Submarine Cables Research Articles

Computational homogenization method for the bending analysis of submarine power cables

Computational homogenization method for the bending analysis of submarine power cables

Research on identification method of abnormal grounding circulating current in single‐core AC submarine cable

Research on identification method of abnormal grounding circulating current in single‐core AC submarine cable

Techno-Economic Assessment of a Full-Chain Hydrogen Production by Offshore Wind Power

Offshore wind power stands out as a promising renewable energy source, offering substantial potential for achieving low carbon emissions and enhancing energy security. Despite its potential, the expansion of offshore wind power faces considerable constraints in offshore power transmission. Hydrogen production derived from offshore wind power emerges as an efficient solution to overcome these limitations and effectively transport energy. This study systematically devises diverse hydrogen energy supply chains tailored to the demands of the transportation and chemical industries, meticulously assessing the levelized cost of hydrogen (LCOH). Our findings reveal that the most cost-efficient means of transporting hydrogen to the mainland is through pipelines, particularly when the baseline distance is 50 km and the baseline electricity price is 0.05 USD/kWh. Notably, delivering hydrogen directly to the port via pipelines for chemical industries proves considerably more economical than distributing it to hydrogen refueling stations, with a minimal cost of 3.6 USD/kg. Additionally, we assessed the levelized cost of hydrogen (LCOH) for supply chains that transmit electricity to ports via submarine cables before hydrogen production and subsequent distribution to chemical plants. In comparison to offshore hydrogen production routes, these routes exhibit higher costs and reduced competitiveness. Finally, a sensitivity analysis was undertaken to scrutinize the impact of delivery distance and electricity prices on LCOH. The outcomes underscore the acute sensitivity of LCOH to power prices, highlighting the potential for substantial reductions in hydrogen prices through concerted efforts to lower electricity costs.

Advp Measurements Of Flow Over Low-Angle Bedforms In A Laboratory Flume Setup

In many coastal and estuarine environments, bedforms develop due to the complex interactions between hydrodynamics, sediment transport and morphology which affect hydro-morphodynamic processes at various spatio-temporal scales. Furthermore, bedforms are considered main drivers of flow resistance via turbulence and affect near bottom processes such as bed roughness, bottom shear stress and turbulent structures. A detailed study and characterisation of flow over bedforms is therefore significant to many fundamental and engineering applications such as sediment transport calculation and prediction, channel managements, or burial of submarine cables. Asymmetric dunes with an angle-of-repose (30°) lee side have been well studied (Best, 2005; Venditti, 2013). They are representative of dunes commonly found in laboratory flumes and small rivers. Over such bedforms, flow is characterised by a permanent flow separation zone and intense turbulence over their lee side. Recently, it was shown that bedforms in large rivers are mainly low- to intermediate-angle dunes (mean lee side ca. 5-20°) having their steepest slope located close to the trough (Cisneros et al., 2020). Over such low- and intermediate-angle river dunes, flow separation is inexistent or intermittent and only little turbulence is generated (e.g. Kwoll et al., 2016; Lefebvre and Cisneros, 2023). Estuarine bedforms also possess mostly low- to intermediate-angle mean lee slopes between 5° and 20° (Dalrymple and Rhodes, 1995; Lefebvre et al., 2021). However, contrary to river bedforms, estuarine bedforms usually have a sharp pointed crest with the steepest slope situated near the crest and a relatively flat trough (Aliotta and Perillo, 1987; Lefebvre et al., 2021). It is not clear yet how much flow properties vary between high-angle flat-crested dunes and low-angle sharp-crested dunes. In particular, it is unknown whether a permanent or an intermittent flow separation can be observed over some segments of the lee side. Furthermore, the relation between the reversing tidal flow and natural estuarine morphology is not well understood yet. In this study, laboratory flume experiments will be conducted to measure the mean flow and turbulence over estuarine bedforms. Previous experiments performed by Carstensen and Holzwarth (2023) demonstrated the potential of high-resolution measurements over a large-scale estuarine dune in a laboratory flume. Building on this, experiments will be carried out over a fixed concrete low- and intermediate- angle estuarine bedform field. The results from this study can be used to characterise in detail the flow dynamics over estuarine bedforms.

Science Monitoring And Reliable Technology (SMART) to monitor the ocean using submarine cables

The Ocean is a fundamental part of life on Earth and therefore its observation is essential; however, there are currently no seabed monitoring networks that cover large areas. The Science Monitoring and Reliable Telecommunications (SMART) Cables initiative aims to combine the growing telecommunications industry with ocean sciences, leveraging the infrastructure of the former to deploy sensors to obtain essential ocean data on the seafloor in real time.

Shunt Reactor Control Performances for HVAC Submarine Cable

Shunt Reactor Control Performances for HVAC Submarine Cable

Prediction Model for Trends in Submarine Cable Burial Depth Variation Considering Dynamic Thermal Resistance Characteristics

Fault problems associated with submarine cables caused by variations in their burial depth are becoming increasingly prominent. To address the difficulty of detecting the burial depth of submarine cables and trends in its variation, a prediction model for submarine cable burial depth was proposed which considers the dynamic characteristics of thermal resistance. First, a parallel thermal circuit model of a three-core submarine cable was established, and a formula for calculating the submarine cable’s burial depth was derived based on a formula for calculating the submarine cable’s core temperature. Then, the calculation result was corrected by considering the dynamic characteristics of the thermal resistance of the submarine cable’s structural materials. On this basis, feature vectors associated with the seabed cable burial depth calculation data and time nodes were mined by a convolutional neural network and used as the input parameters of a long short-term memory network for optimization and training, and a prediction model for trends in seabed cable burial depth variation was obtained. Finally, an example analysis was carried out based on the actual electrical parameter data of submarine cables buried by an offshore oil and gas platform. The results showed that the prediction model for trends in variations in the burial depth of submarine cables based on the CNN-LSTM neural network can achieve high prediction accuracy and prediction efficiency.

საქართველო - ევროპის და აზიის გზაჯვარედინი - მნიშვნელოვანი აქტორი რეგიონალურ ენერგეტიკულ ლანდშაფტში

Since independence, Georgia’s full-fledged integration into the European Union is not only the foreign policy goal of our country, but also the driving force for the construction and development of a democratic state. Georgia’s strategic location and possession of rich renewable, unconventional energy resources give us a unique chance to become a hub, a “middle corridor” and a conduit for “green energies”. Georgians are ready to use this opportunity for further alignment with the ambitious energy goals of the European Union and the “Green Agreement” of Europe. Our push towards the European Union has been preceded by intensive communication and cooperation on energy legislation, regulations and energy policy, as well as improving energy infrastructure. This is how the so-called mega-project of the 21st century – the Black Sea submarine cable project – was created. The initiative involved in the project is more than simple infrastructure development; It is a symbol of Georgia’s integration and interconnection with the European Union. The Black Sea submarine cable will not only enhance energy security and diversity, but also serve as a renewable energy exchange channel between Asia and Europe. The idea of the Black Sea submarine cable project was born in Georgia, and Georgian geologists carried out technical works to explore the bottom of the Black Sea. At the next stage, Azerbaijan, Romania and Hungary were included in this project. The most important agreement was signed by the representatives of all four countries. The purpose of our research is to determine in advance what economic benefits Georgia will receive during the implementation of this important project, and we will be able to export the energy of renewable resources of our country, if we remain only as a transit corridor, which is also very attractive, although less profitable. While working on the article, we evaluated the potential of Georgia’s renewable, non-traditional energy sources, their target indicators and characteristics. Based on the researched information, we developed conclusions and recommendations. Keywords: renewable, non-conventional energy resources, Black Sea submarine cable, energy security, “green energy”, European integration. VIEW ARTICLE

Data Driven and Fuzzy Synthetic Evaluation Based Submarine Cable Health State Assessment

—Health state assessment is of great importance to ensure the safe and stable operation of submarine cables. Submarine cables have composite structural characteristics and work in complex and influential environments, which hinders manual inspection, arouses difficulties in maintenance, and causes challenges on health state assessment. To this end, a data driven and fuzzy synthetic evaluation based submarine cable health state assessment method is proposed in this paper. Firstly, following the technical guidelines of submarine cable health state assessment, dynamic submarine cable online monitoring data and static data including periodic preventive test and operation inspection results are integrated to build a three-layer index system. In addition, long and short-term memory (LSTM) neural network based ultra-short-term prediction models are built to obtain the predictions of online monitoring indices. On this basis, together with the static data, a fuzzy synthetic evaluation method is used to establish a two-stage state evaluation process to obtain the multi-period health states of submarine cables. The effectiveness of the proposed method is verified with an actual submarine cable from an offshore platform in an oilfield of China National Offshore Oil Corporation (CNOOC).

Submarine cable detection using an end-to-end neural network-based magnetic data inversion

Abstract To process magnetic anomaly data, appropriate parameters for field separation, denoising, and Euler deconvolution have to be manually selected. The traditional workflow is inefficient and cannot fulfill the rapid detection of submarine cables due to the complex processing and manual parameter tuning. This study presents an end-to-end deep learning approach for the identification and positioning of submarine cables based on magnetic anomalies. The proposed approach effectively establishes a direct mapping correlation between the magnetic field data and the position of the submarine cable. Synthetic tests suggest that our method has a better performance in terms of positioning accuracy than the conventional Euler method. Our results for the field data are comparable to those obtained using conventional techniques. Furthermore, the proposed method achieves an optimal solution by employing clustering technique and selecting the solution with the maximum confidence, which avoids spurious solutions associated with traditional methods. The proposed method can directly determine the position of the submarine cables using the raw magnetic field data. Contrary to the traditional processing workflow, field separation and denoising are not necessary in this novel approach, resulting in higher processing efficiency and a simpler processing process.

SEATANI: hazards from seamounts in Southeast Asia, Taiwan, and Andaman and Nicobar Islands (eastern India)

Abstract. Submarine volcanism makes up approximately 85 % of volcanism that occurs on Earth, and its eruptions have the potential to cause several hazards including ash dispersal, pumice rafts, pyroclastic density currents, sector collapses, and tsunamis. Recent examples include the eruptions in Japan and in the Kingdom of Tonga in 2021 and 2022 respectively, but there has been little to no study of submarine volcanism in Southeast Asia and surroundings. Here we provide a compilation of 466 seamounts from the region, from different published sources, through the SEATANI dataset (Southeast Asia, Taiwan, and the Andaman and Nicobar Islands). We use this newly compiled dataset to assess on a regional level the seamount hazard potential and exposure potential as a springboard for future more quantitative hazard studies of the region. The hazard potential was assessed through seamount morphological and structural analyses, to determine the seamount evolution stage and grade of maturity. The exposure potential was evaluated with two different approaches: an areal analysis of the number of assets within a 100 km radius of each seamount and the development of a hazard-weighted seamount density map to highlight potential areas of interest for future more-in-depth studies. Our results show that there are several potentially hazardous seamounts in this region. Taiwan has the highest hazard and exposure potential, for all assets considered, while the Philippines, Indonesia, and Vietnam have relatively high exposure potential for submarine communication cables and ship traffic density. The results from this work serve as a first step towards Southeast Asia and neighbouring countries becoming more resilient against and prepared for submarine volcanic eruptions in the region.

Spatial Spillover of the Global Internet Penetration Rate and the Digital Gender Divide

This study investigated the possible contributing factors to the digital gender divide and the spatial spillover effects of submarine communication cables on neighboring areas. Using spatial statistical models and global data, this study examined the Internet penetration rate and the digital gender divide in 186 countries. Data sources included open source data, social media, ITU and UNCTAD databases, and the World Bank. The study estimated the average male and female Internet users in 186 countries using Facebook API. The number of submarine communication cables between countries was used as the basis for constructing the spatial weights matrix. The countries with the highest Internet penetration rate were mostly in Europe. Those with the lowest Internet penetration rate were in Africa, Central Asia, and West Asia. Thirteen of the 15 countries with the worst Internet penetration rate were located in the African region. A significant digital gender divide arose in the developing and the least-developed countries. We argue that connectivity is key to the reduction of the digital gender divide and to ensuring that more women have access to the Internet. The study ascertains that the Internet penetration rate is related to the digital gender divide in individual countries and has a spatial spillover impact in surrounding nations connected by submarine communication cables. The study demonstrates that submarine cables serve as important infrastructure for closing the digital gender divide and deserve increased analytical attention.

Submarine Infrastructures and the International Legal Framework

The purpose of this paper is to identify weaknesses in the international framework for the protection of submarine cables beyond the sovereign waters of coastal States. To illustrate this, the paper uses a hypothetical case study of what a possible attack on a submarine cable may look like. First, it provides an overview over the applicable framework, with a particular focus on international peacekeeping law (ius contra bellum), the law of the sea, protection against piracy, and criminal prosecution under national criminal law. Various international conventions play a key role in relation to submarine cables. Particularly relevant are the Convention on Submarine Telegraph Cables of 1884, the United Nations Convention on the Law of the Sea of 1982, as well as the peacekeeping regulations of the United Nations Charter of 1949. After outlining the legal framework using the classical methods of treaty interpretation, as well as taking the scholarly literature on this subject into account, the example is subsumed under the various means of protection under international law. The peacekeeping law of the United Nations turns out to be ineffective because, on the one hand, an attack as described in the reference scenario does not necessarily constitute an armed attack in the sense of the UN Charter and therefore cannot be met with military countermeasures. On the other hand, an authorisation by the Security Council cannot be given quickly enough to counter the attack militarily. In addition to that, measures taken in the framework of the Law of the Sea Convention are ineffective due to the exclusive flag State jurisdiction which precludes other States from acting in this matter. An exception to this principle, namely universal jurisdiction to combat piracy, is unlikely to be applied in the context of an attack against a submarine cable. Finally, as result of the exclusive jurisdiction of the flag State and the poor implementation of the international obligations under the Law of the Sea Convention, national criminal law is also inadequate as a repressive means of protection.

Comparative Study on the Ampacity of 500 kV Single-Core and Three-Core Submarine Cable

Submarine cable is an important equipment for data communication and power transmission in power systems, which has a complex laying environment. According to its structure, submarine cables can be divided into two types, single-core cables and three-core cables. In practical engineering, cable selection is crucial to ensure the safe and stable operation of the cable and reduce the cost. The present work compares the ampacity of 500 kV single-core cable and three-core cable with the same conductor cross-section area under certain laying conditions. And the temperature rise situation of the three-core cable and the single-core cable is compared under the application of the same current. The results reveals that the ampacity of the three-core cable is less than one-core cable under certain laying situations. And the maximum ampacity reduction of the three-core cable is 28.96%. Furthermore, the highest temperature rise point of the three-core cable is the air section of the J-tube, and the maximum temperature reaches 130.07°C.

Automated detection of fin whale calls recorded with distributed acoustic sensing

As the global biodiversity crisis intensifies, wildlife monitoring has become a necessity. From an oceanographic perspective, the tracking of baleen whales allows studies of their habitat use and can support call density estimates, which are indicative of ocean health. Distributed Acoustic Sensing (DAS) is a promising observational technique that measures strain rates along a spare optical fiber with a spatial resolution of tens of meters to distances of ∼100 km. Over 4-days in November 2021, a public domain DAS dataset was collected on the submarine cables of the Ocean Observatories Initiative Regional Cabled Array off the coast of central Oregon. The experiment recorded the acoustic signals from tens of thousands of fin whale calls as well as blue whale calls, ship signals and T-phases. We will describe preliminary efforts to develop automated methods to detect and localize fin whale calls using small representative examples of the DAS data. Our longer-term goal is to extend this approach to the full data set to understand the sensitivity of DAS to fin whale calls as function of cable geometry and seafloor characteristics and to study the distribution of calling fin whales in coastal waters off central Oregon. [Work supported by ONR.]

Integral Formulation for Losses Computation in Tripolar Submarine Cables With Shield Wires, Moisture Barriers, and Armor

Integral Formulation for Losses Computation in Tripolar Submarine Cables With Shield Wires, Moisture Barriers, and Armor

Thermal circuit model of DC submarine cable considering the influence of seawater property variations

The IEC 60287 standard, when calculating the steady-state current-carrying of DC submarine cables, does not take into account the influence of seawater property variations on changing the heat transfer efficiency of seawater, thereby affecting the current-carrying capacity of the cable. resulting in deviations in the calculated ampacity results. This paper considers the influence of seawater heat transfer characteristics on cable heat dissipation efficiency based on heat transfer theory, and Proposes an improved thermal circuit model for submarine DC cables that takes into account variations in seawater properties. Taking the example of a 160 kV submarine XLPE cable, the current-carrying capacity results of the improved model have an error of no more than 1.9 % compared to finite element simulation results. Under identical environmental conditions, the maximum deviation between the improved model and the IEC thermal circuit model is 123A, confirming the necessity of considering variations in seawater properties in the improved thermal circuit model. The seawater property variations studied in this paper include changes in seawater temperature, salinity, and pressure. If the impact of seawater property variations on submarine cable current-carrying capacity is not considered, the obtained current-carrying capacity results are higher, with a maximum error of 5.5 %. Among these variations, temperature has the most significant impact, with an error reaching 3.3 %, while salinity and pressure have relatively smaller impacts, with errors of 1.1 % each.

Research on key technology to determine the exact maximum allowable current-carrying ampacity for submarine cables

The maximum allowable current-carrying ampacity (MACCA) of a photoelectric composite submarine cable in its design phase is usually patterned considering the weather. However, variations in sea temperature, the uncertainty of the cable's material parameters and the laying environment of the cable greatly influence its CCA. The impact of these factors can damage the cable, regardless of its quality. For this purpose, this paper proposes a developed iterative parameters correction method (IPCM) based on Chord principles, to determine the exact MACCA by means of finite element method (FEM). Different optical fiber temperatures of the cable are collected using Brillouin Optical Time-Domain Analysis (BOTDA); together with the material parameters of the cable, they are modeled in ANSYS modeling software. Then, the proposed approach is conducted before determining the exact MACCA. Results obtained from experiments performed on different data groups show that the mean error rate obtained with the proposed approach is just about 3.78, while that of the other four recent approaches, including AP1, AP2, AP3 and AP4 is about 4.59, 3.96, 4.13 and 4.80, respectively.

Fluid–structure interaction simulation and optical fibre stress analysis of submarine cables in vortex‐induced vibration

AbstractUnder the current scouring, submarine cables are prone to be exposed, suspended, and even vortex‐induced vibration (VIV), threatening their mechanical and electrical properties. In this contribution, a finite element simulation model of 110‐kV single‐core optical fibre composite submarine cable is established. The natural frequency and resonant frequency of the model are obtained through wet mode analysis and harmonic response analysis. Then the VIV is simulated by the fluid–structure coupling method. Moreover, the stress extraction method of the torsional optical fibre position under the VIV is proposed. The results show that when the reduced speed is 2.57, the submarine cable appears beating vibration, which is composed of two vibrations with similar frequencies. When the reduced speed is 7.08, the vibration frequency is about 7.813 Hz, causing a rapid increase in vibration amplitude. The stress distribution of the torsional optical fibre presents a mirror image relationship at two moments separated by half a vibration cycle. Also, the frequency of stress change is the same as the frequency of VIV, which can judge whether the VIV occurs. The VIV range and position can be determined by the location where the stress changes the most.

Simulation of Electrical Trees Grow in Three-Core Submarine Cable

Simulation of Electrical Trees Grow in Three-Core Submarine Cable