The Polish electricity system is undergoing a profound transformation. The growing share of renewable energy sources, mainly solar and wind, is changing how distribution networks operate. Variability in energy production, local congestion, voltage problems, and reverse power flows are becoming everyday occurrences. Traditional network management methods—such as reconfiguration, transformer tap changing, automatic voltage regulation (AVR), or scheduling maintenance work during periods of surplus renewable energy in the grid—may soon prove insufficient. This is why there is talk of the need to develop a flexibility services market, which is becoming the foundation of energy supply security and the key to effective integration of renewable energy sources (RES) into the National Power System (KSE).
What is flexibility for the electricity system?
Flexibility means the ability of the network and electricity system to respond to changes in energy generation and consumption, as well as to unforeseen events. In practice, it involves the ability to quickly adjust power flows, voltages, and loads in such a way as to maintain stability and operational security. Three main types of flexibility can be distinguished:
- Design flexibility – Considered at the network development planning stage. It allows shaping the load curve, optimizing expansion directions and the scale of investments. Thanks to it, infrastructure oversizing can be avoided and existing resources better utilized.
- Operational flexibility – Relates to the existing network and is used in daily management of its operation. It enables response to inaccurate forecasts, variable weather conditions, or failures. This is “everyday flexibility” that allows maintaining system stability under dynamic conditions.
- Contingency flexibility – Used in emergency situations, such as sudden power shortages, equipment failures, or extreme fluctuations in production and energy consumption. Its purpose is to protect system integrity and prevent widespread consequences of disruptions.
Why is flexibility so important today?
The development of RES is changing the nature of network operation. Just a few years ago, energy flowed in one direction, from large power plants to consumers. Today we are dealing with reverse flows, when surplus energy from photovoltaics flows from low voltage levels up the network. Added to this is seasonal variability in power flows—surplus energy from PV in summer, increased demand in winter—as well as voltage and congestion problems in local areas. Non-market redispatching is also appearing more frequently, limiting efficiency and competitiveness. Without new network management mechanisms, it will be difficult to maintain its stability. Flexibility is the answer to these challenges.
Current DSO actions and their limitations
Distribution System Operators (DSOs) currently employ various methods to eliminate network constraints. The most commonly used include network reconfiguration and actions related to voltage regulation on transformers. These methods are effective in many situations, but their effectiveness decreases with the growing share of distributed sources and prosumers.
Meanwhile, in daily operations, operational services often plan and coordinate maintenance work during periods when RES production is high. While this does not constitute a direct method of eliminating constraints, it is an important element of ensuring continuity of energy supply and minimizing the risk of deepening network problems.
Despite using these measures, the capabilities of traditional DSO actions are becoming insufficient. With the increase in the number of RES installations and prosumers, network problems will escalate, requiring active involvement of network users in the constraint management process through the development of flexibility services.
What do flexibility services involve?
Flexibility services are actions provided to DSOs by aggregators, active consumers, generators, or energy storage owners. Their purpose is to ensure network operational security and efficiency of its development. They may involve increasing or decreasing power consumption or changing the power generated to the network. This makes it possible to solve local voltage and congestion problems, often faster and cheaper than through infrastructure investments. In many cases, flexibility services can be a temporary solution until network modernization is completed.
Classification of flexibility services
Flexibility services can be considered across different time horizons:
- Short-term – response within a day (e.g., failures, unplanned outages)
- Medium-term – week to month (e.g., planned repairs, modernizations)
- Long-term – year and longer (e.g., until investment completion)
There is also a division by purpose:
- Investment-related, implemented until network modernization
- Operational, applied during planned abnormal operation
- Intervention-based, activated in emergency situations
Forecasting flexibility needs
Flexibility needs are local, time-variable, and dependent on the current and future situation in the electricity system. DSOs should develop development scenarios for a 5–10 year period, taking into account demand and generation forecasts, national energy and climate plans, as well as the impact of tariffs and connection rules on user behavior. These scenarios must additionally be coordinated with transmission network development plans and take into account local energy strategies.
Statistical analysis can be used to assess flexibility needs, especially with data of high temporal, spatial, and voltage resolution. At the same time, the forecasting process will require support from modern technologies, including artificial intelligence tools, which facilitate prediction of future network operating states. Forecasts should be prepared based on various scenarios of market and technological development. These scenarios should take into account, among other things, the pace of energy infrastructure development, changes in generation structure, development of electromobility, or variability in weather conditions. Thanks to the scenario approach, it is possible to capture a wide spectrum of potential conditions, allowing more precise determination of future flexibility needs in the distribution network.
Benefits of implementing flexibility services
Why is it worth developing flexibility services? It’s a cheaper alternative to some investments, a tool for RES integration, and support for network operational security. Without their implementation, it will be difficult to maintain system stability under conditions of growing distributed generation. Procurement of flexibility services by DSOs is both a legal and technical requirement, resulting from limited network capacity. DSOs must be equipped with modern forecasting tools, enabling prediction of network operation in various perspectives and for different operating states. This will allow responding to network constraints with sufficient advance notice through the most cost-effective and technically optimal means.
Summary
Flexibility is not just technology, it’s a new philosophy of network management. Involving users in the process of balancing and eliminating network constraints is inevitable. The flexibility services market in Poland is just starting, but its development is the key to a safe and effective energy transformation.
Ewa Przybyłek
Senior Specialist in Flexibility Management at TAURON Dystrybucja S.A. I have been working in the energy sector for 12 years. I started in customer service, where I dealt with resolving consumers' daily problems, including issues related to invoices and technical complaints. Subsequently, I worked with energy generators, preparing and concluding contracts defining the operating conditions of sources connected to the grid and supporting them in addressing current challenges related to generation activities. During this time, I enhanced my skills through postgraduate studies in renewable energy sources. Today, I organize the process of managing flexibility services, from defining requirements for providers and their qualification, through contract conclusion, to developing settlement methods. I also work on the methodology for evaluating the effectiveness of flexibility services. I believe that energy is not just about megawatts, but also about relationships, cooperation, and trust. For this reason, I share my knowledge on LinkedIn as part of the TAURON Ambassador Program, creating the series "In Plain Terms About...". I gladly explain the complexities of the energy sector in an accessible way and answer questions from people interested in the industry. My goal is to create practical solutions that help stabilize the grid and engage future generations in the future of energy.
