Decentralized Voltage Balancing and Power Sharing in Islanded Bipolar DC
Microgrids
Abstract
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.