考虑低电压穿越场景的频率稳定约束风电承载能力量化方法

Quantification method of wind power bearing capacity considering frequency stability constraint in low voltage ride-through scenario

具备良好低电压穿越能力的风电机组在故障后有功可逐渐恢复,此过程给系统带来的有功扰动并非阶跃形式。若在评估电网对此类风电的承载能力时仍考虑阶跃扰动,则评估结果将较为保守。针对此问题,提出了可用于量化风电低电压穿越过程系统最低点、平均变化率等关键频率特征的系统频率强度指标,并分析了该指标与系统中风电容量占比的关系。结合该指标和电网对最低点等频率特征的约束,建立了可量化评估低电压穿越场景下系统风电承载能力的双层优化模型,实现了低电压穿越场景下风电承载能力的精准评估。此外,为进一步提升风电承载能力,借助频率强度指标量化分析了给定风电占比目标下,风电机组需提供的最小调频能力。最后,通过仿真验证了所提出的风电承载能力量化方法及提升措施的有效性。

The active power of wind turbines with good low voltage ride-through capability can be gradually recovered after fault,and the active power disturbance brought by this process to the system is not a step form.If the step disturbance is still considered when evaluating the wind power carrying capacity of sys⁃tem,the evaluation results will be more conservative.In order to solve this problem,the system frequency intensity indexes are proposed to quantify the key frequency characteristics of system,such as frequency nadir and the average variation rate of frequency during low voltage ride-through process.Then,the relation⁃ship between the index and the proportion of wind power in the system is analyzed.Combined with the indexes and the constraints of frequency characteristics such as frequency nadir and so on depending on grid,the bi-level optimization model is established to quantitatively evaluate the wind power carrying capacity of system in the low voltage ride-through scenario,which can realize the accurate evaluation of wind power carrying capacity under the low voltage ride-through scenario.In addition,in order to further improve the wind power carrying capacity,the minimum frequency regulation capability that wind turbines need to be provided can be quantitatively analyzed by means of frequency intensity index when the wind power capacity ratio target is given.Finally,the effectiveness of the proposed quantification method for wind power carrying capacity and improvement measures is verified by simulation.