Capacitor Voltage Feedforward With Delay Compensation for LCL-Type Grid-Connected Inverter

LCL filter is widely used in grid-connected inverters because of its excellent harmonic suppression ability. However, the inherent resonance peak of the filter and the delay caused by calculation and pulse width modulation in the digital control system will affect the stability of the system. Therefore, improving the control algorithm and compensating the delay are the premise of improving the stability of the system. Therefore, according to the frequency characteristics of the equivalent virtual impedance of the control loop, the phase compensation link is added to the active damping control of the capacitor voltage, which can effectively suppress the resonance peak and compensate the delay. Finally, the proposed scheme is simulated, and the system can remain stable at high resonant frequency, which verifies the effectiveness of the proposed scheme.