A large number of inverter-interfaced distributed generators (IIDG) represented by photovoltaics and energy storage is connected to the distribution network. This greatly disturbs traditional distance protection, and at the same time there is the risk of refusal or misoperation. Thus this paper analyzes the composite sequence network under different types of faults in the IIDG distribution network, and uses the positive sequence fault component on the IIDG side to obtain the additional impedance angle under different faults. Combined with the complex plane relationship of impedance under fault, the short-circuit impedance corresponding to the fault position of the line is calculated, and a real short-circuit impedance solution method is obtained. An adaptive distance protection scheme suitable for the connection of inverter power supply is also proposed. The solution process uses the single-ended electrical quantity on the IIDG side to solve the problem that the distance protection is affected by the controlled characteristics of the IIDG fault output and the transition resistance. It is not affected by the change of the fault location while effectively reduces the communication cost of the network. The protection scheme is verified by a real time digital simulator (RTDS), and the results show that it has good selectivity and reliability under different types of faults.