Transient AC-bus voltage support for a low-voltage PV-battery shipboard microgrid under CPL-equivalent propulsion transients

Photovoltaic (PV)-battery electric propulsion vessels may experience AC-bus voltage sag during rapid propulsion-power changes and renewable-power fluctuations. This study investigates transient voltage support in a scaled low-voltage shipboard microgrid using a finite-bandwidth constant-power-load (CPL)-equivalent propulsion transient. The sag of conventional Andronov–Hopf-oscillator (AHO) grid-forming control is linked to amplitude-equilibrium displacement, CPL negative incremental impedance, and the inverter/filter/feeder current-to-voltage path. A current-deviation-triggered branch is therefore added only to the AHO amplitude target while retaining the original phase-generation channel. Under an identical 20 kW disturbance, the proposed controller limits the loaded phase-RMS voltage deviation to −1.81%, compared with −11.36% for conventional AHO, while reducing the 1-ms RMS sag depth from 13.43% to 8.20%. A predeclared negative-virtual-resistance benchmark gives a similar transient sag depth but a larger loaded deviation (−6.30%). Undervoltage-derating, mixed ZIP-terminal, and 15 kW–25 kW disturbance tests show that the improvement persists within the available source/current capability, whereas the 25 kW case exposes the common overload boundary. Controller hardware-in-the-loop (CHIL) RT-LAB plots provide complementary real-time implementation evidence. The conclusions are limited to controller-level validation of a scaled shipboard platform.