Model predictive control of a STATCOM based on a modular multilevel converter in delta configuration

This paper proposes a model predictive control (MPC) scheme for the single delta bridge cell (SDBC) modular multilevel converter (MMC) when operated as a static synchronous compensator (Statcom). The controller achieves reactive power compensation and current harmonic elimination while maintaining the branch currents and capacitor voltages within their safe operating limits. The MPC scheme manipulates the setpoints of a subsequent pulse width modulator (PWM). The controller is conceptually simple with an easy to devise objective function, a linearized converter model based on first principles, and constraints on the main physical quantities. The underlying optimization problem is a quadratic program (QP), which can be solved efficiently using off-the-shelf solvers. The developed control framework achieves a good performance at steady-state operation and very fast current response during load transients.