Development Of Tower Impulse Ground Impedance Measurement System

With the development of power system, grounding problem in power system is more and more important. Measuring ground impedance accurately can reflect the performance of grounding device, and make sure power system running safely. There are a lot of damage by lightning on transmission line towers, but now ground impedance measurement only can measure industry frequency ground impedance, but rarely measure impulse ground impedance, so it is very necessary to research a new method of measuring tower impulse ground impedance. This paper has analyzed methods of measuring ground impedance, and has introduced fundamental principle of measuring ground impedance, and has compared the merits and faults of every measuring methods of ground impedance.With analyzing wave process when impulse current flow into ground and impulse characteristic of grounding device, this paper has presented a new method of measuring ground impedance by generating impulse current signal, and has established impulse current generator simulation model and impulse ground impedance measurement simulation model by using MATLAB software. Based on simulation, this paper has designed impulse current generator, which is operated easily and fit field project application. This paper has presented calculative method of ground impedance, and has deployed data acquisition device and programmed up computer ground impedance calculative software. Finally, impulse ground impedance measurement system is established.In the last part of this paper, we have an actual experience to transmission line towers with impulse ground impedance measurement system which has been developed. Based on analyzing characteristic of impulse ground impedance of transmission line towers, experimental results indicate that the impulse ground impedance value measured by this measurement system is true and valid, and this measurement system fit actual project measurement. In the end, this paper has a preliminary research on the relation between inductance,impulse ground impedance and corrosion of tower grounding device.