| Title |
Research on Improving Grid Frequency Stability Using Variable Frequency Transformer |
| Authors |
Byeong-Hyeon An ; Jae-Deok Park ; Jun-Soo Che ; Tae-Hun Kim ; Tae-Sik Park |
| DOI |
http://doi.org/10.5207/JIEIE.2024.38.1.040 |
| Keywords |
Frequency ndir; Frequency sability; RoCoF; VFT |
| Abstract |
Many studies have been conducted around the world to reduce carbon emissions. In the power sector, a policy is being implemented to reduce the proportion of coal power generation and convert to new and renewable energy. However, unlike synchronous generators, renewable power sources vary in power generation depending on environmental changes such as weather. And the increase in distributed generator means that the number of inverter-based power generator in the grid increases and the proportion of synchronous generators decreases. Therefore, the inertia and reserve power of the system are reduced, which poses a threat to system frequency stability. Generally, when analyzing frequency response, the lowest frequency (Frequency Nadir) and Rate of Change of Frequency (RoCoF) are used as representative indicators. To improve frequency stability, many studies have focused on grid-forming converters using inverters and virtual inertial control of wind power. In this paper, we propose a variable frequency transformer (VFT) method to improve the frequency stability of the power grid. VFT allows frequency variations and bidirectional power transmission by controlling the rotation direction and speed of the rotor and has rotational inertia. Using this feature, the grid frequency stability can be improved with VFT. The performance of the proposed scheme was verified through Matlab Simulink simulation. |