With the widespread adoption of inverter-interfaced distributed generation (IIDG) in high-penetration distribution networks

its nonlinear fault current characteristics—constrained by power electronic control strategies—pose serious challenges to conventional current protection

such as reduced sensitivity

malfunction

and failure to operate. To address this issue

this paper provides an in-depth analysis of the output characteristics of IIDG under asymmetrical faults based on low-voltage ride-through control

establishes a quantitative mathematical model coupling positive-sequence power angle with positive- and negative-sequence voltages

and further reveals the evolution of the IIDG output power angle during faults. On this basis

a dual adaptive protection strategy is proposed. On the one hand

the strategy dynamically adjusts the overcurrent protection threshold by real-time monitoring of the equivalent impedance of IIDG

thereby mitigating the insufficient sensitivity caused by limited fault current. On the other hand

by constructing a dynamic direction criterion based on power angle deviation

it achieves accurate identification of fault direction using the distinct power angle response characteristics of IIDG during faults. Verification results based on a real-time digital simulation system show that the proposed method can effectively adapt to different fault types and severity levels. Compared with conventional methods

it significantly expands the protection coverage and improves the accuracy and operating speed of direction discrimination

thus providing a reliable theoretical foundation and technical support for protection configuration of distribution networks with a high share of renewable energy.