针对实时仿真中电压源型换流器（voltage-source converter，VSC）采用传统伴随离散电路（associated discrete circuit，ADC）模型因虚拟功率损耗导致的仿真精度下降问题，提出了一种双模恒导纳方法。首先，通过分析开关状态切换过程中等效储能突变机理，揭示了高频PWM调制下虚拟损耗累积规律。其次，根据解锁和闭锁时开关动作的特点，依据提出的半隐式解耦方法构建了解锁状态下的换流器恒导纳模型，在维持恒定导纳矩阵的同时消除了虚拟损耗；闭锁状态下因为开关切换次数较少，则保留传统ADC模型。仿真验证表明：所提换流器模型在解/闭锁工况下虚拟功耗小，仿真精度高，且状态切换过程无数值振荡。

To address the issue of simulation accuracy degradation caused by virtual power losses in traditional associated discrete circuit(ADC) models for voltage-source converters (VSCs) in real-time simulation, a dual-mode constant admittance method is proposed. Firstly, by analyzing the mechanism of equivalent energy storage mutation during switching state transitions, the accumulation law of virtual losses under high-frequency PWM modulation is revealed. Secondly, based on the characteristics of switching actions during unlocking and blocking states, a constant admittance model for the converter in the unlocked state is constructed using the proposed semi-implicit decoupling method, eliminating virtual losses while maintaining a constant admittance matrix. For the blocked state, where switching transitions are fewer, the traditional ADC model is retained. Simulation results demonstrate that the proposed converter modeling exhibits minimal virtual power dissipation and high accuracy in both unlocked and blocked conditions, with no numerical oscillations during state transitions.