To address issues such as signal delay, impedance mismatch, and stability challenges at the interface of digital-physical hybrid simulation systems, this paper presents a power interface modeling approach based on active disturbance rejection control (ADRC). First, it examines the principles and stability conditions of the voltage source ideal transformer method. The application of ADRC enables real-time estimation and compensation of interactive errors and unmodeled dynamics between the digital and physical domains, thereby improving the hybrid system's resistance to interference. Next, a Smith predictor is designed to produce a delay-free system output, which is then fed back into the extended state observer to enhance control system performance. Additionally, a bandwidth-parameter-based tuning method is proposed from a control design perspective. This method creates a systematic process for parameter tuning in digital-physical hybrid simulation systems by defining system bandwidth and tracking performance metrics. The validity of the theoretical analysis and the effectiveness of the proposed approach are confirmed through digital simulations and power hardware-in-the-loop experiments.