基于有限状态机的次同步振荡在线监测与抑制策略

Subsynchronous Oscillation Online Monitoring and Suppression Strategy Based on Finite State Machine

随着大规模风电接入电网,次同步振荡风险不断提高,现有研究提出的次同步振荡辨识指标不够全面,抑制方法或成本较高,或影响风电场有功输出。针对这一问题,本文对次同步振荡的在线监测方法与抑制措施进行分析,结合次同步振荡的启动门槛、功率振幅门槛、功率周期门槛和振荡次数门槛,提出一种基于有限状态机的次同步振荡在线监测方法及相应的抑制策略。该监测方法根据三相总瞬时功率的变化轨迹辨识次同步振荡的发生,感知次同步振荡的严重程度,并采取分阶段在转子侧变流器q轴、d轴附加阻尼控制器抑制次同步振荡。Simulink仿真结果表明,采取所提策略在不同串补度工况下均能准确辨识并抑制次同步振荡。

With the large-scale integration of wind power into the power grid,the risk of subsynchronous oscillations in⁃creases continuously.However,the identification indicators proposed in existing research for subsynchronous oscilla⁃tions are not comprehensive.Moreover,the suppression method for subsynchronous oscillations either has a high cost or adversely affect the active power output from wind farms.In this paper,a subsynchronous oscillation online monitoring method and corresponding suppression measures are analyzed.By combining the thresholds of start,power amplitude,power period and oscillation count for subsynchronous oscillations,a subsynchronous oscillation online monitoring method and the corresponding suppression strategy based on a finite state machine are put forward.This monitoring method can identify the occurrence of subsynchronous oscillations according to the changing trajectory of the total threephase instantaneous power and perceive the severity degree of subsynchronous oscillations.In addition,a phased imple⁃mentation of additional damping controllers in the rotor-side converter’s q-axis and d-axis is adopted to suppress subsyn⁃chronous oscillations.Simulink simulation results demonstrate that the proposed strategy can accurately identify and suppresses subsynchronous oscillations at various compensation levels.