双馈风电场串补送出系统次同步振荡及参数调整分析

Subsynchronous Oscillation Analysis and Parameter Adjustment of Doubly-fed Wind Farm System via Series Compensation

针对双馈风电场经串补送出系统存在次同步振荡(sub-synchronous oscillation,SSO)问题,基于三相静止坐标系建立了考虑PLL的双馈风机正负序阻抗模型,并从带宽角度分析了转子侧变流器外环控制对阻抗特性的影响,对理论推导阻抗特性和频率扫描结果进行了对比验证;然后,分析双馈风电机组网侧变流器对风机总阻抗的影响;最后,基于奈奎斯特稳定判据定量分析了风机出力、电流环控制器控制参数、系统串补度以及风机台数等因素对送出系统稳定性及振荡频率、振荡风险大小的影响,并提出了抑制次同步振荡的参数调整措施,可以通过调整风机出力、减少并网风机台数、减小线路串补度、调节RSC电流环参数等措施来抑制SSO风险。

Sub-synchronous oscillation(SSO)is observed in doubly-fed wind farms connected to series-compensated transmission system.In this paper,a positive-sequence and negativesequence impedance model of doubly-fed induction generator(DFIG)was presented based on three-phase stationary coordinate system,considering grid-side converters(GSC),rotor-side converters(RSC)and phase locked loop(PLL).It was demonstrated that the dynamics of SSO was much faster than the outer control loops from the perspective of bandwidth.The impedance model was verified and compared respectively by theoretical analysis and simulative results.Then the influence of the impedance of GSC on the total impedance of DFIG was studied.Finally,the influence of factors such as power output,current loop controller parameters,system series compensation and numbers of generators on system stability was analyzed qualitatively based on Nyquist criterion,and parameter adjustment measures for Suppressing SSO were proposed.The SSO risk can be restrained by adjusting the generators output,reducing the number of generators,reducing the line series compensation,adjusting the RSC current loop parameters and other measures.