It is encouraging to see real transformational change in the energy industry in Ireland. There is now a clear message of commitment and positive leadership in the form of the Climate Action Plan and a target of 70% renewable electricity by 2030. However, we need to be cautious as there are clear barriers to delivery in the form of grid deployment and access to grid capacity.
What is Dispatch Down?
For the avoidance of doubt, dispatch down refers to the combined levels of constraint and curtailment. Curtailment relates to situations where the output of generators may be reduced to keep the overall power system secure and is carried out on a pro rata, all island basis.
Constraint, on the other hand, relates to local transmission network limitations, specifically the overloading of transmission lines, cables and transformers and can be considerably different depending on where a generator connects. Constraints can be significantly reduced by transmission network reinforcements.
All-island Yearly Dispatch Down, Curtailment & Constraint (source: EirGrid)
So how can a new generator have any certainty about the commercial viability of their project when entering into the development pipeline? Without understanding the potential constraints facing their connection, developers will need to price this risk into their RESS bid model. This may result in too high an offer price for their generator, resulting in an unsuccessful bid in RESS or the other extreme, bid in too low a price that won’t end up covering return on investment.
Managing the Risk Better
As part of the connection process, EirGrid issues Area specific constraint reports. The analysis looks at a number of broad scenarios over a three-year period and also a future grid scenario which considers the impact of additional major reinforcements. It is not feasible for EirGrid to assess all combinations and permutations for every node on the network when carrying out constraint analysis.
Looking at an array of sensitivities dealing with different connection build-out rates, potential delays in network reinforcements or even additional bulk load growth can tell a very different story for a specific connection. Tailoring constraint analysis can help manage risk and reduce uncertainty when assessing the viability of a project.
Bespoke Constraint Analysis
TNEI has developed a modelling tool to perform network constraint analysis. This tool offers flexibility when calculating the MWh and percentage of wind power reduction, based on a whole-year hourly simulation which includes unit commitment, generation dispatch, calculation of branch and nodal sensitivities, contingency analysis and the minimisation of renewable power reductions.
This in-house tool has been benchmarked against EirGrid’s own published figures. This gives confidence that scenarios and sensitivities studied by TNEI, specific to a particular connection, are robust, dependable and can help form a meaningful assessment by the developer of the actual cost, potential financial loss due to constraints and best approach to trying to manage the risk.
Sensitivities in Action
Let’s take an example; TNEI independently and accurately reproduced the figures published by EirGrid in the ECP-1 Area A Constraints Report, based on the same assumptions. The “Initial Scenario 2022″ for a node in Donegal showed potential constraints of 9%. TNEI carried out sensitivities in subsequent study years, assuming reinforcements based on latest ATR delivery dates and local generator connection build-out.
It was found that in 2024 constraints would potentially increase to 13.5%, due to the increase of generation connections. However, by 2028, due to key reinforcements being delivered, the constraint levels reduce to nearly 8%. This demonstrates that carrying out targeted analysis can show the impact other generator connections and/or various reinforcements can have on the constraint levels at a particular node. It can also indicate how long potential constraints maybe in place and the key tiggers to either increasing or decreasing those constraints.
Bespoke constraint analysis, that is proven to be dependable, can help reduce risk regarding the financial feasibility of generators in the coming years when there is so much uncertainty regarding grid role out and further policy reform. The TNEI team is well placed to provide you expert support and advice regarding constraint analysis, contact us for more information.
