抑制风电-柔直外送系统次同步振荡的并联VSC型次同步阻尼控制器

Shunt-VSC subsynchronous damping controller to suppress SSO in wind power connected by flexible DC sending system

风电经柔性直流输电(简称“柔直”)系统接入交流电网已经成为陆上/海上风电并网的主要方式之一,但风电与柔直系统之间存在控制相互作用引发次同步振荡的风险。为抑制此类振荡,提出一种独立于柔直系统和风电机组变流器的并联电压源变流器(VSC)型次同步阻尼控制器。该控制器使用集电线电压作为输入信号,提取信号中的振荡模态后调制其幅值、相位,然后利用并联VSC向系统注入次同步频率的电流来抑制振荡。基于复阻抗法对控制器参数进行了优化设计。仿真结果表明,所提出的控制器能在不同工况下有效抑制振荡。

Wind power connected to AC grid by flexible DC transmission(here is called flexible DC)system has become one of the main ways for grid connected onshore/offshore wind power system.However,there is a risk of subsynchronous oscillation caused by control interaction between wind power and flexible DC system.In order to suppress the oscillation,a shunt-VSC(Voltage-Source Converter)subsynchronous damping controller independent of flexible DC system and wind turbine unit converter is proposed.The collection line voltage is used as the input signal by this controller and the oscillation modes of the signal are extracted to modulate the signal’s amplitude and phase,moreover the subsynchronous frequency current is injected by shunt-VSC into the system to suppress the oscillation.The parameters of controller are optimized based on the complex impedance method.The simulative results demonstrate that the proposed controller can suppress the oscillation effectively under different operation conditions.