500kV单相自耦变压器空载直流偏磁下的损耗和温升试验及分析

Loss and Temperature Rise Test and Analysis on 500 kV Single-phase Auto-transformer Under No-load DC Bias

为了分析直流偏磁对即将投入运行的某500 kV单相自耦电力变压器的损耗和热点温升的影响,在该单相变压器产品上,在出厂试验后对其进行了直流偏磁试验。在高压侧并联的模拟空载试验条件下,高压直流回路的直流电流最大加到了3.3 A;详细分析了试验测得的电压、电流、谐波、无功、空载损耗随直流电流增大的变化规律。在直流偏磁电流为2 A的模拟空载试验下,测量了铁心热点温度的变化规律。基于场路耦合模型,对比分析了电压源波形对仿真结果的影响。文中研究方法和结论对大容量电力变压器耐受直流偏磁能力的研究具有一定的参考价值。

For analyzing the influence of DC bias on the loss and hot spot temperature rise of a 500 kV single-phase auto-transformer to be put into operation,the DC bias test is carried out on this single-phase transformer product after the delivery test.Under the simulated no-load test condition with high voltage side in parallel,the maximum DC current of 3.3 A in the high voltage circuit is applied.The variation law of the voltage,current,harmonic,reactive power and no-load loss measured by the test with the increase of DC current is analyzed in detail.In the simulated no-load test with the DC bias current of 2 A,the variation law of the core hot spot temperature is measured.Based on the fieldcircuit coupling model,the influence of voltage source waveform on simulation results is compared and analyzed.The study method and conclusion in this paper have certain reference value for the study of DC bias ability of large capacity power transformer.