发电机大轴接地不良引发热工保护误动的原因分析

摘要

针对某电厂#8汽轮发电机组出现的热工保护误动作停机事故，对机组热工保护卡件连续烧损、大轴接地系统存在电压、发电机风冷系统温度高、轴瓦振动数值大等异常情况进行了分析，发现发电机大轴接地系统带电压是机组热工保护卡件烧损的直接原因，热工卡件连续烧损造成保护误动。找出发电机大轴带电压的原因并制定了明确的处理措施。找出了发电机滑环室温度高的原因，提出了控制温升的具体措施。通过采取有效的措施，#8汽轮发电机组恢复了正常运行状态。%The article discusses an accidental shutdown of No.8 generator of a plant for Thermal Protection Miss-operation,in which thermal protection units were burned down.Abnormalities including the continuous burning down of protection clamp units,existing voltage at the large shaft grounding system,high temperature of air cooling system of gen-erator and huge bearing vibration were analyzed and it was found that the large shaft grounding system with high voltage led to the burning down of thermal protection units and the continuous burning down of protection clamp units causedprotection malfunction.Finally,it notes the reason for large shaft with voltage,the slip ring chamber with high voltage and works out a specific way to deal with such problems.After the implementation of efficient measures,No.8 generators regained normal operation.