Adaptive voltage control scheme for DAB based modular cascaded SST in PV application

Solid state transformer (SST) is able to interface PV panels and distributed grid, which could serve as a new structure for future PV plants. However, the wide operating voltage range of PV system reduces the efficiency of DAB based modular cascaded SST system. Thus, this paper analyzes the impact of DAB voltage deviation between input and output side under frequency component analysis. Besides adjusting primary and secondary side duty cycles, which is widely used in previous literature, this paper utilizes DAB output voltage as an extra control freedom in SST. Then, an adaptive voltage control (AVC) scheme is proposed, which changes DAB output voltage in accordance with input voltage. This paper presents the detailed implementation of AVC and thoroughly compares SST cell efficiency with previous modulation method. Finally, the proposed method is verified in 10kV/1MW SST system.