Predictive control based on space vector modulation for the purpose of capacitors voltage balancing and harmonic circulating current suppression of MMC

Abstract

This paper proposes a predictive control algorithm for MMC with spatial vector modulation method to solve the problem of voltage balancing on DC capacitors and harmonic circulating current suppression. Firstly, modulation methods are built on the basis of SVM for an MMC with the capability of achieving an unlimited number of voltage levels at the AC side. The loop current circuit uses PI regulators and PR resonators to eliminate even-order harmonic components such as 2^nd and 4^th of the circulating current to retain only a DC component of DC power transmission. Model forecast browse all the residual status vectors, combined with the adjusted voltage from the circulating current to ensure the smallest deviation from the average voltage value established for the upper and lower branch capacitors, on all three phases of the MMC. The voltage value on each capacitor in the branches is balanced with each other by a separate algorithm, these capacitors are inserted or ignored in each modulation cycle accordingly.