Solid-State Transformer(SST)

Also known as power electronic transformers, solid-state transformers (SSTs) are advanced smart power equipment that replace traditional line-frequency electromagnetic transformers by leveraging power electronics conversion technology and high-frequency isolation technology. Discarding bulky iron-core structures, SSTs integrate multiple functions such as voltage transformation, electrical isolation, and AC/DC power conversion, making them one of the core equipment types in modern power systems.

Their working principle typically adopts a three-stage topology: First, the primary-side rectification stage converts line-frequency AC power into DC power. Then, electrical isolation and voltage amplitude regulation are achieved through a high-frequency transformer, which significantly increases the operating frequency and reduces the equipment size. Finally, the secondary-side inversion stage converts the DC power into AC power of the required specifications, enabling flexible power conversion and stable output.

SSTs have a wide range of application scenarios, primarily used for renewable energy grid integration—such as photovoltaics and wind power—to accommodate the intermittent generation characteristics of renewables. They are also suitable for hybrid AC/DC microgrids, energy storage power stations, electric vehicle fast-charging stations, and railway transit power supply systems. Additionally, they can be utilized in smart distribution networks to achieve precise voltage and power regulation as well as grid fault isolation.

Their advantages are prominent: their size and weight are far smaller than traditional transformers, resulting in high power density; they possess strong controllability, enabling the active optimization of power quality and harmonic suppression; and they support bidirectional AC/DC conversion, adapting to diversified power supply scenarios. Their disadvantages include complex structures, higher device costs, greater switching losses and thermal management pressures under high-frequency operation, as well as weaker high-voltage tolerance and overload capacity compared to traditional equipment, leading to higher maintenance requirements.

Overall, with the rapid iteration of wide-bandgap semiconductor devices such as silicon carbide (SiC) and gallium nitride (GaN), the challenges of losses and thermal dissipation in solid-state transformers are being gradually overcome. In the future, relying on their core advantages of intelligence, lightweight design, and multifunctionality, SSTs will gradually replace traditional line-frequency transformers and find widespread application in renewable energy grid integration, smart grids, transportation electrification, and other fields, boasting broad development prospects.

Data Center Solid-State Transformer

Also known as a power electronic transformer, a solid-state transformer (SST) is constructed from novel power semiconductor devices. The entire equipment adopts a high-frequency conversion architecture, with the core transformation function implemented via the integration of IGBTs and silicon carbide (SiC) power modules. Its core concept is the Power Electronic Building Block (PEBB). They typically adopt a modular series-parallel topology to achieve the flexible integration of different voltage levels, capacity levels, and power forms, facilitating flexible configuration across various application scenarios.

Charging-Type Solid-State Transformer

Also known as power electronic transformers, solid-state transformers are based on the core concept of Power Electronic Building Blocks (PEBBs). They typically adopt a modular series-parallel topology to achieve the flexible integration of different voltage levels, capacity levels, and power forms, facilitating flexible configuration across various application scenarios.

In charging scenarios, solid-state transformers (SSTs) can replace traditional line-frequency transformers and the internal AC-DC stages of charging modules, enabling direct medium-voltage connection. EV charging stations can then be established simply by pairing them with DC-DC modules on the back end. Compared to traditional solutions, the comprehensive charging efficiency of the station is improved by approximately 3 percentage points, which extends the equipment's full life-cycle return and provides higher operational reliability.

The optical-storage-charging DC-coupled solution discards the traditional 380V AC-coupled architecture and can replace conventional power conversion systems (PCS) and PV inverters, thereby improving the comprehensive utilization rate of photovoltaics and energy storage. The DC-coupled control logic is simple, requiring only voltage regulation. It completes all-DC integration in coordination with DC energy storage cabinets and photovoltaic maximum power point tracking (MPPT), further enhancing overall system efficiency.

High-Speed Service Area Integrated Solution: During holidays, the loads on both sides of a service area are often unbalanced. By utilizing SSTs to build flexible interconnection cubicles and connecting the power service areas on both sides via a medium-voltage DC bus, power supply capacity can be shared between them, effectively doubling the overall power supply capability.

After flexible interconnection, the associated charging piles can expand their charging capacity to 1.5 times the original. For example, a traditional 1.25 MW transformer can only support 20 charging parking spaces, but with an SST, this can be expanded to 30–40 spaces, stabilizing load operation through capacity mutual assistance. At the same time, the DC bus can be integrated with distributed photovoltaic and energy storage equipment in the service area, enabling the mutual flow and circulation of regional green energy.