In this paper, a developed technique of Model
Predictive Control (MPC) is proposed to decrease the execution
time of the control algorithm for Modular Multilevel Converter
(MMC) based on grouping the switching states. There are two
stages in the control strategy to get the optimal switching state for
the converter in the next sampling interval. Within the first stage,
the allowable switching states of MMC are divided equally into
(M) groups based on the number of sub-modules (SMs) per arm
of a single-phase line. Therefore, the output of second-stage
obtains the optimal state from each group of the switching states.
In addition, all M groups are running simultaneously to reduce
the execution time. Unlike the previous algorithm, the second
stage of the proposed algorithm uses directly the optimal state
and the corresponding cost function for each group from the first
stage, then the optimal switching state is selected according to the
minimum cost function from the M groups. Therefore, a
reduction in the computational time of the MMC algorithm is
achieved. The control objectives here are the injected grid
currents, balancing the capacitor voltages of SMs at their setpoint,
and minimizing the circulating currents in the MMC. The
effectiveness of the proposed algorithm is verified by using the
nonlinear simulation of MATLAB/SIMULINK.