Small current lightning impulse grounding impedance test method and device

Abstract

The invention discloses a small-current lightning impulse grounding impedance testing method and device. The device comprises an impulse signal generation unit, an impulse signal sampling unit, a signal processing unit and a power supply unit. The testing method comprises the steps that a small-current impulse signal is generated through the impulse signal generation unit, injected into a grounding device and flows into the ground through the grounding device in a scattered mode; the impulse signal sampling unit collects an impulse current and impulse voltage passing through the grounding device; then, the impulse current and impulse voltage are compared through the signal processing unit, and an impulse current peak Im and an impulse voltage peak Um are obtained; finally, operation is performed on Im and Um in combination with the engineering definition of impulse grounding impedance, and then an impulse grounding resistance value is obtained. The device can output various impulse current signals with the amplitude capable of reaching the Ampere level so that impulse characteristics of the grounding device under the action of different types of lightning can be effectively simulated and analyzed. Besides, the device has the advantages of being small in size, portable in structure, high in safety and good in practicability, thereby being high in applicability.

Description

technical field [0001] The invention belongs to the field of grounding device state detection and evaluation, and relates to a grounding device impact grounding impedance test method and its device, more specifically, a grounding device impact grounding impedance simulation test method and device based on a small-amplitude impact current . Background technique [0002] The impact grounding impedance refers to the impedance value between the grounding device and the remote zero potential point when the lightning current flows into the ground through the grounding device. It reflects the overall discharge ability of the grounding device of the power system to the lightning current. An important indicator of lightning protection performance. At present, the test methods for the impact grounding impedance of grounding devices in related industries at home and abroad mainly include: [0003] 1. On the basis of theoretical analysis, establish a mathematical and physical model fo...

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Problems solved by technology

The disadvantage of this method is that it is difficult to establish a mathematical and physical model, and the solution is complicated and cumbersome, and different grounding devices correspond to different mathematical and physical models, which has poor versatility and the results cannot be verified;

[0004] 2. Build an equivalent grounding device in proportion in the laboratory, and then test the impact grounding impedance of the grounding device by simulating the action of lightning. This method is generally only suitable for the simulation experiment of a centralized grounding body with a relatively simple structure, and The experimental current requirements are relatively large, and the required test equipment is huge, which is not convenient for on-site actual measurement and use, and has poor practicability;

In fact, since the power frequency grounding resistance and the impact grounding impedance are the grounding characteristics of the grounding device under different characteristic currents, they are deeply affected by multiple factors such as the current dispersion characteristics, the structure of the grounding device, and the soil condition. The relationship between them is complex and changeable. Using the impact coefficient conversion method to test the impact grounding resistance is too one-sided, and its effectiveness needs to be further studied.

[0006] 4. Estimate according to the empirical formula. Although the calculation is simple and convenient, its disadvantages are relatively obvious. This method has low accuracy and is only suitable for estimation

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