Capacitance health monitoring in the modular multilevel converter using a method with minimum number of sensors and computational burden

Abstract

SummaryThis paper proposes a method for capacitance health monitoring (CHM) of submodule capacitors in modular multilevel converters (MMCs) that uses a reduced number of voltage sensors. In the proposed method, the MMC arms are divided into some groups of submodules and one voltage sensor is used for each group. In addition, a capacitor voltage estimation technique with minimal computational complexity is used to determine the capacitor voltage. The ratio of the estimated to measured capacitor voltage during positive arm current is also used to demonstrate a simple and efficient capacitance monitoring method. Moreover, contrary to the limitations associated with traditional CHM methods, the proposed method reduces the required voltage sensors and minimizes data exchange between the power system and the central processor. The effectiveness of the proposed method is validated through simulation and experimental results under various operating conditions.