Initial designs for ANGLE-DC project: challenges converting existing AC cable and overhead line to DC operation

DC technology has gained considerable interest in the medium voltage applications due to the benefits over the AC counterpart. However, to utilize the full capacity of this development, the selection of a suitable power electronic converter topology is a key aspect. From the pool of voltage source converters (VSC's), it is unclear which topology is suitable for multi-megawatt applications at medium voltage dc (MVdc) levels. To address this, the paper proposes a selection guideline based on reliability and optimum redundancy levels of VSCs for MVdc applications. This will be combined with other functional factors such as operational efficiency and return-on-investment. Three candidate multi-level topologies namely three-level neutral point clamped converter (3L-NPC), modular multi-level converter (MMC) and cascaded 3L-NPC (which is being used for the first MVdc link in the UK) have been evaluated over two-level-VSC from ±10 kV to ±50 kV. Results show that with the increase of MVdc voltage level MMC shows better performance whereas at low MVdc voltage levels 3L-NPC is the prominent topology.

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“…It comprises of 12 cells (pole-topole), each of which is a 3L-NPC. Each cell is rated for 2.55 MVA with the dc-link voltage of 4.5 kV [28].…”

Section: Mvdc Vscs and Reliability Requirementsmentioning

confidence: 99%

Reliability and Cost-Oriented Analysis, Comparison and Selection of Multi-Level MVdc Converters

Abeynayake

Joseph

et al. 2021

IEEE Trans. Power Delivery

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“…Similar implementations are being studied for various projects where transmission capacity expansion is a requirement [36]. Similarly, AC asset conversion is taking place in a pilot project "Angle-DC" in Wales by ScottishPower to convert a 33 kV AC line into ±27 kV Medium-Voltage DC operation with a similar goal of maximizing the line capacity in response to the surging electricity demand [37]. This introductory section serves to illustrate the potential and capabilities of DC transmission as a serious competitor to AC transmission in various applications.…”

Section: Conversion Of Hvac Lines To DC Operationmentioning

confidence: 99%

HVDC Transmission: Technology Review, Market Trends and Future Outlook

Alassi

Bañales

Ellabban

et al. 2019

Renewable and Sustainable Energy Reviews

305

104

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HVDC systems are playing an increasingly significant role in energy transmission due to their technical and economic superiority over HVAC systems for long distance transmission. HVDC is preferable beyond 300-800 km for overhead point-to-point transmission projects and for the cable based interconnection or the grid integration of remote offshore wind farms beyond 50-100 km. Several HVDC review papers exist in literature but often focus on specific geographic locations or system components. In contrast, this paper presents a detailed, up-to-date, analysis and assessment of HVDC transmission systems on a global scale, targeting expert and general audience alike. The paper covers the following aspects: technical and economic comparison of HVAC and HVDC systems; investigation of international HVDC market size, conditions, geographic sparsity of the technology adoption, as well as the main suppliers landscape; and high-level comparisons and analysis of HVDC system components such as Voltage Source Converters (VSCs) and Line Commutated Converters (LCCs), etc. The presented analysis are supported by practical case studies from existing projects in an effort to reveal the complex technical and economic considerations, factors and rationale involved in the evaluation and selection of transmission system technology for a given project. The contemporary operational challenges such as the ownership of Multi-Terminal DC (MTDC) networks are also discussed. Subsequently, the required development factors, both technically and regulatory, for proper MTDC networks operation are highlighted, including a future outlook of different HVDC system components. Collectively, the role of HVDC transmission in achieving national renewable energy targets in light of the Paris agreement commitments is highlighted with relevant examples of potential HVDC corridors.

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“…MVDC links are only beginning to be used 37,38 , so our data was sourced from a demonstration project, the ANGLE-DC project, where an MVDC link will connect the Isle of Anglesey to mainland North Wales [39][40][41] . The proposed link will operate at ±27kV DC and connect two 33kV AC networks, with converter ratings of 30MVA.…”

Section: Model Negotiation Rules and Scenariosmentioning

confidence: 99%

A general form of smart contract for decentralized energy systems management

et al. 2019

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Smart contract platforms have the potential to allow shared automatic control of energy transfer within networks in a replicable, secure, verifiable and trustworthy way. Here we present a general form of smart contract which captures the elements needed for shared control that will help formalise decentralisation. Two mechanisms were defined for agreement of control instructions for a Medium Voltage Direct Current (MVDC) link connecting two separately operated 33kV distribution networks. These were instantiated as smart contracts and were evaluated in terms of cost and the computational requirements for their execution. Real network and converter data from the ANGLE-DC demonstration project were used to model the MVDC link. We demonstrate that using smart contracts to agree control instructions between different parties is feasible. The potential for shared control using smart contracts gives operators and regulators a way of defining and decentralising operating responsibilities within energy systems. 2 Main An energy system can be described as a collection of distinct networks, sources, sinks, their corresponding responsible parties, and the associated physical and information flows 1,2. The information flows come from monitoring physical processes (e.g. voltage and current at a transformer) and decisions made by individual actors 3. Information exchange interfaces are the mechanism by which information is passed between different responsible parties 4. The complexity of energy networks is forecast to increase with higher volumes of information and numbers of controllable components 5. When accompanied by decentralisation of responsibilities, this will lead to the creation of more information interfaces, or mean that more information must be processed at existing interfaces. An example of this, in electricity networks, is the possible transformation of Distribution Network Operators (DNOs) to Distribution System Operators (DSOs) in Great Britain (GB) 6,7. As part of the transition, more localised balancing responsibility would be given to DNOs 8,9. This would lead to a requirement for more complex agreements at interfaces (e.g. between two distribution networks or between a distribution network and a transmission network) as neighbouring parties will rely more on the predictable behaviour of adjacent networks 10. This leads us to ask what standardised rulesets at the interfaces between responsible parties, if any, would make the operation and planning of energy systems more secure and lower cost. The emergence of smart contract platforms (often under the rubric of Distributed Ledger Technology 11 or Blockchain Technology 12), brings the opportunity to securely automate many of the procedures that take place at interfaces and potentially to lower the whole system cost 11. The concept of smart contracts, self-enforcing agreements in the form of executable programs 13 , originating with Szabo in 1994 14 , provides a means of setting out negotiation and self-enforcing settlement rules that operate with a high degre...

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Initial designs for ANGLE-DC project: challenges converting existing AC cable and overhead line to DC operation

Cited by 13 publications

References 1 publication

Reliability and Cost-Oriented Analysis, Comparison and Selection of Multi-Level MVdc Converters

Reliability and Cost-Oriented Analysis, Comparison and Selection of Multi-Level MVdc Converters

HVDC Transmission: Technology Review, Market Trends and Future Outlook

A general form of smart contract for decentralized energy systems management

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