Improved model predictive control for H-bridge cascaded STATCOM

H-bridge cascaded static synchronous compensator (STATCOM) is often used to compensate the harmonic and reactive current derived from non-linear load. In order to improve the performance of STATCOM, an improved model predictive control (MPC) method is put forward in this paper. In the proposed MPC, the difference equations which are derived from the transfer functions of controlling variables and controlled variables in STATCOM are used as the predictive control model, the error between the output of STATCOM and predictive model is used to design feedback correction controller and rolling optimization controller. Meanwhile, the introduced repetitive controller is used to eliminate the inherent steady error. The actual H-bridge cascaded STATCOM is constructed and a series of verification tests are executed. The experimental results prove that the output voltage and current of H-bridge cascaded STATCOM with the proposed MPC have smaller distortion and better sinusoidal shape than those of the traditional Proportion Integral (PI) control. Moreover, the performance of H-bridge cascaded STATCOM is great in high power experiment.