Safe power for high water quality
Water is the most strictly controlled nutrient in Germany. Thanks to the drinking water regulations, passed in 2001, there are clear safeguards for protecting human health. However, if you consider other European countries such as popular holiday destinations Spain and Portugal, you’ll see that water quality varies widely with evaluations ranging from “safe to drink” up to the warning “hazardous to health when consumed in large quantities”.
Germany also adheres to filtering and cleaning operations to ensure a consistently high water quality. Instrumental in this is the daily work of what are known as “water special purpose associations” – regional groupings of municipalities and cities that look after the sustainable protection of the regional water supply.
Water supply for 1.3 million people
As the largest long-distance water supplier in Bavaria, the special purpose association Wasserversorgung Fränkischer Wirtschaftsraum (WFW) is responsible for the water supply to approximately 1.3 million people over a 3,400 km2 area and extends beyond the borders of their own distribution area.
In addition to the regional development and transport of drinking water, they must also ensure that the quality of the drinking water is in accordance with DIN 2000. In collaboration with a specially accredited laboratory, inspections are periodically carried out, for example, in the water catchment basin, at the wells and in the waterworks.
Any failure of the water supply would, within a short period of time, lead to massive problems for millions of citizens, so efforts are made to maintain the supply under all circumstances, including in the event of a “blackout”.
As part of the Federal Ministry of Economics and Technology (BMWi), the research project “LINDA”, grid operator LEW Verteilnetz GmbH (LVN) and BEW (Bayerische Elektrizitätswerke GmbH) examine how in the event of a large-scale power outage, the local power supply of important consumers, such as the high-performance pumps of WFW, can be restored with renewable energy. To this end, after theoretical calculations, the first field trials were successfully undertaken at the Feldheim hydropower plant, the WFW Waterworks in Genderkingen and a biogas plant, as a so-called grid island.
The Feldheim hydropower plant, which represented a core component of the experiment, is one of the few power plants that can be “black started”. This means that should there be a “black-out”, the energy supply can be restored independently as an “island”. For this, the connection to a nationwide grid is not required; however, the timespan before the water supply is reconnected to the grid must be safely bridged by battery back-up systems.
To make it possible for WFW to fulfil its tasks as best as possible, the devices are always kept wholly up to date. They feature a high degree of automation to meet strict safety standards and are subject to careful inspection and maintenance, so as not to exceed the end-of-life periods.
The Genderkingen site replaced their old equipment, including the rectifier and inverter system in one of the horizontal water supply well filters of the waterworks.
The site modernisation project also required the plant availability and efficiency to be maximised. In this context, for the bridging of the necessary power supply system, the WFW was in favour of the adoption of a modular system setup in a n+1 redundancy scheme.
The latter ensures that in the event of a component’s failure, the power required by the horizontal water supply well filter would remain protected. In addition, “hot-plug” capable power modules were required, a feature that contributes to reducing the time necessary for replacement and service. The number of modules can be adjusted depending on future power needs (scalability).
Intensive planning phase
The first technical planning of the project began in early May 2016, when BENNING presented potential system solutions following a written invitation from the head of the Genderkingen working group. Based on this and in-depth discussion, it developed a system concept optimally tailored to the needs and necessities of the application. Two weeks later, BENNING transmitted its first CAD-construction design draft. All individual customer feedback in relation to the switchgear and, for example, the desired terminal type, was considered.
Being close to the Genderkingen waterworks, the regional BENNING Southern Branch could respond quickly to customer requests. BENNING also independently enquired about the DC and AC distribution systems specifically designed for WFW with the component suppliers, and integrated them into the system costing and design. The illustrated offer followed on 25 May. Then, further to consultation with WFW and some minor adjustments, BENNING submitted the final technical bid early June. Negotiations in late July proved successful as BENNING won the contract and initiated a partnership marked by great mutual trust.
The power system supplied by BENNING includes a rectifier system, based on TEBECHOP 3000 HDI modules (24 V and 70 A); a 24 V battery system with twice 335 Ah for a scheduled back-up time of 12 hours; an inverter system made up of
inverter modules of the INVERTRONIC compact series that enable an output of up to 8,800 VA; and a remote MCU 2500 monitoring system. The latter is used for visualising the condition of the system and can be integrated via Modbus and
Profibus adapters into the customer's monitoring systems.
High availability and flexibility
The modern DC and AC power supply system started its operation in early November, only a few weeks after delivery. In addition to its high availability and energy efficiency, it is notable for its flexible system concept and scalable performance. A result offered by the modular design, which combined with the rectifier and inverter plug-and-play capability increases system availability and significantly reduces operating costs, because, for example, a module exchange can be carried out by the plant operator on site.
An ongoing project
Although formal factory acceptance is yet to take place, WFW has already requested another system for use in an elevated tank. BENNING earned this vote of confidence due to their excellent project planning, a comprehensive approval documentation (which was partially visualised in 3D), and their common-sense approach. This is the foundation for solid teamwork, which will help to ensure the delivery of drinking and industrial water to a population of 1.3 million.