含双馈风力发电场的多机系统暂态功角稳定性分析方法

A Method to Analyze the Transient Angle Stability of Multi-machine System With DFIG-based Wind Farm

随着风电装机容量不断增大,风电场的接入对电力系统的暂态稳定造成的影响不容忽视。该文提出一种双馈风力发电机（double-fed induction generator,DFIG）组成的风电场接入的多机系统暂态功角稳定性分析方法。在理论分析风电场有功无功输出对系统暂态稳定性影响方式的基础上,将风电场对外功率特性表示为接地导纳,通过对系统节点导纳矩阵的收缩处理,将接地导纳所包含的有功无功信息糅入同步机群节点导纳矩阵中,风电场对系统功角的影响转化为对同步机之间电气联系的影响,表现为对同步机内电势节点的自导纳和互导纳的影响。利用节点注入功率方程推导各同步机电磁功率的改变量,分析风电场对同步机之间互同步性和系统暂态功角稳定性的影响,解决风电场对系统暂态稳定性影响分析难以量化的问题。针对含有DFIG的3机9节点算例,分析DFIG接入情况下同步机的自导纳和互导纳的变化,并仿真比较发生短路故障时,DFIG采用两种不同低电压穿越方案下系统的暂态稳定性,验证分析方法的正确性。

In the wake of increasing capacity of wind power,the impact of wind farms on transient stability of power system becomes no longer negligible.In this paper,a method for analyzing transient angle stability of multi-machine system with DFIG-based wind farm was proposed.Based on the theoretical analysis of the influence of wind farms＇ active and reactive power output on transient stability of power system,the power external characteristic of wind farm is equivalent to grounding admittance.By contracting the bus admittance matrix,the grounding admittance which contains active and reactive power information was melted into the bus admittance matrix of synchronous machines,and the influence of wind farm on power angle was transformed into the influence of electrical distances between synchronous machines which refer to the self and mutual admittances.The change of each synchronous machine＇s electromagnetic power was derived by using the nodal power equation.The influence of wind on the mutual synchronization and transient angle stability of system was analyzed,overcoming the difficulties of quantifying the transient stability.A three-machine nine-bus system with DFIG was used to calculate the changes of synchronous machine nodes＇ self and mutual admittances.By simulating and comparing the transient stability of the system under two different DFIG low voltage ride through schemes in case of short circuit fault,validity of the method is verified.