Intelligent Control of a Battery Swarm

But now, instead of laying new lines at great cost, the network operator has decided to invest primarily in intelligent measures for hardening the existing grid – above all in a system of distributed storage batteries. This battery system supports the local grid with sophisticated algorithms, as well as communication, measurement and control technology from WAGO. The batteries, each with a capacity 500 kilowatts, were installed specifically where a great deal of electricity is fed into the grid and withdrawn again with a time delay.

The swarm storage system, christened “SchwarmSpeicher Allgäu,” went online at the end of 2017. The design, planning and operation of the battery system were handled by egrid applications & consulting GmbH, a joint venture of Allgäuer Überlandwerke and Siemens specializing in consulting services related to the design of intelligent distribution networks.

36 lithium ion battery packs, stacked to form a black wall: The local network operator, Allgäuer Überlandwerke, uses a total of five of these large batteries spread throughout the greater Kempten area to ensure the stability of the distribution network. For management of the swarm storage system, egrid relies on multi-purpose operation. This makes it possible to exploit different earnings sources. “The most important function of the system is to supply primary control power. We generally also support the local network with this,” explains egrid Managing Director Bernhard Rindt. Furthermore, the storage systems occasionally absorb peaks that arise during grid use. The battery packs also serve as an emergency power system. This allows the network operator to invest less money in procuring and operating diesel generator sets, which normally handle this.

With the right energy management framework, even more operating modes will be possible in the future – for example in the context of “Demand Side Management” (DMS) or providing reactive power.

Whether control energy, grid peak reduction or other applications: WAGO controllers guarantee reliable communication between the individual system components. WAGO has been on board with egrid projects for some years. “Among other things, we like WAGO’s long-term orientation in product development,” says Rindt. “Many large companies are constantly moving on to the next big thing. And they withdraw from a market segment again quickly if things don’t go as planned there. In contrast, in our experience, WAGO maintains a very different culture.” This also includes the manufacturer’s service orientation: “We’ve always gotten the right support from WAGO very quickly,” emphasizes Rindt.

Besides this, technical considerations also favor WAGO products. “WAGO’s open source strategy suits us very well,” explains the egrid director. With Linux® as the base operating system for the controllers, the smart grid specialist is able to react to new requirements quickly and without great expense. “WAGO combines Linux® with CODESYS Runtime and the possibility of adding our own source code on top. Hardly any other vendor offers such flexibility,” says Rindt with conviction. Every now and then, the technical and functional requirements for a battery system change after installation. “Because, for example, a network operator might want to have access to additional information on the status of the batteries after the fact. With WAGO, we can meet such requests very easily – we just need to add a few lines of code.”

Text: Ulrich Menzel | WAGO
Photo: Ralph Diermann | EGRID APPLICATIONS & CONSULTING GMBH