Data transparency in Germany’s largest water company
The enormous quantity of some 125 million cubic meters of drinking water is distributed annually by the Lake Constance Water Supply to four million residents of Baden-Württemberg. The power consumption of the pumps in Germany’s largest water companyis also enormous. However, there was still potential for optimization.
Transporting drinking water from the volumetrically second-largest inland body of water in central Europe into the water-poor regions of Baden-Württemberg — that is the task of the Lake Constance Water Supply Administrative Union. 320 towns and municipalities with four million inhabitants obtain their drinking water here. Up to 7,755 liters per second of Lake Constance water are withdrawn at a 60-meter depth in Überlingen. The water flows over enormous removal heads into three 1.3- to 1.6-meter thick steel pipes that lead to the lake pumping station Süssenmühle, where it is then pumped by six powerful pumps into the processing plants on the Sipplinger Berg — some 312 meters higher up. The purified Lake Constance water starts its journey through the 1,700-kilometer-long pipeline network in order to arrive about seven days later at the farthest consumers in North Württemberg’s Bad Mergentheim — some 250 kilometers from the withdrawal location in Sipplingen. All of this is a challenging task that, due to the large pumps and complex processing technology, places high demands on the electrical engineering. It is also very energy intensive, with an overall demand of around 155 million kilowatt hours per year.
Automated data acquisition
Since 2013, Lake Constance Water Supply has been certified according to DIN EN ISO 50001 and therefore can claim tax relief for major consumers according to the current tax law, provided that consumption data are continuously recorded. In the past, the utility relied on cumbersome manual methods for recording data. It therefore decided to switch to automated data acquisition using an power monitoring solution. “For us it was mainly a question of increasing the measurement accuracy and data quality. Errors during reading and manual transmission could never be completely excluded,” explains David Stüble, responsible director of the Conveyance and Processing Technology area at the Lake Constance Water Supply. The new system needed to automatically detect and evaluate the energy data of medium- and low-voltage consumers as well as data from other consumption meters in the form of logs, with the ability to connect to the existing control system.
Perfect combination for medium and low voltage
These complex requirements prompted the company to choose the power monitoring system from Siemens. “The largest scope of services, lower cabling costs, and easy coupling with the control system convinced us,” says Stüble.
This resulted in the implementation of an power monitoring solution for medium- and low-voltage consumers at lake pumping station Süssenmühle and at Sipplinger Berg, the core of the system with several hundred points of consumption. Here the measuring devices, energy management software, and the existing control system all interact perfectly. The communication-capable measuring devices for recording the electric energy data could be easily incorporated into the existing medium-voltage control cabinets. The software ensures a transparent analysis of energy flows: electrical characteristics such as voltages, currents, power, energy values, and frequencies, and other data such as water quantity can be monitored and archived.
Continuous energy management ensured
The experts at the Lake Constance Water Supply are highly satisfied with the power monitoring solution: The average power values of the monitored parameters are displayed in hydrograph form and can be compared with each other. Load profiles of the individual processing lines can also be displayed next to each other. In this way, the technicians have a current overview of the consumption values at all times. In addition, all relevant data are archived centrally, read out twice per month, and exported to an Excel list for further processing. “It’s great that everything runs automatically,” says practitioner Stüble.
Using the data the energy consumption can be optimized. An important parameter is measuring how many kilowatt hours are needed per cubic meter of treated water. The self-imposed goal of the water utility was to reduce energy consumption to below 1 kWh/m³. This goal has since been achieved. The success of individual measures can also be precisely tracked. Other data sources such as volume of water can likewise be processed using the powermanager software. At the same time, data acquisition is an important component for certification according to DIN EN ISO 50001, which has been successfully confirmed for 2016 to 2019. Annual audits check for whether the targeted efficiency objectives have been achieved.
Picture credits: Siemens AG/W. Geyer
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