变频器供电对电厂电机绝缘状态的影响研究

在电厂中,采用变频器给电机设备供电可获得良好的电气性能,但如果未考虑电机绝缘系统长时间耐受脉冲电压的能力,则可能导致电机绝缘系统发生过早失效,影响电厂的正常运行。为了解变频器供电时对电机绝缘的具体影响,考虑电厂电机设备的特殊工作环境,主要从介电应力、匝间绝缘、损耗及局部放电四个方面深入分析了变频器供电下电机的绝缘劣化机理。为提高变频器供电时对电机绝缘状态判断的准确性,提出一种电机绝缘状态评估方法,通过其获得电机运行过程中的真实绝缘状态,并以此来判断电机是否需要检修维护,以避免发生贯穿性的绝缘击穿事故。针对提高电机设备的运行可靠性,提出了多种变频器供电时降低电机绝缘劣化程度的措施,延长电机的绝缘寿命。

In power plants,good electrical performance can be obtained by using s to supply power to motor,but if the motor insulation system to withstand pulsed voltage for a long time was not considered,it may lead to premature failure to motor insulation and affect the normal operation of the power plant.In order to analyze the specific impact on motor insulation,the insulation deterioration mechanism of the motor fed by the inverter was analyzed mainly from four aspects including the dielectric stress,inter-turn insulation,loss and partial discharge,considering the special working environment of the motor in power plants.In order to improve the accuracy of judging the motor insulation status when motor was supplied through the inverter,an evaluation method of the motor insulation status was proposed.Through this evaluation method,the real insulation state during the operation of the motor can be obtained and used to determine whether the motor needs maintenance and repair,in order to avoid a penetrating insulation breakdown accident.In addition,various measures to reduce the degradation of motor insulation during inverter power supply were proposed to improve the operational reliability and extend the insulation life of motor equipment.