油纸绝缘结构介质响应电路模型的参数辨识方法研究

Research on the Method of Parameter Identification for Dielectric Response Equivalent Circuit of Oil-paper Insulation

介质响应法能够有效地无损诊断油纸绝缘结构的老化状态。油纸绝缘结构的介质响应电路模型的参数辨识是介质响应法评估老化状态的关键。笔者根据介质响应的极化过程的特点,提出利用去极化电流辨识油纸绝缘结构的扩展徳拜模型,并通过分析去极化电流的形成和扩展徳拜模型的特点,将多指数拟合问题转化成单指数拟合问题,同时将模型中RC支路的时间常数转换成直线的斜率来求解。最后,笔者基于1台110 kV变压器的实测去极化电流曲线,用文中的方法辨识出其扩展徳拜模型,并在MATLAB中仿真了所得扩展徳拜模型的去极化电流曲线,仿真曲线与原曲线重合度为95.8%,从而验证了该方法的正确性。

The dielectric response method is an effectively non-destructive testing method for diagnosis oil-paper insulation aging status. Identifying the circuit model of oil-paper insulation is the key to assess aging status using dielectric response method. The extended Debye model is identified by using depolarizing current of oil-paper insulation in this paper, based on the characteristics of the depolarization process of dielectric response. The multi-exponential fitting problem is simplified into a single-exponential fitting problems and the RC time constant is transformed into the slope of straight line in the identify progress by analyzing the characteristics of the depolarization process and the extended Debye model. Finally, an extended Debye model of an 110 kV transformer is identified through its depolarization current curve, using the method proposed in this paper. And a simulation is done in MATLAB .Then the 95.8% coincidence degree of simulation curve with the original curve verifies the correct of this method.