Wallstadt in Mannheim (Germany)

[EU Project: More Microgrids]

This field test site is an ecologically-oriented residential estate in the district “Wallstadt” of Mannheim, Germany. It is considered as a key success factor for sustainable development to start awareness building with consumers and producers (prosumers) who have a positive attitude towards innovation and renewable energy. The settlement includes 580 households. The site includes several privately owned small photovoltaic systems and one private Whispergen cogeneration unit. Further PV-installations are in progress.

One measure for awareness building in preparation of the field test was the customization and installation of the display panel “VisiKid” at the entrance of the “Kinderhaus” in Mannheim-Wallstadt. VisiKid shows in real time, which power and how much energy is being produced by the PV-Panels. This intuitive explanation brings the timely value of energy from photovoltaic systems closer to parents and children.

The VisiKid panel displaying the PV-generation at the Kinderhaus entrance

The LV distribution grid represents a typical residential area with an intermeshed ring grid structure. It is fed from the MV-grid via three 20/0.4 kV, 400 kVA transformers and is operated in closed configuration. The LV grid, whose neutral is directly grounded at the MV/LV substation, is a three-phase network with distributed neutral. Within the More Microgrids project, the LV-grid was modified in order to prepare it for optional islanding. The new distribution area including all relevant loads, distributed generators and storage is served by one transformer.  Power quality and grid characteristics have been monitored since 2006.
Within the above described grid segment, the MVV team prepared the Kinderhaus to operate as a Microgrid comprising two PV systems with a Sunny-Backup System, controllable loads and adding sufficiently designed battery storage as buffer, able to supply 10 kW for 1 hour.
To prove the feasibility of an iterative switching from islanded to grid connected mode and vice versa an additional battery for stabilizing the frequency was installed in combination with a system of inverters that are able to realize an islanding mode.
A Multiagent System for Energy Management was installed. The experiments carried out have shown that it was possible to control flexible loads (air-conditioning units) by increasing or decreasing their total consumed power according to a defined percentage of photovoltaic power virtually assigned to them.
The system implementation focused in the usage of the agent based software as well the available equipment in the test site. The system architecture was designed taking into account the existing BPL communication networks.

The system architecture in Wallstadt.