Improvements in Grounding Practice: Topology of Grounding Systems, Soil Characteristics Impact, and Simulation Methods for Transients’ Studies

Dear Colleagues,

The safety of power systems at different voltage levels and the limitation of external overvoltages strongly rely on grounding, as a fundamental, yet simple, solution adopted by engineers and utilities around the world. Nevertheless, to the simple concept underlying its application, there are corresponding complexities in the real practice. Indeed, depending on the grounding system topology and dimension, and on the magnetic and electric properties of the soil, the resulting ground impedance may only be poorly approximated to a constant-valued quantity. Advanced simulation methods and modelling approaches are necessary to account for frequency-dependent soil properties, the frequency response of the grounding system, and nonlinearities when soil ionization occurs.

In particular, studies of fast transients within power networks, including the effects of lightning impulse currents, should not neglect these important aspects of the grounding actual physics.

The spread of renewable energy power plants has resulted in increasing interest in the topic of impulse response of wind turbines’ grounding systems, also due to the relevant number of observed lightning strikes to the blades.

The interconnection of grounding systems is also being adopted as a method of reducing the low frequency ground resistance. However, the effectiveness of the measure should also be considered with respect to the impulse response of the connected earthing system.

Topics of interest include, but are not limited to, the following:

• Modelling approaches and equivalent circuits for grounding systems;
• Measuring grounding systems’ impulse impedance;
• Impact of soil characteristics and soil ionization;
• Grounding in renewable energy power plants;
• Role of the ground impedance in transient studies and protection coordination;
• Innovative grounding configurations and topologies;
• Interaction between grounding systems;
• Simplified approaches for the computation of ground impedances of complex systems;
• Case studies.

Dr. Erika Stracqualursi
Prof. Dr. Salvatore Celozzi
Guest Editors

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• grounding systems
• transient ground impedance
• grounding modelling
• power systems transients
• soil properties