Decentralized Voltage Balancing and Power Sharing in Islanded Bipolar DC Microgrids

Decentralized Voltage Balancing and Power Sharing in Islanded Bipolar DC Microgrids

This paper presents a decentralized control scheme for voltage balancing and power sharing in bipolar dc microgrids. This relies on utilizing a converter topology which offers three levels of output voltage availability with the key features of boosting the input voltage and balancing the output voltages. This converter makes it possible to further improve the structure of bipolar dc microgrids as it does not require a central voltage balancer. Small-signal analysis is done and system transfer functions are derived. Based on the RGA concept the highly coupled input-output pairs are found which helps with replacing the MIMO control system of the converter by two SISO systems. The appropriate voltage and current controllers are designed based on SISO principles. Moreover, a double droop control method is proposed which fulfills the simultaneous power sharing and voltage regulation of DG units in the host microgrid. The effectiveness of the proposed control strategy is demonstrated through simulation studies conducted on an islanded bipolar dc microgrid involving unbalanced loads, while the voltage balancing of the bipolar dc microgrid and the power sharing accuracy are evaluated