Performance Comparison Between Hydropower and Battery-Based Frequency Containment Reserves in the Nordic Power System

Sammanfattning

As power systems transition toward high shares of renewable energy generation,maintaining grid frequency stability becomes increasingly complex. This degreeproject investigates the performance of hydropower and battery energy storage systems(BESS) as frequency containment reserves (FCR) in the DK2, SE4, and SE3bidding zones during contingency events in a future power system scenario characterizedby high wind generation and varying demand. The investigation assessespotential improvement in transmission capacity and grid efficiency in the congestedarea of southern Sweden and eastern Denmark during contingencies. Using updatedNordic 56 that contains 56 busbar and a detailed DK2 grid models with 141busbars as the simulation environment in PowerFactory, the work evaluates networkrobustness under both pre-contingency and post-contingency conditions. Static contingencysimulations focused on the operational envelope of the 0.95–1.05 voltage inp.u. and phase angles of ± 30◦ within transmission networks to identify deficienciesand assess proximity to voltage violations and angular instability. The simulationsshowed that increased BESS FCR participation relieves transmission capacity incontingencies during current and future high wind high load conditions, but alsocorresponded to increased losses in future high wind low load conditions. The increasedlosses likely correlate to a future shift in generation and demand centers inthe Nordics, with a corresponding shift in congested transmission corridors acrossthe Nordic power system, rendering BESS FCR located in DK2, SE3 and SE4 lesseffective during low load conditions. Consequently, depending on the grid loadingconditions, these potential alleviations could unlock previously reserved transmissioncapacity for energy markets, thereby influencing electricity price. Limitations concerningthe simulations were noted, including the lack of dynamic modeling whichlikely influenced the static simulation outcomes.