Generating The Arm Voltage References Of Modular Multilevel Converters Employing Predictive Technique

This paper proposes an effective method to control the modular multilevel converters (MMC). The whole control scheme can be divided into three stages. Firstly, the prediction technique is employed to derive a quadratic programming problem from a cost function, leading to the voltage reference for each arm of the MMC. Secondly, the simple nearest level control is adopted to get the number of on-state SMs for each arm. At last, within each arm the submodules (SMs) are selected based on the sorting results of their capacitor voltages. Simulation based on a three-phase grid connected MMC system is conducted to evaluate the effectiveness of the proposed method. The results show that the proposed technique is capable of tracking the output current reference with very low distortion, while the SM capacitor voltages are well balanced and the circulating currents are almost suppressed. The transient response is fast and accurate as well.