特高压自耦变压器三侧同时满容量时的温升试验

Temperature Rise Test of Ultra-high Voltage Autotransformer During Simultaneous Three-side Full Power Operation

确定特高压变压器在三侧同时满容量运行方式下的热状态需要专门的温升试验,对温升试验的原理和结果进行了分析。基于Kirchhoff电流定律、磁势平衡原理以及特高压变压器的调压原理,研究了各绕组电流之间的关系,推导了在三侧同时满容量运行方式下各绕组分布电流大小的计算公式。通过具体实例与3组双绕组运行方式下各绕组的电流值进行了对比,归纳出公共绕组的电流大于其额定电流这一主要特点。从测量有效性和绕组电流分布2个方面阐述了温升试验分别在主变和调压补偿变上进行这一方案的可行性和合理性。通过对实例温升试验数据的计算和分析,得出用三侧同时满容量运行方式下的实际电流计算的总损耗比用额定电流计算的值大9%、公共绕组的平均温升比用额定电流计算的值大13.9K的结果。最后明确了主变和调压补偿变各自总损耗的计算方法,指出各绕组的铜油温升应该按照三侧同时满容量运行方式下的实际电流大小进行修正,同时提出加大公共绕组热容量设计的建议。

In order to determine the thermal state of ultra-high voltage（UHV） autotransformer during simultaneous and full power operation on three sides, we analyzed the mechanism and results of testing the particular temperature rise. On the basis of the Kirchhoff＇s current law and the magnetic potential balance principle, we studied the relationship between the currents of individual windings and derived the formulas to calculate the currents. Through calculation of a practical example, the current values of individual windings in different operation conditions were compared. It is concluded that the current value of a common winding is higher than its rated value during the three- side full power operation. Testing the temperature rise on the main set and the regulation-compensation set separately is feasible and reasonable from the aspect of validity and taking the distribution of current into consideration. Analyzing the data from the practical case reveals that the total loss of winding current and the average temperature rise of common winding calculated from the target value are 9~if0 and 13.9 K higher than those from the rated value, respectively. A method of calculating the total loss is also proposed. It is recommended that the results should be corrected with the target value of winding current, and the thermal capacity of common winding needs to be increased.