Open framework for parameters computation of submarine cables

Power cables are playing a vital role in the energy transition worldwide. Covering AC and DC applications for integrating renewable generation or cross-border interconnections, they are critical enablers in coping with environmental rules and help achieving climate and energy goals towards an integrated energy market. For instance, the concept of energy islands approved by the Danish government to concatenate offshore wind energy and cross-country interconnections will require extensive use of submarine cables.
Cost-effective projects are widely used for long-distance transmission of electrical power and rely on accurate analysis. Digital simulations allow work to get done faster and more efficiently. Nevertheless, they rely on accurate numerical models to provide reliable results. The substantial deviation between simulations and field measurements confirms the lack of accuracy of current submarine cable models, which might result in larger cross-sections and more expensive cable systems than necessary.
Submarine cables present challenges on many levels to assess the respective transient behavior. Firstly, the determination of its electrical parameters. Secondly, its systematic implementation as a reliable digital twin. Expressions for underground cables have been developed to a greater extent than those for submarine ones and parameter routines embedded in electromagnetic transients (EMT) tools cannot deal with the proximity effect. Nevertheless, proximity effect is of important due to the tight spacing between conductors in DC, three-phase, and pipe-type applications.
Parameter routines embedded in EMT-like software commonly represent submarine cables as if they were buried in the ground. However, the external media heavily influences the electromagnetic transients on cables due to the return impedance and admittance per-unit-length. Modeling a cable buried in the seabed represents a challenge as both media are lossy. Therefore, the approach used by Pollaczek for underground cables no longer applies. Numerical techniques like the Finite Element Method (FEM) have been employed for calculating the per-unit-length parameters in complex cable configurations. FEM leads to expensive computing times and limited applicability to be implemented in EMT-type software for analyzing voltage and current profiles throughout the whole subsea system.
The paper presents the development of a framework to allow the computation of electrical parameters of submarine cables exploiting recent developments in analytical and numerical formulations to take the impact of the external media in conjunction with the constructive aspects of submarine cables into account. The main goal is to deliver a Universal Cable Constants routine for parameter estimation with improved accuracy when compared with current EMT models and also considerably faster while retaining a good match when compared to FEM. The tool aims to be shared to the whole industry and academia societies as an open-source web application featuring the possibility of generating ready-to-use data to be imported by EMT tools like ATP, PSCAD and EMTP software. The application aims to be as general as possible encompassing several cable cross-sections and conductor arrangements to enable in-depth investigations regarding equipment sizing, system failures, fault location techniques, power quality, and others.