[目的]针对弱电网背景下直驱风机网侧电流内环PI控制器带宽影响并网系统稳定性,诱发次同步振荡(subsynchronous oscillation,SSO)现象,提出改进线性状态误差反馈(linear state error feedback,LSEF)控制律的线性自抗扰控制器(linear active disturbance rejection control,LADRC)替换电流内环的PI控制器去抑制SSO.[方法]首先,对LADRC控制器的LSEF进行改进,并对其跟踪误差、抗扰性能进行分析.然后,推导出计及频率耦合影响的系统阻抗模型,并且利用Nyquist判据分析线路阻抗值对于网侧变流器并网系统稳定性的影响.最后,通过PSCAD/EMTDC仿真软件进行分析验证.[结果]相较于传统LADRC,改进LADRC使直流侧电压波动范围减少了85%,有功功率波动范围减少了89%.[结论]与传统LADRC控制器相比,改进LADRC控制器可以更好地缩小功率波动范围及直流侧电压波动范围,减小跟踪误差.
Subsynchronous Oscillation Suppression of Direct-Drive Wind Turbines Based on Improved Linear Active Disturbance Rejection Control and Analysis of Impedance Stability
[Objectives]In response to the impact of the bandwidth of the current inner loop PI controller on the stability of the grid connected system of direct drive wind turbines under the background of weak electricity network,which leads to the induction of sub synchronous oscillation(SSO)phenomenon,a linear active disturbance rejection control(LADRC)was proposed to replace the current inner loop PI controller with an improved linear state error feedback control law(LSEF)to suppress SSO.[Methods]Firstly,the LSEF of the LADRC controller was improved,and the tracking errors and anti-interference capabilities were studied.Moreover,an impedance model for the system considering frequency coupling effects was developed,and the Nyquist criterion was employed to assess the impact of line impedance values on the stability of the grid-connected converter system.Finally,the analysis and validation were performed using PSCAD/EMTDC simulation software.[Results]Compared with traditional LADRC,the improved LADRC can reduce the DC side voltage fluctuation range by 85%and the active power fluctuation range by 89%.[Conclusions]Compared with traditional LADRC controllers,improved LADRC controllers can better reduce the range of power fluctuations,DC side voltage fluctuations,and tracking errors.
wind powersubsynchronous oscillation(SSO)linear active disturbance rejection control(LADRC)impedance modeldirect-drive wind turbineweak gridconnection to grid
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