The hard coal-fired Heyden power station, which is located near Minden, Germany directly on the River Weser, was commissioned in 1951 as the first German power station after the Second World War.
Following various optimizations, its current unit capacity of 875 MW makes it the largest conventional single-block power station in Europe.
The cooling water needed for operating the power station is taken from the River Weser and returned to the river after use. To protect the environment, the water temperature of the River Weser may only be raised by a maximum of three Kelvin.
The water authorities for the Minden-Lübbecke district therefore require that the temperatures are measured and logged on removal, return, and after combination with the river water. These values are important for the approval process and are used directly for management of the power station. If the measured temperature exceeds the permitted value or if measurement fails, the operator will have to reduce the unit capacity of the power station or even shut it down.
A reliable connection between the individual measuring points and the control room is therefore extremely important. The operator was looking for an opportunity to create a redundant path for the almost 40-year-old measuring lines without the need for underground work.
In the first step, the measuring line for the cooling water intake at the Lahde campsite had to be connected to the power station building wirelessly. Due to the distance of several kilometers that had to be covered as well as the precision transmission requirements for the analog temperature value, the Radioline wireless system was selected. The large number of trees around the instrumentation container prevented a direct line of sight to the power station, which meant that a 2.4 GHz wireless signal could not be used for the communication link.
Since the Radioline system supports the use of different radio frequencies, the wireless specialists performed a test with 868 MHz devices. At this frequency, the radio waves propagate better, which means that applications can be implemented even when obstacles prevent a free line of sight between the stations.
During the test phase, the 868 MHz modules demonstrated the reliability of the wireless connection. In addition to the large number of trees, the installation of another Radioline component proved to be a challenge due to the position of the power station by the water. The antenna had to be positioned just a few meters above the surface of the water and fully shadowed by the solid concrete building. The power station employees were able to analyze the quality of the wireless path at any time, both during startup and in normal operation. The Radioline modules offer several diagnostic facilities. During the test installation, the temperature values are acquired permanently by the control system and then compared with the corresponding data from existing wired connections. The high degree of accuracy of the analog modules of 0.02% meant that there was no deviation, so the values forwarded wirelessly could be used for regular operation.
The location selected for the wireless receiver in the power station was an almost 40 meter high ash silo. Due to its central and elevated position, in future additional stations can be integrated into the wireless network.
With fast startup and safe operation, the Radioline system is ideal for both temporary applications and fixed installations. Integrated functions to protect against data manipulation – such as packet authentication, the proprietary protocol, and optional AES data encryption – enable use even in critical applications in the fields of power generation and distribution or process technology.
Thanks to various wireless head modules with license-free frequencies combined with flexible network structures and numerous operating modes, even large networks and long distances between two devices can be implemented reliably.