Comparative admittance-based analysis for different droop control approaches in DC microgrids

Abstract

In DC microgrids, virtual resistance based droop control is broadly used as the fundamental coordination method. As the virtual resistance guarantees load sharing effect in steady states, the output admittance determines the dynamic response of converters in transient states, which is critical in stability analysis and system design. So far, two different approaches of droop control (i.e. V-I droop and I-V droop) are proposed. Although they can achieve the same steady-state power sharing effect and fully compliable with each other, the output characteristics are not the same due to significant difference in control architecture. In this paper, a comparative admittance-based analysis is carried out between these two approaches. State-space models and more general analytical models are established to derive the output admittance of droop-controlled converter in DC microgrids. Simulations and impedance measurement is carried out using PLECS to validate the analytical results.

A Decentralized Control Architecture Applied to DC Nanogrid Clusters for Rural Electrification in Developing Regions

“…Moreover, as discussed by Zheming et. al [24], I-V droop exhibit superior transient performance in comparison to other droop methods (e.g. V-I droop), therefore, transition from one mode to other is smooth.…”

“…Ideally, in such architectures, it is desirable that if SOC is above a certain threshold, it must be maintained to that level rather than undesired balancing. Moreover, Zheming et al [24] showed that the V-I dual loop droop control exhibit slower dynamics in comparison to I-V droop, therefore, it cannot achieve fast power sharing among the distributed resources.…”

Stability of DC Distribution Systems: An Algebraic Derivation

“…However, these are not easily applied and require a suitable construction of the Lyapunov storage function. Lastly, the roots of the system can be derived from the eigenvalues of its state-space matrix [19,[33][34][35][36]. This approach, which is also used in this paper, relies on the validity of averaging, linearizing, and simplifying the power electronic converter.…”

An Alternative Realization of Droop Control and Virtual Impedance for Paralleled Converters in DC Microgrid

“…4. For comparison, a state-space based average-value model of the study case controlled by conventional droop control (detailed in [12]) is also included in the simulation as a average-value reference due to its good accuracy. The simulation results show that the transient response of conventional realization and proposed method has only neglectable difference.…”