Portable Lightning Current Generating Device and Method for Impulse Impedance Test of Grounding Device

Abstract

The invention discloses a portable lightning current generating device and method for testing the impact impedance of a grounding device, comprising a generator and a lightning current generator main circuit test box; The output terminal of the step-up transformer T2; the energy storage capacitor C is connected in parallel with the DC voltage divider; one end of the discharge switch S is connected to the positive pole of the energy storage capacitor C, and the other end is connected to one end of the adjustable wave-modulating resistor R2, and the adjustable wave-modulating resistor The other end of R2 is connected to one end of the adjustable wave-modulating inductance L, and the other end of the adjustable wave-modulating inductance L is connected to the grounding grid to be tested through the grounding test current injection point; the grounding grid to be tested is surrounded by grounding test return poles and reference The voltage pole; the grounding test return pole is connected to the negative pole of the energy storage capacitor C of the main circuit of the lightning current generator. The device can truly simulate the inductance effect and the soil spark discharge effect, and truly test the impact grounding resistance.

Description

【Technical field】 [0001] The invention belongs to the technical field of power system grounding, and particularly relates to a portable lightning current generating device and method used for impact impedance testing of a grounding device. 【Background technique】 [0002] The power system has various grounding requirements such as work, lightning protection, and safety. They are an indispensable part of ensuring the safe and stable operation of the power system. With the realization of the national networking strategy of west-to-east power transmission and north-south mutual supply, my country's power industry will maintain rapid growth in the next 15 to 20 years, requiring the construction of a large number of 330kV, 500kV, 750kV and 1000kV ultra-high voltage substations and towers At the same time, in order to ensure the safety of staff and electrical equipment during the operation of the power grid, it is necessary to build a large number of grounding facilities for these s...

AI Technical Summary

Problems solved by technology

In the current research work at home and abroad, many scholars often design and calculate lightning protection based on the experience of power frequency grounding. However, compared with power frequency current, lightning current has its unique properties. The most important ones are The following two points: First, the frequency of the lightning current is very high, which makes the impact of the inductance effect of the grounding system under the impact current much greater than that under the power frequency. Therefore, the inductance of the grounding system under the impact current The effect must be considered, while the inductive effect of the grounding system is often ignored under the power frequency current

Second, the magnitude of the lightning current is quite high. When the lightning current spreads in the ground, the field strength of the current field is high enough to ionize the soil around the grounding electrode, resulting in a spark discharge effect, thereby changing the surrounding soil. If the electrical characteristics are not considered, it will be seriously out of reality. However, under power frequency, it is difficult to generate such a high electric field strength

However, there are obvious differences between the impact characteristics and power frequency characteristics of the tower. The impact grounding resistance of the grounding device under the action of lightning current and the grounding resistance under the action of power frequency current have different values. The frequency grounding resistance is small, but the tower still suffers from counterattack

The existing technology uses a specific value of concentrated parameter resistance to simulate the grounding device for lightning protection analysis of transmission lines, which cannot truly simulate the effect of inductance and soil spark discharge, and the error is extremely large

Images