MTVN: Multi-Terminal VSC-HVDC Networks - Grid Control

Reliable electricity supply forms a one of the basic requirements of modern 21st Century life. Sustaining this reliable supply is one of the key challenges for the coming decades. A solution is not straight-forward and will have many parts. Integrating offshore wind energy generation as cheaply as possible is one part. Linking our electricity transmission network to the generation and services of other European countries is another part. Reinforcing the onshore electricity network to cope with new power flows, is a further part.
Addressing these challenges requires an offshore electricity network, which is controlled to support our existing infrastructure. Such an offshore network disrupts far less of the onshore countryside and living environment than conventional onshore solutions. Enabling this necessary offshore network is the goal of this proposal. The technology needed to achieve such a solution is so-called Voltage-Source High-Voltage DC Transmission (VSC-HVDC): DC connections using converter stations with the latest state-of-the-art, high-voltage semiconductor power processing technology. Only such stations have the required flexibility, compactness offshore and ability to transmit power over long sub-sea cables. However our experience with such technology is limited to point-to-point systems. No small networks (so-called multi-terminal systems) have been built. No large networks (so-called DC grids) have been constructed. Very little research has been published into how to control such systems. There is a dearth of information on how to make large offshore networks 'work'. However many industrial and academic organizations have highlighted the substantial potential benefits in terms of reduced cost, improved reliability and greater functionality which could be offered by such DC offshore networks to our existing electricity infrastructure.
This project will undertake the research urgently required to assess the best way to control and mange such networks. Since telecommunications, controller architecture and control are intimately linked, research to assess and include the impact of these constraints will also be incorporated. Candidate networks will be formulated, analyzed and simulated using state-of-the-art models. These models will be improved to include the effects of distributed control and telecommunications effects/Quality of Service. New techniques will be developed that allow similar benefits to 'perfect' (idealized Master) control to be achieved with more realistic distributed hardware systems.
The transformative goals of this project are thus:
1. To establish how Master and Distributed Master controllers can improve VSC-HVDC-grid performance and offer robust and reliable services to AC onshore networks.
2. To investigate advanced controls, and effective exploitation of state-of-the-art and developing telecommunication technologies, to integrate this control with local station control and to overcome conventional operational speed limitations.
Better system understanding, models, and improved control will result. This in turn should allow the creation of a cheaper, more effective offshore network.

The principle impact of this project will be the thorough assessment of the benefits accruing from multi-terminal control of large DC networks compared with traditional local only control. This will significantly inform multi-terminal design, investment decisions in future networks by transmission utilities and design decisions by manufacturers. It will also influence grid code development and system regulation decisions.

The project is also expected to generate IP in the form of new control algorithms and methodologies. This will be protected and developed through the intellectual property management arm of the University of Manchester (UMIP) either in the form of licensing, or should sufficient novelty arise, as potentially a spin-out company in partnership with project sponsors.

The investigation of how such control can affect the robust operation of HVDC networks and AC networks, will significantly influence policy decisions in the UK, Europe and beyond as such HVDC connections are developed. The assessment of the degree to which gaming could take place, has a major impact on the markets and international cooperation treaties which need to be negotiated prior to the creation of such a combined market and network structure. This work is thus important and extremely timely.

The potential expenditure on offshore VSC-HVDC networks is up to £30billion in just the UK, and just in the foreseeable future. Savings of up to one third (Peter Jones, ABB) as possible for getting the system 'designed right.' Making the right networks design decisions is important - this proposal aims to ensure that the appropriate research as regards high-level control and operation is available to inform such decisions.