A system for estimation of grid impedance in a power converter controller, comprising: a processor for executing program modules of a system memory; the system memory having program modules comprising: a current controller configured to inject an injection current while operating online and coupled to a power grid at a point of common coupling, PCC,, the injection current being benign to an operating current of the power converter; a voltage controller configured to regulate input voltage of the power converter; and an impedance module configured to: determine parameters for the injection current including injection interval and duration, current magnitude, current frequency, and symmetrical component; extract measurements of current and voltage at the PCC at an operating point shifted from a previous operating point in response to the injection current; characterized in that the impedance module is configured to extract symmetrical components of current and voltage measurements; and compute an estimated grid impedance based on the extracted symmetrical components. a processor for executing program modules of a system memory; the system memory having program modules comprising: a current controller configured to inject an injection current while operating online and coupled to a power grid at a point of common coupling, PCC,, the injection current being benign to an operating current of the power converter; a voltage controller configured to regulate input voltage of the power converter; and an impedance module configured to: determine parameters for the injection current including injection interval and duration, current magnitude, current frequency, and symmetrical component; extract measurements of current and voltage at the PCC at an operating point shifted from a previous operating point in response to the injection current; characterized in that the impedance module is configured to extract symmetrical components of current and voltage measurements; and compute an estimated grid impedance based on the extracted symmetrical components. a current controller configured to inject an injection current while operating online and coupled to a power grid at a point of common coupling, PCC,, the injection current being benign to an operating current of the power converter; a voltage controller configured to regulate input voltage of the power converter; and an impedance module configured to: determine parameters for the injection current including injection interval and duration, current magnitude, current frequency, and symmetrical component; extract measurements of current and voltage at the PCC at an operating point shifted from a previous operating point in response to the injection current; characterized in that the impedance module is configured to extract symmetrical components of current and voltage measurements; and compute an estimated grid impedance based on the extracted symmetrical components. determine parameters for the injection current including injection interval and duration, current magnitude, current frequency, and symmetrical component; extract measurements of current and voltage at the PCC at an operating point shifted from a previous operating point in response to the injection current; characterized in that the impedance module is configured to extract symmetrical components of current and voltage measurements; and compute an estimated grid impedance based on the extracted symmetrical components.