The SST has several advantages when applied in the modern electric distribution grid. Among them, the availability of the dc link for connection of dc microgrid is mentioned in this chapter. There are many different possibilities to implement the architecture of the SST, and an overview and classification have been presented. For electric distribution, the three power processing stages architecture is cited to be the best choice, because it provides the decoupling between the MV side and LV side and also providing dc link connectivity. Furthermore, the dc-dc stage plays an important role on the SST architecture design, because it is responsible for the major losses of the system, besides to be in charge for controlling the LVDC link. Therefore, the SRC and the DAB have been pointed out as the most promising choice. The SRC can provide a very high efficiency, but it is not able to control the power flow and the regulate the LVDC link properly. The DAB converter, on the other hand, can provide a high efficiency solution and provide full control. The design aspects of the power stage and control stage of the DAB converter focusing on the SST application has also been discussed in this chapter.

Chapter Contents:

• 9.1 Solid-state transformer: concept
• 9.2 SST in electric distribution grid application
• 9.3 ST architecture classification
• 9.3.1 Power conversion stages
• 9.3.2 Modularity
• 9.3.3 Modularity level
• 9.3.4 dc Link voltage availability
• 9.4 Solid-state transformer and smart transformer architectures overview
• 9.5 dc–dc Stage: power converter topologies
• 9.5.1 Requirements
• 9.5.2 Basic module topologies
• 9.6 Series resonant converter
• 9.6.1 Current stress
• 9.6.2 Efficiency expectation
• 9.7 Dual active bridge (DAB) converter
• 9.7.1 Modulation strategy
• 9.7.2 Analysis of the DAB using the PSM
• 9.7.3 Current stresses on the DAB
• 9.7.4 Efficiency calculation
• 9.8 Active-bridge converter: control description and tuning
• 9.9 Summary
• References

Inspec keywords: resonant power convertors; load flow control; distributed power generation; power system control; DC-DC power convertors; power grids; power transformers

Other keywords: DC-DC stage; low-voltage grid; DAB converter; LV grid; SST architecture design; medium-voltage grid; MV grid; electric distribution grid; solid-state transformers; power flow control; dual active bridge converter; series resonant converter; LVDC link control; DC link; DC microgrid

Subjects: Power electronics, supply and supervisory circuits; Distributed power generation; Control of electric power systems; Power system control; Transformers and reactors; DC-DC power convertors