Review on Topology and Control Applications of Medium-High Voltage Power Electronic Transformers I

With the proposal of the energy internet concept and the widespread application of smart grid-related technologies, the proportion of renewable energy sources such as wind and photovoltaic power in the existing energy system will significantly increase. This indicates that future power grids will become more intelligent and flexible. In the energy internet, as the proportion of distributed users and energy resources rises, electricity transmission demands highly controllable capabilities. In smart distribution networks, the grid must maintain highly stable and high-quality power supply while compatibly integrating a large number of distributed renewable energy sources and monitoring/managing grid operational states. These requirements place stringent demands on the intelligence of energy grid equipment, whereas traditional power frequency transformers inherently face functional limitations.

Power Electronic Transformers (PETs), implemented through power electronic conversion circuits for energy transformation and utilizing medium-to-high-frequency transformers for magnetic coupling and isolation, represent an advanced solution. Compared to conventional power frequency transformers, PETs enable AC/DC energy conversion and integrate functions such as power factor correction, reactive power compensation, harmonic mitigation, and relay protection due to their embedded power electronics. Owing to their high controllability, PETs demonstrate significant application advantages in energy internet and smart distribution grid scenarios.