Utilities around the world recognize the benefits of demand-side management (DSM) strategies and integrating distributed energy resources into power systems and electrical markets. Initiatives combining the benefits of these DSM programs with the advantages of information and communication technologies are enabling the effective growth of smart grids. An effective way to profit from linking all of these technologies is with a virtual power plant (VPP).
The French smart grid demonstration project Integration and Optimization of Distributed Generation, Demand-Side Management and Renewable Energies (known as PREMIO) is co-funded by the Provence-Alpes-Côte d’Azur (PACA) region. PREMIO integrates distributed energy resources (DERs) into a VPP, develops demand response, distributed generation and storage, and contains all the principal components of future smart grids. Furthermore, PREMIO addresses deficiencies in the reliability of supply in the PACA region of France.
Electricity demand in the PACA region is concentrated on the Mediterranean Coast and accounts for 80% of the total regional power consumption. Local generation capacity is only sufficient to supply less than 50% of the regional demand, thus the shortfall in electrical energy has to be imported from other regions.
A double-circuit 400-kV transmission line supplies the PACA region, and when the regional system is overloaded, the French transmission system operator may have to limit the load transfer through this circuit to prevent power outages. When power shortages occur, the local generating facilities are requested to increase their power output in accordance with their operating capacities. Particularly in the summer, an N-2 contingency is possible on this double-circuit 400-kV line because of forest fires. In this case, a 225-kV transmission line that often has insufficient load-transfer capacity is the only alternative circuit to supply the PACA regional load requirements.
Electricité de France Action Plan
Electricité de France (EDF) launched an action plan, called Energie Efficace, to secure the electricity supply in the PACA region by developing DSM strategies and integrating renewable energies. The objectives of the utility’s plan closely match those of the PREMIO project. EDF is a participant in PREMIO, which is led by Capenergies — an association of companies, research centers and training centers dedicated to low carbon-dioxide emission energy sources: energy efficiency, renewable and nuclear energy — in collaboration with three local and seven regional authorities, two research centers and EDF.
PREMIO was designed to test the control of various DERs in a local territory.
Its objective is to provide participants in the electricity market, or power system operators, the possibility of reducing their electrical consumption or increasing their generation, based on their needs or constraints.
One of the first smart grid projects in France, PREMIO is currently hosted by the city of Lambesc, but some DERs are located in two other nearby cities, Gardanne and Frejus. The PREMIO demonstration project brings lessons from the field to its project partners, enabling different stakeholders to identify potential technologies. They are then in a position to assess the advantages and disadvantages, participate in the development of standards, identify technical or functional gaps, and work with the drivers that will determine the shape and deployment of smart grids.
Additionally, EDF is a member of the Electric Power Research Institute (EPRI) and participates in its smart grid demonstration initiative. EPRI conducts regional demonstrations and supports research focused on smart grids and the integration of DERs. PREMIO is the host site supported by EDF and offers opportunities for research and collaboration, disseminating its findings throughout the international community.
The DER Integrated into PREMIO VPP
The goal of this VPP is to offer day-ahead and day-of (up to 30 minutes before) services for optimal load reduction from the perspective of an upstream operator. Note that PREMIO uses load reduction to denote either a decrease in electrical demand or an increase in generation. The VPP will respond to the needs of an upstream operator by controlling the different DERs connected to a single control unit.
To make an offer to the upstream operator, the control unit receives, or calculates, the individual capacity for the load reduction of each DER. The control unit also receives information from the upstream operator about the time periods when the operator will need more capacity. All this information, represented by a score and a color, converges into the control unit as an offer, optimized according to its critical periods, is then communicated back to the upstream operator. The control unit operator thus transmits the capacity of its portfolio, that is, its aggregated capacity for load reduction. Following the load-reduction request sent by the upstream operator, the control unit dispatches individual requests to downstream DERs by a process of economic optimization, taking into account both the DERs’ operating capacity and the host customers’ comfort constraints.
In theory, PREMIO allows the integration of all types of DERs. Nevertheless, taking into account present environmental restrictions and the partners’ ambitions to generate electricity through low carbon-dioxide emission resources, DERs are limited to controllable loads, renewable distributed generation and storage. Additionally, the DERs participating in PREMIO should be a pre-existing, mature technology compatible with the weather, energy sources, commercial activity and population. Seven DERs were selected:
- Cooling storage: Thermal storage for industrial and tertiary cooling applications — one system, Cristopia Energy Systems
- PAC: Hot-water tanks coupled with heat pumps to provide load shifting in residential homes — six systems, EDF
- Microscope: Domestic electric storage units coupled to photovoltaic panels — 22 systems, EDF
- Optilesteur: Load-shedding modules dedicated to residential and small tertiary buildings — 12 systems, EDF
- Pulssi: Load-shedding boxes for residential homes and apartments — six systems, Watteco
- Public lighting: Adapted light-emitting diode-based public lighting — 10 systems, Watteco
- Solar thermal: Small solar thermal power plant with thermal storage — one system, Sophia Antipolis Energie Devéloppement (SAED).