*5.3. Experimental Validation in Scenario #3 (SD-GD)*

In this test, the Split-pi converter and the microgrid voltage generator were controlled in droop mode with *Rd* = 0, so the resulting microgrid was not stiff. For the sake of clarity, a droop resistance of 1.33 Ω and a no-load voltage of 180 V were chosen as droop parameters for both devices. In this way, such devices always contributed equally to supplying the load. A stepwise variation of load resistance from 130 Ω to 260 Ω and back again was applied using the electronic load; this sequence corresponded to load power transitions from 250 W to 125 W and back again. The waveforms obtained in the test are shown in Figure 12 and show that the system exhibited good dynamic behavior, as expected based on the simulation results.

The system response was aperiodic, thanks to the high phase margin that was imposed. Furthermore, the current sharing ratio was respected for both load power values. Finally, the voltage variation at each power level was precisely the one expected according to the droop resistance value and the delivered current (−0.26% and −0.52%).

**Figure 12.** Experimental results in scenario #3 (SD−GD): (**a**) grid−side currents; (**b**) input inductor current; (**c**) percentage variation of microgrid voltage; (**d**) duty cycle.

#### *5.4. Experimental Validation in Scenario #4 (SC-GD)*

In this test, the Split-pi converter was operated as a current-controlled source exchanging power with a non-stiff microgrid. The external voltage generator was controlled in droop mode. The droop resistance was 1.33 Ω, and the no-load voltage was 180 V. The output current reference for the converter was changed at t = 0 s with a stepwise variation from −1.37 A to 1.37 A. Instead, the electronic load was operated to reproduce a stepwise variation of load resistance from 130 Ω to 65 Ω at about t = 0.7 s; these resistance values correspond to nominal load current (power) levels of 1.385 A (250 W) and 2.770 A (500 W), respectively.

The most relevant waveforms obtained in the test are presented in Figure 13 and are coherent with the simulation results. Before t = 0 s, the converter was controlled to draw −1.37 A from the DC microgrid recharging the emulated storage system. The external generator delivered 1.37 A to the converter and 1.345 A to the load for a total of 2.715 A. At t = 0 s, the current reference for the converter was increased to 1.37 A. Thus, the converter almost entirely supplied the load, and the current of the external generator automatically approached zero. Finally, at about t = 0.7 s, the load requested a current of 2.710 A. Since the converter's output was kept constant, the external generator automatically provided the additional current contribution of 1.34 A. In addition, the voltage variation was precisely the one expected according to the droop resistance value and the current supplied by the external voltage generator, i.e., −2%, 0%, and −1% for 2.715 A, 0 A, and 1.34 A, respectively. Furthermore, the system's dynamic behavior was good with fast aperiodic transients, coherently with the simulation results.

**Figure 13.** Experimental results in scenario #4 (SC−GD): (**a**) grid−side currents; (**b**) input inductor current; (**c**) duty cycle; (**d**) percentage variation of microgrid voltage.
