Simulation Experiment Study Onthe Impulse Characteristics Of Typical Grounding Device

Tripping of transmission lines caused by lightning is one of the most common power system faults. In order to guarantee the stable operation of the transmission line, reducing the impulse grounding resistance of the tower grounding device is an effective method for better lightning protection of transmission lines. Impulse grounding resistance of grounding device, whose features are more complex under the action of lightning current, is different from the power frequency grounding resistance. Hence we need to do more research on the impulse characteristics of grounding device.In this paper, simulation experiment method is used. Using the existing impulse current generator we designed a test circuit to measure the characteristics of the ground device and built the actual test device in accordance with the test circuit. The circuit is tested to meet the test requirements. We also designed an experiment method with the test circuit to do simulation experiments. Using the experiment method some experiments on the regularity of the impulse current dispersal and the characteristics of the approximate impulse grounding resistance are completed.When doing experiments on the regularity of the impulse current dispersal, the impulse current generated by impulse current generator is injected to several different typical grounding devices. Currents of some particular points are measured under different current amplitudes and different current injection points. The distribution of current on a variety of typical earth electrodes and the current diffused to the soil by each segment are analyzed with the data.When doing experiments on the impulse characteristics of the grounding electrodes, we inject the impulse current to various grounding electrodes and measure the impulse current waveform and the impulse of potential rise waveform under different current amplitudes and different current injection points. Due to limitations of the experimental conditions, approximate impulse grounding resistance is defined according to the concept of impulse grounding resistance. And the approximate impulse grounding resistance is calculated. The approximate impulse grounding resistance of various grounding electrodes are compared to each other and the variation of the approximate impulse grounding resistance is analyzed in combination with the regularity of the impulse current dispersal of different grounding electrodes.In this paper, simulation experiment method is used to study the impulse characteristics of the tower grounding device. Experiment methods and experiment results can actually provide some reference for engineering design.