The shift from a centralized one-way electricity system is demanding a new architecture to manage and balance the grid with distributed energy resources including intermittent renewables and storage. [Engerati-Creating A More Open Interconnected Grid Architecture- NiceGrid’s Experiences]
This challenge was taken up by France’s distribution system operator (DSO), ERDF, in partnership with Alstom, in the Nice Grid project in the southeastern French city of Carros. With the potential for renewable energy the city has seen growing levels of solar PV, while with its location at the periphery of the country’s transmission grid, it is also challenged in winter due to the high peak demand for heating, explains Thomas Drizard, Nice Grid project engineer, in an Engerati webinar. [Engerati-Build your Microgrid learning from the NiceGrid experience]
New energy management architecture
The challenge: to develop an open architecture to manage these summer and winter constraints, and in particular:
• Optimize massive PV integration in the grid
• Test islanding of an LV district
• Test a 3.5MW load management
• Develop the ‘prosumer’ role of the consumer.
“We see Nice Grid with the integration of distributed energy resources at the local distribution grid node as the natural evolution of the further integration of applications into the control room environment,” says Laurent Schmitt, vice president Smart Grid Solutions, Alstom Grid, in the webinar.
In the webinar, Schmitt describes the new energy management architecture and Drizard presents the technical aspects of the Nice Grid project, which is also one of the six demonstrators in the Grid4EU initiative, and the first results from the new architecture.
Network energy manager
The approach is based on a transactive model and at its heart has a network energy manager (NEM), which balances demand and supply based on system flexibilities. Grid flexibilities are via battery storage, which is distributed along the grid. Residential flexibilities, particularly in the summer, include time-based tariffs and subsidies. C&I flexibilities, particularly in the winter, include public street lighting and industrial load.
In essence the NEM receives demand requests from the TSO and DSO and in conjunction with generation and consumption forecasts these are forwarded to aggregators, who in turn submit flexibility bids. In this case there are the three aggregators, commercial, residential and network storage, but the system is scalable so others can be added. Selection of the bids is via a bid ladder optimization.
Schmitt says that a new concept introduced is “commercial location”, which recognizes constraints such as congestion or voltage restriction in specific areas of the grid. He also highlights the need for visualization, with newly developed TSO and DSO user interfaces.
“The system has been demonstrated as a secure end to end application and is now live in ERDF’s IT environment,” says Schmitt. He adds that data exchanges are per the ENTSO-E CIM model, which conforms with the CEN-CENELEC-ETSI smart grid architecture for Europe.
Looking ahead, Schmitt says the Nice Grid consortium has decided to extend the project for a further year to focus on refining the cost-benefit analysis.
“We see the NEM as a future IT architecture for the operation of microgrids embedded within the distribution grid,” he says. He also mentions that while the focus so far has been on demonstrating management of the flexibilities, the intention is to develop a version 2 of the NEM to bring this management down to a real-time basis.