基于傅里叶分析的高压直流输电次同步振荡控制研究

Research on Control of Sub-synchronous Oscillation in HVDC Transmission Based on Fourier Analysis

摘要:

当高压直流输电遭受短时扰动时，电气量变化产生的电磁转矩变化量所包含的电气负阻尼转矩，加剧了汽轮发电机的转速变化，使得输电线路中产生次同步振荡现象。文中通过傅里叶分析方法计算得出电网次同步振荡频率，在汽轮发电机的转子转速控制系统中通过调节励磁系统锁相环的频率合成，减小励磁电流波动，生成一个新的附加电磁转矩量，使最终的电气阻尼转矩分量为正，实现对转子转矩控制。仿真结果表明，在电网出现短时扰动时，汽轮发电机的转速没有出现大波动，实现了对次同步振荡的有效抑制。

Abstract:

When high voltage direct current (HVDC) transmission is subject to short-term disturbance, the variation of electromagnetic torque caused by the change of electric parameters includes the component of electric negative damping torque, which intensifies the variation of turbo-generator speed and causes sub-synchronous oscillation in transmission lines. The frequency of sub-synchronous oscillation is calculated by Fourier analysis method. In the rotor speed control system of turbine generator, the fluctuation of excitation current is reduced by adjusting the frequency synthesis of phase locked loop in excitation system, and a new additional electromagnetic torque is generated, so that the final electrical damping torque component is positive, and the rotor torque is controlled. The simulation results show that the speed of turbine generator does not fluctuate greatly when power grid is disturbed in a short time, and the sub-synchronous oscillation is effectively suppressed.