate the equivalent inductance L in the equivalent circuit, and divide L by the inductance per unit length of the fa...

Embodiment 2

[0044] Such as image 3 Shown is the second-order fault equivalent circuit diagram of the faulty line. In the figure, L is the equivalent inductance of the line between the current injection point and the fault breakdown point, which is proportional to the fault distance; R 0 is the line equivalent resistance between the current injection point and the fault breakdown point, which is proportional to the fault distance; R 1 is the ground transition resistance after fault breakdown, C 1 It is the equivalent capacitance converted from the fault line to the fault point.

[0045] Perform Laplace transform on the second-order fault equivalent circuit to obtain its transfer function, after discretization, obtain a discrete pulse transfer function, use the dynamic system identification method to obtain the parameters of the pulse transfer function, and obtain by solving the equation The transfer function parameters of the continuous system, and then calculate the equivalent inducta...

Embodiment 3

[0047] Such as Figure 4 Shown is the third-order fault equivalent circuit diagram of the faulty line. In the figure, L is the equivalent inductance of the line between the current injection point and the fault breakdown point, which is proportional to the fault distance; R 0 is the line equivalent resistance between the current injection point and the fault breakdown point, which is proportional to the fault distance; R 1 is the ground transition resistance after fault breakdown, C 0 is the equivalent capacitance converted from the line capacitance to the current injection point, C 1 It is the equivalent capacitance converted from the line capacitance to the fault point. The line capacitance includes each branch line, the line between the fault point and the current injection point, and the line capacitance between the fault point and the end of the line.

[0048] Perform Laplace transform on the third-order fault equivalent circuit to obtain its transfer function, after ...

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Abstract

The invention belongs to the field of power systems, and in particular relates to a distance measuring method for an arc-light grounding fault of a power supply line. Most of the grounding faults of the power supply lines are arc grounding. After the faulty line is powered off, the DC current generator is used to charge the line to increase the voltage of the line to ground. When the fault breakdown voltage is reached, the fault point is broken down again. The high-resistance state quickly changes to a low-resistance state, the distributed capacitance of the line discharges through the breakdown point, and the voltage on the line drops sharply at the same time. The line is regarded as a dynamic system, the dynamic model of the line is established, and the dynamic system parameter identification method is used to identify the dynamic model parameters of the line according to the current and voltage sampling series on the line, and the fault distance is calculated according to the model parameters.

Description

technical field [0001] The invention belongs to the field of power systems, and in particular relates to a distance measuring method for an arc-light grounding fault of a power supply line. Background technique [0002] More than 80% of power supply line faults are ground faults. Ground faults are roughly divided into two types: resistance grounding and arcing grounding. In medium and high voltage power supply lines, the proportion of arc grounding is much higher than that of resistance grounding. [0003] Most of the existing ground fault location methods are online detection, that is, the fault location equipment is always hung on the power grid, and after the ground fault is detected, the location function of the equipment is started immediately to complete the fault location. During online fault location, the fault line has not been separated from the grid system. When the power grid structure is complex, such as many branches and users, the ranging results are often ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08
Inventor 刘隆华黄洪全黄启哲李民强卢绍成邓春明李步锦韦唯危秋珍
Owner 广西电网有限责任公司河池供电局
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