风火打捆经直流送出的次同步振荡分析与抑制措施

摘要

传统火电机组与直流输电控制器相互作用会产生次同步振荡,大规模双馈风电机组接入对这种振荡产生的影响有待深入研究.本文建立了风火打捆经直流送出的典型模型,并对风火打捆经直流送出系统次同步振荡机理进行了分析,结果表明双馈风机接入能够缓解直流输电引起的火电机组次同步振荡,且风火打捆比例越高效果越好.分析了风机变频器特性与系统运行工况对火电机组次同步振荡的影响,结果表明,风机转子侧变频器内环增益系数增大、内环积分时间常数减小、直流输送功率上升、送端交流系统减弱、直流输电整流侧控制器积分时间常数减小、换流器触发角增大,会引起火电机组振荡加剧.对工程应用较多的直流附加宽带通式次同步阻尼控制器(SSDC)在风火打捆经直流送出系统中的适用性进行分析与验证,结果表明,宽带通式SSDC仍具有抑制效果.%The interaction between thermal generator and controller of HVDC may excite sub-synchronous oscillation (SSO).The influence of the injection of doubly fed induction generators (DFIG) is worthy of further research.The typical wind-thermal bundling system with HVDC transmission was modeled,and the mechanism of SSO in wind-thermal bundling system with HVDC transmission was analyzed.Results indicated that the injection of DFIG can release the SSO of thermal generator caused by HVDC,especially in high wind-thermal bundling ratio.The influence of the characteristic of DFIG and operation conditions was investigated.Results indicated that increase of gain coefficients,DC power,trigger angle of rectifier and decrease of integral time constant,AC system of rectifier all exacerbated the deterioration of SSO in thermal generator.The application of broad band-pass sub-synchronous damping controller (SSDC) in wind-thermal bundling system with HVDC transmission was verified.Results indicated that the broad band-pass SSDC remained to work in wind-thermal bundling system with HVDC transmission.