Analyzing the model of transformer windings under very fast transient overvoltage

An experimentally determined field winding model with frequency‐dependent parameters

“…According to the literature, the most used circuits models for studying transients in electric circuits are based on Transmission Line Model (TLM) or Lumped Element Model (LEM) [25][26][27]. Some models assume the circuit parameters to be constant [28,29] even though the winding resistance and inductance show a strong dependence on frequency [30][31][32][33]. Other models assume a constant wave propagation speed in the windings, resulting in an easy extraction of the inductance values from the winding capacitances [24,34].…”

Validity of circuit‐based models for air‐cored helical windings at high‐frequency regimes

“…The PD signal measured at the transformer terminals is only indicative of the discharge [11] and the nature of propagation of the impinging fields through the windings is not known quantitatively. To tackle these issues and to get a better resolution and accuracy in the required frequency range, multi‐conductor transmission‐line (MTL) model has been used [4, 12–15]. In this approach, every turn is modelled as a transmission line and both the frequency and time‐domain responses and the internal windings stresses were evaluated.…”