Including IIDG distribution network, due to the current limiting control of power electronic devices and different control strategies, traditional protection will be invalid. Therefore, an IIDG distribution network protection scheme based on the difference between the amplitude of the impedance measured at both ends of the line before and after the fault and the phase difference of the measured impedance at both ends of the line is proposed. This scheme can realize the distribution network area. Effective identification of internal and external faults to achieve the correct action of protection.The effectiveness of the solution was verified by the PSCAD/EMTDC simulation software.