Power System Flexibility – Foundation of Transformation in the Era of Renewable Energy

The energy transformation in Poland and Europe is a process that is changing the way energy is generated and consumed. The growing share of renewable energy sources (RES), primarily wind and solar power, is crucial for achieving climate goals and reducing costs associated with greenhouse gas emissions. However, this change brings challenges that the traditional power system has not faced before. The system, which was created several decades ago, was designed in times when energy flowed in one direction: from large power plants to consumers. Today, this order has been reversed. Energy generation is distributed, and energy also flows in the opposite direction. This reverse energy flow poses an enormous challenge for stable network operation. Meanwhile, Distribution System Operators (DSOs) and the Transmission System Operator must not only continuously monitor but also actively manage networks saturated with RES. However, the most important task remains ensuring the security of electricity supply, regardless of source and direction of flow, and this requires a new approach – system and network flexibility.

Challenges of Modern Energy Sector

In Poland and Europe, we are observing dynamic growth in installed RES capacity. This is a huge step toward sustainable development, but at the same time a significant challenge for the power grid. Why?

• RES are unstable and weather-dependent. Energy production from wind or solar depends on atmospheric conditions, which we cannot fully control.
• EU climate goals enforce a rapid pace of transformation – by 2050, Europe aims to achieve climate neutrality.
• The energy market is changing. New cooperation models, regulations, and technologies are emerging.

The system, which was once simple and unidirectional, must now cope with energy flows in both directions. This causes problems that were marginal just a few years ago.

Problems Resulting from Distributed Generation

When many small energy sources appear in the network, its character changes. Here are the most important effects:

• Change in power flow – networks can become overloaded, energy losses increase.
• Voltage rise – the greater the power fed into the network by local sources, the bigger the problem with voltage regulation.
• Higher short-circuit currents – they may exceed permissible values for equipment.
• Threat to generator stability – in case of failure, they may disconnect.
• Problems with protection systems – the change in current flow direction requires new settings or equipment replacement.
• Decline in power quality – voltage flicker, harmonics from inverters.

All of this means that the traditional approach to network management stops working. We need something more – flexibility.

What is Energy Flexibility?

This concept has become key in discussions about the future of energy, as it encompasses both technical and market aspects. Flexibility is the ability of the power system to adapt to changing conditions, both in energy generation and consumption.

In European Union documents, this concept is described as the system’s ability to adapt to variable patterns of energy production and consumption, as well as network availability within specified response times. In practice, this means that the network must be ready for rapid changes, both predictable (e.g., change of time of day) and unpredictable (e.g., sudden drop in RES production). However, energy flexibility operates on two different levels – system and network.

System flexibility is the ability of an entire country or region to maintain balance between energy production and consumption across different time horizons, from seconds to years. Its goal is to ensure security of supply (stable frequency, available capacity). When we talk about network flexibility, we mean the actions of TSOs and DSOs to manage energy flows and avoid local problems: overloads, voltages outside the norm. Both layers must work together. Without a flexible network and flexible system, it is impossible to effectively utilize RES and ensure stable energy supply on a national or European scale.

Why is Flexibility the Foundation of Transformation?

Without flexibility, it is impossible to safely integrate RES. The network must be modern, digital, equipped with tools for:

• prediction – forecasting changes in load and generation,
• observability – real-time operation monitoring,
• active management – responding to and shaping energy flows.

Flexibility is not just technology. It is also regulations, market models, and a new approach to cooperation between operators, generators, and consumers. In short: flexibility is both a tool and a goal of energy transformation.

Four Main Streams of Flexibility

How to achieve flexibility? There are four basic mechanisms:

1. Regulatory Approach

Codes and regulations enforce the use of technologies that increase flexibility – e.g., control devices, measurement systems, communication. Thanks to this, the network becomes more receptive to the integration of new sources.

2. Connection Agreements

The source owner agrees to limitations – e.g., temporary power reduction during periods of network congestion. This allows better utilization of existing infrastructure.

3. Tariff Structures

Tariffs encourage consumers to change behaviors – e.g., using energy during hours of high RES production. Examples of this solution include dynamic tariffs.

4. Market Orders

Operators can purchase flexibility on the market – e.g., through contracts, platforms. Market participants are compensated for changing behaviors (reducing consumption or generation), which increases network security.

Summary

Flexibility is the foundation of modern energy. Without it, it will be impossible to achieve climate goals or safely integrate RES. It is the ability to dynamically adapt to changing conditions – technologically, regulatorily, and through the market.

Thanks to flexibility, operators can optimize network development, and users can benefit from cheaper energy and support system stability.

Energy transformation is not just about building new sources, but also changing the way we think about the network. Flexibility is the key to the future of energy.