BKW central control centre: Farewell to Mühleberg

BKW’s electricity grid extends over 22,000 kilometres and supplies electricity to more than one million people. This widely ramified grid is monitored by the ZLS. The original ZLS was commissioned in 1972 together with the Mühleberg nuclear power plant and has been the heart of the BKW electricity grid for decades. Between 2002 and 2012, all regional medium-voltage control centres were brought together in the ZLS. Since then, it has served as a digital control centre in which all lines and switches of the BKW electricity grid are mapped and monitored.

Operation under extreme conditions

The major winter storms such as Lothar and Burglind were particularly challenging for the employees of the ZLS in Mühleberg. During Burglind, up to 40,000 customers were without power at times, and the phones were ringing off the hook. “Sometimes we had to spend the night directly in the control centre because we knew that from 3 a.m. onwards the winds would be very strong and therefore the probability of faults would be high,” recalls Philippe Rothermann, Head of Grid Operations Planning & Engineering, who has worked at BKW for 17 years. “Back then, we spent up to 48 hours in Mühleberg. But we were prepared – with sleeping rooms, a shower and a kitchen.”

The fear of the millennium

The clean-up work after Storm Lothar was still in full swing on 31 December 1999. At the same time, another spectre was preoccupying the engineers at the ZLS in Mühleberg. The turn of the year into the 2000s was imminent: the millennium. The experts were concerned about the so-called millennium bug. It was feared that the existing IT infrastructure would not be able to cope with the automatic changeover from 1999 to 2000 and that the computer system would crash. The consequences this would have for the electricity supply did not bear thinking about. At the ZLS, regional television station «TeleBärn» was on site, ready to report live on the turn of the year into 2000 and any possible consequences. “Fortunately, nothing happened back then; the power grid did not fail,” reports Philippe Rothermann. The computers and IT infrastructure performed as usual. Thanks to BKW’s meticulous preparation and ABB’s backups, the algorithms continued to operate reliably even after midnight.

From fax to cloud – the rapid evolution of technology

Dispatcher Thomas Spycher has been there the longest. “You could write an entire book about the time in Mühleberg,” he says. Looking back from 1991 to today, the progress seems almost like science fiction. In 1991, a calculator with a solar cell was high-tech; digital control centres were considered a thing of the future. Today, when it comes to large solar installations, the dispatchers actively intervene in feed-in capacity from the ZLS, walk through the building with tablets and wireless measuring devices, and access switching programmes via VPNCloud. Mountains of folders full of paper switching requests, red sticky notes and the indispensable fax machine – for Swissgrid warnings about congestion reserves, for example – are now history. Instead, video conferences, screen sharing and database queries in seconds provide an overview. Only one thing has remained the same over more than 30 years: the always well-maintained coffee machine.

The development of the command room 1974–2025

The trouble with slurry

For the more than 30 employees, Mühleberg was far more than just a workplace – it was a place with a special character. “Being away from everything was pleasant. We could go jogging along the Aare or spend our lunch break there. There was also enough space for pilot projects or spontaneous ideas,” say Thomas and Philippe, both describing the advantages of the location in the same way. What remains in their memories, both professionally and personally, are above all the shared challenges: “In difficult moments and during disruptions, we always functioned as a team. At the same time, we became a small family – shared barbecue days, Christmas dinners, sausage mornings and fondue gatherings strengthened our sense of togetherness,” Philippe recalls. And what will not be missed about the old location? Philippe smiles: “The days when the farmer spread slurry right outside my office.”

The journey to the new site was challenging

With the move away from Mühleberg, BKW has opened a forward-looking chapter for the ZLS. The new site not only offers modern technical infrastructure and stronger networking with other operational units, but is also easier to reach by public transport. As part of the critical infrastructure, the operation of the ZLS could not be interrupted at any time. The transition therefore required meticulous planning, extensive testing and the parallel operation of both sites over several weeks. Thanks to the great commitment of the employees and the close collaboration between technology, IT and operations, the move in June 2025 went smoothly – with no impact on security of supply. The new central control room symbolises BKW’s innovative strength: firmly rooted in decades of experience while also geared towards the challenges of the energy future. Thomas and Philippe have already settled in at the new location. After all, the cohesion among the ZLS employees will remain strong at the new site too. And there will still be room for shared barbecue days, sausage mornings or a fondue get-together.

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