1. Univ logo Presenter: Xin Zhang Supervisor: Prof. Qing-Chang Zhong University: The University of Sheffield UKACC PhD Presentation Showcase Stabilization Method of DC Cascaded System With Adaptive Parallel-virtual-impedance Control Strategy

2. Univ logo UKACC PhD Presentation Showcase Slide 2 Instability Problem of DC Cascaded System DC Cascaded system If Z oS mismatches Z iL, the System will be unstable Stability problem Unstable Connection Need re-design of the whole system

3. Univ logo UKACC PhD Presentation Showcase Slide 3 Concept of Adaptive Parallel-virtual- impedance (PVI) Power module Source converters Stable  Can Connect to any source converters stably  No need to change the product even at different systems

4. Univ logo UKACC PhD Presentation Showcase Slide 4 Adaptive PVI Control Strategy

5. Univ logo UKACC PhD Presentation Showcase Slide 5 Experimental Results Case 1 Case 2

6. Univ logo UKACC PhD Presentation Showcase Slide 6 Conclusion and Future Work  Conclusion:  Mismatching of source output impedance and load input impedance may cause instability problem of DC cascaded system;  Proposed adaptive PVI control strategy to solve the instability problem;  With the adaptive PVI control strategy, the converter can work stablely with any source stages.  Future Work:  Popularize the adaptive PVI control strategy to single phase AC cascaded system;  Popularize the adaptive PVI control strategy to three phase AC cascaded system.