An energy management and communication system was developed as part of the InnoNet Joint Project “DEMAX” (Decentralised Energy and Grid Management with flexible Electricity Rates), sponsored by the German Federal Ministry of Economy.

The main component of the smart grid energy management system includes an ‘embedded system’ of the newest generation that allows internet based communication.

“In order to be able to use the generated energy locally, the supply and demand must be optimally matched. For instance, the energy generated by a photovoltaic system can be used directly for charging the electric vehicle. During peak load in the evening, the cogeneration can supply a part of the electricity demand,” explains Dr Christof Wittwer, Head of the Group Operation and System Controls at Fraunhofer ISE.

The smart grid energy management concept functions as follows:

Distributed grid-connected energy systems in smart grids require an efficient integration into a communications network. A conventional internet access is used for transacting the entire communication e.g. for billing, remote monitoring, process visualisation, etc. - without incurring any appreciable costs for data transmission.

For the connection between the smart meters and the smart grid system components, the researchers developed a standardised DEMAX gateway. From within a local network, the gateways communicate with the service providers through a central proxy server using secure data connections. The server can, for example, be installed in the transformer station of the low voltage grid. Then, all involved parties, e.g. measurement services providers, electricity suppliers and grid operators, are connected by highly available internet connections.

In practice, a superordinated virtual power plant operator can take over control of the energy generators and loads, or an indirect request is made by means of a variable pricing rate.

“In DEMAX, we realise an automated local optimisation of the operation where, in addition to weather and consumption prognoses, an innovative control algorithm also considers flexible pricing rates,” says Christian Sauer, responsible project leader at Fraunhofer ISE.

Together with the pricing system from the electricity provider EWS Schönau in Germany, an attractive tariff model is offered to private operators of co-generation systems. The energy management smart grid system is an economic, incentive-based operational system for loads and suppliers that also considers the charge condition of the thermal storage.

Here the work of the research partner Steinbeis Innovation Center – Embedded Design and Networking (sizeden) – on wireless communication including standardised components (MBUS RF with Open Metering System, OMS) as well as the concept of flexible electricity tariffs offered by the project partner EWS Schönau are equally shown to advantage, Fraunhofer ISE says.

With the development of an intelligent control module from the embedded hardware manufacturer SSV Embedded Systems, a link between decentralised cogeneration plant and a virtual power plant is made possible. As a specialist for virtual power plants and at the same time an electricity and stock trader, in.power GmbH contributes its expertise and its software platform in.power energy manager (i.pem) to the project. The project partner GÖRLITZ makes a substantial contribution to the project’s success with its know-how in the field of energy data acquisition and management, Fraunhofer adds.

At present, the consortium is testing the energy management smart grid system technology in a small distribution grid in Bad Bellingen, operated by the EWS Netze GmbH. The project results will be used to develop products and services for the market in cooperation with the industry.