温度对油浸式套管Cole-Cole介电模型参数的影响

Influence of Temperature on Cole-Cole Dielectric Model Parameters of Oil-Immersed Bushing

为了能够更好地利用Cole-Cole介电数学模型诊断油浸式套管受潮状态,需要解析温度对油浸式套管Cole-Cole介电模型参数的影响。在实验室制备了72.5kV油浸式套管,并在不同测试温度下对油浸式套管进行了频域介电响应测试,采用带修正的双弛豫Cole-Cole介电模型对实验数据进行了拟合,并分析了温度变化对油浸式套管频域ColeCole介电模型参数的影响。结果表明:油浸式套管Cole-Cole介电模型中的直流电导率σdc与热力学温度T的关系与变压器中的相关研究一致,满足Arrhenius关系,而弛豫时间和弛豫强度与变压器的研究结果有明显的区别;其中油浸式套管弛豫时间τ1随测试温度的升高呈指数式减小,τ2随温度的升高而下降且下降过程中存在一个放缓区;弛豫强度Δε1随测试温度的升高指数式增加,Δε2随温度升高呈现出先增大后减小再增大的趋势。

In order to make better use of the Cole-Cole dielectric mathematic model to diagnose the damp-state of oil-immersed bushing,it is necessary to analyze the effect of temperature on the Cole-Cole dielectric model paremeters of oil-immersed bushing. In this paper,72. 5kV oil-immersed bushings are produced in laboratory,and the frequency-domain dielectric response tests of oil-immersed bushings are carried out at different test temperatures. The experimental data are fitted by using the modified double relaxation ColeCole dielectric model,and the influence of temperature variation on the Cole-Cole dielectric model parameters is analyzed. Results showthat the relationship between the DC conductivity σdcand the thermodynamic temperature T in the Cole-Cole dielectric model of oil-immersed bushing is consistent with that in transformer,the Arrhenius relation is satisfied; however,the relaxation time and relaxation strength are quite different from those of transformer; the relaxation time τ1decreases exponentially with the increase of test temperature; τ2decreases with the temperature rise and there is a slowdown in the process of change; the relaxation strength Δε1exponentially increases with the increase of test temperature; Δε2shows a tendency to increase first,then decreases and then increases with the increase of test temperature.