用于风电场小干扰稳定性分析的结构保持等值方法

针对风电等新能源集中并网带来的宽频带振荡问题,需要研究具有良好精度的风电场动态等值模型,以解决详细电磁暂态建模的维数灾问题.为此,文中提出一种分析风电场小干扰稳定性的结构保持等值方法.该方法根据广义短路比(gSCR)参与因子的数值大小和所需等值精度,将场站内设备划分为保留群和等值群2组,在将保留群内所有设备动态保留的同时,将等值群内所有设备的动态用内电抗等值为电流源,具体内电抗的大小可由gSCR指标得到,而网络侧实现结构和参数的保持.该等值方法在不含摄动的场景下可以保证等值前后系统主导模态不变,在含摄动的实际场景下仍具有一定的鲁棒性.同时,保持等值前后交流网络拓扑不变可以增强方法的工程实用性.最后,基于仿真算例验证了所提等值方法的有效性和实用性.

Structure-retained Equivalent Method for Small Signal Stability Analysis of Wind Farm

In view of broadband oscillation problems caused by the concentrated grid connection of renewable energy such as wind power, it is necessary to study the dynamic equivalent model of wind farms with good accuracy to solve the dimensional disaster problem of detailed electromagnetic transient modeling. For this reason, this paper proposes a structure-retained equivalent method to analyze the small signal stability of wind farms. Based on the numerical value of the generalized short-circuit ratio (gSCR) for the participation factor and required equivalent accuracy, devices in the station are divided into two groups: retention group and equivalent group. While preserving the dynamics of all devices in the retention group, the dynamics of all devices in the equivalent group are equivalent to current sources with internal reactances. The specific internal reactance can be calculated by gSCR indicator. Moreover, the structure and parameters on the network side are retained. This equivalent method can keep the dominant modes of the system unchanged before and after the equivalence in the scenario without perturbation, and has robustness in the real scenario with certain perturbation. Besides, keeping the topology of AC network unchanged can enhance the engineering practicability of this method. Finally, the simulation example verifies the effectiveness and practicability of the proposed equivalent method.