面向低频振荡分析的直驱风电机组阻尼转矩建模

针对直驱风电机组直流电压环和锁相环失稳问题，基于直驱风电机组电流源型线性化模型，分析了电网强度、直流电容输入功率以及控制参数对直驱风电机组稳定性的影响；建立了适用于直流电压环和锁相环稳定性分析的电流源型阻尼转矩模型，通过阻尼转矩法揭示了直驱风电机组失稳机理；进一步地将阻尼转矩法拓展至多机并联系统。研究结果表明：电网强度的减小、直流电容输入功率的增加、控制参数(直流电压环比例参数、锁相环比例参数)的减小会降低直驱风电机组低频振荡模式(直流电压环模式、锁相环模式)的阻尼系数，当阻尼系数小于0时，该模式下系统失稳，表现为直驱风电机组发生低频振荡。

Damping torque modeling of direct-drive wind turbine for low-frequency oscillation analysis

Aiming at the instability problem of DC voltage loop and phase locked loop of direct-drive wind turbine, based on the current-source linearization model of direct-drive wind turbine, the influence of grid strength, DC capacitor input power and control parameters on the stability of the direct-drive wind turbine is analyzed. The current-source damping torque model suitable for the stability analysis of DC voltage loop and phase locked loop is established. The damping torque method is used to reveal the instability mechanism of direct-drive wind turbine. Furthermore, the damping torque method is extended to multi-machine parallel systems. The research results show that the decrease of grid strength, the increase of input power for DC capacitor, and the decrease of control parameters such as proportional parameters of DC voltage loop or phase locked loop will reduce the damping coefficient of the low-frequency oscillation mode, DC voltage loop mode or phase-locked mode for direct-drive wind turbines. When the damping coefficient is less than 0, the system will be unstable under this mode, which is manifested as low-frequency oscillation of direct-drive wind turbine.