In this chapter, distributed and decentralized control approaches for dc microgrids are discussed. Distributed approaches employ a communication system among different converters in order to regulate the dc voltage and improve the load sharing accuracy. Some of the distributed methods utilize point-to-point communication links among converters; however, some of them use a sparse communication system based on consensus protocol. Sparse communication-based control approaches are more reliable and resilient than the fully communicated methods. On the contrary, the decentralized methods use no communication (physical link) between converters to reach the power sharing objectives. In these approaches, the control system of each converter uses local voltage and current information to control the output power (current) of the corresponding converter. Since these converters do not need to communicate with other converters, the overall stability and reliability can be enhanced. The centralized control approaches can be categorized as mode-adaptive (autonomous) droop control, nonlinear droop control and frequency droop control, and these methods are conceptually discussed in this chapter.

Chapter Contents:

• 2.1 Introduction
• 2.2 Decentralized approaches
• 2.2.1 Mode-adaptive (autonomous) droop control
• 2.2.2 Nonlinear droop control
• 2.2.3 Frequency droop control
• 2.3 Distributed approaches
• 2.3.1 Fully communicated control
• 2.3.2 Sparse communicated (consensus-based) control
• 2.3.3 Sparse communicated control using current information
• 2.3.3.1 Current regulator
• 2.3.3.2 Voltage regulator
• 2.4 Conclusion and future study
• References

Inspec keywords: power distribution reliability; decentralised control; power distribution control; DC transmission networks; distributed power generation; distributed control

Other keywords: nonlinear droop control; mode-adaptive droop control; load sharing improvement; distributed control; dc microgrids; stability; converter communication; output power control; frequency droop control; control system; reliability; power sharing; consensus protocol; sparse communication system; decentralized control; current information; point-to-point communication links; communication system; dc voltage regulation; local voltage information

Subjects: Distributed power generation; Control of electric power systems; Multivariable control systems; Reliability; Power system control; Distribution networks; d.c. transmission