虚拟同步发电机输出阻抗建模与弱电网适应性研究

研究了弱电网条件下虚拟同步发电机-电网互联系统的交互稳定性。在考虑主电路参数、控制参数等因素影响的基础上,提出一种dq旋转坐标系下虚拟同步发电机的输出阻抗模型,并推导其解析表达式。分析了该输出阻抗的频率特性,得出虚拟同步机在弱电网下运行易失稳的结论。基于广义奈奎斯特判据研究电网强度及功率环控制参数对虚拟同步机运行稳定性的影响,以此为依据提出一种基于增大有功环参数的虚拟同步机致稳控制方法,从而提高其弱电网运行的适应性。基于RTDS的硬件在环仿真平台进行仿真计算,验证了理论分析的正确性。

Output impedance modeling of virtual synchronous generator and its adaptability study in a weak grid

The interaction stability of the virtual synchronous generator integrated power network in weak grid conditions is studied. Based on the influence of main circuit parameters and control parameters, the output impedance model of virtual synchronous generator in dq rotating coordinate system is established and its analytical expression is derived. The frequency characteristic of the output impedance is analyzed, obtaining the conclusion that the virtual synchronous generator is easy to be unstable in a weak grid. Based on the generalized Nyquist criterion, the influences of grid strengths and power loop control parameters on the stability of virtual synchronous generator are studied, based on which a method of stabilization control for virtual synchronous generators based on increasing active loop parameters is proposed to improve the adaptability of virtual synchronous generators in a weak grid. Simulation in the RTDS-based hardware-in-loop simulation platform verifies the correctness of the theoretical analysis.