The high penetration of distributed photovoltaic (PV) integration results in a significant discrepancy between the impedance of the distance protection on the weak feeder side of the distribution network and that of the faulty line. This discrepancy poses a risk of protection failure or maloperation. In order to address this issue

this paper proposes an adaptive distance protection principle for distribution networks

based on the Thevenin equivalence of systems with high penetration PV integration. First

the mechanism by which high penetration PV integration affects the distance protection of the weak feeder side of the distribution network is analyzed. This is followed by the derivation of the formula for calculating the faulty line impedance

which is based on the measured impedance and the additional impedance angle. Then

the Thevenin equivalent method for the distribution network with high penetration PV integration is presented. Combining it with negative or zero sequence networks of short circuit faults

equations for solving the additional impedance angle are derived. Finally

the adaptive distance protection criteria are established based on the precise determination of faulty line impedances

and the comprehensive protection scheme is presented. Simulations based on PSCAD indicate that the proposed method is capable of accurately identifying asymmetrical short-circuit faults in distribution networks with high penetration PV integration

even under conditions where only single-end information is available. Furthermore

the method exhibits particularly good computational accuracy

high reliability

and excellent anti-transition resistance capability.