高压直流输电次同步振荡轴系扭振分析

Torsional Vibration Analysis of Subsynchronous Oscillation in HVDC Transmission System

传统的次同步振荡抑制方法通过阻尼滤波器阻断机械系统和电气系统之间的相互作用来抑制次同步振荡,但阻尼滤波器对环境的适应性较差,设计参数要求严格,运行维护比较困难。因此,提出了在整流端定电流系统加入附加阻尼控制器,通过调节系统电流、增强轴系模态阻尼来抑制次同步振荡。该控制方法实时有效,容易控制,又不会影响系统其他控制器的控制性能。通过分析发电机轴系特征值、轴系模态阻尼、次同步频率分量的传递过程,研究系统控制参数、轴系模态与次同步振荡之间的关系,设计了发电机转速偏差与三相母线瞬时电压联合作为输入信号的附加阻尼控制器,有效减小了次同步频率变换环节的输出误差,提高了控制器精度。采用IEEE第一标准次同步研究模型参数,在PSCAD软件中搭建高压直流输电次同步振荡仿真模型。仿真结果表明,所设计的控制器能有效抑制系统次同步振荡。

The traditional subsynchronous oscillation suppression method suppresses subsynchronous oscillation through blocking the interaction between mechanical system and electrical system by using damping filter.However,the adaptability of the damping filter to the environment is poor,the design parameters and operational maintenance are difficult.Therefore,the supplementary damping controller is added in the constant current system at the rectification terminal.The subsynchronous oscillation is suppressed by adjusting the system current and enhancing the modal damping of the shafting.This control method is effective,easy to control,and features good real time performance;and it doesn't affect the control performance of other controllers in the system.The transfer process of generator shafting eigenvalues,shafting modal damping,subsynchronous frequency component are analyzed,and then the relationship among the system control parameters,the mode of shafting and subsynchronous oscillation is studied.The supplementary damping controller which combines the generator speed deviation with the instantaneous voltage of the three-phase bus as input signal is designed.It can effectively reduce the output error of subsynchronous frequency conversion and improve the accuracy of the controller.The model parameters are studied by IEEE first standard,and the simulation model of subsynchronous oscillation of HVDC transmission is built in PSCAD.The simulation results show that the designed controller can effectively suppress subsynchronous oscillation of the system.