The power system is transitioning toward a higher share of variable renewable energy sources, such as wind and solar. As a result, the task of maintaining power system balance becomes increasingly challenging due to the inherent variability and forecast uncertainty of these resources, highlighting the need for robust methods to assess and quantify system flexibility. To address this challenge, this study explores how future balancing and flexibility needs can be assessed using a scenario-based modeling framework.

The study applies the Balancing Tool Chain (BTC), a multi-stage modeling framework that links long-term planning, day-ahead scheduling, hour-ahead balancing, and real-time frequency control. By capturing the interactions between forecast errors, dispatch decisions, and resource availability, BTC enables a more consistent and comprehensive analysis of system flexibility across scenarios and weather years.

A case study of the Nordic power system in 2030 is conducted to quantify regional flexibility needs in terms of volume and ramp rates. These are derived from BTC outputs by comparing updated hour-ahead wind forecasts with day-ahead dispatch schedules. This approach allows for the identification of net imbalances and available regulation capacity across technologies and areas, enabling an analysis of flexibility requirements in relation to system conditions, technology mix, and geographical constraints.

The results highlight how scenario assumptions and system configurations influence balancing needs in future Nordic power systems. The findings also demonstrate the potential of integrated modeling frameworks like BTC to support electricity market development and system design.