Frequency sweeping test method for measuring power frequency ground resistance of grounding device and test instrument for frequency sweeping test method

Abstract

The invention provides a frequency sweeping test method for measuring the power frequency ground resistance of a grounding device and a test instrument for the frequency sweeping test method, which are used for solving the problems that in the conventional measurement, wires are inconveniently laid, measurement is interfered and the like. The measuring method comprises the following steps of: arranging a voltage electrode, a current electrode and a lead according to a preset ground resistance test way; selecting a frequency with a small interference signal as a test frequency; measuring ground impedance at the selected test frequency; and computing the power frequency ground resistance according to the measured ground impedance. The adopted test instrument comprises a variable-frequency alternating current power supply, a current sensor, a voltage divider, an isolating transformer, a signal acquisition device, an analog/digital (A/D) convertor and a portable personal computer (PC). The frequency sweeping test method for measuring the power frequency ground resistance of the grounding device and the test instrument for the frequency sweeping test method can effectively avoid each interference frequency and acquire a reliable test result.

Description

technical field [0001] The invention relates to the field of high voltage technology, in particular to a frequency sweep test method and a tester for measuring the power frequency ground resistance of a ground device. Background technique [0002] The power frequency grounding resistance value is an important technical index of the grounding system of the power generation substation. It is an important parameter to confirm the effectiveness and safety of the grounding system and to identify whether the grounding system meets the design requirements. The measurement of the power frequency grounding resistance of the grounding grid is the only means to check the acceptance and operation of the grounding grid, and it has become an important task to ensure the safe operation of the power system. At present, the relevant technical regulations stipulate that the power frequency grounding resistance needs to be tested regularly. [0003] For the regular test of the power frequency...

AI Technical Summary

Problems solved by technology

This test method causes many problems due to the use of large currents: 1. The equipment is very heavy; 2. The current leads are very thick, and the workload of setting out the wires is heavy; 3. It is not safe, and a large number of people need to be sent to prevent electric shock accidents along the line; 4. Forward The current is applied once in the opposite direction, and the equipment is complicated; 5. The reading of the meter jumps, which is difficult to read accurately

[0006] However, there are still some problems in the different frequency method or the frequency conversion method, especially in the case of more and more abundant disturbance frequencies and wider disturbance frequency bands in the background environment, such as the presence of new high-power reactive power compensation devices, near electrified railways, etc. , not only the power frequency interference is very strong, but also the interference around the power frequency is very strong

At this time, if the different frequency method or the frequency conversion method is used, since the frequency of the output current is fixed, although this frequency has escaped the power frequency interference, it just falls under another interference frequency, and due to the usual frequency difference method Or the output current of the frequency conversion method is small, which may not be able to eliminate the influence of interference, resulting in large errors in the measurement results

[0007] In short, although the different frequency method or frequency conversion method and its instruments of power frequency grounding resistance test at present have the advantages of simple test, light equipment, small test workload and relatively safe advantages, there are still problems in the measurement results due to background interference. The problem of large error needs further improvement

Images