Method for automatically identifying and correcting impedance in wind power plant PCC (program-controlled computer) system

The invention provides a method for automatically identifying and correcting impedance in a wind power plant breaker system. PPC (program-controlled computer) is arranged on a sending line of a wind power plant. The method comprises the following steps: detecting the current value of PPC voltage; comparing the current value of the PPC voltage with expected value of the PPC voltage for determining whether the current value of the PPC voltage deviates from the expected value of the PPC voltage and exceeds a first preset threshold; if so, computing the current value of a PPC system impedance according to voltage and current measured at the PCC; comparing the current value of the PCC system impedance with previous value of the PCC system impedance for determining whether the current value of the PCC system impedance deviates from the previous value of the PCC system impedance and exceeds a second preset threshold; and if so, updating the previous value of the PCC system impedance with the current value of the PCC system impedance for correcting the PCC system impedance.