A general real-time simulation method for cascaded power electronic converters based on N-port submodules

Power electronic converters are gradually developing towards modularization and cascaded structures to adapt to high voltage, large capacity, and various energy conversion scenarios. However, the real-time simulation models of cascaded power electronic converters are mainly aimed at specific topologies. For example, commercial real-time simulators have developed various package models for modular multilevel converter (MMC). But package models are difficult to meet the simulation requirements of more new topologies such as solid-state transformer (SST). This paper proposes a general real-time simulation method for cascaded power electronic converters based on N-port submodules of any topology and any cascaded structure. Firstly, a general equivalent model of N-port submodules is built. Based on the equivalent model, the topology of each N-port submodule can be customized, and the simulation efficiency can be improved by eliminating the internal nodes of each submodule. Secondly, the incidence matrix is redefined to describe the cascade structures of submodules, which is more flexible than the traditional method and can avoid the decoupling between submodules. Cascaded power electronic converters based on single-port, dual-port and four-port submodule are simulated on the NI-PXI based real-time simulation platform, which verifies the universality and efficiency of the proposed method.