New operating system for stand-alone grids

Even in a remote village far from the public electricity grid there is modern everyday life with radios, washing machines and electrical appliances. In energy terms this is a “standalone” system. The electricity is supplied by a hybrid system that combines various renewable energy sources and an additional diesel generator, and is buffered with a battery system. An information and control network with a new operating system keeps the stand-alone grid (mini-grid) stable.

The Universal Energy Supply Protocol (UESP) communication protocol, which has been developed by the Fraunhofer Institute for Solar Energy Systems ISE together with its industrial partner Steca, enables optimised interaction between the generators and loads in decentralised power supplies. If a superordinate energy management system (EMS) is available for the operational management, it calculates an optimised schedule and controls the individual loads and generators. Without the EMS, the batteries distribute their charging state in the network so that the generators and storage systems can accordingly switch themselves on or off.

The results of the UESP project are incorporated into the new CiA 454 CANopen application profile for energy management systems. KACO new energy is using this as part of a new research project in which it is designing larger stand-alone grids that can also supply commercial machines and, if required, can also be linked to the public grid.

Bild 1 - projekt 1611 00:
Copyright: Fraunhofer ISE

Bild 2 - projekt 1611 01 engl: Fig. 1: Simple UESP system for supplying an appliance (with separate connection and supply to the intelligent interface).
Copyright: Fraunhofer ISE / KACO new energy GmbH

Bild 3 - projekt 1611 02 engl: Fig. 2: The new system concept for larger stand-alone systems combines AC and DC sources to form a regional network and storage system.
Copyright: KACO new energy GmbH

Bild 4 - projekt 1611 03: Fig. 3 The tracker directs the concentrating PV modules precisely to the position of the sun. In the stand-alone system at Wadi Al Natroon in Egypt, the water pumps are powered with electrical energy and the communication is achieved via the standardised CANopen protocol.
Copyright: Fraunhofer ISE

Bild 5 - projekt 1611 04: Fig. 4: The trunked radio system on the Brandeckkopf tower near Offenburg, Germany, which is used for communicating with and monitoring a regional railway line, is operated with a PV hybrid system.
Copyright: Steca Elektronik GmbH

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The market for autonomous electricity supplies is potentially enormous: around 1.4 billion people in rural regions still do not have any electricity connections. Another application area is provided by measurement and transport control systems as well as telecommunications systems. According to Fraunhofer ISE, there are around 300,000 homes, hotel and catering businesses in Europe that are not connected to the public electricity grid. These could make excellent use of renewable energies, since it is often more economic to generate electricity with a solar power system than to develop a supply network or use diesel generators.

Overview of contents Projektinfo 16/2011: