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Grounding impedance measuring method

A technology of grounding impedance and measurement method, which is applied in the direction of grounding resistance measurement, measuring device, measuring electrical variables, etc. It can resist problems such as large calculation errors of components, and achieve the effect of improving measurement accuracy.

Inactive Publication Date: 2021-03-16
GUANGDONG POWER GRID CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above ground impedance measurement method has many disadvantages, mainly because the input current is a single sine wave signal, and the induced voltage signal generated by the ground impedance is also a single sine wave voltage signal
In the process of calculating the resistance component and inductive reactance component of ground impedance, the signal amplitude of the current pole, the voltage signal amplitude induced by the voltage pole, and the phase information between the voltage signal and the current signal are required. There are different types of interference, and it is very difficult to accurately measure and calculate the phase information between voltage and current. Since the ground impedance and inductance are calculated through mathematical formulas, they are obtained indirectly, so a small phase angle error can be obtained Causes large calculation errors in the resistance component and inductive reactance component of the grounding impedance

Method used

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] This embodiment proposes a ground impedance measurement method, the ground impedance measurement method can be configured in a ground impedance tester, and the ground impedance measurement task can be completed by the ground impedance tester. figure 1 It is the flow chart of the grounding impedance measurement method in the embodiment, refer to figure 1 , which includes:

[0042] S101. Generate a current fundamental wave, and generate a harmonic of the current fundamental wave.

[0043] Exemplarily, in this step, the fundamental current wave adopts a sine wave, the frequency of the fundamental current wave can be power frequency or different frequency, and the amplitude of the fundamental current wave depends on the type of the grounding device to be tested.

[0044] Exemplarily, in this step, the frequency of the current fundamental wave is preferably a power frequency.

[0045] Exemplarily, in this step, the number of harmonics is one or more, and the phase of the h...

Embodiment approach

[0086] Figure 4 It is another kind of ground impedance measuring method flow chart in the embodiment, refer to Figure 4 , as a possible implementation, the grounding impedance measurement method includes:

[0087] S201. Generate several different-frequency current fundamental waves, and generate harmonics of each current fundamental wave.

[0088] Exemplarily, in this step, the ground impedance measurement is performed through multiple different-frequency current fundamental waves, for example, the frequencies of the current fundamental waves may include: 45, 65, 95, 105, 115, and 125 Hz.

[0089] Exemplarily, in this step, the calculation of the harmonic is performed according to each current fundamental wave, and the phase of the harmonic is the same as that of the corresponding current fundamental wave.

[0090] Exemplarily, in this step, taking the fifth harmonic as an example, the amplitude of the harmonic can be obtained in the following manner:

[0091] The express...

Embodiment 3

[0120] Figure 5 It is another kind of ground impedance measuring method flow chart in the embodiment, refer to Figure 5 , as a possible implementation, the grounding impedance measurement method includes:

[0121] S301. Generate a current fundamental wave, and generate a harmonic of the current fundamental wave.

[0122] Exemplarily, in this step, the fundamental current wave is a sine wave, the frequency of the fundamental current wave is a power frequency, and the amplitude of the fundamental current wave is determined according to the type of grounding impedance to be measured.

[0123] Exemplarily, in this step, the number of harmonics is one or more, and the phase of the harmonics is the same as that of the current fundamental wave.

[0124] Exemplarily, in this step, taking the 11th harmonic as an example, the amplitude of the harmonic can be obtained in the following manner:

[0125] The expression after the superposition of current fundamental wave and harmonic is: ...

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Abstract

The invention discloses a grounding impedance measurement method, which comprises the steps: generating a current fundamental wave, generating a harmonic wave of the current fundamental wave, superposing the harmonic wave and the current fundamental wave to generate an impedance measurement injection current, injecting the impedance measurement injection current into a grounding device to be measured, and measuring a first induction voltage of the grounding device, and calculating a grounding resistance value according to the first induction voltage and the impedance measurement injection current, injecting the current fundamental wave into the grounding device to be measured, measuring the impedance of the grounding device to be measured through the current fundamental wave, and calculating the grounding impedance according to the grounding resistance value and the impedance. When the grounding impedance measurement method provided by the invention is used for operation, the phase angle measurement links of injection current and detection voltage in the traditional measurement method can be omitted, and the measurement precision of the grounding impedance can be greatly improved.

Description

technical field [0001] Embodiments of the present invention relate to power grid testing technology, in particular to a grounding impedance measurement method. Background technique [0002] The substation grounding system provides a common reference ground for various electrical equipment in the substation. When the power system fails, the fault current can be quickly discharged into the reference ground to control the maximum potential of the grounding grid and ensure the safety of people and equipment. With the continuous increase of power system capacity, the current flowing into the ground grid will increase accordingly. In order to ensure that the potential of the ground grid does not exceed a specific allowable value, the area of ​​the ground grid may be large, and the maximum diagonal of the ground grid The length can reach thousands of meters. The long-distance and large-span grounding grid impedance on-site measurement work will be affected by many factors, and the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R27/02G01R27/20G01R27/08G01R25/00
CPCG01R27/02G01R27/20G01R27/08G01R25/00
Inventor 张云温慧玲董玉玺肖云黄晓波唐松平李冲胡晓晖
Owner GUANGDONG POWER GRID CO LTD