大规模双馈式风电机群暂态等值建模方法研究

The output characteristics of a wind farm are determined by the combined effect of all generators in the wind farm. The reasonable model of a wind farm is a necessary condition for the studies of power system contained wind power. The wind farm model should be developed from the model of single wind turbine according to the credible theoretical foundation. However, the theoretical method of the modeling of wind farm is far from perfect, especially under grid fault condition. The transient characteristics of a single wind turbine which employed doubly-fed induction generator (DFIG) cannot cover the overall characteristics of a wind farm because the electromagnetic process and responses of controllers of DFIG-based wind turbines could be different under grid fault. The equivalent model of a DFIG-based wind farm during fault is still absent, which has severely restricted the transient analysis of the power system contained large-scale wind power.. This project is committed to research on the equivalent model of DFIG-based wind farm under grid fault. The transient characteristics of the single and multiple DFIG-based wind turbines are analyzed. The transient coupling mechanism of multiple DFIG-based wind turbines and the spatial and temporal distribution of the transient operating points of DFIG-based wind farm are studied. On the basis of these characteristics, the theoretical breakthroughs in the grouping and parameter aggregation of coherent DFIG-based wind turbines and the equivalent of current collection system under grid fault are achieved. Consequently, an reliable and universal modeling approach is established for the large-scale DFIG-based wind farm under grid fault. The achievements provide the theory reference for the planning, protection and control of power system contained large-scale wind power, which can deepen and improve the basic theory about wind generator.

风电场的输出特性取决于风电场内所有风电机组的共同作用，合理的风电场建模是风电并网研究的基础。从内部单台机组模型到风电场整体模型的过渡必须建立在可信的理论基础之上，而相关理论方法尚不完备。特别在电网故障期间，双馈式风电机群中各机组的电磁过程和控制器响应均可能不同，单机暂态特性并不能代表机群整体特性，双馈式风电机群暂态等值模型的欠缺已成为制约风电并网电力系统暂态特性分析的主要瓶颈。. 本项目拟对双馈式风电机群在电网故障期间的动态等值模型进行研究。从双馈风电机组单机和多机的暂态特征分析出发，通过研究双馈风电机组多机暂态耦合机理和机群暂态运行点时空分布特性，在暂态同调机群划分、机群参数聚合、集电系统等值和模型验证等核心问题方面形成理论突破，从而建立具备可靠性和通用性特点的双馈式风电机群暂态等值建模方法，用以支撑大规模风电并网电力系统规划设计、保护控制的实施，深化并完善风电并网理论。

风电场的输出特性取决于风电场内所有风电机组的共同作用，合理的风电场建模是风电并网研究的基础。在电网故障情况下，双馈式风电机群中各机组的电磁过程和控制器响应可能不同，双馈式风电机群的电磁暂态特性尚无法准确模拟。为此，本项目提出对双馈式风电机群的电磁暂态特性与机理进行研究，建立具备可靠性和通用性特点的双馈式风电机群暂态等值建模方法。.本项目明确了外部电网故障冲击作用下双馈风电机组定、转子故障参量的特性及其产生机理；明确了低电压穿越控制对双馈风电机组暂态过程的影响；提出了电网对称和不对称短路时双馈风电机组的故障计算等值模型；导出了双馈风电机组短路电流相关性的解析式；提出了双馈风电机组多机并联运行下短路电流的变异规律；提出了基于短路电流轨迹的双馈风电场电磁暂态同调机群划分和等值方法；提出了混合风电场中双馈风电机组暂态特性受直驱风电机组影响的特征及其等值模型，可为大规模风电并网电力系统规划设计、保护和控制的实施提供理论支撑。