What are Microgrids?

Microgrids are parts of the electricity grid that have a certain local intelligence for control. The sub-grid can cover a single area, a neighborhood or a larger area. Often, these are parts of the distribution grid (grid level 7), but grid level 5 can also be integrated. Microgrids can be used to ensure the power supply independently of the rest of the grid for a certain period of time (minutes, hours or days), for example in the event of a power outage. This option for self-sufficiency increases the security of the power supply in the affected area and distinguishes microgrids from the more general term «smart grid» (see also: Difference between smart grids and microgrids).

Autarky

To enable a microgrid to function autonomously when required, it includes not only electricity consumers but also (adjustable) electricity producers and often electricity storage devices such as batteries. Intelligent grid components (smart grid) ensure that the energy balance remains balanced and that voltage stability is guaranteed in the microgrid. Various techniques such as demand-side management (DSM), production control and/or storage management can be used for this purpose.

The intelligent network components that are necessary for controlling the microgrid lead to another major advantage: Irregularly feeding power sources, such as photovoltaic systems or wind turbines, can be integrated into the power grid more easily and at lower cost. Thanks to the formation of microgrids, a possible grid expansion is either completely unnecessary or significantly cheaper in many cases.

Future

Today, the integration of stochastic renewable energy sources in Switzerland is not yet a problem. However, if in the future significantly more electricity is fed into the grid from renewable energy sources, expensive adjustments to the grid infrastructure may be necessary to prevent individual grid components from being overloaded, which would endanger grid stability.

The power grids are very long-term investments. What will be necessary or cost-effective in 10 or 20 years should therefore be taken into account today. Our research group simulates power grids (grid levels 5 and 7) and finds optimal solutions for maximizing security of supply and cost-effective integration of renewable energies.

Research topics

• Optimal design of microgrid components for different levels of autonomy (hours, days or weeks)
• Simulation of grid sections for load flow analysis
• Control of production plants and energy storage
• Options for load limitation (demand-side management DMS)
• Short- and medium-term demand forecasts and production forecasts for electricity and heat

Competencies / Services offered

• Planning, implementation, support and evaluation of microgrid projects and microgrid studies
• Concepts and economic feasibility studies for the optimal integration of renewable energies into the existing grid
• Simulation of grid sections and development of special planning tools (using Matlab, Homer, Labview and R, among others)
• Analysis of possible load limitations in real grid sections