The Digital Energy Transition with High-Tech Controllers

The expansion of renewable energies can only succeed if the fluctuating supplies from solar and wind arrays are compensated by flexible electrical consumers and batteries. Digital technology can help to solve this problem: Intelligent systems convert the analog electrical network into a communicative smart grid and pave the way for linking virtual power plants, generators and consumers.
There are troubles ahead for wind energy. Although wind turbines are supposed to provide the lion’s share of the electrical supply in the long term, the federal government wants to put the brakes on new construction in northern Germany to a significant degree. Since 2017, Bremen, Hamburg, Schleswig-Holstein, Mecklenburg-Western Pomerania and the northern parts of Lower Saxony have only been permitted a maximum new wind output of 902 megawatts – this is not even 60 % of the output that is currently available. This is because the electrical lines in the stormy coastal regions have reached their capacity limits. Wind turbines are increasingly switched off as part of so-called supply management, because the large amounts of green energy could damage network stability.

The difficult question is how to take the breaks off the energy transition. New electrical lines are supposed to transport the wind power from the coast of the North Sea to the south; however, the network expansion has been held up because laying the ground cables has taken longer than planned. Another challenge is gaining control over the weather-dependent, fluctuating green energy production. Solar arrays and wind farms already provide one-third of the electricity required in Germany – a proportion which is supposed to increase to 100 percent by 2050. According to experts, technical adaptations and new business models for marketing renewable energy are desperately needed. “We are relying on a type of generation that fluctuates, is decentralized and distributed and involves small producers This leads to new requirements on the infrastructure, the electrical grid, the control and the flexibility that used to be available in controllable power plants,” says Tobias Kurth from Energy Brainpool, energy marketing experts from Berlin.

The industry faces a mammoth task: It must develop solutions that retain stability in the electrical grid at a frequency of 50 Hz, even with increasing renewable energy production. Possibilities include batter storage units, as they can quickly accommodate excess current and discharge it again as needed. If they were installed, for example, at the base of large wind farms, then the stored energy could be used as balancing power to compensate for short-term fluctuations in the electrical grid. This would also avoid forced switch-off of wind turbines. The combination of batteries with photovoltaics is also logical. If solar batteries are coupled to charging stations, then EV charging stations can operate around the clock, providing solar energy to electric vehicles, or the batteries could also be used in the residential sector as storage systems. These could increase personal consumption and simultaneously cap the midday peaks from solar production that endanger the electrical grid.

The good news: according to the study, “Germany’s Energy Suppliers are Going Digital”, conducted by the consulting firm pwc, more than two-thirds of the energy production companies consider decentralized energy solutions highly relevant and view digitization as a lever for increasing their process efficiency. Digitization potential arises along the entire energy added-value chain. Flexible electricity pricing, which follows the availability of renewable energy, is an approach that is especially appealing to commercial and industrial consumers: When solar arrays and wind turbines produce a lot of energy, suppliers offer electricity at reduced prices. This encourages consumers to adjust their use to the fluctuating generation. This is merely a first step: “Increasing numbers of households produce their own electricity with small CHPs and solar modules. They are no longer just consumers, but have become prosumers, who both consume and provide excess power to the grid,” says Kurth.

If these households were networked together, they could balance supply and demand among themselves. Virtual power plants are a move in the same direction. They combine decentralized producers, like biogas, solar arrays, wind turbines, CHPs, heat pumps, emergency generators and batteries, with intelligent control technology to form a flexibly controllable group. Network operators supply balancing energy from registered suppliers to compensate for fluctuations in the higher-level transmission networks. Some companies are already using virtual power plants to offer this service. Trianel, a municipal utility cooperative, bundles generating and storage technologies into a balancing pool with more than 700 megawatts of total output. In practice, the biogas systems, storage facilities etc. in the Trianel power plant are operated as usual. If the network operator calls for balancing power, then an algorithm in the control system selects the suitable systems and controls them from the control center. The advantage of the Trianel power plant is that it is composed of 400 individual systems and thus offers a high level of flexibility. It can thus cushion short-term fluctuations quite well.

The WAGO Controllers protect the data flow against unauthorized access by encrypting the data using TLS1.2 and also by transmitting the data via specially secured connections, like IPsec or OpenVPN in accordance with the BDEW White Paper. WAGO’s technology provides secure communication and control for virtual power plants as well. The generators and consumers combined into this type of power plant speak different languages and can thus barely communicate. The new open-source communication standard VHPready (Virtual Heat and Power Ready) can change this. It functions like a translator so that control centers and distributed systems understand one another. Instead of a system-specific set of variables, as was previously used, VHPready communicates via predefined profiles using uniform data point systems. In addition to communication, domain-specific specifications, e.g., concerning behavior and reaction times, are also defined. This provides the ability to control systems using timetables. Thus, the power plant control center can transmit control parameters for a time period of 24 hours. Without digitization, the energy transition will not succeed – intelligent control systems are thus becoming the key technology on the energy market.

Text: Heiko Tautor, WAGO

Photo: Manfred H. Vogel | vor-ort-foto.de, iStockphoto.com