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Hybrid Renewable Energy Systems

Photovoltaic and Wind power have made spectacular gains in the last 10 to 15 years, with both forms of RE being a common sight in most countries. As noted by some there are issues with having a high concentration of intermittent generators attached to the electricity grid. One fortunate observation has bene the complementarity of solar and wind i.e. when solar is poor, wind power tends to be good and vice versa. Furthermore, there is the possibility of building 'hybrid' plants where the solar and wind are collocated very readily. The final piece of the puzzle is the use of energy storage to both act as a buffer for the short term variability in generation, and to allow arbitrage with respect to sending electricity to the grid. The last part is important as solar peak generation is typically in the middle of the day while peak demand is in the morning and early evenings. Energy storage allows the electricity being generated by solar (or wind) to be time shifted.  

We have been looking at the use of weather forecasting, allied with machine learning approaches to help optimise the design and operation of hybrid renewable energy systems that have energy storage. Due to our collabporation with Dr Chris Menictas, in the School of Mechanical Engineering, an expert in battery technology, we have focused on the use of battery energy storage systems (BESS). Below is shown a simple diagram to indicate how the RE systems work to supply electricity to the grid. Using an assortment of heuristic approaches, including neural networks and ARIMA, different planning strategies can be implemented, including hour ahead, day ahead, and a constantly updating approach that combines the two - receding horizon. Interestingly it is extreme days, where price spikes take place, due to the grid being under stress, that provide the most value for RE systems in these scenarios. Further work is continuing looking at the impact of the weather forecasting on battery operation and the impacts of expected climate changes in the future to RE generation and the need (and suitability) of battery storage. 

There is still plenty to understand in this exciting area of research!  

Some recent papers we have had published:

Impact of forecasting error characteristics on battery sizing in hybrid power systems,

Y.Yang, S. Bremner, C. Menictas, M. Kay

Journal of Energy Storage, 39, 102567, 2021

A Mixed Receding Horizon Control Strategy for Battery Energy Storage System Scheduling in a Hybrid PV and Wind Power Plant with Different Forecast Techniques,

Y. Yang, S. Bremner, C. Menictas, M. Kay

Energies, 12(12), 2326, 2019.

Battery energy storage system size determination in renewable energy systems: A review,

Y. Yang, S. Bremner, C. Menictas, M. Kay

Renewable and Sustainable Energy Reviews91, 109-125, 2018.

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