贵州火电机组机网耦合扭振典型故障分析与寿命评估

Typical fault analysis and life evaluation of generator grid coupling torsional vibration of thermal power units in Guizhou

贵州电力系统是典型的多电源、远距离,交、直流混合输电系统,该类型发输电系统容易引发机网耦合扭振问题。本文从贵州电力系统网、源分;布及运行特点入手,分析贵州电力系统中发生机网耦合扭振风险较高的机组,针对性地进行了机网耦合扭振典型故障仿真分析及响应特性计算,给出所研汽轮发电机组轴系扭转疲劳寿命损耗的理论计算公式和相关曲线。以最为严重的汽轮发电机组机端出口两相短路故障和换流站与火电机组轴系耦合振荡故障为例,计算评估了机组轴系在两种故障中的扭转疲劳寿命损耗情况。结果表明:满负荷工况下发生机端两相短路故障将引起大约4.8倍的额定电磁力矩,一次事故造成轴系的扭转疲劳损耗量约为33.86%;而等幅振荡的SSO故障对轴系的扭转疲劳损耗量长期累积也会使机组轴系失效。

Guizhou power system is a typical multi power,long-distance,AC and DC hybrid transmission system,which is easy to cause the torsional vibration problem of generator grid coupling.Starting from the grid,source distribution and operation characteristics of Guizhou power system,this paper analyzes the units with high risk of generating unit grid coupled torsional vibration in Guizhou power system,carries out simulation analysis on typical faults of turbine grid coupled torsional vibration and calculation of response characteristics,and gives the theoretical calculation formula and relevant curve of torsional fatigue life loss of steam turbine generator unit.Taking the most serious two-phase short-circuit fault at the turbine generator end outlet and coupling oscillation fault between converter station and thermal power unit shafting as examples,the torsional fatigue life loss of the unit shafting in the two kinds of faults is calculated and evaluated.The results show that under full load condition,the two-phase short-circuit fault of generator terminal will cause about 4.8 times of rated electromagnetic torque,and the torsional fatigue loss of shafting caused by one accident is about 33.86%;and the long-term accumulation of torsional fatigue loss caused by SSO fault with equal amplitude oscillation will also lead to shafting failure.