Page 298 - 2024-Vol20-Issue2

294 | Abdulabbas & Salih

Fig. 10. Simulation of three-phase grid voltage and grid Fig. 11. Simulation of three-phase grid voltage and grid
current without capacitor voltage loop. current with capacitor voltage loop.

predicted values are in agreement with the real parameters. Fig. 12. Simulated response of three phase grid voltage and
By comparing the grid currents shown in Fig. 10 and Fig. grid current obtained by the proposed control strategy when
11 , it is evident that the grid current achieved by the sug- there is 15% variation in LCL filter parameters.
gested control approach does not exhibit oscillations. This
indicates a significant improvement in resonance damping. Fig. 13. Response simulating V? (x) in two cycles.
Fig. 12 displays the simulated steady-state responses of the reference frame. These graphs demonstrate the precise track-
grid voltage and current using the suggested control approach ing of the actual signal to the reference value, with minimal
with the capacitor voltage loop. These responses are pro-
duced when the estimated parameters deviate from the real pa-
rameters by 15% ( Lie = 1.61mH , Loe = 0.575mH , rie =
0.115?, roe = 0.0575?, and Ce = 57.5µF ). The control sys-
tem is most affected by parameter fluctuations when all of the
changes occur simultaneously. Regardless of the variations
in these parameters, the grid currents exhibit nearly the same
amplitude and are in phase with the grid voltages, as shown
in Fig. 11. The efficiency of Lyapunov-based control in fol-
lowing the grid current reference is demonstrated, even in the
presence of parameter fluctuations.

Fig. 13 displays the simulated response of V? (x) in change of
reference current, which corresponds to the scenario depicted
in Fig. 12. Despite a 15% fluctuation in the parameters of
the LCL filter, the value of V? (x) remains negative, indicating
that the suggested control method is globally asymptotically
stable.

The spectral analysis of the grid current, with a value of
Io* = 30 A, is depicted in Fig. (14). The total harmonic
distortion (THD) of the grid current in phase a, as deter-
mined through simulation, was 0.09%, this is smaller than the
amount shown in [19]. It is known that the main component of
the grid current is approximately 30 A , indicating the absence
of any steady-state inaccuracy in the grid current. The other
components (3rd, 5th, and 7th) are insignificantly small.

Fig. 15 and Fig. 16 show the d-q axis grid current and
d-q capacitor voltage, respectively, in the d-axis synchronous