This Network Capacity project was commissioned to: assess the feasibility of using new technologies to enable the installation of significantly increased levels of renewable energy sources in the UK and provide recommendations identifying possible technology development intervention opportunities derived from the analysis. The technologies considered in the project included: a range of power electronic based conversion systems and active network management techniques, reactive power compensation technologies, multi-terminal HVDC systems, and the feasibility of incorporating multi-terminal HVDC into the existing UK electricity network.
High level findings:
There are a number of important issues in the onshore grid system that is a function of the grid network, rather than the technologies themselves.
New wide band-gap materials such as silicon carbide (SiC) andgallium nitride have the potential to deliver increased power electronic device voltage ratings, reduced switching losses, and raised operating temperatures. This has the potential for significant impact on the cost and performance of power electronic converters.
The deployment of TCSCs on selected transmission corridors in the UK may improve the grid system’s ability to recover to stable operation following selected (unplanned) double circuit outages.
In some circumstances, HVDC transmission can provide benefits by enabling long distance power transmission, eliminating reactive power flows from long HVAC cable circuits and enabling asynchronous system connections.
The conversion of selected transmission corridors from AC to HVDC may improve the grid system’s ability to recover to stable operation following selected (unplanned) double circuit outages
Multi-terminal HVDC (necessary for embedding DC interconnectors in a meshed system) is feasible with both LCC and VSC technologies.
For a given transmission tower (‘pylon’) size significantly more power can be transmitted on a DC circuit than on an AC circuit (typically two to three times).
There appears to be no benefit case for converting individual transmission lines in the UK Grid to HVDC to gain additional transmission capacity
A total of 26 specific technology opportunity areas were identified by the project consortium as worth further examination by the ETI.