Estimation Scheme for Instantaneous Sub-Module Capacitor Voltage of Modular Multilevel Converter Sensed at Low Sampling Rate

The modular multilevel converter for HVDC application consists of hundreds of sub-modules per arm. One way to sense the capacitor voltages of these many number of submodules is to communicate the sensed data to the controlling platform through time multiplexing. However, time multiplexing also reduces the sampling rate and hence can cause loss of information. In this work, a scheme to estimate the capacitor voltages is proposed that can accurately reconstruct the actual capacitor voltage from the sensed data having low sampling rate. The estimation scheme also eliminates noise from the sensed data. The mathematical model of the estimation technique is presented. The verification of the different features of the scheme is presented in the form of experimental results.