Project Summary
Offshore wind energy is pivotal for the UK's net zero grid ambitions, increasingly, cable failures pose financial and reliability challenges for new and existing projects. New, innovative condition monitoring can improve the commissioning and operation of offshore cables to mitigate the risk of failure and overcome the limitations of existing techniques (e.g. maximum cable length). In this project, we will research state-of-the-art monitoring techniques, including for temperature, vibration and integrity of electrical insulation. The aim is to create an integrated monitoring system, aiding network operators in decision-making for a more flexible grid and robust commissioning practices.
Innovation Justification
In the UK, there is currently a total offshore wind pipeline of around 77 GW across 80 projects that are either in construction, consented, in development and planned in future seabed leasing auctions. In addition to newly built wind farms, there are planned cable replacements in the offshore wind industry due to known issues with the undersea cable protection system.
International standards and industry guidance are often not aligned with commercially available equipment, leading to various approaches for high-voltage DC testing at cable commissioning. The safety and operational implications from a measurement perspective are also not well understood when projects are specified, leading to inferior field measurements that offer little value to asset owners.
Offshore wind farm operators make critical decisions on the test voltage waveform to use during commissioning testing based on technology available on the market, cost of equipment, and space at the wind turbines or offshore substations. To target the offshore commissioning testing market, the ability to work with all test voltage waveforms is key and is a core innovative aspect of the project that will be an essential part of any testing techniques developed.
This project complements and builds upon previous innovation projects related to condition monitoring. Previous projects have tended to explore individual electrical testing techniques. A novel aspect of this project is the consideration of multiple techniques, including partial discharge and time and frequency domain reflectometry (current TRL 2-5). An integrated solution could help to overcome issues around certain techniques not being suitable for longer cable lengths and to filter out reflections that are not from the cable itself during operation.
Our project is well aligned with the SIF objectives and, in particular, the sequence of the SIF stages. Following a successful Discovery Phase, in Alpha, we intend to conduct laboratory-scale testing on a rig at Deeside Innovation Centre to test the feasibility of new methods for assessing cable health and increase the TRL. This testing will provide data to inform the predictive abilities of the integrated monitoring solution and increase the knowledge about the costs and benefits of the novel condition monitoring system. The Beta Phase will then be a large-scale demonstration of the novel condition monitoring methods, for instance, by installing it on an in-situ section of the network to understand performance in a live operating environment.
Impacts and Benefits
Future reductions in the cost of operating the network
Improved monitoring methods will allow earlier identification of damage to cables to ensure networks are safe and reliable, avoiding dangerous and costly, unplanned outages. These methods allow networks to carry out preventative maintenance, which lowers costs compared to isolating an area of the network with a failure and waiting for the next planned outage to carry out the repair.
Cost savings per annum on energy bills for consumers
Interconnectors give the UK access to cheaper electricity from abroad. National Grid estimates that hitting the UK government’s ambition of 18 GW of interconnector capacity by 2030 would save UK consumers up to £20 billion between now and 2045. This estimated benefit is only plausible if we can ensure that DC interconnectors are reliable and do not suffer from premature failure. Additional repair costs elevate the costs of insurance premiums, as seen recently for the BritNed interconnector after multiple cable faults caused outages of up to 90 days.
Indirect CO2 savings per annum
By 2030, National Grid estimates that 90% of the electricity we import from mainland Europe via National Grid interconnectors will be from zero-carbon sources. The interconnectors will help Britain prevent over 100 million tonnes of carbon emissions before 2030. By effectively monitoring the condition of these interconnectors during both commissioning and operation, we can ensure they are reliable and deliver their intended environmental benefits.
Improved access to revenues for users of network services
Offshore wind developers and OFTOs will also benefit from the earlier identification of damage from improved condition monitoring, particularly in light of the high cable replacement costs. Export and array cables can take up to 6 and 2 months, respectively, and cost between £25-50 million per export cable and £4-5 million per array cable. In 2016-2017, the DolWin 2 offshore grid connection project saw a £375 million loss of revenue due to defective cable joints onshore.
Products, processes and services
The development of new electrical and mechanical-based monitoring instruments promises to detect earlier signs of insulation degradation. This project will determine the suitability of frequency and time domain reflectometry or line impedance monitoring for this application. Following the project's successful conclusion, Monitra could look to offer new commissioning and operational testing techniques for DC cables to TOs that help evaluate cable health over long distances and identify signs of progressively deteriorating conditions.
