考虑风速不确定性的风电场暂态有功支撑能力在线评估方法

Online Evaluation Method for Transient Active Power Support Capability of Wind Farm Considering Wind Speed Uncertainty

风电高比例接入的电网在受扰后常规机组调频尚未启动的惯量响应阶段内调频资源匮乏,风电场可采用转子动能控制方式快速调整有功功率为电网提供频率支撑,且不影响风电场正常运行。同时,为便于电网侧制定调控策略,需在线评估各风电场的暂态有功支撑能力。以双馈风机为例,构建了考虑风机转速、轴系及逆变器安全限制的风电场暂态有功支撑能力优化模型,并针对模型约束需迭代计算引起的高复杂度,提出采用差分离散化等方法将模型转化为混合整数线性规划问题进行高效求解。同时考虑风速不确定性,提出采用核密度估计与拉丁超立方抽样对风速预测误差进行建模与采样,获取不确定条件下的评估结果。最后,以某实际风电场为例,说明了所提方法的有效性。

For a power grid integrated with high proportion of wind power,the frequency regulation resources are insufficient in the inertia response stage when the frequency regulation of conventional units has not been started after the system is disturbed.The wind farm can quickly adjust the active power by using the rotor kinetic energy control mode to provide frequency support for the power grid without affecting the normal operation of the wind farm.At the same time,in order to formulate the regulation and control strategies at the grid side,it is necessary for each wind farm to evaluate its transient active power support capability online.Taking the doubly-fed wind turbine as an example,an optimal model for the transient active power support capability of the wind farm is proposed considering the safety constrains of the wind turbine speed,shafting and inverter.Aiming at the high complexity caused by the model constraints which require iterative calculations,a difference discretization method is proposed to transform the model into a mixed-integer linear programming problem for efficient solution.Besides,considering the wind speed uncertainty,the kernel density estimation and Latin hypercube sampling are proposed to model and sample the prediction error of the wind speed,so as to obtain the evaluation results under uncertain conditions.Finally,an actual wind farm is taken as an example to illustrate the effectiveness of the proposed method.