基于LVRT期间无功功率特性的双馈风电场等效建模方法

Equivalent modeling method for DFIG wind farms based on reactive power characteristics during LVRT

风电场的等效模型可以降低机群模型的阶数,对大规模风电场进行等效建模是对含风电电力系统研究分析的有效手段。同时各国标准要求风电机组需具备低电压穿越能力(Low Voltage Ride Through,LVRT)。基于以上两方面,使用合适的LVRT方案建立风电场的详细模型,确定合理的分群指标搭建等效模型,使其在保证准确度的前提下加快仿真速度是风电场等效建模需要解决的关键问题。考虑双馈风电机组低电压穿越特性,提出了一种基于LVRT期间无功功率特性的双馈风电场等效建模方法。该方法使用的LVRT控制策略可以确保DFIG转速不越限的同时,对电网提供无功功率支持;以整定得到的无功功率为分群指标,将风电场内的机群分群,得到基于LVRT期间无功功率特性的风电场等效模型。仿真对比结果表明,该方法基于LVRT功率特性整定了输出功率,能有效抑制风电机组在LVRT期间超速脱网,提高等效准确度。

Equivalent model of wind farms can reduce the order of the model, and equivalence modeling of largescale wind farms is an effective tool for analysis of power systems containing wind power. At the same time, national standards require wind turbines to have low-voltage ride-through capability(LVRT). Based on the above two aspects,using a suitable LVRT scheme to build a detailed model of the wind farms, and then determining reasonable subpopulation indexes to build an equivalent model so that it can speed up the simulation with guaranteed accuracy is the key problem that needs to be solved for the equivalent modeling of the wind farms. A DFIG wind farm equivalence modeling method based on the reactive power characteristics during LVRT is proposed considering the LVRT characteristics of DFIG wind turbines. The LVRT control strategy used in this method can ensure that the DFIG speed does not exceed the limit while providing reactive power support to the grid;at the same time, the rectified reactive power is used as the grouping index to group the turbines in the wind farm and obtain a wind farm equivalence model based on the reactive power characteristics during the LVRT. The simulation comparison results show that the method rectifies the output power based on the LVRT power characteristics, which can effectively suppress the wind turbine overspeed off-grid during LVRT and improve the equivalence accuracy.