电机定子绝缘频域介电谱解析与老化评估方法研究

Analysis and Aging Evaluation Method of Frequency-domain Dielectric Spectroscopy for the Motor Stator Insulation

为利用频域介电谱对发电机定子绝缘进行老化状态评估,提出了频谱解析策略及老化评估方法,并设计加速老化试验进行了验证。通过复介电常数实部与角频率的偏导曲线判断测试频段内的极化弛豫数量,并对高频段数据进行拟合分析,将拟合结果进行推广到全频段,并利用统计检验确保了拟合结果与原始数据的一致性,实现了频谱弛豫极化损耗与电导损耗的分离。利用傅里叶逆变换实现了频域极化电流到时域极化电流的转换,研究了转换之后的电流幅值随老化程度的变化规律。结果表明,所提出的频谱解析策略具备可行性与有效性,获取的时域极化电流幅值与直流电导率对老化状态具有较高敏感度,可以应用于定子绝缘的老化状态评估。

In order to evaluate the aging state of motor stator insulation by using frequency-domain dielectric spectroscopy,the analysis strategy and aging evaluation method of frequency-domain dielectric spectroscopy are proposed,and the accelerated aging test is designed to verify the method.Firstly,the number of polarization relaxations in the test band should be judged by the partial derivative curves of the real part of the complex relative permittivity and the angular frequency,and used the dielectric relaxation model for fitting analysis of high frequency spectrum data.Then,the fitting results are mapped to the whole frequency band,and the consistency between the fitting data and the original data is tested by statistical test.The separation of spectrum relaxation polarization loss and conductivity loss is realized.Furthermore,the inverse Fourier transform is used to realize the conversion of the current in the frequency domain to the current in the time domain,and the variation law of current amplitude with aging degree after conversion was studied.The results show that the time domain polarization current amplitude and DC conductivity obtained are highly sensitive to the aging state,and can be used to evaluate the aging state of stator insulation.