Evaluation of reactive power compensation and grid losses in the Nordic transmission grid

Paper in proceeding, 2026

Existing publicly available models of future energy systems neglect power system stability. However, to ensure the reliability of future electricity systems, mapping stability and ancillary service needs is crucial. One key stability aspect is voltage stability. As a first step towards the modelling of future voltage stability-related ancillary services, we analyse the required reactive power compensation of the current grid. This work improves an existing grid model of the Nordic High-Voltage transmission grid based on open-source data with around 400 buses and performs power flow analyses for each hour in the reference year 2022. We evaluate the reactive power demands per bus to find the required reactive power compensation capacity for steady-state operation. We also analyse the available dynamic reactive power compensation from generation. For this, we use current grid code requirements for reactive power capabilities for generators. We also consider a scenario where STATCOM operation is required from all converter-connected generation. We further validate the model by analysing system losses and compare them with reported TSO losses. The work serves as a foundation for modelling voltage stability in the case of N-1 contingencies for future scenarios.