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Traditionally, electricity supply is one-directional. Electricity is generated centrally and flows outwards, through the national grid, to homes, factories and businesses. However, driven by environmental concerns, more renewable energy is increasingly generated locally – from wind turbines in fields to solar PV panels on individual homes. These distributed renewable energy sources (DRES) bring new technical and regulatory challenges.
The technical challenges include connecting a large number of small generation units to the distribution grids. With many DRES – which are also intermittent as they depend on the wind and sunlight – congestion may become a problem. Electricity flows are more variable and no longer one-directional – a sophisticated management system is needed to avoid overload and power failures.
The EU-funded SUSTAINABLE project developed tools to deal with these challenges. By leveraging information from smart meters, weather forecasts and historical demand data; the project demonstrated an efficient and cost-effective management system for distribution systems that will enable the large-scale incorporation of DRES into smart electricity grids.
“SUSTAINABLE and other related EU projects confirm we have the technology to manage complex smart grids at distribution level,” explains project coordinator Pedro Godinho Matos of EDP Distribuição Energia in Portugal. “We have also shown that, although more complex and with more players, our solutions can be commercially viable – which is important for more competitive energy markets, more efficient energy usage and a low carbon economy based on renewables. However, the pace of policy and regulatory innovation is slow and now needs to up its game to meet the enabling advances in grid technology.”
Empowering the grid
National grids comprise a national transmission system operator managing the long distance, high-voltage supply; and several distribution system operators controlling the lower voltage, regional distribution of power to towns, factories and homes.
As many new DRES supply energy into the distribution grids, distribution system operators must play an enhanced role in managing an increasingly complex and smarter grid. SUSTAINABLE focused on the distribution system operators level and developed the tools to move these from a ‘connect and forget’ approach to a new ‘connect and manage’ paradigm.
The project made proposals for the conditions needed for the roll-out of new technologies, for example on the wider market use of smart meters, a new regulatory framework to empower distribution system operators to implement the necessary changes and incentives for innovation.
The project’s recommendations are feeding into the EU and national energy policymaking process and are being assessed by the European Distribution System Operators' Association for Smart Grids (EDSO), says Matos.
Tools to connect renewable technologies
The SUSTAINABLE solution is based both in a better management of the existing grid infrastructure and the integration of newly-developed smart elements. A field trial conducted in Évora in Portugal combined smart meter data with short-term weather forecasts to predict the DRES supply and consumer demand.
This improved forward operational planning for power system management, avoiding congestion and overload. Furthermore, this opens opportunities for smaller market players such as virtual power plants by giving them a role in supporting the grid.
Virtual power plants are usually commercial energy suppliers that aggregate many small DRES at the local level and sell their combined electricity onto the regional market. SUSTAINABLE research developed a ‘technical virtual power plant’ function in power management, which could integrate these suppliers.
Based on distribution system operators planning, a virtual power plant can help reduce congestion by re-adjusting the schedules of its DRES units – a vital service for grid stability at all levels. And importantly, this could be a commercial service that can boost the profitability and sustainability of small scale aggregators such as virtual power plants.
“The technical virtual power plant concept is an important SUSTAINABLE concept.” says Matos. “Grid operators are largely blind to events in low-voltage residential grids where an increasing number of DRES will be pumping power into the grid. The residential grid needs to become smarter and our work shows how this can be technically feasible and commercially viable. And this in turn will help ensure European environmental and energy security goals are realised.”.