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Background
As the concept of the smart grid is getting more and more attractive, the power conversion in the smart grid becomes worth paying attention to in both academia and industry, especially focusing on the utility interface. Figure 1 shows the schematic diagram of a possible area of the smart grid. Beside the buildings, the renewable energy resources such as photovoltaics (PV) and wind turbines (WT) are installed for power generation. Besides, the batteries are also installed for energy storage and grid stabilization. Moreover, the electric vehicles (EV) along with chargers are included as well. As can be imagined, the utility interface plays an important role in this area because the surplus and shortage of energy are both probable in the smart grid.
Figure 1. Schematic diagram of a possible area of the smart grid.
As mentioned above, the utility interface is necessary for the smart grid to exchange energy with the utility grid. Assuming the fast charging station to be connected with the utility grid, the traditional utility interface is schematically illustrated in Figure 2, in which the bulky and costly step-down transformer is indispensable for adapting to the low-voltage (LV) power converter. In order to remove the transformer, the recent utility interface is then promoted and schematically illustrated in Figure 3, in which the isolation requirement is shifted to the power converter. The most suitable power converter is the so-called modular multilevel cascaded converter (MMCC), which can be directly connected to the medium-voltage (MV) utility grid.
Figure 2. Schematic diagram of the traditional utility interface.
Figure 3. Schematic diagram of the recent utility interface.
Different from the traditional multilevel converter like the diode clamped converter or the flying capacitor converter, the MMCC is characterized by the modular structure so that it is much easier to adjust the cascaded modules. In other words, it is more flexible to adapt to the medium/high voltage. As a result, high expectations are placed on the MMCC.
Achievement
Ongoing Research Topics
In addition to the above-mentioned research work, other research topics are also under development...
To be updated
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