Solid-State Transformer vs Traditional Transformer: Advantages and Applications Explained
A solid-state transformer (SST), also known as a power electronic transformer (PET), is a static electrical device that integrates power electronic conversion technology with high-frequency energy conversion based on electromagnetic induction. It transforms electrical energy from one set of power characteristics into another. SSTs can enhance power system stability, enable flexible power transmission, and are suitable for smart grid applications.
Traditional transformers suffer from drawbacks such as large size, heavy weight, mutual disturbances between grid and load sides, and lack of energy storage capability, making them increasingly unable to meet market demands for stable and secure power system operation. In contrast, solid-state transformers are compact and lightweight, and offer flexible control over primary current, secondary voltage, and power flow. They improve power quality and have clear advantages in addressing voltage disturbances, ensuring stable system operation, and enabling flexible power transmission. Beyond the power industry, SSTs can be applied in electric vehicles, medical equipment, chemical processing, aerospace, and military fields.
Features
The electronic transformer is a novel power conversion device. In addition to the basic functions of conventional power transformers—voltage transformation, electrical isolation, and energy transfer—it also provides additional capabilities such as power quality regulation, power flow control, and reactive power compensation. These enhanced functionalities are made possible by incorporating power electronic conversion and advanced control technologies, which allow flexible manipulation of the amplitude and phase of voltages and currents on both primary and secondary sides. As a result, power flow can be precisely controlled according to system requirements, enabling more stable and flexible power transmission. SSTs can address many challenges in modern power systems and thus hold broad application prospects.
Compared to conventional power transformers, PETs offer the following characteristics:
Compact size and lightweight;
Air-cooled operation without the need for insulating oil, reducing environmental pollution, simplifying maintenance, and improving safety;
Ability to provide a constant output voltage amplitude on the secondary side;
Improved power quality with sinusoidal input current and output voltage, capable of achieving unity power factor. Both voltage and current on primary and secondary sides are controllable, allowing arbitrary adjustment of power factor;
Built-in circuit breaker functionality—high-power semiconductor devices can interrupt fault currents within microseconds, eliminating the need for separate protective relays.
Additionally, power electronic transformers offer unique functionalities, such as: improved power supply reliability when connected to batteries; the ability to perform special phase conversions (e.g., three-phase to two-phase or three-phase to four-phase); and the capability to simultaneously deliver both AC and DC outputs. In a referenced study, the authors conducted simulation comparisons between conventional power transformers and self-balancing power electronic transformers under five different operating conditions.
The simulation results show that the PET exhibits superior input and output characteristics under full-load rated operation, single-phase open circuit on the low-voltage side, three-phase short circuit, unbalanced three-phase voltage on the high-voltage side, and harmonic pollution. The PET effectively isolates imbalances or disturbances on one side from affecting the other side, demonstrating significantly better performance than conventional transformers.
