气泡和纤维素颗粒对变压器油冲击击穿特性影响研究

发布时间：2018-05-06 14:14

本文选题：变压器油 + 冲击击穿　；参考：《华北电力大学(北京)》2017年博士论文

【摘要】：运行中的电力变压器会受到各种冲击电压的作用,是导致现场变压器绝缘故障的主要原因之一。气泡和纤维素颗粒的存在将降低变压器油的绝缘性能。气泡和纤维素颗粒对变压器油冲击击穿特性影响研究对于掌握变压器油绝缘的冲击击穿机理,获得变压器油间隙的冲击击穿特性具有重要的科学价值和工程实际意义。论文开展了气泡和纤维素颗粒对变压器油冲击击穿特性影响的研究工作,主要内容如下:研究了冲击电压波形对变压器油间隙击穿特性的影响。根据试验要求设计搭建了一套基于固态开关的冲击电压发生器,可以产生满足试验要求的多种波形参数的冲击电压。采用波形参数分别为1.4/50μs,14/220μs,80/850μs和240/2400μs的四种正极性冲击电压对25#矿物变压器油中稍不均匀电场间隙进行了冲击试验,获得了油间隙击穿电压和击穿时间随冲击电压波形参数的变化特性。研究了纤维素颗粒含量水平对变压器油冲击击穿特性的影响规律。通过对低、中、高三种纤维素颗粒物含量水平油间隙在4种冲击波形下的击穿试验,获得了不同纤维素颗粒含量油间隙击穿电压的分布规律。对纤维素颗粒在冲击电压和交流电压作用下的运动特性进行了试验观测,获得了不同冲击电压波形下油中纤维素颗粒的运动和聚集特征,解释了不同冲击电压波形及不同纤维素颗粒含量水平对油间隙击穿特性的影响机理。建立了冲击电压下纤维素颗粒在油间隙中的动力学数值模型,从理论上研究了纤维素颗粒在不同波形冲击电压下的动力学行为,对比了电压波形、颗粒大小对纤维素颗粒运动特性的影响。计算分析了冲击电压作用过程中,纤维素颗粒运动对间隙电场分布的影响。从纤维素颗粒的运动机制角度,揭示了纤维素颗粒高含量水平下油间隙U50%在240/2400μs冲击电压下显著降低的原因。研究了变压器油纸绝缘不同水分含量情况下的气泡生成规律及气泡存在对变压器油间隙击穿特性的影响。通过对2%、4%和6%三种水分含量纸板的气泡生成模拟试验,获得了快速升温过程中各水分含量油浸纸板的气泡生成起始温度及气泡生成后的运动状态。对气泡在冲击电压和直流电压作用下的运动特性进行了试验观测,获得了不同冲击电压波形下油中气泡的运动规律。通过对存在气泡的油间隙在4种冲击电压下的击穿试验,获得了冲击电压下气泡对油间隙冲击击穿电压的影响规律。建立了 1.4/50μs和240/2400μs两种冲击电压下气泡在油间隙中的动力学数值模型,从理论上研究了气泡在不同波形冲击电压下的动力学行为,对比了不同电压波形对气泡运动特性的影响。计算分析了气泡存在对间隙电场分布的影响,分析讨论了气泡生成及其运动特性可能对油间隙击穿特性带来的影响。
[Abstract]:Power transformers in operation will be affected by various impulse voltages, which is one of the main causes of insulation failure of field transformers. The existence of bubbles and cellulose particles will reduce the insulation performance of transformer oil. The study of the effect of bubbles and cellulose particles on the impact breakdown characteristics of transformer oil has important scientific value and engineering practical significance in mastering the impact breakdown mechanism of transformer oil insulation and obtaining the impact breakdown characteristics of transformer oil gap. In this paper, the effects of bubbles and cellulose particles on the impulse breakdown characteristics of transformer oil are studied. The main contents are as follows: the influence of impulse voltage waveform on the breakdown characteristics of transformer oil gap is studied. An impulse voltage generator based on solid-state switch is designed and built according to the test requirements, which can produce a variety of waveform parameters to meet the test requirements. Four kinds of positive impulse voltages with waveform parameters of 1.4 / 50 渭 s / 220 渭 s / 80 / 850 渭 s and 240 / 2400 渭 s were used to test the slightly uneven electric field gap in 25# mineral transformer oil. The characteristics of the breakdown voltage and breakdown time of the oil gap with the impulse voltage waveform parameters were obtained. The effect of cellulose particle content on the impact breakdown characteristics of transformer oil was studied. The breakdown voltage distribution of the oil gap with different cellulose content was obtained through the breakdown test of the horizontal oil gap with low, middle and high cellulose particle contents under four shock waves. The motion characteristics of cellulose particles under the action of impulse voltage and AC voltage were experimentally observed. The motion and aggregation characteristics of cellulose particles in oil under different impulse voltage waveforms were obtained. The influence mechanism of different impulse voltage waveform and different cellulose particle content on the breakdown characteristics of oil gap is explained. A numerical model of cellulose particle dynamics in oil gap under impulse voltage is established. The dynamic behavior of cellulose particle under different waveform impulse voltage is theoretically studied, and the voltage waveform is compared. The effect of particle size on the movement characteristics of cellulose particles. The effect of cellulose particle movement on gap electric field distribution during impulse voltage was calculated and analyzed. From the point of view of the movement mechanism of cellulose particles, the reason why the oil gap U50% decreases significantly at 240 / 2400 渭 s impulse voltage at high content of cellulose particles is revealed. The formation rule of bubbles in transformer oil paper insulation with different moisture content and the influence of bubble existence on the breakdown characteristics of transformer oil gap are studied. By simulating the bubble formation of the paperboard with 4% and 6% moisture content, the initial temperature of bubble formation and the movement state of the bubble formation were obtained during the rapid heating process. The motion characteristics of bubbles under impulse voltage and DC voltage are experimentally observed, and the motion laws of bubbles in oil under different impulse voltage waveforms are obtained. Through the breakdown test of the oil gap with bubbles under four impulse voltages, the effect of the bubble on the impulse breakdown voltage of the oil gap is obtained. A numerical model of bubble dynamics in oil gap under 1.4 / 50 渭 s and 240 / 2400 渭 s impulse voltages is established. The dynamic behavior of bubbles under different wave impulse voltages is studied theoretically, and the effects of different voltage waveforms on bubble motion characteristics are compared. The influence of the bubble existence on the electric field distribution of the gap is analyzed and the influence of the bubble formation and its motion characteristics on the breakdown characteristics of the oil gap is discussed.
【学位授予单位】：华北电力大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM41

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