Grid control of renewable power
The rise of distributed renewable energy sources (DRESs) places the secure operation of national electricity grids under great strain. The problem is bidirectional power flow, which electricity suppliers must control in order to provide service at acceptable quality and cost. The EU-funded INCREASE (Increasing the penetration of renewable energy sources in the distribution grid by developing control strategies and using ancillary services) project offered management solutions. The work addressed management of renewable energy sources in low- and medium-voltage networks. The purpose was to allow ancillary services, especially voltage control and provision of reserve capacity. Researchers developed a simulation platform that enables development of solutions and assessment of the solutions on congestion. The platform further permits study of the influence of DRESs on distribution networks. The team studied regulatory frameworks, grid code structure and ancillary market mechanisms. As a result, the group proposed adjustments that allow ancillary services necessary for effective operation of the grid, including flexible market products. Recommendations included a three-level approach for maximising the integration of renewables. The first level uses local parameters for control, ensuring system reliability and stability. A second level of control yields an optimal system, minimises the loss of renewable energy and ensures fair distribution. Second-level control would depend on a multi-agent aggregator concept, plus coordination of control and inverter systems to control congestion. The final level was the service layer. Project recommendations achieve optimisation via several strategies, resulting in flexible energy products able to provide ancillary services. The control mechanisms include a traffic light system that gives distributed system operators control over schedules. The project’s solutions mean more efficient exploitation of grid capacity, allowing higher DRES penetration at reduced cost. Researchers verified the recommendations via simulation, laboratory testing and field trials in Belgium, the Netherlands, Austria and Slovenia. Results from INCREASE solve the growing problem of distributed energy resources on electricity grids. They also mean improved stability and lower costs.
Keywords
Bidirectional power flow, distributed renewable energy sources, INCREASE, distribution grid
