## 5 Simulation Verification
Figure 14c displays the grid-connected current when using the AHE-DSOGI-PLL proposed in this study, combined with the grid voltage feedforward control method. Notably, the grid-connected current in Figure 14a exhibits significant asymmetry and high distortion, attributed to the absence of the proposed grid voltage feedforward control strategy, which allows grid voltage harmonics to disrupt the current. The grid-connected current in Figure 14b sees an improvement in asymmetry due to the application of the grid voltage feedforward control presented in this paper, which eliminates the impact of grid voltage imbalance. However, the traditional DSOGI-PLL's inability to accurately obtain the positive-sequence grid voltage results in high distortion of the grid-connected current. In contrast, Figure 14c demonstrates that during LVRT, the grid-connected current remains balanced with minimal harmonics and a stable amplitude of 40 A, highlighting the effectiveness of the proposed control strategy. Figure 14: _Cont._  
In Figure 14a, despite the adoption of an improved PLL, the traditional VSG LVRT control strategy still causes the grid-connected current to be strongly influenced by asymmetry in the grid voltage, resulting in distorted and asymmetric current waveforms. In Figure 14b, although the imbalance of the grid-connected current is improved, the grid-connected current experiences significant distortion due to the shortcomings of the traditional DSOGI-PLL. On the other hand, Figure 14c demonstrates the performance of the VSG LVRT control strategy when both the improved PLL and the proposed grid voltage feedforward control strategy are improved. Figure 14: Comparison of VSG Low\(-\)Voltage Ride\(-\)Through Currents Under Complex Grid Faults. are implemented simultaneously. The resulting grid-connected current is notably balanced, with a substantial reduction in harmonic content, and its amplitude remains constant at 40 A throughout the LVRT process. This comparison emphasizes the importance of adopting the proposed grid voltage feedforward control strategy in achieving a stable and harmonic-free grid-connected current. Figure 15 presents a comparison of active and reactive power under different control strategies, In the diagram, \(P\) represents active power and \(Q\) represents reactive power. From Figure 15a, it can be observed that, without the implementation of grid voltage feedforward control, both active and reactive power experience significant fluctuations, hindering the ability of the VSG control system to achieve LVRT capability. Figure 15b demonstrates that, when grid voltage feedforward control is used but the AHE-DSOGI-PLL is not employed, the fluctuations in active and reactive power are reduced to some extent, yet they still cannot provide stable active and reactive power to the grid. However, as shown in Figure 15c, when the improved control strategy proposed in this paper is applied, active and reactive power exhibit abrupt changes only during grid voltage variations. This approach enables the system to supply reactive power to the grid during complex fault scenarios. Specifically, during the LVRT period, active power remains stable at 10 kW, while reactive power stabilizes at 2483 Var, ensuring the successful achievement of LVRT for the VSG system. Figure 16 presents the distortion rate of the A-phase current during the LVRT period, obtained through Fourier analysis. Figure 16a depicts the distortion rate image of the compensated A\(-\)phase current under traditional control, with a fundamental current content of 61.3 A and a Total Harmonic Distortion (THD) of 63.7%, which is significantly higher than the grid connection standard of 5%. Figure 16b displays the distortion rate image of the A\(-\)phase current after applying grid voltage feedforward control but without using the AHE\(-\)DSOGI-PLL. The fundamental current content is 39.4 A, and the THD is 14.7%, still exceeding the grid connection current distortion standard.