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Energy Grids


Transparent supply routes and autonomous, automated power and water supply – the Immenstadt public utility company in the Allgäu region relies on these and has done so with WAGO since 2009. Automation and telecontrol technology make this possible and clarify the potential for expansion and savings at the same time.

Over 14,000 residents, 30 square miles (80 km²), all at 2,400 feet (730 m) above sea level. Immenstadt in the Oberallgäu district of Swabia is a tranquil locale. But it would be a mistake to assume that time stands still in this idyllic Alpine town – the Immenstadt public utility company, a municipally owned and operated enterprise, is focusing on sustainable technology for municipal energy management and the distribution of district heating, as well as for the water supply, wastewater management and even flood control. “The modular WAGO I/O-System simplifies plant control and system monitoring. It improves the energy management, reduces the calculation effort for the energy supply and makes it possible to integrate remote stations into the network smoothly,” says Paul Müller of ETM Elektro- und Systemtechnik in summary. His company is handling the planning on site as the system integrator.

But what specific technical products does this involve? “To be exact, since 2009 we have been using the 750-841/-881 Controllers and the PFC200, as well as the 750-652 Serial Interface,” says Paul Müller, listing the products in detail. A total of 45 systems have been equipped with this technology to date: 18 water supply stations, 13 wastewater plants, five systems belonging to the building management of the public utility company, three for flood control measures, five in district heating and one drinking water power plant.

Transparency and Innovation

The biggest advantage of the WAGO controller technology for the Immenstadt public utility company is that every supply route can be monitored and controlled comprehensively and transparently. A central process control system (FlowChief) is used to collect, visualize and archive the data and to forward the error messages for the on-call service.

In addition, the monitoring of the existing systems also simplifies billing for the energy supplied: “The existing M-Bus interface allows all third-party products of the energy meters to be read and the meter values to be stored and processed by them directly in the process control and energy data management systems,” explains Paul Müller.

The Immenstadt public utility company is focusing on independence for heat and electricity generation – with renewable energies. The town generates heat itself with a biomass heating plant. This heating network is monitored with WAGO controllers. The public utility company generates electricity with photovoltaic systems. And hydroelectric power has also been used since the middle of October 2017. The large elevation differences in the supply area and a 55 kilowatt Pelton turbine in the drinking water pipeline should make this possible. This connection of the systems to the public utility company’s control center is also implemented with WAGO controllers, says Paul Müller.

Straightforward Expansion to All Utilities

Extending the control to additional utilities and services like the water supply, wastewater, flood control and IT technology was just as straightforward.

Paul Müller explains the procedure: “Integrating the remote stations via the existing network interfaces was straightforward. All programmable logic controllers work autonomously. That means that each of the systems can be controlled and regulated on site with the help of the available information.” The technical integration of the remote stations over existing network interfaces is done via DSL, SIM card, microwave transmission and SHDSL extender. The maintenance of the individual remote stations has also been improved with direct programming access over the network with CODESYS.

Flood Risk Even in the Mountains

The elevation of Immenstadt does not in itself protect the town, located in the Oberallgäu region, from flooding, since Immenstadt is located right on the water, namely several rivers like the Konstanzer Ach and the Iller, which flow through the municipal area. Therefore, the flood protection has been modernized too. WAGO controllers are used to monitor and control a weir system and flood control polder.

As of recently, a system of two weirs is controlled autonomously with WAGO PLCs: “When the Iller exceeds a certain level, one weir is triggered and the water floods the polders in a targeted way. A second weir then controls and limits the drainage of the water from the flood control polder through a stream to at most 2,600 gallons (10 cubic meters) per minute,” explains Paul Müller. All data for visualization, logging and alerts is transferred to the control system via a mobile router.

Automation from an Environmental Perspective

Besides the automation of all supply areas, environmental issues also play a special role in the overall modernization of the public utility company. According to the current energy report of the City of Immenstadt, between 1995 and 2015 alone, it was possible to cut CO2-emissions in half, from about 4,000 metric tons to 2,000.

A large portion of the heat energy demand is already covered by a biomass heating plant. Through continual expansion of the district heating network, more and more municipal buildings should be converted to a sustainable heat supply. But the demand is growing in the private sector as well. Therefore, the modernization is focusing particularly on the stability, but also the flexibility, of the automation of the supply.

In addition, the greatest potential for greenhouse gas reduction lies in improving the energy efficiency of buildings. Communal energy management has been introduced in the City of Immenstadt for this purpose. Energy controlling helps to monitor consumption and identify weaknesses – this process is especially precise and reliable with the help of programmable logic controllers (PLCs) from WAGO, emphasizes Müller.

A Project Becomes a Partnership

The cooperation with WAGO for most of the past decade started serendipitously: In 2009, the technology that had been used till that point was discontinued, so the search for a new vendor began.

After intensive research and comparison of various vendors, the Immenstadt public utility company chose WAGO. According to them, what was decisive was the relevance of a variety of interfaces with a view to unlimited extensibility of the CODESYS programming interface, as well as the connectivity of the network protocols for communication with third-party vendors.

“At the end, it was simply a matter of having a scalable system that can be extended for different requirements. The WAGO products were and are able to do make a valuable contribution in this regard.

Besides that, their optimal price–performance ratio continues to be a decisive factor,” says Müller, summarizing the decision criteria that justified and continue to maintain the cooperation between the Immenstadt public utility company and WAGO.

Text: Ulrich Menzel, WAGO
Photo: WAGO