State Space Modelling and Control Framework of the Distributed Energy Storage System based on Cascaded H-Bridge STATCOM

The development of large-scale energy storage systems faces significant technical obstacles, such as dynamic modelling of complex systems and coordinated multi-objective control of energy storage units and the power grid. This paper presents the independent variable state-space modelling procedure of the distributed energy storage system based on the cascaded H-Bridge STATCOM topology. A multilayer control framework is proposed consisting of energy management, linear quadratic current regulator, and a low-level submodule capacitor voltage balancing algorithm. The simulation results of an H-Bridge STATCOM cascade with 15 submodules in each phase show that the system can output both active and reactive power with low switching frequency (1 kHz) and low THD (≈ % 0.63 for 1 pu active power output and ≈ % 0.96 for 1 pu reactive power output) while maintaining the voltage balance of all submodule capacitors, verifying the effectiveness of the proposed modelling method and the control framework.