强阻尼电压源型虚拟同步发电机大扰动功角稳定性分析

虚拟同步发电机与传统同步发电机具有相似的外特性,在大扰动下,虚拟同步发电机也具有与传统同步发电机相似的失稳机理。但是,与传统同步发电机相比,虚拟同步发电机逆变器会受到电流限幅的影响,功角曲线与传统同步发电机不同;同时虚拟同步发电机阻尼系数比同步发电机大得多,无法简单判断虚拟同步发电机的功角稳定性。因此,以虚拟同步发电机—无穷大系统为例,首先,介绍虚拟功角由饱和曲线向非饱和曲线的转变,分析虚拟同步发电机强阻尼系数的特性。然后,指出受扰后虚拟同步发电机系统动态响应的强时变特性,给出虚拟同步发电机大扰动功角稳定性的判断方法。最后,基于PSCAD仿真验证了所提方法的合理性。

Analysis on Large Disturbance Power-angle Stability of Strong-damping Voltage-source Virtual Synchronous Generators

The virtual synchronous generator(VSG)has similar external characteristics to the synchronous generator(SG). The VSG has the same instability mechanism as the SG under the large disturbance. However, compared with the SG, the inverter of VSG is affected by the current limit, whose power-angle curve is different with SG as well. Meanwhile, the damping coefficient of VSG is much larger than that of SG and the power-angle stability of VSG cannot be easily determined. Considering the integration of the VSG and infinity system, the power-angle curve transformed from saturated current to unsaturated current is described and the strong damping of coefficient characteristic of the VSG is analyzed firstly. Then, the strong time-varying characteristic of VSG systems is illustrated. The method which can judge the stability of the VSG system is put forward. Finally, based on the PSCAD software, the simulation is conducted to verify the reasonability of the method mentioned above.