新能源并网逆变器并联运行宽频聚合建模方法

Broadband Aggregation Modeling Method for Parallel Operation of Renewable Energy Grid-connected Inverters

摘要:

大规模新能源发电基地存在振荡风险，有可能发生宽频失稳事件，给电力系统稳定运行带来极大挑战。阻抗分析是一种研究并网逆变器宽频特性的有效方法，可以揭示宽频失稳机理。首先，以L型的两电平三相定电流控制并网逆变器为研究对象，通过对L型并网逆变器的拓扑结构和数学模型的推导，结合复矢量建模方法，建立了逆变器的输出阻抗复矢量模型，刻画了单台逆变器宽频输出特性；进而，结合网络拓扑结构，提出了多台逆变器并联运行场景下的宽频聚合建模方法，分析了多台逆变器经不等长输电线路并联运行的宽频特性；最后，采用考虑频率耦合的导纳扫频测试方法，验证了所建模型的准确性。

关键词:频率耦合; 并网逆变器; 宽频特性聚合; 并联运行

Abstract:

Large scale renewable energy power generation bases have oscillation risks, and the instability of broadband oscillation may occur, which brings great challenges to the stable operation of power system. Impedance analysis is an effective method to study the broadband characteristics of grid-connected inverters, which can reveal the mechanisms of instability of broadband oscillation. Taking the L-filtered two-level three-phase constant current control grid-connected inverter as the research object, and by deriving topology and mathmatic model of L-filtered grid-connected inverter with the complex vector modeling, the complex vector model of inverter is established. Next, and the output impedance of multiple inverters operated in parallel with unequal length transmission lines is analyzed. Finally, the accuracy of the model is verified by sweeping test method considering frequency coupling.

Key words:frequency coupling; grid-connected inverter; broadband characteristic aggregation; parallel operation