In recent years, with the rapid development of the coastal economy and the large-scale development of marine resources, power demand has risen sharply. So it is urgent to promote the construction of UHVDC projects. Coastal saline areas often contain more chloride and other salts than other inland areas due to the high humidity, salinity and light intensity of the marine climatic and environmental conditions, which lead to the different electrical performance of grounding electrodes under different layouts. Therefore, one of the key issues to realizing the rapid development of UHVDC in coastal countries is how to choose the best layout of the coastal DC grounding electrode. It is intended to simulate the coastal environment and establish a mixed stratified soil model using CDEGS to verify the validity of the model through experiments in this paper. Based on the mixed soil model, the changes in grounding resistance, surface potentials and step voltage of grounding electrode sites under zigzag shape, two-row and circular shapes layouts are studied. The results show that when the zigzag shape layout is selected, the ground potential amplitude of the grounding electrode is reduced by 45.77% and 42.7%, the step voltage amplitude is decreased by 39.85% and 32.22%, and the grounding resistance is decreased by 28.45% and 27.68%, compared with the two-row and circular layout. In addition, its utilization rate of electrodes is better than the other two layout shapes.

为改进当前瞬变电磁探测系统的局限,提高接地网缺陷识别的效率与精度,提出一种MWOA-Elman神经网络,完成数据由采样到成像的转化过程,快速实现视电阻率成像,精准识别接地网的不同缺陷.首先,通过理论计算完成接地网瞬变场参数样本集,构造Elman神经网络的单映射关系.其次,围绕收敛因子、自适应权重与阈值对鲸鱼算法进行改进,用改进鲸鱼算法(modified whale optimization algorithm,MWOA)优化Elman神经网络的权值和阈值.测试结果表明,MWOA-Elman 神经网络在第 854 步收敛,4 项误差指标 MAE、MSE、RMSE、MAPE 分别为 0.103 51、0.040 09、0.126 64和0.333 52％,接地网缺陷识别精度为99.678％,识别效率与精度均优于其他模型.最后,通过分析3×3接地网3种典型缺陷位置的成像结果,验证了MWOA-Elman神经网络应用于接地网缺陷识别的有效性,为嵌入瞬变电磁探测系统的智能算法提供参考.

针对红外图像信噪比低,易受背景环境影响的问题,提出一种基于不可分离小波的多尺度方向分析(NSWMDA)和连接突触计算网络(LSCN)的图像增强算法.该算法首先将原始图像进行冗余提升的不可分离小波变换(NSWT),得到高频细节子带和低频近似子带,然后对高频细节子带进行多方向滤波后LSCN算法进行增强,对低频近似子带直接采用LSCN算法增强,最后对处理后的子图进行融合重构得到增强后的红外图像.在电力变压器红外图像中,该算法相比其他算法在边缘强度、信息熵、峰值信噪比、结构相似度、平局梯度5种指标中分别至少提升了 10.86％、14.39％、19.95％、7.06％、6.70％.实验结果表明,该算法不仅提升了红外图像整体清晰度,同时也使得图像的细节纹理和对比度得到加强,具有很好的红外图像增强效果.

针对现有电力设备红外与可见光图像配准难度大、配准时间长等问题,提出一种基于深度学习的电力设备红外与可见光图像配准融合的方法.本文将特征提取与特征匹配联合在深度学习框架中,直接学习图像块对与匹配标签之间的映射关系,用于后续的配准.此外为了缓解训练时红外图像样本不足的问题,提出一种利用红外图像及其变换图像学习映射函数的自学习方法,同时采用迁移学习来减少训练时间,加速网络框架.实验结果表明:本文方法与其他4种配准算法相比性能指标均有显著提升,本文平均准确率为89.909,同其余4种算法相比分别提高了2.31％、3.36％、2.67％、0.82％,本文平均RMSE(Root Mean Square Error)为2.521,同其余4种配准算法相比分别降低了14.68％、15.24％、4.90％、1.04％,算法平均用时为5.625 s,较其余4种算法分别降低了5.57％、6.82％、2.45％、1.75％,有效提高了电力设备红外与红外可见光图像配准的效率.

为提高接地装置的抗腐蚀性能,利用超音速火焰喷涂技术分别制备了Ni60、NiCr涂层.通过扫描电镜分析了两种涂层的微观形貌、组织结构,并对两种涂层的孔隙率、抗腐蚀性能、电气性能进行了对比.结果 表明:Ni60涂层的致密度好,其在抗腐蚀性能和电气性能方面优于NiCr涂层的.

通过模拟高压开关柜内起火,采用适量的热气溶胶灭火剂对一次设备所在的隔室实施灭火,测试热气溶胶在高压开关柜内的实际灭火能力,得出结论如下:热气溶胶发生剂的化学反应速度很快,装置启动后能够迅速产生具有灭火功能的热气溶胶灭火剂;热气溶胶能够在密闭条件良好的高压开关柜中快速散布于整个防护空间,不存在保护死区;相较于干粉灭火剂,热气溶胶灭火剂的降尘率较低,是一种非常清洁的灭火材料.

并网情况下交直流混合微电网的经济稳定运行是微电网建设和运营的基本要求.文中从经济调度的角度出发,建立了考虑微电网设备的维护成本、蓄电池储能损耗成本、AC/DC换流成本、并网售购电费用的联合优化经济模型.针对传统灰狼算法(GWO)在全局搜寻能力上的不足,引入混沌序列Logistic映射对灰狼算法初始化进行改进,丰富灰狼种群的多样性,使初始种群更加均匀的分布在求解区间内.为验证混沌灰狼算法(CGWO)算法的性能,基于实际算例进行仿真分析,验证所提模型与算法的正确性与有效性,在相同算例下将CGWO的优化结果分别与GWO、粒子群算法(PSO)、混沌粒子群算法(CPSO)进行对比分析,结果表明CGWO性能优于其它三种算法,能有效的进行经济调度并保证具有良好的全局搜寻特性和收敛速度.

现有的10kV高压开关柜温度场仿真分析中,由于10kV高压开关柜的内部结构、材料属性和传热过程复杂,难以准确地对其内部温度进行求解计算.为解决上述问题,利用COMSOL中共轭传热模块对10 kV高压开关柜的温度场进行仿真计算.应用该仿真方法,可以有效求解10 kV高压开关柜的稳态温度值,准确模拟稳态温度场,并且结果误差小,符合实际温度分布规律.最后通过红外测温试验对比分析,验证了本仿真方法的有效性和准确性.

随着近年来光伏发电的飞速发展,光伏发电在电网中渗透率越来越高,在带来了清洁能源的同时也对电网造成了一定程度的影响.对分布式光伏系统接入配电网时接入前后并网点电压变化机理进行了研究,利用双向DC-DC变换器在光伏并网系统直流侧加装储能装置,在逆变器无功-有功调压方式的基础上提出含储能装置的并网点电压越限调整方案,通过仿真分析可以得出当光伏出力突变或配电网线路负荷变化的情况下,该方案能很好地抑制并网点电压的波动.

为研究土壤特性对特高压直流接地极跨步电压分布的影响,采用CDEGS软件建立了双圆环直流接地极仿真模型,对比分析了不同土壤特性下双圆环直流接地极上方跨步电压分布规律.计算结果表明:在均匀土壤中,双圆环直流接地极上方跨步电压随着土壤电阻率的增大而升高;在水平双层土壤中,表层土壤电阻率的变化对双圆环直流接地极上方跨步电压分布影响较为显著,当表层土壤超过一定厚度后,表层土壤厚度的变化对双圆环直流接地极上方跨步电压影响较小.

Background: Currently, how to measure the magnetic field accurately is a difficulty in the study of strong magnetic field. Methods: This paper summarizes several methods of measurement techniques for strong pulsed magnetic field presently, the principles and characteristics of various measurement methods are compared and analyzed. The maximum measurement intensity of electromagnetic induction method can reach 103T. The magneto-optical effect method of Faraday can measure the magnetic field intensity of 0.1~10T, and the measurement error is within 10-2T. Results: The MOKE effect can measure a magnetic field intensity up to 100T, with an error 3×10-2T. The Zeeman effect can be measured in a magnetic field intensity of 1~20T. Conclusion: The existential problems of various methods are described. Lastly, some solutions are proposed according to the existential problems, and the development of measurement techniques for strong pulsed magnetic field in the future is prospected.

In order to investigate the influence of soil properties on the current density along buried metal pipe, the simulation model of DC grounding electrode and buried metal pipe was established by CDEGS software.The current densities of metal pipes under the condition of different soil properties were analyzed comparatively.The results show that in homogeneous soil, the current density of pipe increased with the increase of soil resistivity.In horizontal twolayer soil, the current density of pipe decreased with the increase of the resistivity of top soil, and the current density of pipe increased with the increase of the resistivity of bottom soil.The change of the resistivity of bottom soil had a significant effect on the current density at both ends of the pipe.The change of top soil thickness had less influence on the current density of the pipe.

三峡大学输电线路工程国家级实验教学示范中心伴随着我国输电线路工程专业高等教育的内涵式发展而成长.针对输电线路工程专业实验教学体系的研究空白,实验教学中心结合三峡大学构建的输电线路工程专业办学思想和知识体系,从自制实验设备开始,以“平台建设四层次,实验教学五模式,工程应用四技能”的“四五四”为架构,形成了完整的输电线路专业实验教学体系及其平台,并通过校企联合,科研助推的方法,实现了实验教学中心的持续高水平发展.该实验教学示范中心作为当前输电行业的唯一国家级教学平台,极大地推进了我国输电线路工程高等教育的发展.

To improve the heating efficiency of the induction cooker system, this paper adopts the method of introducing an adiabatic layer between the pot bottom and the coil. By using COMSOL software, the electromagnetic - thermal coupling model of the induction cooker is established to analyze the effect of the adiabatic layer on the food temperature and coil temperature, and finally the heating efficiency is explored. The obtained simulation results show good agreements with the experimental results, and then the effectiveness of the proposed method is verified.

输电线路铁塔塔腿锈蚀问题现已严重影响到输电线路安全稳定运行.为此,利用ANSYS有限元分析软件针对已锈蚀铁塔主材建立了桁架混合模型,对已锈蚀塔腿主材在最恶劣运行工况下的受力情况进行了计算,由计算结果提出了一种新型加固方案—分解加固法,并以加固补强后的铁塔为基础重新建立了仿真计算模型,对补强后铁塔的应力强度及整体稳定性进行了分析,验证了该种加固补强方案在力学性能方面的可行性;同时从施工周期、施工难易程度、以及经济性方面与传统的铁塔加固补强方案进行了对比,所提出的的新型补强方案均明显优于传统方案.

为加强电池组的管理与保护以及减少电池组各单体参数之间的差异,设计了一套基于STM32F103VET6的电池管理系统;并提出在电阻耗能法的基础上结合能量转移思想对电池组进行均衡管理.运用MATLAB/Simulink工具建立了锂电池模型,并对电池所采用的均衡方案进行了仿真分析.仿真结果表明:采用改进的均衡方案电压偏差明显减小,单体之间的电压逐渐趋近到一个固定的值.此外通过18650型锂电池对电池管理系统进行了均衡实验测试,求出了均衡前后电压的期望值和方差值.经过对比分析,进一步验证了电池管理系统电压均衡的有效性.

Magnetic field measurement is one of the key contents in the field of electromagnetic protection. In this paper, a magnetic field measurement system based on distributed magnetic sensing and a high-accuracy numerical integration method is proposed. And a magnetic field sensor with simple structure, small size, and wide measurement band is designed, which includes three magnetic field measurement coils that can realize the accurate measurement of a three-dimensional magnetic field. The output of the magnetic field measurement coil is a differential signal that needs to be reduced by the integrator. To solve the problems of traditional analog integrator and common digital integrator, this paper proposes a high-precision digital integral algorithm based on Gauss algorithm, which can effectively improve the accuracy of the integrator. Test results indicate that the error of the magnetic field measurement system is less than 5% in the range of 0.05-5T.

An accurate soil resistivity horizontal hierarchical model (SRHHM) is critical to selecting the site of the DC ground electrode. In order to build an relatively accurate model, current inflow test is carried out to test the accuracy of the initial SRHHM. However, there is no existing unified method to guide how to amend the initial model through current inflow test. Therefore, based on practical cases, this paper establishes a two-dimensional axisymmetric finite element model for current inflow test by using the ANSYS software, and studies the effect of each layer soil resistivity on the Earth surface potential (ESP) distribution. Based on these studies, some basic rules of amendment for SRHHM are proposed. Furthermore, the proposed rules are applied to the current inflow test of the actual project in Yi’an Chong, Hunan. The results show that the amended soil resistivity horizontal hierarchical model is better in fitting the ESP distribution obtained from the current inflow test.

At present, the cylindrical coil is used to generate the electromagnetic force in electromagnetic tube expansion process. The obtained radial electromagnetic force in the end of the tube is less than the one in the middle of the tube for the end effects. Hence, the tube deformation is inhomogeneous in the axial direction. This paper presents a method named electromagnetic tube expansion with a concave coil to obtain more homogeneous deformation. By using COMSOL software, it gives the simulations for the effect of the geometry parameters of the concave coil on the distribution of the radial electromagnetic force and deformation behavior for the given AA6063-T6 tube. Simulations show that the concave coil with suitable parameters can obtain the homogeneous deformation. Furthermore, the homogeneous deformation range obtained by the concave coil is 36 mm, which is better than the obtained range by the cylindrical coil.

Low forming accuracy is the main defects in electromagnetic forming process of sheet metal. One of the main reasons is that shapes of the coil and required workpiece are cylindrical and deep concave respectively. The distance between the coil and the side wall of deformed sheet metal is too far in forming process, which leads to a consequence that electromagnetic force in the side wall is not enough. To solve this problem, a solenoid field shaper was introduced to enhance the electromagnetic force at the side wall, and then improve forming accuracy of electromagnetic forming of sheet metal. To verify the effectiveness of the method, a series of simulations based on circuit-electromagnetic-structure were finished. The results showed that the maximum electromagnetic force with field shaper increased more than 10 times at the side wall. And the maximum deformation was 1.18 mm which can improve forming accuracy effectively. The presented method and results can be helpful in designing electromagnetic forming systems of sheet metal.