INTERFLEX, or how to achieve grid complementarity

On 14 December 2018, the City Council of Carros in the Alpes-Maritimes region, in partnership with GRDF, installed a rooftop hybrid system on the roof of the Planet gymnasium. This impressive operation enables the Nice Smart Valley project to experiment hybrid flexibility, one of the three use cases developed in this project, the French brick of the European INTERFLEX project!

The Carros gymnasium is now equipped with a product which operates both on electric power and gas power, and provides heating in winter and cooling in summer.

(Watch the video)

The objective of this rooftop system for the Nice Smart Valley project?

To relieve the electricity grid without any constraint for the gymnasium users. This is 85 kW of flexibility on which the Nice Smart Valley project can count thanks to the complementarity of the gas/electricity networks!

For the gymnasium users, this flexibility is achieved transparently, without any change in comfort, because heating continues to be provided.

The role of GRDF in Nice Smart Valley?

Within the framework of Nice Smart Valley, GRDF is experimenting gas/electric flexibilities. To do so, it was first necessary to identify sites which could receive these flexible products, and convince the owners or managers of the potential benefits of this project.
Several devices were therefore deployed from western Nice to the Var plain to experiment flexibilities:

  • 10 hybrid boilers each of 1.5 kW electrical capacity in detached houses;
  • 1 rooftop hybrid system of electrical capacity 88 kW in a gymnasium;
  • 1 mini-cogeneration system of electrical capacity 70 kW in a service-sector building.

The boiler experiment began on 1 July 2018 and the rooftop experiment on 15 January last, while the cogeneration plant experiment will begin on 1 February 2019.

In addition to this initial phase of site “recruitment”, GRDF worked on the development of a communication chain to control these devices at a distance. The systems deployed operate normally from a perspective of energy optimization. Here we have installed a specific control system capable of switching from electricity to gas according to the electricity grid’s constraints. In future, the flexibilities will be valued for the end user who could be remunerated for the service rendered to the electricity grid. Moreover, one of the objectives of the demonstrator is to define the value of these flexibilities.

How does it work?

When a constraint is detected on the electricity distribution system, Enedis makes a request for flexibility to the project aggregators (ENGIE and EDF). This request comprises a source substation and a need expressed in kW for a given time. Each aggregator has an aggregation portfolio in which the various flexibilities appear. The communication chain developed by GRDF can produce a link between the aggregator and these flexibility solutions. At a distance, without intervention by the end user, the aggregator can thus switch the hybrid systems from electric power to gas power or start up the cogeneration plant.

The rooftop system and three hybrid boilers out of the ten installed are reversible. In summer, the aggregator can also decide to suspend cooling. This is the only case in which the end user’s comfort is altered. However, the discomfort is limited to 2°C. For example, when the predetermined temperature setting is 28°C, the hybrid boiler can be stopped remotely, but it is restarted as soon as the indoor temperature reaches 30°C.