ExpectedOutcome:
Project results are expected to contribute to at least three of the following outcomes:
- High Voltage (HV), Extra High Voltage (EHV) or High Power/superconducting cable systems, including dynamic AC – DC cables.
- Development of not only better performing, but also more environmentally friendly materials for cable and accessory insulation.
- Improved tools for remote monitoring, repair and maintenance of equipment.
- Assessment of the feasibility of new cable system technologies.
- Increased reliability of HVDC or High-Power cable systems, through improved cable accessory design and/or ageing studies and/or use of cable condition monitoring techniques.
- Reduced cost of HVDC or High-Power cables, which increases feasibility of implementation in smaller projects, reducing the visual impact and improves social acceptability compared to AC overhead lines.
- Reducing the environmental impact of HVDC or High-Power cable systems through use of component designs with smaller climate footprints such as gas-free accessories or through conversion and reuse of existing infrastructure to increase power transfer capacity.
- When power demand increases and the ampacity of the power line is reached, the replacement of HVAC overhead lines with HVDC or with High-Power cable systems can avoid building new lines or reinforcing the grid.
- Increased power transfer over the same corridor and same or smaller right of ways.
- Methodology development of the OHL conversion from AC to DC with minimal line outage
- Contribution to the emergence of standards for DC OHLs in Europe
- Benefits of power dense technology options and avoidance of grid reinforcement.
Scope:
Projects are expected to implement at least three of the activities in (1) for one or more subtopics (A, B, C) or (2) for one or more subtopics (D, E, F) and the practical validation in (3) as described below:
1. R&I, methodologies and tools involving the activities listed below. These can be developed/complemented with others pertinent to the topic.
A. Innovation in cable systems
- Development of new insulating materials for dry type accessories for high temperature and above 525 kV
- Optimisation of newly developed high electrical resistivity insulating materials for use above 525 kV in cable and/or accessories.
- Development of new network components with reduced environmental impact such as EHV/HV cables without lead, application of superconductors, AC, DC cables/gas insulated lines for voltages above 525 kV.
- Development of larger conductor cross sections.
- Development of smaller conductor cross sections and leveraging higher current superconductors - greater power density benefits.
- Increase of maximum insulation operating temperature, such as for high load urban areas where available space for power transfer is limited.
- Further improvement of different types of extruded insulation materials (e.g., AC, DC-XLPE, Polypropylene) cables, and render recyclability of the materials feasible by refining the procedure of separation of the many components of the cable – insulation, wires, tapes, sheaths, etc. – from each other. Establishment of procedures for recycling and related possible products.
- Feasibility study for use of superconducting cables for submarine connections to determine their environmental benefits e.g., extremely low heat emittance, since they do not emit any heat, zero magnetic field benefits to marine fauna, smaller cable corridors for higher power densities, smaller landfall space requirements, etc.
- Simulation and design of innovative dynamic cable systems to meet the needs of the growing floating offshore applications.
B. Predictive models for cable system ageing (fraction-of-life lost, remaining life), life and reliability
- Modelling of space charge phenomena (as well as other relevant phenomena) in newly developed insulating materials, in full size cables and accessories.
- Modelling of its effects on cable system aging taking advantage of advanced experimental space charge measurement techniques.
- AI methods for managing a cable fleet angle.
- Impact of water absorption on ageing of lead-free wet-design HVDC or High-Power cables.
- Ageing of cable systems, including effect of contaminants, humidity and temperature, and its implications for space charge accumulation and lifetime estimations. Test methods to quantify ageing in a DC environment, such as voltage form for DC-specific breakdown testing.
C. Monitoring and fault location systems
- Continuous temperature and acoustic monitoring of long cable system lengths.
- Accurate and instantaneous fault location systems for long cable system lengths.
- Further development and improvement of on- and off-line diagnostics and condition monitoring techniques for HVDC or High-Power cable systems such as PD and leakage current measurements for online and space charge and dielectric permittivity and loss factor measurements for offline.
- Innovative technological solutions such as fibre-based and/or robotic technologies for data collection and maintenance in in all type of location (easy-to-access and inhospitable).
- Development of procedures for optimised maintenance and repair concepts of offshore stations using BIM and 3D-Models.
2. Investigation and development of potential replacement of HVAC overhead lines with HVDC or High-Power cable solutions to increase capacity transfer without the need of building new infrastructures but reusing existing right of ways.
D. Cost-Benefit Analysis for different options of HVAC OHL conversion
- Mapping of the potential use cases for replacement of HVAC with HVDC or High-Power solutions (buried or overhead) supported by a Cost-Benefit Analysis.
- Cost-Benefit Analysis for conversion of HVAC OHL to HVDC, High Power OHL or buried High-Power cable solutions.
- Resilience and reliability analysis of different HVAC OHL conversion options – underground cable, HVDC OHL and buried High-Power cable solutions.
E. Technical innovations and design methodologies of hybrid HV AC/DC overhead lines
- Insulation coordination and clearances calculation methodologies, for HVDC and hybrid HV AC/DC overhead lines.
- Electrical field and ion current density calculation methodology under hybrid HV AC/DC OHLs ion flow field.
- Operation, control and protection of hybrid AC/DC overhead lines.
- Management of long-distance mixed cable and OHL HV corridors.
F. Pan-European grid studies and unification of voltage level of the converted OHLs from HVAC to HVDC
- Proposal of a unified DC voltage level of the converted lines considering the standard towers and line designs of HVAC OHLs (220 kV, 400kV) in the European network to provide a general conversion approach, compatible with minimum operation downtime.
- Perform pan-European grid studies to propose a unified strategy toward an overlaying HVDC grid based on the converted HVAC OHLs and existing corridors with minimized environmental impact, link downtime and implementation time.
- Dynamic grid studies to demonstrate the impact of the HVAC OHL conversion to HVDC.
- Develop identification criteria for the candidate HVAC OHL corridors (to be converted in HVDC).
3. Test and validation of the activities developed in (1) consisting of at least one of the activities described in each subtopic A, B, C or (2) consisting of at least one of the activities described in each subtopic D, E, F in at least two validation tests in different EU Member States/Associated Countries.
Specific Topic Conditions:
Activities are expected to achieve TRL 4-5 by the end of the project – see General Annex B.
