Measurements for validation of high voltage underground cable modelling

Abstract -- This paper discusses studies concerning cable modelling for long high voltage AC cable lines. In investigating the possibilities of using long cables instead of overhead lines, the simulation results must be trustworthy. Therefore a model validation is of great importance. This paper describes field test setups and measurements on an already installed cable line with several cross bonding points. These measurements are to be used for cable model validation, which are prepared using simulations. The proposed field tests should be used to validate the cable model for overvoltage problems. The verification shall be done both in the frequency domain and in the time domain. Keywords : Cable lines, Cable model, Transient test, Cable measurements, Cable simulation. I. I NTRODUCTION In recent years, interest towards using underground high voltage (HV) cables in power transmission, has increased considerably. In order to research the possibility of using large HV AC cable systems, it is necessary to have precise simulation models. HV transmission cable models are to correctly represent the transient behaviour of underground cable systems. Small errors for short cables can become a larger problem when length of the cables and number of cross bonding points are increased. It is therefore important that differences between simulations and measurements are eliminated. It has been recommended that the cable models be validated by use of a frequency response model with inverse Fourier transform [1]. The aim of this paper, on the other hand, is to describe necessary field tests, in order to investigate the accuracy of cable terminal conditions transient behaviour and build a comprehensive and precise model for HV AC cables. Results from performed field test [2] have been used to validate various models through the years [3][4]. These field tests only include a fast-front impulse. This paper introduces