A Novel Active Damping Method in Grid Connected Inverter using Multiple Feedback

In grid-connected converters, LCL filters exhibit a resonance effect that jeopardizes system stability and elevates harmonic content in the output current of the inverter at the resonant frequency. This paper explores an innovative active damping technique for LCL filters aimed at reducing the resonance effect in voltage source inverters connected to the grid. The method introduced here generates the virtual effects of two separate damping resistors by using the current through the capacitor and the feedback variables from the grid-side current, achieving the same outcome as the passive damping approach. The calculated feedback gains are devoid of any frequency terms and lack differential or integral components, simplifying their implementation, avoiding noise amplification, and reducing computational demands in the control loop for the current. The proposed technique is validated through MATLAB/Simulink simulations, and the results are presented to substantiate the method.