Analysis of electromagnetic fields produced by high voltage submarine cables

With the growing investment in interconnectors and OWFs (Offshore Wind Farms), there has been an increased need for the environmental assessment of high voltage (HV) submarine cables. To investigate their impact on marine life, the exact values and distributions of electromagnetic fields (EMFs) produced by these cables need to be characterised and reproduced in experimental conditions. The existing literature does not accurately address several aspects relevant to the calculation of electromagnetic fields from HV cables, in particular, aspects related to electric fields. Additionally, experimental approaches commonly employed to reproduce EMFs often neglect relevant factors such as vector orientation or distribution of the EMFs. To address the shortcomings of the literature regarding electric fields produced by cables, two methods are developed as the main contributions of this thesis. Firstly, a method for numerical modelling of electric fields produced as a result of the water movement near HVDC cable systems is developed. This work demonstrates that the approach commonly adopted in the literature does not accurately represent spatial distributions of the electric field close to the cable system, as it neglects the electric fields induced in the seabed and the water velocity distribution. Additionally, the reference frame of a moving organism and the impact of media conductivities on the electric fields are considered and are shown to have a significant impact on both the magnitudes and the distributions of the computed electric fields. Secondly, a novel analytical method for the calculation of magnetic and electric fields from three-phase HVAC cables with magnetic armour is presented and compared against a numerical solution. The analytical approach developed in this work creates a more accessible and computationally efficient alternative to numerical approaches. It includes the contributions of the conductor twist, insulating cable boundaries, magnetic armour, and metallic sheaths to the electric fields, none of which have been considered in previous work. Following the criticisms of the experimental approaches used to recreate fields typical of HV cable systems, an experimental setup for producing EMFs from HV cables is also designed and tested. The outlined experimental approach aims to reproduce both the correct magnitude and vector orientation of magnetic fields produced by HV subsea cables. Electric fields are introduced into the experimental setup to address an aspect largely absent from the literature.