© BMWE
How is our electricity grid kept stable?
To ensure secure and reliable grid operation, electricity generation and consumption must always remain in balance. Voltage levels also need to stay within defined limits. The System Stability Roadmap lays out how this can be achieved – even with a power grid running on 100% renewable energy.
The widespread blackout in Spain and Portugal on 28 April 2025, which left millions without power for several hours, highlighted the importance of this issue. The cause of the incident is still under investigation – but it raises the question: how do we keep our electricity system stable?
Let’s take a quick journey into the inner workings of our power grid – the invisible backbone that quietly keeps our sockets powered 24/7. In order to ensure grid stability, supply and demand must constantly be in sync. Frequency – the grid’s heartbeat – is a key indicator. It responds instantly to any imbalance between how much power is produced and how much is used. Think of it like a set of scales: if one side (generation) outweighs the other (consumption), the frequency tips – potentially destabilising the system.
© BMWE, Frequency control illustrated as a set of scales balancing generation and consumption
Voltage must also stay within strict technical limits (usually ±10%), or else equipment – from factory machinery to household appliances – may be disrupted or damaged. In the event of sudden voltage swings caused by faults, grid-connected systems must be robust enough to remain securely online for a period of time.
© BMWE, Deviations in voltage and frequency
Maintaining system stability requires what are known as ancillary services. These are delivered based on mandatory technical connection rules, provided through market-based mechanisms, or directly by grid operators. Key examples include black start capability: the ability of a power plant to restart independently of the grid, even during a blackout; reactive power: used to keep voltage levels within the required operating range; and momentary reserve: an automatic, immediate response to power imbalances that stabilises grid frequency.
The electricity system is dynamic and continuously changing. Growing power flows across regions, the decline of conventional power stations, and the rapid expansion of renewable energy are constantly shifting the balance. As a result, operators must overcome increasingly complex challenges to ensure the grid remains secure and stable.
Between autumn 2022 and the end of 2023, the German government worked with 150 experts from over 80 institutions to develop Germany’s System Stability Roadmap. Since last year, more than 50 specific measures based on its recommendations have been put into action – all aimed at securing a robust and reliable grid for the future.
In total, the roadmap outlines 41 topic-specific stability processes and 10 cross-cutting processes. These are grouped into key areas such as frequency, voltage, resonance stability, short-circuit current, angular stability, system operation, and grid and supply restoration.
Ready for a deep dive into the workings of tomorrow’s power system? Click on the link below to explore the full roadmap and learn how these processes are interconnected.
As with its development, the implementation of the System Stability Roadmap is a joint effort between government, regulators, and industry. It is overseen by the Federal Ministry for Economic Affairs and Energy (BMWE) and the Federal Network Agency (BNetzA). Coordination of the many workstreams and stakeholders is led by the Forum for System Stability, chaired by the BMWE.