新能源发电并网系统的同步参考坐标系阻抗模型及其稳定性判别方法

Synchronous Reference Frame based Impedance Model and Stability Criterion for Grid-connected Renewable Energy Generation Systems

近年来,新能源发电并网系统中出现了新型的次同步振荡问题。为应对该问题,迫切需要开展适用于新能源发电并网系统的建模和稳定性判别方法研究。首先以一个简单的直驱风机–交流并网系统为例,分别推导了直驱风机和交流电网基于同步参考坐标系(synchronous reference frame,SRF)的阻抗模型,进而构建了系统整体的SRF阻抗模型;然后,基于该模型提出一种新的稳定性量化分析方法,并通过数学推导证明其有效性;最后,采用时域仿真和特征值分析验证了模型和判稳方法的有效性和精确性。所提方法具有针对实际复杂新能源并网系统开展阻抗网络建模和稳定性量化分析的潜力。

Recently, new types of subsynchronous oscillation （SSO） issues have occurred in grid-connected renewable energy generation systems. To address these issues, there is an urgent need to develop appropriate modeling and stability analysis methods. In this paper, a direct drive permanent magnet synchronous generator-based wind farm connected to an AC system was selected as an example. The synchronous reference frame （SRF） based impedance models for both the wind farm and the AC system were established, and they were connected to form a total SRF-based impedance model according to system topology. Then, a novel stability criterion based on such total SRF impedance model was proposed to estimate the stability of SSO and to calculate its damping/frequency. Finally, both time-domain simulations and eigenvalue analyses were carried out to verify the effectiveness and accuracy of the proposed method. It offers promising potential to perform impedance network modeling and quantitative stability analysis for the practical complex renewable energy generation systems.