Decentralized control of voltage compensation and power sharing for CHB converters with unbalanced DC voltage sources

To reduce the negative impact of CHB DC voltage variations on the output and improve the system supply quality, this article proposes a decentralized control approach that not only reduces the impact of DC voltage imbalances but also compensates for voltage drops on the transmission line and enables power sharing. Firstly, the central controller captures the DC voltage values of each module. After calculations, the voltage compensation reference, power factor reference, and module voltage adjustment ratio can be sent to the local controller via low bandwidth communication (LBC). Then, the local controller adopts inverse droop control to obtain the frequency reference, while the voltage amplitude reference is obtained by multiplying the nominal value by the voltage compensation reference factor and the module voltage adjustment ratio. Finally, double loop control is utilized to achieve reference voltage tracking.