110 kV变压器中性点用带并联间隙避雷器参数配合特性研究

Study on Parameter Coordination Characteristics of Arrester with Parallel Gap for 110 kV Transformer Neutral Point

为了减小单相接地短路电流,我国110 kV系统运行中大量变压器中性点采取不接地方式,这些变压器中性点绝缘面临着严重的过电压威胁,曾出现过多次绝缘损坏事故。为了有效抑制变压器中性点过电压,针对传统的保护方式存在的结构复杂、配合有盲区,使用场合具有局限性等问题,文中提出了一种新型带并联间隙避雷器的保护方式,理论分析了带并联间隙避雷器的结构和性能特点。实验研究了在工频电压和冲击电压作用下带并联间隙避雷器本体单元和并联单元承担的工作负荷以及并联单元电阻片参数和并联间隙参数对分压特性的影响。实验结果表明,工频电压下,并联间隙会使并联单元承担的电压降低,并且并联单元的电阻片片数越多,间隙对分压比的影响越大;冲击电压下并联间隙对并联单元承担的电压影响较小可忽略。最后提出了110 kV变压器中性点用带并联间隙避雷器的参数配置原则和具体参数。

In order to reduce the short-circuit current when single-phase grounding happened,a large number of transformer neutral points in 110 kV system are not grounded.These transformer neutral points is facing serious over-voltage threat and many damage accidents occur.Aiming at the problems of complex structure,blind area and limita-tion of traditional protection methods,a new type of protection method with parallel gap arrester is proposed.Structur-al and performance characteristics of arrester with parallel gap is analyzed.The workload of main unit and parallel unit as well as the influence of resistor parameters and gap parameters in parallel unit on voltage distribution charac-teristics under continuous power frequency voltage and impulse voltage are studied through the test.The results show that under the power frequency voltage,the parallel gap can reduce the voltage of parallel unit,and the more the number of resistance pieces of the parallel unit,the greater the impact of the gap on the voltage ratio;under the im-pulse voltage,the impact of the parallel gap on the voltage of the parallel unit can be ignored.Finally,the configura-tion parameters of arrester with parallel gap for 110 kV transformer neutral point are given.