Power grid impedance detection method and distributed power generation system

The invention provides a power grid impedance detection method and a distributed power generation system, the distributed power generation system comprises a DC source and a plurality of inverters in parallel operation, each inverter comprises a DC/AC converter and a controller, the input end of the DC/AC converter is used for being connected with the DC source, and the output end of the DC/AC converter is used for being connected with a power grid or an electric load. The DC/AC converter is used for converting direct current provided by the direct current source into alternating current and outputting the alternating current to a power grid or an electric load; and the controller is used for starting impedance detection of the power grid after the duration of the voltage at the output end of the DC/AC converter exceeding a first voltage threshold value or being lower than a second voltage threshold value is greater than or equal to a time threshold value and delay of random duration, so that the plurality of