With the so-called green transition, EU member states have adopted a decarbonization plan. As a result, the power system is undergoing rapid changes. Expensive conventional power plants with large turbines are being shut down and decommissioned, while they are being replaced by cheaper and alternative sources such as solar and wind power plants. Consequently, the power system is losing rotational inertia in the rotating masses of generators, leading to grid instability.
Power converters are a crucial part of our electrical system. Nowadays, they already play an important role in integrating solar power plants into the grid, and their role will be even more significant in the future. However, this also brings some challenges. Traditional power converters were designed solely to track the voltage and frequency from the grid (grid-following). As long as the number of these converters was relatively small, this technology was entirely sufficient. However, with the rapid increase in the number of renewable energy sources in recent years, it is necessary to direct research towards the study of technologies where power converters do not merely follow the grid but establish and maintain stable voltage and frequency within the grid (grid-forming). This means that power converters are capable of operating independently, even without an external voltage and frequency source. The Grid-forming technology's ability opens up numerous possibilities, enabling greater flexibility and integration of renewable energy sources into the electrical grid. It also assists in addressing challenges associated with battery systems and microgrids.
This thesis will begin by introducing the concept of grid stability and frequency regulation. It will then present power converters and their control schemes that enable their operation. Grid-following power converters and their basic operation and components will be described, followed by an explanation of grid-forming power converters and the technology supporting the grid. Two different cases of power converter synchronization will also be presented.
In conclusion, a Grid-following power converter with a voltage amplifier, maximum power point tracking and a filter interconnected with the grid, will be implemented in the Simulink simulation environment. Voltage, current, power, and frequency profiles at various points in simulation will be displayed.
This work can serve as an introductory understanding of concepts related to grid stability, power converter operation, new technologies, and their challenges.
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