Researchers from the University of Southampton have devised a novel method for forming “virtual power plants” – from the small and distributed energy resources (DERs), like wind farms, solar panels, small hydro and others that have begun to appear in greater numbers in the electricity supply network or the “Grid”.
To make sure energy demand is met without interruptions, the Grid requires power suppliers to provide an estimate of their production and the confidence in meeting that estimate. The Grid depends on the confidence placed on the estimates, making it possible to choose the appropriate generators needed to produce and supply energy whenever it is needed. The more accurate the provided estimates, and the higher the confidence placed in those estimates, the better for the Grid scheduling activities.
Those DERs in mass deployment can reduce reliance on conventional power plants. But their integration into the Grid is problematic since the DERs, given their small size, are largely ‘invisible’ to the Grid. Even if they are visible, the uncertainty, intermittency and uncontrollability of renewable energy sources makes it difficult for individual DERs to participate in the wholesale electricity market because they are often unable to meet the set generation targets or profitably deal with the Grid operators directly.
Virtual Power Plants (VPPs) are fast emerging as a suitable means of integrating DERs into the Grid. They are formed via the aggregation of a large number of such DERs, enabling them to reach similar size and supply reliability as conventional power plants.
University of Southampton researchers have ready a new study to promote the formation of ‘Cooperative’ VPPs (now CVPPs) using intelligent and multi-agent software systems. The major interest is they designed a payment mechanism that encourages the DERs to join CVPPs with large overall production.
Dr. Valentin Robu, from the University’s Agents, Interaction and Complexity Research Group, who worked on the study explains, “There is considerable talk about how to integrate a large number of small, renewable sources into the grid in a more efficient and cost effective way, as current feed in tariffs, that simply reward production are expensive and ineffective. CVPPs that together have a higher total production and, crucially, can average out prediction errors is a promising solution, which does not require expensive additional infrastructure, just intelligent incentives.”
Using a mathematical technique called “proper scoring rules” (a scoring rule, is a measure of the performance of an entity, be it person or machine, which repeatedly makes decisions under uncertainty), intelligent software agents, and representing the individual DERs with a payment system, makes worthwhile incentives to report accurate estimates of their electricity production.
The Southampton researchers devised the scoring rules-based payment mechanism that encourages providing accurate predictions from the CVPPs – and in turn, the member DERs – which aids in the planning of the supply schedule at the Grid. The mechanism guarantees that DERs are rewarded for providing estimates that are both accurate and have a high confidence, ensuring that software agents are given credit for high probability estimates that are close to the realized ones.
Dr. Robu fills the idea out with, “Scoring rules with specific incentive properties have long been used to design payment mechanisms that incentivise agents to report private probabilistic predictions truthfully and to the best of their forecasting abilities. We show that our mechanism incentivises real DERs to form CVPPs, and outperforms the current state of the art payment mechanism developed for this problem.”
The Southampton researchers collected half-hourly wind-speed data for a 10-week period from 16 commercial wind farms in the UK in order to validate their approach.
The team, Valentin Robu, Ramachandra Kota, Georgios Chalkiadakis, Alex Rogers, and Nicholas R. Jennings presented their paper “Cooperative Virtual Power Plant Formation Using Scoring Rules” this past Tuesday at the Association for the Advancement of Artificial Intelligence conference, in Toronto, Canada.
The team’s work will be welcome from both the Grid operators and a lot of alternative energy enthusiasts.