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Orchestrating Distributed Energy Generation

Who is actually waving the baton when it comes to conducting the “orchestra” of renewable energies? Politicians like to see themselves as the “conductors” of climate change. But the music is playing somewhere else: in the distribution networks. And they will soon buckle under the strain of increasingly distributed, highly volatile feed-ins. In this scenario, it’s up to the distribution network operators themselves to direct the energy transition. How is that possible in a technically efficient and economical way? You’ll find out in this article.

According to the German Federal Network Agency, grid stabilization measures cost a record 1.4 billion euros in 2017. However, grid stability is still at risk, due to increasing e-mobility, for example. Although technologies like battery storage systems, sector coupling and virtual power plants contribute to making solar, wind, and hydroelectric power useable, the network managers need data in order to navigate the networks. This is the only way for them to identify and exploit the condition and potential of their networks. Martin Breitenbach from NGN Netzgesellschaft Niederrhein puts it in a nutshell: “We first need to know more about our network in order to be able to make better decisions.”

How Distributed Grid Operators Direct the Energy Transition Themselves.

If the Grid is an Orchestra, Data is the Score

It is essential to replace estimates with real knowledge. This brings the probabilities better in line with reality and allows realistic forecasting. Generation and load management can only be efficient and economical if they are aligned with reality. Such management provides a solid foundation for sensible prioritization of network expansion and planning that are both anticipate and cost-effective – especially with respect to grid stability. However, this first requires transparency about the state of the network. To stick with the orchestral metaphor: Data is the score that the conductor of the network needs in order to “conduct” the orchestra of distributed energy generation.

4 billion €
The annual total costs nationwide for stabilizing network interventions could grow to this number after the shutdown of the last nuclear power plants in 2022. (Source: Federal Network Agency)
1,043,300 miles (1,679,000 km)
This is the total length of the electrical circuit of the distribution networks in Germany, which is managed by 883 distribution system operators. (Source: dena)
New Year’s Day 2018
On January 1, 2018, at 6 a.m., Germany got its power exclusively from clean energy for the first time – purely in terms of figures, of course. (Source: Federal Network Agency, SMARD Platform)

The Demand for Coordination is Growing

But how can such a useful data foundation be established and expanded? The most important data arises where the power is generated – in the low voltage network. It is already being used to allow control of the direct local network stations. Where it gets interesting is when these local network stations completely bundle the data and prepare it intelligently and automatically, and it is used to control the level above them – the medium voltage network. This widens the focus to the networks, and not just that: It increases the range of what can be controlled. Therefore, this is also referred to as wide-range control. And this scenario will continue to gain importance. As the Agora Energiewende GmbH think tank says in its twelve-point discussion paper: “The future will be characterized by closer connections and higher demand for coordination between the voltage levels – and thus also between the transmission and distribution networks.” To achieve this, the communication requirements and interfaces between the transmission and distribution system operators, as well as the control and regulation priorities, must be clearly specified.

Remaining Competitive

When it comes to making the existing network infrastructure stable and future-proof and keeping it competitive, a far-reaching, data-based foundation for communication will be indispensable for every network operator. New technologies that reduce network load can allow them to achieve network transparency, which makes anticipatory network planning possible and shows where exactly the most urgent need for action exists. After all, the energy transition is not just about climate change mitigation – it also concerns internationally competitive power generation, says Patrick Graichen, Director of Agora Energiewende. But that is only possible if the network is “singing the right tune.” Time to take up the conductor’s baton yourself.

Text: Linda Bögelein | WAGO

Photo: Getty Images und Pixabay

70,000 charging points
For 2020, the Federal Association for Energy and Water Management (Bundesverband der Energie- und Wasserwirtschaft – BDEW) and the German National Platform for Electric Mobility (Nationale Plattform Eletromobilität – NPE) have calculated a demand for about 70,000 publicly accessible charging points and about 7,100 quick charging points. (Source: BDEW)
€ 610 million
Plant operators’ claim for reimbursement for the clean energy not produced for network safety reasons was about 610 million euro in 2017. Consumers paid around 237 million euro more for clean energy not produced than in 2016. (Source: Federal Network Agency)
36%
The renewables in the electricity sector now cover 36 percent of the consumption and are on a course to break new records. In 2017, wind beat out coal and nuclear power – both of which fell to their lowest levels since 1990 – in the electricity mix for the first time. (Source: Agora Energiewende)

The Background of Network Instability

In the new energy system, the great majority of distributed generation systems are connected directly to the distribution network. A large proportion of the new loads, like electric vehicles, heat pumps and other flexible loads also draw their electricity from the distribution network. Therefore, in contrast to the conventional system, the electricity no longer simply flows “top down” from the transmission network to the distribution network. Instead, there is a “two-way street” in the form of back-feed from the distribution network into the transmission network. In particular, this occurs when more and more electricity generated in the distribution network can no longer be withdrawn by the on-site loads. As a result of the backflows, cities are also supplied by renewable energy plants from the surrounding area, for example.

If bottlenecks in the transmission network arise, control of the systems in the distribution network (flexible generators and loads) is also often needed in order to eliminate these bottlenecks. Furthermore, the new kinds of loads, especially electric vehicles, can lead to new network operation challenges in the distribution network if many often draw power from the network at the same time. When transmission and distribution network operators intervene, it is always necessary to consider the repercussions for the other higher or lower network levels. (Source: Agora Energiewende GmbH)