As the need for flexibility grows with the growing penetration of renewable energies and particularly at the distribution level with behind the meter solar PV and storage and electric vehicles (EVs), the need for market models to value and deliver that flexibility is likewise becoming more pressing.
Numerous initiatives are under way within Europe and elsewhere to build the technologies and models that are required, with a key one the Horizon 2020 supported InterFlex. As an evolution from the earlier Grid4EU project it reflects the complexities and effort that is involved.
One of these is that at the distribution level the need for flexibility is very localised. InterFlex, now in its third and final year – the results due for presentation on 28 November – has been implementing technologies and solutions in real-world settings to investigate the ‘inter’actions between ‘flex’ibilities on a local scale.
The project is focussed around six industry-scale demonstrations led by the respective distribution system operators (DSOs) in five countries – France with Enedis as project coordinator, Czech Republic with ČEZ Distribuce as technical director, Germany, The Netherlands and Sweden – thereby enabling insights under varying energy market models and conditions. Technologies under test include energy storage, electric vehicle smart charging, demand response, islanding, grid automation and the integration of different energy carriers including gas, heating and cooling.
The six demonstrations were selected to test different combinations of technologies and are well under way.
Nice Smart Valley, the French demonstrator led by Enedis, is located in Nice and is investigating flexibilities to support the grid, storage systems and automatic islanding operation. Among recent progress, the first successful islanding tests have been carried out on the Lérins Islands, with the distributor’s storage system stabilising the MV network on two islands independently from the main distribution grid. With that completed, a second storage system is set to come on line to act as a grid supporting unit.
The Czech demonstrator led by ČEZ Distribuce, located in several areas of the country, is using grid automation and energy storage to integrate decentralised renewable energy within the distribution grid and smart functions of EV charging stations as a source of flexibility.
The German demonstrator led by Avacon is located in a rural area between Helmstedt and Salzgitter in central Germany and has comprised development of a centralised ‘smart grid hub’ to coordinate flexibilities and distributed resources to relieve local grid constraints. Key is connection to the country’s national smart meter framework along with connection to the distributor’s grid control SCADA and with these completed, precise curtailment of residential solar PV generation and control of domestic heaters including heat pumps and night storage units has been demonstrated.
The Swedish demonstrator led by E.ON is in two parts. The first, located in Malmö, is investigating use of the heat inertia of buildings as a flexibility measure to optimise district heating production and distribution. A key criterion is customer comfort and the solution developed restricts temperature changes to only +/-0.5oC.
The second, located in Simris in southern Sweden, is focussed on islanding a portion of the distribution grid with a 100% renewable powered microgrid. With customer involvement, islanding times are being increased.
The Dutch demonstrator led by Enexis is located in Eindhoven and is developing a multi-service approach to unleashing local flexibility including stationary storage and EVs through interaction between the DSO, balance responsible party and EV charge point operators. Initial analysis shows that the stationary storage can be a more reliable source of flexibility than EVs but may not be the most cost-effective option and an optimum model is being evaluated.
“Overall the different demonstrations are testing different flexibilities for different DSO needs,” says Grégory Jarry, who is responsible for dissemination at Accenture.
The demonstrators can be further categorised into two broadly different approaches for flexibility procurement – the integrated approach, as in Germany and Sweden, in which the DSO procures directly from providers through a dedicated platform via legal or contractual agreements, and the market approach, as in France and Netherlands, in which procurement is via aggregators.
“These both have a place but ultimately the approach that is adopted must comply with the country’s regulatory, business and other specificities.”
Guaranteeing service quality
While the flexibility models are advancing in the demonstrations, findings to date also have thrown up some remaining challenges.
One is how to make flexibilities readily available and accessible within the timeframes bound to DSO needs. Another is how to deal with the risk of mismatched or lacking offers and linked to that the potential competition between different value pockets, for example between the local needs of DSOs and national needs of TSOs.
“Regulation and market mechanisms need to reach a sound equilibrium,” says Project Coordinator Christian Dumbs.
Arguably the biggest challenge is to find the economic match between supply and demand, which is key for a viable market model. On the demand side the key factor is the DSO’s willingness to pay, which would depend on the cost savings that flexibility would bring. On the supply side the minimum price for flexibilities is set by the aggregator’s expenses to access them, which in turn depends on factors such as the market size, standardisation of products and tools and interactions with other markets.
“There are still regulatory and market design issues that need to ironed out,” Dumbs says. “We are making progress but still have a long way to go.”