Frequency Stabilization in low Inertia Systems With Battery Power Injections

Sammanfattning: The challenges for the power system of the future becomes increasingly larger when large amountsof renewable energy sources are integrated, and when conventional forms of power such asnuclear power are phased out. This results in a greater difficulty in quickly deploying FrequencyContainment Reserves in the event of of power balance disturbance, to stabilize frequency andvoltage. The reason is the proportion of total kinetic energy in the rotating mass of the turbinedecreases, resulting in a reduction in the system's inertia. The renewable energy sources are oftenconnected to the system with power electronics, which is also the case for more loads.They do not contribute to the system's inertia or oscillation damping. The aim of the project is tostudy effects of this transition, with focus on frequency and inertia, with varying proportions ofwind power gradually replacing nuclear power plants. The simulation tool Simpow is used for thispurpose with a given model of a power system "Nordic test System". The results show that themaximum frequency deviations increase with decreasing inertia, both for frequency-dependentand frequency-independent loads, but they are greater for the latter. Simulations were also doneafter implementing Fast Frequency Response with battery in the model, to attempt to suppressfrequency deviations after a disturbance. This was successful, but it requires both a higher powercapacity for the battery and more energy depending on the degree of inertia reduction. For caseswith frequency-independent loads, these values were higher.