The characteristics for distributed generation (also called DG), is that the power plants have installed low capacity related to conventional power plants. Hydro plants between 100 kW and 5 MW (and sometimes even up to 10 MW), are often denoted as "small scale".
To this time the generation of electricity has mainly be performed by large power plants. The development of more renewable energy increases the share of smaller production plants. Such plants are often connected to the distribution grid, and even on the customer level. A customer with a PV (photovoltaic) panel on the roof, and that in a limited number of hours during the year, feed electricity into the grid, is denoted as a "prosumer".
Increased volume of distributed generation and power flow both to and from a customer, involve technical challenges that require focus related to system and voltage stability, connection conditions, planning and operation of the distribution grid.
SINTEF Energy Research has through previous and ongoing research projects established knowledge related to distributed generation – both for small hydro plants and prosumers.
SINTEF Energy Research has developed best practices for connecting small-scale hydro plants. Research has been performed on different alternatives to grid reinforcement when connecting new production, to reduce the need for costly and resource-demanding grid reinforcements. Special focus has been given on voltage control with use of the voltage control in the small-scale hydro plants, tap changes in the transformer, and the interaction between these. Related to new requirements for transient stability in small-scale hydro plants (Network codes), testing of transient stability in small-scale hydro plants are tested with use of the mobile short circuit laboratory, DIP LAB.
Prosumers are a relatively new concept in the distribution grid, and research in this topic will contribute to improved knowledge for the energy business, securing that the integration of the increasing number of prosumers in the distribution grid are performed in a cost efficient and rational way. This includes among others, connection specification for prosumers, establishment of methodology for load and generation profiles for prosumers and how the DSOs should take the prosumers into consideration when planning existing and new distribution grids.
The prosumers and PV panels are important resources for the rest of the power system, especially related to how flexibility in the consumption and introduction of energy storage can contribute as balancing services for distributed generation, and to improve security of supply and quality of supply in the distribution grid.
