特高压输电线路分裂导线表面电场特性分析

特高压输电线路能减小走廊面积,有效提高单位输电线路走廊宽度的输电容量,从而提高输电线路的经济效益。特高压输电线路常采用多分裂导线,导线表面电场强度的计算精确度直接影响导线的合理选型和布置。为此,以有限元法为理论基础,以COMSOL Multiphysics软件为仿真工具,以1000 kV特高压交流输电线路为研究对象,建立典型特高压交流输电线路的二维静电场仿真模型,研究分析分裂导线在水平排列、同塔双回、正三角对称、倒三角紧凑型对称布置方式下周围空间电场的分布,以及地面是否水平、是否有杆塔等因素对电场分布的影响。分析结果可以为特高压交流输电线路的设计提供一定的参考。     

±1100 kV特高压直流导线表面标称电场及其影响因素研究

我国±1100 kV特高压直流(UHVDC)输电工程已经进入设计和建设阶段.近年来,特高压输电导线表面的电晕放电所引起的电磁环境现象逐渐受到学者的重视.当高压导线表面场强超过临界值时,导线周围的空气分子将被电离,发生电晕放电,形成正负离子或空间电荷.由于导线表面电场强度与诸如无线电干扰(RI)、可听噪声(AN)、地面处...     

高压输电导线电晕特性探讨

介绍了输电导线电晕放电特性的试验方法和试验结果,研究了导线电晕放电物理过程、起始电晕及伏库特性等。试验表明不同直径导线电晕放电物理过程是不同的,输电线路中导线和其它部位的电晕放电过程也是不同的,并对今后特高压输电导线电晕特性研究提出一些看法和建议。     

直流输电线下存在建筑物时合成电场计算的有限元方法

随着中国直流输电工程的快速建设,经济发达地区输电走廊日益紧张,直流输电线路附近存在建筑物时的合成电场问题日益受到关注.对上流有限元法进行改进,使导体表面电场强度计算精度比单元电场插值方法的计算精度提高了近2个数量级,对计算过程中导线表面场强满足起晕场强约束具有重要意义.同时,对迭代过程中的节点电荷更新策.略进行改进,使算法更易于实现.依托中国电力科学研究院的实验平台,对线下存在建筑物时的实际境况进行模拟实验,测量结果验证了计算方法的有效性.最后,对线下存在建筑物时的合成电场分布特点进行分析.     

超高压输电导线起始电晕电压测量方法的探讨

本文介绍了在电晕试验圆筒中测量输电导线起始电晕电压和电晕损失的试验方法,通过对导线电晕损失和电容变化与微光观测的对比分析,观测到起始电晕过程中导线上的粗糙因素与其本质因素对过程的影响有根本的差别。     

750kV三相输电导线表面的起晕电场分析

通过有限元法计算了不同分裂导线、截面积、对地高度时分裂导线表面场强。计算结果表明采用分裂导线可以有效降低表面场强,从而达到抑制电晕放电的作用。借助皮克的导线电晕起始场强经验公式,得出750 kV输电线路采用6分裂导线比较合理。同理,适当改变导线截面和对地高度也可以降低导线表面场强。     

大气离子迁移率对直流线路合成电场与离子流密度影响的研究

为了研究离子迁移率对直流线路合成电场与离子流密度分布的影响,计算了一定温度和湿度下,气压改变导致离子迁移率和导线起晕场强变化后,合成电场与离子流密度的分布变化.合成电场的控制方程为Poisson方程和电流连续性方程.使用的电极结构为一维圆柱电晕笼和二维±1100 kV双极输电线路结构.计算结果表明,在相同导线电压下,若离子迁移率增加约一半,同时起晕场强降低33％,电晕笼处的合成电场增强约80％,离子流密度增加约6倍.若离子迁移率平均增加16％,起晕场强降低16％,±1100 kV线路地面合成电场增强约一半,离子流密度增加约1.5倍.     

雨雾天气对导线电晕放电的影响分析

分析了雨雾天气高压输电导线上悬挂的水滴受电场力形变过程,对水滴引起的电场畸变进行了动态数值计算。计算结果表明：水滴受到重力和电场力的作用被拉长而曲率半径变小,最大场强值变大。解释了雨雾天气输电线路电晕放电变得强烈的原因。     

Development of three-dimensional electric field analysis by segment arrangement based on a charge simulation method

This paper describes the development of three-dimensional electric field analysis by using the so-called segment method which enables the electric field to be calculated with high accuracy and with enhanced efficiency, for high-voltage apparatus. In the segment method, electrode configuration of high-voltage apparatus is simulated by small components which are called segments and by the arrangement of several kinds of such segments. In this calculation, the charge simulation method is used which is suitable for segment application. As basic segments, spherical, cylindrical and ring segments are used and in addition to these, as subsegments, disc and elbow segments are adopted for good simulation of the total electrode configuration. In this paper, the fundamental construction and arrangement parameter of segments were discussed. Moreover, the segment method was applied to an actual high-voltage apparatus and the calculation accuracy was discussed. It was clarified that the segment method has sufficient calculation accuracy and is a very efficient means for three-dimensional electric field analysis.     

Impulse partial discharge characteristics and their mechanisms under non-uniform electric field in N/sub 2//SF/sub 6/ gas mixtures

We have investigated impulse partial discharge (PD) and breakdown (BD) characteristics of a needle-plane gap in N/sub 2//SF/sub 6/ gas mixtures under positive lightning impulse voltage application, and discussed their physical mechanisms. The 50% probability PD inception voltage (PDIV/sub 50/), leader discharge onset voltage (LOV) and BD voltage (BDV/sub 50/) were measured and analyzed as a function of gas pressure and SF/sub 6/ content. Experimental results revealed the stepwise propagation process of the impulse PD and enabled us to classify the impulse PD in N/sub 2//SF/sub 6/ gas mixtures into two types, the streamer discharge and the leader discharge. We also discussed the impulse PD propagation mechanisms in terms of PD parameters such as propagation length, time interval and current pulse magnitude, and suggested a sequential relationship in the PD propagation process under non-uniform electric field.     

表面电荷法在复杂地势下超高压输电线路的工频电场计算

为了更准确地研究超高压输电线路穿越较复杂地区时的工频电场,利用表面电荷法的思想,给出了该方法的实施步骤并进行了验证。综合考虑了输电线路的弧垂,建立了复杂地势三角坡和凸面的三维模型,并仿真分析了其周围工频电场的分布。研究结果表明:1三角坡和凸面对输电线路下的工频电场影响较明显;2随着三角坡坡角的增大场强值畸变越大,且使临近三角坡坡脚处场强值减少越大;3不同的输电线排列方式下,复杂地势周围的工频电场畸变不同,倒三角排列下其值畸变大于其他排列。该仿真结果可为复杂地势下输电线路的架设提供参考依据。     

支柱绝缘子表面电场分布特性研究

为研究支柱绝缘子表面电场分布特性,经理论分析建立其有限元计算模型,获得了工程设计中所关心部位的电场强度分布。计算了3种典型支柱绝缘子理想情况下表面电场强度分布,并与增爬裙计算结果进行比较分析,结果表明,绝缘子两端电场强度较大,中间部位较低;增爬裙对其电场强度分布的改善没有明显的作用,电力线走向发生一定改变。     

滑动式等延伸系数条件下拉线配模的应用

本文主要叙述等延伸系数条件下 ,滑动式拉线配模的公式推导和配模应用。     

Breakdown electric field calculations of hot SF/sub 6/ for high voltage circuit breaker applications

The critical reduced electric field strengths of hot SF/sub 6/ corresponding to the dielectric recovery phase of a high voltage circuit breaker are calculated for a large temperature range (300-3000 K). Calculations are based on a multi-term Boltzmann equation solution using, in comparison to the literature works, improved cross section sets for the interactions of electrons with various SF/sub 6/ dissociated products. The obtained critical electric fields show a reasonable agreement with the available data. These results are then used in hydrodynamics simulations which correctly predicts the circuit breaker behaviors observed in the case of a successful breaking test as well as in a failed one.     

Numerical simulation of electric field distributions in electrohydrodynamic two-phase flow regimes

In electrohydrodynamic (EHD) flow boiling and condensation heat transfer applications an interdependence exists between two-phase flow patterns and the applied voltage, and subsequently the electric field distribution established. Unlike single-phase flow, in liquid/gas or phase change processes the electric field established is continuously changing as the flow pattern changes due to interfacial vaporization or condensation. To further complicate the variation in this dynamic field effect, the interaction between the electric field and the fluid introduce an electrical force that can also cause a redistribution of the phases. In an effort to understand and analyze this interaction, the electric field distribution must be determined. To contribute to this effort, the evaluation of the static electric field distribution is performed for various flow regimes to provide a qualitative assessment regarding the direction of phase migration and possible flow pattern transition and,to determine the net EHD force acting on the flow for an instant in time, i.e. for a given phase distribution.     

反向电场细颗粒脱除机理及实验研究

基于反向电场除尘原理,构建了反向电场电袋复合除尘实验装置,并实验测试了其对中位径1.49 μm气溶胶颗粒的捕集性能。该实验装置由预荷电器和带反向电场的袋式除尘器组成。反向电场电袋复合技术的除尘增效机理是,在反向电场对预荷电粒子的静电斥力减缓了预荷电粒子向滤袋的运动速度,且增加了滤料附近场强。实验结果表明:过滤风速越高,反向电场电袋复合除尘器相对于常规电袋复合除尘器的增效作用越明显;当过滤风速由 1.0 m/min增加到2.5 m/min,反向电场电袋复合的除尘效率相对于常规电袋复合的增效幅度由3.9%提升到11.8%,其压力损失比常规电袋复合除尘器的增加约5.0%;反向电场静电复合除尘技术能实现细颗粒物的高效控制,并能为反向电场工业应用提供技术支撑。     

多波长边缘电场传感器介电测量系统的研究

边缘电场传感器在工业生产过程控制中应用广泛。多波长传感器具有多个穿透深度,能够同时测量非均匀样本不同深度处的介电特性。以三波长叉指型传感器为研究对象,研制以TMS320F28335DSP为核心的介电测量系统,系统硬件包括驱动电路、调理电路、信号采集、人机接口、电源管理等。系统软件包括初始化、驱动控制、调理输出、计算模块、中断模块等。提出采用遗传算法优化的BP网络建立介电特性和极间电容之间的模型,根据系统测量的电容值求解介电常数。研制三波长传感器,利用测量系统进行实验,结果表明,该系统能够有效实现非均匀样本的分层分析。     

基于局部电场的零值绝缘子检测技术研究

通过电场法可检测出绝缘子串零值片,而现有的技术都是通过扫测整串绝缘子电场分布曲线来找出零值片,此方法操作难度大、效率低。本文提出通过探测绝缘子局部电场的方法来识别零值绝缘子。首先建立了零值绝缘子检测仿真模型,得到了含检测装置的绝缘子串电场畸变特性,然后通过该特性,获得了零值片的局部电场识别判据。最后,通过设计传感器、探测装置,验证了仿真结果,并实现了零值绝缘子的点测识别。研究结果表明,采用三阵列电场法可以实现零值绝缘子检测。装置长度应大于电场的畸变区间长度,对于本文研究对象可取130mm;识别判据为探头1、3变化率?13<10% ,探头2偏差率?2<50% 。检测时,对于高压端和中压端,检测装置应为正对钢脚,在低压端应为正对伞裙。研究结果可为输配电外绝缘智慧运维提供技术支撑。