含双馈机组转子侧附加控制的风电场次同步振荡抑制方法

A Method to Suppress Sub-Synchronous Oscillation of Wind Farm Composed of Doubly Fed Induction Generators With Additional Rotor Side Control

针对含双馈机组风电场通过串联补偿外送功率时产生的次同步振荡(sub-synchronous oscillations,SSO)问题,建立了包含两质量块轴系、d-q解耦控制回路等的详细模型。采用测试信号法绘制分析阻尼曲线。该曲线显示,串联补偿的加入改变了电气阻尼特性。如果控制器参数不合理,较低串补度下也有发生振荡的风险;随着串补度的加大,电气谐振点的负阻尼越大,对应于转子侧的电气谐振频率越低。当轴系参数耦合时会发生轴系扭振。针对双馈机组转子变换器控制回路的特点,在转子侧注入次同步电流,以激发次同步电磁转矩阻尼振荡,设计附加功率控制的次同步阻尼控制器(sub-synchronous damping controller,SSDC)对次同步振荡予以抑制,并给出了控制器参数的整定方法。时域仿真结果表明:采用该SSDC方案,能够有效抑制串补引发的风电场SSO问题。

In allusion to sub-synchronous oscillations （SSO） occurred in wind farm composed of doubly fed induction generators （DFIG） while the wind power is transmitted to power gird via the series compensation, a detailed wind farm model including two mass block shaftings and d-q decoupling control circuit is built. The damping curve is plotted by test signal method and analyzed. The damping curve shows that the addition of series compensation changes the electrical damping characteristics. When the parameters of the controller is not reasonable, there is the risk of occurrence of SSO under a lower series compensation degree; along with the increase of series compensation degree, the negative damping at electric resonance point increases, so the corresponding electric resonance frequency at the rotor side decreases. When the parameters of the shaftings are coupled, the torsional vibration of shaft system occurs. According to the features of the rotor converter control circuit of DFIG, the sub-synchronous current is injected in at rotor side to energize damping oscillation by sub-synchronous electromagnetic torque, meanwhile a sub-synchronous damping controller （SSDC） based on additional active power control is designed to suppress the SSO and the setting method of the parameter of the controller is given. Results of time-domain simulation show that using the designed SSDC the SSO in wind farm caused by series compensation can be effectively suppressed.