以箱壁温度为判据的油浸式变压器绕组热点温度计算模型及试验分析

Model of Hot Spot Temperature in Oil-immersed Transformers Using Temperature Estimation of Tank Wall

电力变压器的热点温度是影响其绝缘寿命非常重要的因素,准确估计电力变压器热点温度,有助于提高电力变压器的经济与安全运行水平。为此,提出了一种估计变压器绕组热点温度的改进方法。该方法依据变压器热路模型,采用变压器油箱壁温度来估计绕组热点温度。为了验证该方法的准确性,在实验室的试验变压器上进行了负载试验,得到不同负载下的变压器绕组热点温度和油箱壁温度的实测值,并将热点温度的实测结果与该方法计算值以及IEEE负载导则公式的计算值进行了比较。分析结果表明,改进方法具有较小的热点温度估计误差,证明了改进方法估计变压器热点温度的有效性。

Hot spot temperature is a very important factor that influences lifetime of insulation in power transtormers. Accurate estimation of the hot spot temperatures of transformer windings is helpful to improving economic and safe operation levels of transformers. Consequently, an improved approach was presented to estimate hot spot temperatures of transformer windings. The improved approach was based on a thermal circuit of power transformers. Temperatures of transformer wails were used to estimate the hot spot temperature of transformer windings, and load of transformers was tested in laboratory to obtain the measurement data of temperatures of hot spot and transformer walls. The measurement results were compared with the estimated results of the improved approach and the calculated results of IEEE loading guide equations. The analysis results show that the improved approach has smaller estimation errors of hot spot temperature than the IEEE load guide equations. The improved approach is verified to be effective for estimation of hot spot temperature in transformers.