Synergetic Control of High-Frequency-Link Based Multi-Port Solid State Transformer

摘要

Solid state transformer (SST) has drawn tremendous attention in the academia since its appearance, and it is considered as a suitable choice to replace the regular distribution transformer in the future energy internet. In order to integrate various kinds of renewable energy sources and loads, multi-port SST based on the DC-link has been focused on previously, which provides a common interaction point for the energy flow. Considering the isolation requirement among different ports, a high-frequency-link based multi-port SST topology is proposed in this paper. It has the features of modularity, scalability, isolation and independence among all the ports. The core of the topology is modular-multi-active-bridges (MMAB), with multiple high-frequency transformers. After analyzing its working principle, it turns out that the mathematical model is similar as that of multi-active-bridge (MAB) with a multi-winding transformer. Then based on its mathematical model, a set of synergetic control strategy is proposed to improve the dynamic performance of the multi-port SST, which includes two feedforward control schemes and cross-coupling suppression control. The effectiveness of the proposed control strategy has been confirmed through simulation in MATLAB/Simulink.