Direct model predictive control for medium voltage modular multi-level STATCOM with and without energy storage

Static reactive power compensators or STATCOM devices are well known as equipment for controlling the power flow in transmission grids. However, the evolution of distribution grids is calling for similar function adapted to the distribution level. Besides handling the major differences between distribution and transmission systems, with the smart grid vision of the future distribution grids; flexibility, accessibility and open modular equipment are main features of future distribution STATCOMs. This paper proposes the direct model predictive control (D-MPC) as a tool for achieving all the above keywords. D-MPC is simple, easily upgradable and can be easily adapted to facilitate the integration of different active devices at the distribution level. In this paper, D-MPC is implemented for the internal and external control of distribution STATCOMs having modular multilevel designs. It is shown that it is possible to control both active (using energy storage) or reactive power flow at the grid with the same simple control approach in addition to balancing the DC voltage of all modules.