基于阻抗法的风火打捆串补系统次同步振荡分析

Analysis of Subsynchronous Oscillation in Wind-Thermal Bundled System Integrated to Series Compensation Based on Impedance Method

风火打捆串补系统在异常情况下易发生火电机组轴系扭振问题而造成严重的设备故障,揭示风电场接入对火电机组轴系扭振影响机理有助于保障系统安全稳定运行.通过构建风火打捆串补系统等值阻抗模型,分析风电场运行条件(风电机组控制器参数、运行工况、并网规模)变化带来的系统阻抗特性迁移规律,进一步探究风电场接入对火电机组轴系扭振作用影响,研究结果表明DFIG双馈风电场接入使得系统电气振荡频率增大,设置合适的参数可能使系统避开火电机组轴系扭振频率,有利于系统稳定.构建EMTDC/PSCAD仿真算例系统,验证了理论分析结果的准确性.

The shaft torsional vibration of thermal power units will occur in the wind-thermal bundled series compensation system under abnormal conditions and cause serious equipment failure.Revealing the influence mechanism of shaft torsional vibration is helpful to ensure the safe and stable operation of the system with wind farms accessing on the thermal generators.In this paper,the equivalent impedance model of the wind-thermal bundled series compensation system is constructed,the transition law of the system impedance characteristics with the change of the operating conditions of wind farms(DFIG controller parameters,operating conditions,grid-connected scale)is analyzed,and the influence of shaft torsional vibration of the thermal generators with wind farms connection is further explored.The results show that DFIG wind farm makes the electrical oscillation frequency of the system increase,and setting appropriate parameters may make the system avoid the torsional vibration frequency of the shafting,which is conducive to the system stability.An EMTDC/PSCAD simulation example system is constructed to verify the accuracy of the theoretical analysis results.