Streamer initiation and propagation in transformer oil under positive and negative impulse voltages

Abstract

Electro-thermal hydrodynamic modeling of streamers formed by positive and negative impulse voltages in transformer mineral oil is presented. Negative streamers initiate at roughly two times higher applied voltages while positive streamers propagate about two times faster and occupy much less space. Charge carrier mobilities dependence on the temperature is taken into account as well as the electric field effect on the ionization potential of hydrocarbon molecules. Negative streamer dynamics greatly depend on the variations of electron mobility. On the other hand, positive streamers are mostly dependent on applied impulse voltage rise-time for a given applied voltage peak. Higher applied voltage peaks form faster streamers called higher mode streamers in both polarities.

Effects of Impulse Voltage Polarity, Peak Amplitude, and Rise Time on Streamers Initiated From a Needle Electrode in Transformer Oil

“…(1), and Eq. (3) enables the model to describe the negative streamers and positive streamers formed by extra high voltages (≥200kV) [15]. Representative parameter values for the ionization potential function are listed in Table I as well as other parameters used to solve governing equations (1)(2)(3)(4)(5)(6).…”

The Numerical Analysis for Electrical Streamer Discharge Behaviour in Transformer Oil

“…It is difficult to capture this complex discharge process in detail in an experimental approach. Therefore, recently, many researchers have proposed various methodologies using numerical analysis techniques to analyze the electric discharge phenomenon [1][2][3][4][5]. To develop such a numerical analysis technique, the discretization method using the finite element method (FEM) has been applied.…”

Simulation of positive streamer discharges in transformer oil

“…Many factors can reduce the performance of liquid insulators which can even happen during normal operation. This is caused by the moisture and oxidation that occurs in addition to cellular material and dissolved gases that appear in the liquid [1,2]. Eventually, during normal operation, the presence of the above can reach a point where the insulating performance of the oil deteriorates so much that it must be replaced, to avoid electrical discharge.…”