油纸绝缘混合极化的频域谱模型及参数辨识

采用等效模型分析是间接评估油纸绝缘老化状态的一种有效方法,而构建油纸绝缘系统的等效模型及参数计算是研究的基础和难点。针对目前广泛采用扩展德拜模型存在的不足,引入界面极化支路的油纸绝缘混合极化等效模型更为贴合实际极化过程,同时研究油纸绝缘混合极化过程的频域介电谱模型参数辨识方法。首先,在新型极化等效电路基础上导出频域谱与电路参数之间的关系;其次,建立求解多元方程组的目标函数,然后应用自适应收缩因子粒子群算法(ACPSO)进行参数求解;最后,通过实测数据验证该方法辨识模型参数的可行性与准确性。计算结果表明,考虑有界面极化的混合等效模型更能真实反映油纸绝缘的弛豫过程,它更符合变压器绝缘极化的实际情况;基于频域介电谱的油纸绝缘等效模型参数辨识法,相比于此前基于时域介电谱的辨识方法,具有求解过程简单、参数计算结果准确可靠等优点。

Frequency domain spectrum model and parameter identification of oil paper insulation mixed polarization

The equivalent model analysis is an effective method to indirectly assess the aging state of oil paper insulation, and it is essential and difficult to construct the equivalent model and identify model parameters of the oil paper insulation system. In view of the shortcomings of the extended Debye model, the mixed polarization equivalent model of the oil paper insulation with the interface polarization branch is introduced to describe the actual polarization process. At the same time, the parameter identification method of dielectric spectrum model in frequency domain for oil paper insulation mixed polarization process is studied. Firstly, the relationship between frequency spectrum and circuit parameters is derived based on a new polarization equivalent circuit. Secondly, the objective function for solving multivariate equations is established, and then the parameters are solved by ACPSO algorithm. Finally, the feasibility and accuracy of the method for identifying model parameters are verified by measured data. Results show that the mixed equivalent model considering the interface polarization can reflect the relaxation process of oil paper insulation more truly, and it is more consistent with the actual situation of transformer insulation polarization. Compared with the identification method based on time domain dielectric spectroscopy, the identification method of the equivalent model of oil paper insulation based on FDS is simple, accurate and reliable.