【作者】 张喜乐；

【导师】 崔翔；

【作者基本信息】 华北电力大学（河北） ， 高电压与绝缘技术， 2008， 博士

【摘要】 由于气体绝缘变电站(GIS)中断路器、隔离开关以及接地开关操作或带电线路对地闪络产生的特快速暂态过电压(VFTO)会对GIS相连的设备造成危害,因此,研究VFTO对电力变压器的影响问题具有极为重要的理论意义和实用价值。本文结合河北省自然科学基金项目“特快速暂态过电压对变压器的影响”(项目编号503624)和保定天威集团有限公司开发GIS电站用750kV和1000kV电力变压器的需要,重点研究了VFTO下电力变压器高压绕组电压分布时域快速计算和谐振分析以及实验研究方法等问题。论文主要包括以下工作:1.为了获得VFTO进入变压器高压绕组后的电压分布规律,设计制作了两种变压器绕组实验模型,制定了实验方案,并分别进行了电压测量和电压分布特性分析,研究了上升时间对变压器绕组电压分布影响的变化规律。研究结果表明:施加电压的上升时间越长,变压器绕组中的电压分布越均匀,反之电压分布越不均匀;变压器绕组在暂态电压作用下,绕组首端区域和两种绕组结构不同的交界部位电压分布最不均匀,且相邻线饼电压梯度最大,这一特点随施加电压上升时间的缩短表现得愈加明显;内屏蔽式结构变压器绕组不仅可以改善雷电冲击电压下绕组的电压分布,而且也可以改善VFTO下绕组的电压分布。2.针对VFTO下变压器高压线圈的频变参数多导体传输线模型,通过将参数频变部分用无源矢量匹配逼近,转化为时域卷积描述,并用递归卷积技术进行处理,提出了一种基于紧凑有限差分法计算VFTO下变压器高压绕组电压分布的时域快速方法。并通过对变压器绕组模型和实际变压器的陡波测量和仿真计算,验证了所提方法的快速性和正确性。3.为了进一步提高计算速度,针对VFTO作用下变压器绕组内部绝缘事故一般发生在首端位置的事实,提出了变压器绕组的一种改进传输线电报方程与状态方程相结合的时域综合简化模型。4.将变压器绕组视为单输入多输出端口模型,推导了该模型中传递函数的求解公式。通过对变压器绕组的幅频特性分析,研究了绕组中的谐振情况,并对谐振可能发生的位置进行了定位。更多还原

【Abstract】 It is of great theoretical significance and practical value to research the effect of the very fast transient overvoltage (VFTO) on power transformers in gas insulated substations (GIS). Supported by Province Natural Science Foundation of Hebei (No.503624), in order to meet the requirement of manufacturing 750kV and 1000kV power transformers, the experimental research methods, the fast time-domain algorithm for calculating the voltage distributions of power transformer windings under VFTOs and the resonant analysis method are emphatically researched. The dissertation main contributions and works are as follows:1. To obtain the voltage distributions in the high voltage windings of transformers under VFTO, two kinds of transformer winding models are designed and manufactured. The voltage waveforms of each end windings in the two models are measured; the peak voltage and peak voltage gradient distributions of the transformer windings are mapped and studied. The effects of rise time on the distributions are discussed. It is concluded that, the longer the rise time, the more homogeneous the voltage distributions, contrariwise, the more inhomogeneous; The most inhomogeneous areas exist in the coils close to the lead-in of the transformer windings and the interface of the two different structure of the windings; Internal-shielded structure can improve the overvoltage distributions not only under lightning, but also under VFTO.2. Based on multiconductor transmission-line (MTL) model, a fast time-domain method is presented to calculate the voltage distributions along transformer windings, through combining the compact finite difference (CFD) theory and the backward differentiation formulas (BDF). Vector fitting and recursive convolution are used to dispose the frequency-dependent parameters. There is a good agreement between the simulation and the measurement.3. To further improve the computational efficiency, a simplified model for large power transformer HV windings is presented considering the fact that the insulation faults usually happen in the coils close to the lead-in of the transformer windings under VFTO. The simplified model proposed in this paper is represented by modified Telegrapher’s equations and state equations.4. Based on MTL model, a single-input-multiple-output network model is presented for transformer windings. The procedure to determine the transfer function is deduced. The resonant frequencies and the location of resonance are determined by analysis of amplitude frequency response characteristics. For validation, the calculated results are compared with the measurements and the results are satisfactory.更多还原