Identification of problems when using long high voltage AC cable in transmission system I: switching transient problems

Due to political and environmental pressures from the public and government side, upgrading and building new transmission facilities are becoming more and more difficult and in some cases the expansion of overhead transmission lines are impossible. This means that underground cable technology is the proper substitution and solution which make the transmission expansion possible with minimized visual impacts on the communities. Within European countries, Denmark was been at the forefront of replacing the transmission lines with cables. The project was supplying the power to the greater Copenhagen area in early 1990s. Recently, the Danish TSO Energinet.dk has initiated a research project for analyzing the HV underground cable in transmission system. The objective of this paper and the companion paper is to address the most important problems expected in transmission system with relatively larger share of long HV underground cables. The end goal will be a guideline to special solutions and precautions to avoid dangerous over voltage problems and also resonance problems in a transmission network with future increased share of cables. Two major categories of problems are switching transient and resonance problems. In each category of the possible problems, first some theoretical background is provided and then the problem and countermeasures are discussed. In this paper switching transient problems are addressed and discussed. Some preliminary guidelines for modeling of the components will be given which are used especially for switching transient studies. Companion paper is dedicated to address the different types of resonance problems.