White-box detailed transformer models are used by manufacturers for predicting internal overvoltages in transformer windings during the lightning impulse test. One such model is the d-factor model which is based on a lumped-parameter description based on winding discretization with inclusion of loss...

Offshore umbilical cables often include both power cables and elements such as metallic tubes and signal cables. It was concluded from a recent failure of stainless tubes that AC corrosion was the failure cause. This paper describes how AC corrosion can lead to tube failure if a puncture exists in t...

Transformer manufacturers make routine use of white-box detailed transformer models for ensuring that the transformer will pass the lightning impulse test. For use in general simulation studies, the model should additionally be multi-phase and properly reproduce the transformer's input impedance cha...

Transformer terminal equivalents obtained via admittance measurements are suitable for simulating high-frequency transient interaction between the transformer and the network. This paper augments the terminal equivalent approach with a measurement-based voltage transfer function model which permits ...

Connection of offshore wind farms to shore requires the use of submarine cables. In the case of long HVAC connections, the capacitive charging currents limit the transfer capability and lead to high losses. This paper shows that the losses can be substantially reduced by continuously adjusting the c...

A stable and passive six-terminal model is developed for a 45-MVA generator step-up transformer based on frequency sweep measurements in the range 5 Hz–10 MHz and curve fitting with rational functions. The modeling employs separate treatment of the zero sequence system in combination with a new vari...

Cable-series impedance modeling is widely applied in electromagnetic transients simulations and power-loss calculations. The calculations are usually performed in a 2-D frame using the finite-element method or alternative approaches, such as MoM-SO, thereby losing the 3-D effects imposed by twisting...

Frequency-dependent transmission line modeling by the traveling wave method requires to approximate the propagation function with a delayed rational function. Some approaches are based on modal decomposition where scalar functions are fitted with a rational model plus a single time delay. The delay ...

Admittance frequency-sweep measurements is an accepted procedure for characterizing transformer terminal behavior for the purpose of frequency-dependent black-box modeling. The errors introduced by the measurement cables is with one existing practice mitigated by removal of the associated shunt capa...