Low-Frequency Coupling Resonance Suppression Method of PLL-based Current Controlled Inverter Based on Coordinated Control

The increasing penetration of new energy generation has made the stability of the power system challenging at the same time. The current-controlled inverter based on phase-locked-loop synchronization (PLL-CCI) is prone to interactive coupling with the power grid, triggering low-frequency coupling resonance. In order to suppress the low-frequency coupling resonance of PLL-CCI, this paper firstly derives a stability analysis model based on the coupled sequence admittance to reveal the mechanism of low-frequency coupling resonance. Then a coordinated control method based on q-axis voltage feedforward and PCC voltage feedforward is proposed, using q-axis voltage feedforward to weaken the negative effect of PLL bandwidth on stability and using PCC voltage feedforward to improve the small-signal synchronization stability of PLL-CCI. It is applied to the PLL-CCI grid-connected system and the theoretical analysis shows that the control method can improve the stability of the system while ensuring the PLL response speed, and the method also realizes the decoupling design of control parameters, which has practical engineering application value. Finally, the effectiveness of the proposed control method is verified by experiments on a semi-physical simulation platform.