WP6: Network Interaction of Marine Energy

The aim of work package 6 was to quantify the interaction of future marine energy converters with the onshore distribution network and to identify means of mitigating their impact to allow greater access to the electricity market.

To carry out network studies, the transmission network across Scotland and the distribution network in resource-rich areas were modelled. The latter included Orkney/Northern Highlands with wind, wave and tidal resources and Lewis/Harris with a strong wind resource and a high potential for wave power developments. With existing and consented renewable projects, these areas offer the prospect of a high penetration of time-varying electricity generation. The traditional static method of checking that network conditions remain acceptable for a maximum demand winter case and a minimum demand summer case does not identify the coincidence of renewable energy production from differing sources or relate that to demand variation. Probabilistic methods contain limited knowledge of correlation between the renewable energy production and demand. A new approach using historic time series was investigated. These power time series were created from measurements and hindcast records (for wind, wave and also demand) or directly calculated (for tidal current) for a period in the past and applied to existing or future generation scenarios. The results of multiple power flow analyses, with hourly time steps over a period of several years, were then analysed statistically, to obtain both typical and extreme values for the network conditions.

Loading duration curves and the benefits and limitations of generator curtailment were produced from the above. This work package has shown that time series analysis has advantages which would help a network operator in generation planning, strategic network reinforcement and improved asset management. The need for balancing generation has been emphasised, and the extent to which this could be done with hydro and diesel capacity has been identified.

A novel means has been developed to explore the synergies between wind, wave and tidal current energy resources and to explore their aggregate network impact over time.