Parameter Estimation of Sub-module Capacitors of Modular Multi-level Converter Based on Adaptive Observer

This article first introduced the structure and working principle of the modular multilevel converter(MMC), and then according to the sub-module(SM) capacitor input excitation and circuit structure characteristics, the state equation of the capacitor is derived, and it is clear that the system matrix is zero and the control matrix can identify the target. By constructing an adaptive observer, the capacitance value and leakage resistance of the capacitor were estimated to realize the fault diagnosis of the system. Simulation experiments had shown that the proposed parameter estimation method is effective.