Novelty Underground Cable Model for Power System Transient Simulation

Abstract

This paper presents an extension of the A-line model (Garcia-Sanchez et al., 2016) for underground cables that takes into account the frequency dependence and includes the conductance matrix; the new cable model is named the U-Cable model. This paper also presents the mathematical development that supports the new U-Cable model; thus, following the methodology, it can be observed how the cable parameters are related to the construction of the final mathematical model. This model has the characteristic that the fitting is generated by real poles in a natural manner without forcing vector fitting to change to only real poles, which makes the developed model extremely stable from a numerical point of view. The numerical Laplace transform (NLT) and PSCAD software are used for comparison purposes. The reason for the use of the NLT is that, if it is properly programmed, it always yields a reliable solution. For the comparisons, a short-circuited line is simulated first, followed by a matched line and then an open line with a unit step. A second simulation is performed by changing the unit step to a three-phase sinusoidal source. A comparison of the results obtained from the proposed model with those of the NLT and PSCAD provides support and reliability to this model because the differences observed, in most cases, are barely perceptible. Thus, it can be concluded that the presented model is an additional option to the existing models.

Keywords

• Underground cable model
• U-Cable model
• frequency dependence model
• numerical Laplace transform