发电机主绝缘加速老化的频域介电特性

Frequency domain dielectric properties of accelerated aging generator stator insulation

为研究大型发电机主绝缘的频域介电特性,在实验室搭建多因子加速老化平台对发电机定子线棒试样进行加速老化,通过频域介电谱法(FDS)测试不同老化程度下发电机绝缘试样的频域介电特征量,研究环氧云母绝缘试样复电容和老化状态之间的关系,同时分析温度对发电机绝缘频域介电特征量的影响规律,并采用Arrhenius方程求得了发电机主绝缘的活化能。研究结果表明:发电机环氧云母绝缘的复电容实部和虚部随着老化周期增加明显增大,可反映绝缘老化状态;温度对绝缘介电特征量影响显著,根据复电容虚部的曲线和Arrhenius方程计算出第三个老化周期之后绝缘的活化能是67. 36kJ/mol;通过"频温平移"可以有效消除测试温度对FDS结果的影响,同时可以拓宽已知测试温度下的测试频率范围。

To study the FDS characteristics properties of large generator stator insulation,a multi-factor accelerated aging platform was set up and the generator stator bars were accelerated aging in laboratory.The FDS of generator insulation samples of different aging degrees were measured,and the relationship between the complex permittivity and the aging state of epoxy mica insulation was studied.The effect of temperature on characteristics of FDS of the generator insulation was studied and the activation energy of the generator insulation with Arrhenius equation was obtained.The results show that the real part and imaginary part of complex permittivity of the generator insulation increase obviously with the increase of the aging cycle,which can reflect the insulation aging state.The effect of temperature on FDS of generator insulation is significant and the activation energy of the insulation after the third cycle aging period is 67.36kJ/mol according to the Arrhenius equation.The temperature effect on the FDS can be eliminated effectively by“translation of temperature dielectric spectroscopy”.At the same time,the test frequency range under known test temperature can be broadened.