Grounding Impedance Measurement Equipment for Lightning Protection System Maintenance

Currently, impedance measurement equipment is usually implemented with monolithic frequency small signal sinusoidal excitation method. In special geographical conditions where deep grounding structure is not possible, grounding rods with complex impedance characteristics are usually deployed. To precisely measure such impedance, high current excitation and full digital control have to be implemented. This paper proposed a new type of intelligent ground impedance measurement system with high current output capacity and wireless data transmission function. A bidirectional DC/DC converter is chosen as the power stage for current excitation. Firstly, the converter was modeled and simulated in close loop. Since a single excitation current could not ensure the accurate measurement of ground impedance, a stepped pattern of current excitation is introduced. The current level can be adaptively switched based on the obtained resistance value and state-of-charge of the batteries. The system also realizes the functions of data visualization and data transmission. The experimental measurement results show that the system can achieve high measurement accuracy, and has considerable engineering application potentials.