大容量风电场柔直并网系统的送/受端次同步振荡分析与抑制

电力系统中风电渗透率不断升高,系统送/受端次同步振荡受到送端风电控制系统参数、送端风电场风速、受端发电机出力及交流线路长度等因素影响。为了通过抑制风电出力不确定性来降低以上因素导致系统出现送/受端次同步振荡的可能性,建立了大容量风电柔直送出、受端含常规机组的试验系统模型。基于特征值分析法对系统送/受端的振荡机理进行了分析,并对次同步振荡的产生原因和影响因素进行分析。最后,依托静止同步补偿器建立了基于H∞理论的鲁棒控制器用以抑制系统次同步振荡,并在DIgSILENT/PowerFactory仿真平台上搭建算例系统,仿真验证了无论风速为何值时所设计的控制器对送/受端次同步振荡均有较好的抑制效果。

Analysis and suppression of SSO at sending/receiving end in VSC-HVDC system connected large-capacity wind farms

The wind power penetration rate in power system is increasing. SSO(Sub-Synchronous Oscillation) at sending/receiving end in the system is affected by the parameters of wind power control system,the wind speed of wind farm at sending end,the output of generator and the length of AC line at receiving end. In order to suppress the uncertainty of wind power output to reduce the possibility of SSO at sending/receiving end caused by the above factors,a test system model with large-capacity wind farms connected to grid by VSC-HVDC(Voltage Source Converter based High Voltage Direct Current) at sending end and conventional units integrated into receiving end is established. Based on the eigenvalue analysis method,the oscillation mechanism of both the sending and receiving ends of the system is analyzed,and the causes and influences of SSO are analyzed. At last,a robust controller of STATCOM(STATic synchronous COMpensator) based on H∞theory is established to suppress SSO,and the test system is built with DIgSILENT/PowerFactory. Simulative results verify that the designed controller has good suppression effect on the SSO at both the sending and receiving ends of the system under different wind speeds.