直驱风电机组阻抗建模及次同步振荡影响因素分析

Impedance model and analysis of subsynchronous oscillation influence factors for grid-connected full-converter wind turbines

弱电网条件下直驱风电机组与电网的交互影响得到了国内外的广泛关注。目前,阻抗分析法是研究风电机组并网系统稳定性分析的主要研究方法之一,传统的基于dq坐标系的阻抗建模过程中忽略了直流侧电压波动及直流电压环的影响,并且未分析风电机组控制参数对系统稳定特性的影响。因此,以直驱风电机组并网系统为例,计及锁相环动态特性、直流侧电压波动和直流电压环,建立风电机组在dq坐标系下的阻抗模型,并通过扫频实测阻抗特性验证了理论模型的正确性。结合基于系统总阻抗矩阵行列式的稳定判据分析系统稳定性的影响因素,为风电机组控制参数的优化奠定基础。时域仿真结果验证了理论分析的正确性和有效性。

The interaction between the direct drive permanent magnet synchronous generator(D-PMSG)and the grid is paid great attention in weak grid connection condition.At present,impedance-based analysis method is the main research means for the SSO issues of the system.The influence of DC voltage perturbation and DC voltage loop are ignored in the traditional impedance modeling process based on dq frame,and the influence of the control parameters of the wind turbine on the stability of the system are not analyzed.Therefore,a direct drive permanent magnet synchronous generator-based wind farm connected to an AC grid is selected as an example,the impedance of D-PMSG based on dq frame is established,and the dynamic characteristics of the PLL,DC voltage perturbation and DC voltage loop are taken into account,and the correctness of the impedance model is verified by the simulation"scanning".Then,the influence factors of the system stability are analyzed based on the determinant of the total impedance matrix of the system.The foundation for the optimization of the control parameters of the wind turbine are proposed.Finally,the correctness and effectiveness of the theoretical analysis are verified by the simulation results in time domain simulation.