High-Voltage Impulse Tests on Transmission Lines [includes discussion]

On the influence of corona on lightning-induced overvoltages

“…It is based on the extension of the field-to-transmission line coupling equations of Agrawal et al [10] in order to take into account both the presence of a finite conductive ground and corona. The model is described by the following equations: (2) being:…”

“…In particular, from a macroscopic point of view, corona can be described by a charge-voltage diagram [2,3] in which, after a linear increase of the line charge with the voltage, a sudden change of the derivative of charge with respect to the voltage takes place by exceeding a threshold voltage (v th ). This derivative defines the voltage-dependent dynamic capacitance C' dyn that clearly becomes a function of time and space C' dyn (x,t).…”

“…In this respect, the evaluation of the influence of corona on lightning-originated surges has been treated both for the case of direct strokes to high voltage transmission lines (e.g. [2][3][4][5][6][7]) as well as for the case of indirect lightning-induced voltages in medium voltage distribution lines [8,9]. As known, this non-linear phenomenon is one of the responsible in the travelling waves surge distortion and its effects for lightninginduced overvoltages are as important as those associated to the finite ground conductivity.…”

Modeling Nonuniform Transmission Lines for Time Domain Simulation of Electromagnetic Transients

“…The ground resistivity is assumed to be 100 -m. The configuration of the line in Fig. 2 is similar to the one used in [15] for measurements of voltage and current propagating along the line.…”

“…Three identical voltage waveforms reported in [15] are simultaneously injected in all phases at the sending end when the receiving end is open. The sending end voltage and the corresponding receiving end voltage are shown in Fig.…”