Hardware test and validation of the angular droop control: Analysis and experiments

Abstract

We present a hardware-based validation of angular droop control for grid-forming DC/AC converters, a control strategy that establishes active power-to-angle droop. Angular droop control enables exact frequency regulation at steady state, thereby combining primary and secondary control into a single layer. We provide traceable analysis and suggest solutions to the main implementation challenges with angular droop control, specifically addressing the challenges concerning discretization and clock drift in hardware experiments. This is illustrated in two different scenarios. Experimental results from the single converter to load scenario demonstrate black start capability and power-to-angle droop behavior for two different implementation schemes. A multi-converter setup validates frequency synchronization and power-sharing properties, proving the ancillary services that angular droop control provides in the real-world experimental setup.

Figures (24)

• Figure 1: Overview of a programmable DC/AC converter system for the hardware experiments.
• Figure 2: A three-phase DC/AC converter model under study. Each phase-leg consists of a half-bridge module fn:PEB8038. The modulation input $\bar{u}$ is obtained either directly (direct control) or via well-known cascaded voltage and current control (indirect control), for control diagrams and further details see Appendix \ref{['ap:appendixA']}.
• Figure 3: Exemplary image of the half-bridge modules fn:PEB8038 contained in the power rack.
• Figure 4: Resistive load represented by incandescent light bulbs.
• Figure 5: Transmission line replica in our experimental setup.