Analys av ett simulerat batterilagringssystem som används förfrekvenshållningsreserv vid låg och hög svängmassa i elnätet

The nominal frequency in the Nordic power grid is 50 Hz, as sources and loads are connected anddisconnected from the grid the frequency deviates from 50 Hz. The Nordic TSOs are responsible forkeeping the frequency stable in the Nordic synchronous area. Depending on how big the differencebetween production and consumption, the frequency deviations vary in size. Another factor in frequencystability is the inertial energy from synchronously connected generators. A lower inertial energy in thegrid leads to a lower frequency stability and a higher inertial energy leads to higher frequency stability.The inertial energy in the grid changes as the production mix changes, power sources like wind and solardo not provide inertial energy.In this thesis, an analysis is conducted on the revenue and performance of a lithium-ion battery energystorage system (BESS) delivering frequency stability services to the Nordic power grid, the calculationsand simulations were done using python. The frequency regulation services that were focused on in thisthesis are the three Frequency Containment Reserves (FCR). The three FCR variants are FCRN, FCRDup and FCRD down. When providing FCR services to SVK it is done one operational hour at a time,for each operational hour that companies want to deliver FCR they need to send a bid to SVK.A simple module of a BESS was implemented in python, real frequency and price data was downloadedand used in the program. 22 days from 2024 were chosen, 11 days with low inertia and 11 days withhigh inertia. The simulated BESS was based on a real battery system installed in the Swedish powergrid. The real battery is a 1/1.1 MW lithium-ion BESS, the BESS is installed to the grid but is not yetoperational. The goal of this thesis is to get an understanding of BESS performance and profitabilitywhen providing FCR services in connection to inertial energy in the grid. This thesis was done incollaboration with Karlstad kraftteknik AB.The results showed that FCRD down was the most profitable FCR variant when the inertia in the powergrid was low. FCRN was shown to be more profitable when the inertial energy was high and FCRD upwas the least profitable in the low and high inertia days. It was also discovered that when the BESS wasdelivering FCRN, the BESS was constantly either receiving or delivering energy which accelerates SOHdegradation.