过负载下变压器绕组平均温度梯度建模及分析

Modeling and Analysis of Average Temperature Gradient of Transformer Windings Under Overload

目前,随着电力负荷的增长,变压器时常面临着过负载运行的情况。为了研究其过负载运行时绕组平均温度梯度的变化规律,该文提出了一种过负载下变压器稳态温升计算模型。该方法基于流体阻力特性建立全局油路动量模型。针对绕组、油流及散热器间的耦合传热问题,应用能量守恒建立描述场域温度分布的控制方程。同时,建立三维数值模型与实验测试平台对比验证该文所述模型。研究结果表明:应用该文所提变压器温升计算方法可根据其设计参数求出任意过负载运行时的绕组平均温度梯度及其变化规律;该文模型计算结果与CFD软件计算结果基本一致,二者平均相对误差为3.35%,与实验测试结果相比,平均相对误差为5.37%,验证了该文模型的准确性与有效性。

Currently, with increase of load, power transformers are often faced with overload operation. In order to find out the law of average winding temperature gradient under overload operation, a calculation model for steady temperature rise of transformer under overload is presented in this paper. Firstly, a global oil momentum model is established based on fluid resistance. Then, according to the coupled heat transfer between winding, oil flow and radiator, a control equation describing temperature distribution is established using energy conservation law. Simultaneously, a three-dimensional numerical model of transformer and the temperature rise test platform are established to verify the proposed model. Studies show that, according to the design parameters, the average temperature gradient of transformer winding under overload operation can be obtained using the calculation method presented in this paper. The average error between the calculated method and CFD software is 3.35%, and the average error is 5.37% compared with actual test results, verifying accuracy and effectiveness of the model.