An ESP for power grids 

Four white containers on a green field in western Bavaria, Germany, next to a village that is a pioneer in integrating renewables into the grid: In Wildpoldsried, the story of Joachim Bamberger and Ulrich Münz started ten years ago. Together with internal and external partners, they developed a software tool that automatically stabilizes grids with a 100 percent share of renewable sources. From this first testbed of a small island grid, Joachim and Ulrich have been driving innovation for larger island grids as a constant up-scaling of the number of inverters. The two pioneers are awarded as Siemens “Inventors of the Year 2021” in the category “Outstanding Invention”.

“If we as societies want to achieve our climate goals, we need to raise the share of renewables in our energy systems,” Joachim Bamberger says. He is now working as a portfolio manager for Digital Services at Siemens Smart Infrastructure. The scenery behind him is perfect for a statement like this. In Joachim’s back are the houses of Wildpoldsried, almost all of them covered with photovoltaic panels. On the hilly fields surrounding the village, wind turbines are holding their blades into the breeze – and all in the back, the silhouette of mountain peaks decorates the horizon.

“A rising share of renewable energy sources and the goal to reach one day 100% renewable generation is a challenge for grid operators”, Joachim adds. “The challenge they face is: How can they still provide resiliency - for example against hurricanes - and avoid blackouts?” The path that the Siemens inventors chose at that time was to develop and validate solutions for small power systems first – and then scale up towards large systems. 

“What started in Wildpoldsried, developed into Siemens’ first microgrid project with 100% renewable generation on Galapagos Islands”, Ulrich Münz explains. He is now located in Princeton, United States, working as a Principal Key Expert for Control Systems and Head of Autonomous Systems & Control at Siemens Technology. He says that the biggest challenge on Galapagos Island was to orchestrate all these renewable generators to control jointly voltage and frequency and avoid power outages.

They addressed this challenge with simulations, lab tests, and through the learnings from their field tests in Wildpoldsried in Germany. All this helped them to understand how they could build a resilient microgrid with 100% renewables. “We immediately realized that simulations and field tests provide solutions for microgrids, but for larger power systems with thousands of power electronic converters, we would need more sophisticated and scalable software tools”, Ulrich explains.

Renewable generators like wind turbines, solar power plants, and batteries use power electronic converters to supply power to the grid. “As we move from conventional to renewable generation, the number of power electronic converters increases drastically in our power systems. Therefore, we have to understand how to orchestrate a very large number of power electronic converters to stabilitze the grid and avoid power outages.” This orchestration is achieved by a high-performance optimization algorithm that tunes thousands of controller parameters in hundreds of generators.

“Our software provides recommendations for grid operators how to maximize renewable integration while keeping the lights on”, Ulrich says. Joachim compares this service for grid operators with an Electronic Stability Program (ESP) for cars: “With a higher share of renewables, the energy system becomes kind of wobbly. Our software supports the decision of where to brake within milli-seconds and to which degree.”

Starting from Wildpoldsried and Galapagos, they are currently driving innovation for high renewable integration as a constant up-scaling of the number of converters. “Here, in our hardware lab in Princeton, we run experiments in hardware with more than 20 converters and simulations of Hawaii representing more than 100 converters”, Ulrich explains.

They are also integrating their software tool in a virtual operational environment of Hawaii with 100% renewable generation. This shall become a blueprint for even larger power systems around the world – to make sure the lights stay on as we make our power systems more sustainable.