鲁西背靠背混合直流输电工程引发次同步振荡的风险评估及抑制方法研究

Risk Assessment and Suppression Method Study on Sub-synchronous Oscillation Resulted From Luxi Mixed Back-to-Back HVDC Project

鲁西背靠背混合直流输电工程与云南电网的滇东和雨汪电厂电气距离较近,可能引发电厂汽轮机组轴系次同步扭振。为此,采用机组作用系数法和时域仿真法对该直流工程引发次同步振荡的风险进行了有效评估。根据复转矩合成原理,分别为该直流工程的常规直流单元和柔性直流单元设计了窄频带、多通道次同步阻尼控制器,EMTDC时域仿真结果显示,所设计的控制器阻尼效果明显,在滇东和雨汪电厂在严苛条件下运行,也依然能有效抑制上述电厂汽轮机组的轴系次同步扭振,且对电网运行方式和直流控制模式具有较强的鲁棒性。

Luxi mixed back-to-back HVDC project is close to Diandong Power Plant and Yuwang power plant in Ymman Power Grid in electrical distance, which may lead to sub-synchronous torsional vibration of the above-mentioned two power plants＇ steam turbine shafts. For this reason, the methods of UIF and time domain simulation are used to evaluate the risk of sub-synchronous oseiilation caused by this HVDC project. According to the principles of complex torque synthesis, two narrow-band muhi-ehannel sub-synchronous damping controllers are designed respectively for conventional DC unit and flexible DC unit of this HVDC project. EMTDC time domain simulation results show that the damping effect of designed controllers is obvious, even in harsh conditions the controllers still can effectively inhibit the sub-synchronous torsional vibration of the power plant steam turbine shafts,and have strong robustness in terms of power grid operation mode and HVDC control mode.