Solid-state transformer (SST) technology is one of the developing technologies that will be widely used in the future to integrate low-voltage and high-voltage networks with control circuitries and power electronics converters, facilitating renewables integration in smart grid applications. SST technology has crucial key advantageous features, including compact size and weight, low cost, and ease of connection in offshore applications. However, SST technology exhibits a few concerns, such as implementation, protection, economic, and communication compatibility, that need to be addressed. This paper aims to review SST technology with its advanced control schemes and provide future directions for research and development, applications, and prospects. In line with this, highly cited SST technology papers are examined to derive and summarize concerning issues related to its operation and control with further research development of power grids. Moreover, this review discusses the assessment and state-of-the-art technology of SSTs in different applications, focusing on configurations, control circuitry, and their drawbacks and benefits. Numerous issues and challenges of SST technology are explored to identify the existing knowledge gaps and potential future recommendations. All these critical analyses, information, and evaluations would benefit power engineers and researchers in developing and implementing advanced intelligent SST technologies for sustainable energy management in future power systems.

Large-scale industrial loads, sensitive loads, and electrical power distribution systems suffer from power quality issues such as voltage interruptions, flickering, and sags which can cause a significant financial loss. The semiconductor based solid-state transfer switch (SSTS) can utilize the dual power feeders to protect the loads against these power disturbance issues. Conventional SSTS often requires more than quarter cycles to complete the transfer process because of load dependent commutation. Numerous researchers proposed the improved SSTS with impulse commutated circuit, which can reduce the transfer time and provide better ride-through capability against voltage sags. However, the SSTS specification depends on the application types and design procedure. Recently, hybrid SSTS has been introduced by the researchers to overcome all these issues. It has been investigated that not much papers are available in literature so far to aggregate all these issues. Therefore, towards the novel contribution of research, this review critically described the requirements, standards, and specifications of SSTS; control and switching mechanisms; and application of SSTS as single or hybrid topology, to give a comprehensive idea to the future researchers about the design of SSTS for a specific application. This paper also contributes to analyzing the key issues related to the SSTS applications, which can provide an easy control strategy and reduce the transfer time significantly. Overall, this research will strengthen the efforts of the researchers and industrialists to select, develop, and design the appropriate SSTS for a particular application.