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Modeling, Design, and Control of Solid-State Transformer for Grid Integration of Renewable Sources
Published in Md. Rabiul Islam, Md. Rakibuzzaman Shah, Mohd Hasan Ali, Emerging Power Converters for Renewable Energy and Electric Vehicles, 2021
Md. Ashib Rahman, Md. Rabiul Islam, Kashem M. Muttaqi, Danny Sutanto
The use of a smart solid-state transformer (SST), instead of the traditional distribution transformer, has been envisioned as a potential solution for the integration of renewable energy sources, such as distributed generators, battery energy storage systems (ESS), and electric vehicle charging stations to the distribution grid. The internet of things (IoT)-based SST framework can perform the same function as an embedded energy router in a power grid. Such a framework removes the complexities associated with the interconnection of the traditional distribution grid and distributed microgrid (MG) (AC, DC, or hybrid) units from the viewpoints of reliability, controller performance, and communication functionalities. In comparison with the traditional distribution transformer, the smart SST exhibits several unique functionalities, such as improvement of the grid power quality, regulation of the voltage and power factor, support of the grid reactive power, provision of real-time communication, and intelligent management of the energy flow.
Power Electronics in Distribution Systems
Published in Chengshan Wang, Jianzhong Wu, Janaka Ekanayake, Nick Jenkins, Smart Electricity Distribution Networks, 2017
Chengshan Wang, Jianzhong Wu, Janaka Ekanayake, Nick Jenkins
As shown in Figure 5.32, a solid-state transformer (SST) typically includes a medium-voltage AC–DC power conversion stage to generate a medium voltage DC bus, a medium-frequency (0.5–1 kHz) DC–DC converter stage to produce a regulated low-voltage DC bus and a DC–AC converter stage to produce a regulated low-voltage AC bus [15, 16]. As discussed in [16], in order to achieve the required voltage, a modular design based on a number of H-bridge modules connected in series at the input side is considered. These converters are switched using an interleaved carrier-based PWM technique. Each PWM carrier is phaseshifted by 360°/N (where N is the series-connected module). The PWM for each cell is generated by comparing a reference signal with a corresponding PWM carrier, as shown in Figure 3. An SST can be considered as a three-port energy router which integrates the distribution system, a residential AC system, and a DC system. In order to improve system efficiency, the DC type sources and energy storage can be connected to the DC port.
High Frequency Transformer Design and Optimization using Bio-inspired Algorithms
Published in Applied Artificial Intelligence, 2018
Jeyapradha Ravichandran Banumathy, Rajini Veeraraghavalu
The evolution of Solid State Transformer (SST) in recent years as a promising new class of grid assets can be attributed to their ability to offer service extensions beyond voltage transformation, such as provision for dual power output (both dc and ac), input–output decoupling, high switching frequency, fault isolation, better power quality, etc. The heart of the SST system is the high frequency (HF) isolated dc–dc converter, which provides galvanic isolation between the medium voltage AC grid and a low voltage AC/DC grid as shown in Figure 1. Though the choice of HF results in reduced footprint for the transformer, it also leads to higher switching losses and saturation of magnetic components. Further, the reduction in footprint entails an increased loss density in the transformer, which necessitates significant efforts on thermal management (Meier et al. 2009). Thus a robust design procedure is required which collectively addresses the HF, isolation and thermal management issues and yields desired efficiency concurrently retaining the %regulation and power losses within specified limits.