Aiming at the sub-synchronous oscillation (SSO) problem that direct-drive permanent magnetic synchronous generator (PMSG) based wind farm under low operating conditions connects to the grid, based on the idea of graphical block modeing, the wind turbine generation (WTG), collector circuit and grid are regarded as discrete components. On the basis of establishing detailed models of each component, two linearized models of direct-drive PMSG based wind farm under different collector circuit topological structure is constructed. Wind farm impedance model is constructed based on state space equation of linearized model. The influences of current inner loop control parameters, grid strength, operating conditions on SSO characteristics are analysed. The difference between the two models in the study of SSO is compared. Finally, a time-domain simulation model of direct drive PMSG based wind farm connected to grid is built in EMTDC/PSCAD and the validity of the theoretical analysis is verified.

中文翻译：

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低运行工况下直驱PMSG风电场次同步振荡分析

针对低运行条件下基于直驱永磁同步发电机（PMSG）的风电场并网的亚同步振荡（SSO）问题，基于图形块建模的思想，风力发电机组（WTG） 、集电极电路和栅极被视为分立元件。在建立各部件详细模型的基础上，构建了两种不同集电电路拓扑结构下直驱式PMSG风电场的线性化模型。风电场阻抗模型是基于线性化模型的状态空间方程构建的。分析了当前内环控制参数、电网强度、运行条件对SSO特性的影响。比较了两种模型在SSO研究中的差异。最后，