About SOLID STATE TRANSFORMER

overveiw

1. Seminar on Solid State Transformer(SST) and its implementations BY MUDA BALA NAIK M200207EE

2. Contents Introduction About solid state transformer, Disadvantages of classical transformer, Classification of SST topology, Applications Advantages of SST Conclusion Reference

3. Introduction About Solid State Transformer (SST)? Disadvantages of Conventional Transformer. Advantages of SST over Conventional Transformer. Topologies of SST. Applications of SST

4. About Solid State Transformer? Solid state transformer (SST) is an element/component consisted of multi stage power electronics converters isolated with high frequency transformer A solid state transformer can actively regulate voltage and current.

5. Disadvantages of classical Distribution Transformer Bulky size and heavy weight. Transformer oil can be harmful when exposed to the environment. Core saturation produces harmonics, which results in large inrush currents. Many more….

6. Classification of SST topology There are many topologies which can be categorized as below

7. Single stage Its simplest SST topology. It has only a direct power conversion with transformer isolation to step down the HC to LV. It operates in direct DC-DC or AC-AC power conversion stages offer better efficiency and higher reliability. It uses phase shift angle between the secondary and the primary bridges to control the direction and magnitude of power transfer.

8. Advantages It can be used in bidirectional power flow with four-quadrant switches which help to improve control strategy and regulate harmonic content. It can control power transferred to the load between bridges.

9. Single phase dual active bridge converter The single phase Dual Active Bridge (DAB) converter consists of a full bridge circuit on the primary and the secondary side of the high frequency transformer. The DAB utilizes the leakage inductance of the transformer to provide energy storage and to modify the shape of the current waveform.

10. Modulation used Phase shift modulation Trapezoidal modulation Triangular modulation

11. Single phase dual active bridge converter N

12. Operation Switch 1 interval Switch 2 interval ZVS transient

13. Power transferred It is controlled by the phase shift angle between two bridges Primary bridge Secondary bridge Transformer current Power flow

14. Design parameters Transformer ratio Switching frequency Leakage inductance Filter capacitance

15. Two stage It has additional design of DC-link either on the HV side or the LV side. The power flow is bidirectional though it can be used into unidirectional by deploying an uncontrolled rectifier at the LV side of the AC-DC converter. It has capability to reduce the harmonic distortion in both input and output current under unbalanced load conditions.

16. Three stage It can optimize the performance of distribution and transmission grids apart from lower volume and weight in this SST The three stage SST topologies are designed with two DC links that are able to address power quality issues and also supply and utilize any devices. It can be differentiated on basis of voltage and frequency MEDIUM VOLTAGE STAGE(AC-DC) LOW VOLTAGE STAGE (DC-AC) MEDIUM FREQUENCY CONVERTER HIGH FREQUENCY TRANSFORMER

17. Trending applications of SST SOLAR PHOTOVOLTAIC APPLICATION WIND ENERGY CONVERSION SYSTEM TRACTION APPLICATION OTHER FUTURE APPLICATION RENEWABLE ENERGY SOURCE MICROGRID APPLICATION

18. Renewable Energy Source As renewable energy sources are gaining interest in order to conserve energy for future generation. As some of the RESs are generated as DC power and require the power conversion i.e. inverter which would decrease the power efficiency. In addition, a bulky converter is also required in order to be connected to the conventional power grid. In this context the replacement of a conventional power transformer by SST is the solution to many these issues. More importantly as most of the RESs systems disconnect during overvoltage conditions. The SST provides a solution by controlling the power output and the power could still be generated.

19. Solar Photovoltaic Application As PV generates a low voltage, there is a effective options to connect solar PV to load or network. Thus a low frequency transformer is utilised or large PV arrays are used. These have some disadvantages. Hence SST is alternative A dual active bridge inverter topology based on SST applied in PV module arrays is proposed where high frequency transformers are utilized instead of bulky medium voltage line frequency ones.

20. Wind Energy Conversion System Main reason behind SST in wind energy conversion system are reduction in weight and volume. SST could offer reduction in fluctuation of voltage. And many more future applications

21. Application areas

22. Advantages of SST Small in weight and volume. Power factor correction and reactive power compensation Harmonic isolation Fault isolation Environmental benefit Instantaneous voltage regulation

23. Conclusion Solid state transformer (SST) is emerging technology integrating with a transformer, power electronics converters and control circuits that could help in developments in many areas such as smart grids, traction systems and with renewable energy sources (RESs).Here Dual active bridge converter is implemented for solid state transformer. A high frequency transformer is used to minimize the bulk of passive components. Four quadrant switch cells and phase shift modulation to ensure that energy can flow in both directions.

24. Reference M. A. Hannan “State of the Art of SSTs: Advanced Topologies, Implementation Issues, Recent Progress and Improvements” Year: 2020 | Volume: 8 | Journal Article | Publisher: IEEE Hengsi Qin, Jonathan W. Kimball “Ac-ac dual active bridge converter for solid state transformer” Energy Conversion Congress and Exposition Year: 2009 | Conference Paper | Publisher: IEEE Xu She;Alex Huang “Solid state transformer in the future smart electrical system” Power & Energy Society General Meeting Year: 2013 | Conference Paper | Publisher: IEEE