The coordination of generation, consumption and storage units as well as the mechanisms used to enhance the capacities of the local distribution grids targeted the integration of renewable energies to the largest possible extent. The field test in the Harz region set an emphasis on the marketing of bundled energy quantities generated from regionally available sources by means of a Virtual power plant (VPP) on different markets. In fact, the IEC-61850 Standards were further developed to ensure an easy and secure plug-and-play interface between generation, consumption and storage units and the virtual power plant’s control room.
This newly developed generic data model enabled an automated integration of the units into the overall energy management processes and scheduling of the virtual power plant. Hundreds of decentralized generation units already exist in the Harz region and their number is steadily increasing. In order for all of these small-sized generators to capitalise on their full potential in a Smart Grid, they need an interoperable interface. The RegModHarz consortium (in this case led by Siemens) has developed the so called PowerBridge. This product is based on the aforementioned IEC 61850 standard that includes DER interconnection. It enables the owners of the decentralized unit to offer their energy services and products to the Smart Grid. On the other hand, the PowerBridge enables the grid to access the offered services and to optimally integrate the units’ variability into its network operation. In fact, the energy management system (EMS) works for generation as well as consumption and storage units and leverages benefits for the market/ economic optimization of utilities and the network management.
While the entire ICT-infrastructure was implemented during the field trial phase in summer 2012, six different decentralised units (two photovoltaic plants, two wind generation units, a biogas plant and a fuel cell) received schedules they had to implement, in order for the virtual power plant to be able to market the aggregated energy bundles at a simulated EPEX-Day ahead and intraday market in an optimized manner.
With this mechanism and within fourteen days, the virtual power plant could sell 3.3 GWh from the decentralized units and could generate a turnover of about €250.000 (calculation based on EPEX data from 2008).
The newly developed pool coordinator function aggregating and offering the decentrally generated electricity was considered to be of particular importance.
The stability of the underlying ICT-architecture building the foundation of the RegModHarz-infrastructure deserves thorough appraisal. During the time in which the virtual power plant was trialled in full operation, a stable recording of metered data and effective dispatching of schedules could prove the reliability of the chosen technological solutions.
The dispatching of schedules happened quickly, despite the optimization algorithms in the process and the generic data model that cannot detect all unit-specific data proved to be practical and efficient in the field-test.
The so-called „regional innovative electricity tariff from renewable energies“ which was created and tested in the field-test of this project enabled ca. 50 test customers to buy and receive electricity from the Harz region that was produced from renewable energy sources such as wind, sun and biomass. The tariff targeted a minimum residual load in the region and tried to incentivise the customers to actively contribute to the balancing mechanism between supply and demand. The tariff signals could be implemented manually by the field test customers or by means of an energy management system and smart home appliances that were automatically switched on and off within pre-defined parameters set by the customers.
The overall approach fostered the consumer acceptance towards decentralised generation plants such as wind plants in the regional public opinion. An online-platform furthermore offered the end-users the possibility to receive information on the tariff and the current, past and future generation of green electricity. The demonstration site in the Harz region also served to prove that gains from direct marketing of renewable energy can be increased significantly by means of short term wind prognoses. The flexible operation of biogas units can contribute to the balancing of intermittent generation. The installation of Phasor Measurement Units in order to improve the quality of the distribution grid monitoring constituted a further step in the rollout of the RegModHarz infrastructure. Ten PMUs were installed in four of E.ON Avacon’s local power sections and a data storage system to store the metering data as well as an online web application for a seconds reserve display of selected PMU metering parameters was programmed and implemented.
This way, during the first six months of 2012, the region’s distribution grid was analysed in detail and led to the finding that the number of local voltage and frequency events in the distribution grid would increase in the coming years.
This article is connected to the following knowledge articles:
PowerBridge – Siemens
energyPRO prognosis system – Cube Engineering, EMS International, University of Magdeburg
Virtual Power Plant control room (software) – Fraunhofer IWES
OGEMA – Fraunhofer IWES
RedSim software for energy management systems and to calculate schedules for decentralised units - Fraunhofer IWES
RegModHarz (Regenerative Model Region Harz)
Regionale Kontaktstelle RegModHarz
Kirchplatz 241a, 38836 Dardesheim