Design of Control Architecture for Stacked Low-Inertia Converters with Fast Dynamic Control

Control architectures based on distributed controllers are favored in control of modular stacked converters because of their scalability, ease of installation and stable structure. However, the existing solutions are only applicable to traditional voltage source converters (VSCs) with high-inertia components, i.e., larger DC-link capacitance which are controlled with slow proportional-integral controllers. Therefore, there is no demanding requirement on the communication speed. This paper presents the challenges in the design of control architecture of lowinertia converters, such as soft-switching solid-state transformers (S4T), particularly using fast-dynamic control. It also proposes a methodology to realize the control architecture for such stacked low-inertia converters. The proposed control architecture is verified on a two-module S4T operating at 4 kV using hardware-in-loop simulation in the OPAL-RT platform and by experiments.