计及不对称负荷的配电变压器短路电抗在线检测方法

On-line Detection of Short-circuit Reactance of Distribution Transformers Considering the Condition of Asymmetric Load

短路电抗是配电变压器的一个重要参数,可以反映绕组健康状态,对配电变压器损耗监测和容量评估起到重要作用。为此,通过对单相变压器的分析并结合不同连接方式三相变压器的特点得到其短路电抗与高低压侧电压、电流的关系,进而提出了配电变压器短路电抗在线检测新方法。以实际因素为出发点,建立了在电压波动和谐波影响下的仿真模型,并基于实际负荷数据进行了短路电抗在线测量及绕组变形仿真实验,结果显示所提方法能够计算不对称负荷、电压波动及谐波影响下的绕组短路电抗值,且与设定值相比误差<0.2%。表明所提方法不受上述实际因素的影响,能够精确有效检测绕组短路电抗值,为实际检测绕组短路电抗提供了一种方案。

The short-circuit reactance which can reflect the healthy status of the windings and plays an important role in detecting the losses and assessing the capacity is an important parameter of transformers. Therefore, the relationship among the short-circuit reactance, the primary voltage, the secondary voltage and current is obtained from the characteristics of the single-phase transformer and the basic knowledge of three-phase transformer with different connections. A novel method of on-line measurement of short-circuit reactance is proposed according to the relationship. The simulation model is established based on the actual factors considering the effect of voltage fluctuation and harmonics. The simulation related to the on-line measuring of the short-circuit reactance and the deformation of transformer winding is conducted based on the actual load data. The results show that the proposed method can calculate the short-circuit reactance under the influences of asymmetric load, voltage fluctuations and harmonics, and the error of the short-circuit reactance is less than 0.2%. Therefore, the presented method can accurately calculate the short-circuit reactance under the influence of the above actual factors, and provide an option for the monitoring of the short-circuit reactance of the winding.