5kHz交流电压下电极覆盖窄空气隙放电非线性动力学行为

为了研究电极覆盖下窄空气隙放电非线性动力学特性,以空气介质作为研究对象,建立一维自洽流体力学的气体放电模型,其中包括电子和离子的连续性方程和动量方程,且耦合了泊松方程,研究了窄间隙空气放电过程及其动力学特性。通过求解气隙放电的非线性方程组,获得了频率5k Hz正弦电压下电极覆盖窄空气隙放电非线性动力学行为的时空演化过程,并以二维和三维相图展现了内部放电参量的关系,同时给出了空气间隙电场、电子密度和离子密度的时空分布规律。分析结果表明,当空气隙中电场超过其击穿阈值时,形成放电电流脉冲;随着外加电压幅值的增加,放电电流的幅值和放电电流脉冲数目也明显增加;窄空气隙放电表现出明显的非线性动力学行为特征,介质表面积聚的异性电荷产生反向电场是形成多脉冲放电流脉并触发混沌现象的根本原因所在。     

Brushless dc motor with large air gap

The authors propose a new brushless dc motor for pumps, with a large air gap of 8 mm, compared with the conventional gap of 1 mm. The conventional pump system is composed of an induction motor, a magnetic coupling, and a magnetic rotor with vane. This rotor receives power from the magnetic coupling. In the new motor, the rotor has a vane without magnetic coupling. The air gap is very large in order to provide a seal between the stator and rotor. The seal protects the stator coil against liquids such as water and chemicals. The performance of the motor was analyzed by FEM and compared with experimental results. The analytical results agreed with experimental results with good accuracy. In the experiments using a four-pole 0.75-kW test motor and high-efficiency drive inverter with power factor control, the motor efficiency was about 88%, and the motor power factor was about 98%. © 1998 Scripta Technica, Electr Eng Jpn, 125(3): 67–74, 1998     

运用物理隔离技术构建分层调度通信网络

调度通信网络的安全是电力系统正常生产和管理的基础。根据调度通信网络各组成系统的安全级别将其分为实时、准实时和非实时系统。阐述了物理隔离技术的基本原理,提出了运用物理隔离系统对调度通信网络进行分层保护的方案,将调度通信网络在拓扑结构上改进为以实时系统为核心层的多层网络。对方案的具体实施及网络安全体系的建设进行了讨论。     

Breakdown mechanism of a gap with a small arc current in SF6 gas

Using an experimental apparatus modeled for a gas-insulated switchgear (GIS), the influence of the arc duration on the breakdown voltage between the contact and the grounded tank of the GIS was investigated in the case that the arc was kept ignited in the contact area. From the result, characteristics of the breakdown voltage vs. the arc duration were found to be divided into six stages and the characteristics in each stage were estimated     

干式空心电抗器匝间电弧性短路故障特征提取及诊断方法研究

针对干式空心电抗器早期匝间短路故障,通过分析电抗器匝间电弧性短路过程中的状态参数变化规律,提出了基于时变参数模型的电抗器故障特征提取及诊断方法。首先建立了基于Mayr电弧模型的电抗器匝间短路故障的时变电路模型,并利用傅里叶变换分析了故障电抗器等效电感的频谱特性,发现其等效电感不再恒定而是存在周期性振荡。然后利用时变电路状态方程求解方法,分析在工频激励下故障电抗器输出电流的转移解、零状态响应及频谱特性,证明在匝间电弧的周期性短路过程中,故障电抗器输出电流中将激发出特定次数的谐波分量,分析电流谐波特性可对干式空心电抗器匝间短路故障进行诊断。通过对一起电抗器故障的电流互感器（CT）和电压互感器（PT）录波数据进行求解和分析,验证了本文提出的故障特征提取及诊断方法的可行性和有效性。     

短间隙磁控放电离子电流特性及影响因素研究

传统Penning磁控放电理论测量真空间隙要求真空间距大于10mm,无法测量现有短间距1~7mm触发真空开关内部真空度。因此,本文实验研究了在短间隙1~7mm条件下,磁控管放电离子电流特性及其影响因素。实验结果表明,Penning磁控放电下随着气压由10-4Pa向10-1Pa增加时,离子电流波形由三角波逐渐向方波转变,并非呈一方波不变。在电场和磁场满足Penning磁控放电着火条件下,离子电流峰值只受电场影响,与磁场无关;离子电流脉冲宽度只受磁场的影响,与电场无关。离子电流峰值与电荷随气压的变化呈幂函数变化。     

On the modeling of long arc in still air and arc resistance calculation

An important macroscopic arc parameter, describing its complex nature is the arc resistance. It can be easily calculated by using the well-known Warrington formula. Authors investigated the results of Warrington's tests. By taking into account the conditions under which they are obtained (e.g., inaccurate measurement devices), it is unquestionable that these results are today highly empirical and not accurate and general enough. Laboratory testing provided in the high-power test laboratory FGH-Mannheim (Germany), in which long high current arcs are initiated, was the basis for the research results presented in the paper. Based on the analysis of laboratory-recorded arc voltage and current waveforms, the new arc model is derived. An example of arc computer simulation using the new model is given. Based on the new arc model, a new approach to arc resistance calculation is presented. The new formula for arc resistance is compared with the old Warrington formula.     

Controllability of arc jet from arc horns with slits

Ultrahigh-voltage transmission lines must be protected from lightning surges and the large-current fault arcs which follow. Horns which are installed at the jumpers on the strain towers have a role in protecting the insulators from the fault arcs by coordinating insulation strength and holding large-current fault arcs between the horns. Although a flat surface of the electrode tip with a small diameter effectively meets these requirements, it results in the deterioration of corona discharge depressing capabilities in a steady state on power transmission lines. To improve corona discharge depressing capabilities and to reduce deflection of arc jets, finally two types of hemispherical-shaped arc horn electrodes with slits are developed. The arc jet control performance of those horns was disclosed experimentally as follows:

• (1) Two types of arc horn electrodes with our or six slits show remarkable arc jet control performance in the current of larger than 5 kA.
• (2) The addition of a rod-type central electrode at the center of the hemispherical-shaped electrodes results in the considerable extension of arc jet controllability in the wider current zone by containing the arc spot within the tip area of the central electrodes.

Based on the foregoing results, arc horn electrodes with slits have been designed and utilized for practical application.     

Prediction of spark paths in a point/two-rod gap in air

Three-dimensional images had been obtained of some 400 positive point/plane sparks in air during previous work and analysis showed that on average each section of the spark was related to the previous one. However there was a large random perturbation (within a probability distribution) which accounted for the tortuous shapes of the spark paths. Simulations based on these findings gave satisfactory agreement in terms of, for example, appearance and fractal dimension. A more fundamental test of this analysis and simulation method has been tried by attempting to simulate a significantly different electrode system: the grounded plane electrode was replaced by two parallel grounded rods. The simulation is then used, firstly to predict the general shape of the spark paths; and secondly to predict how many of the sparks will be between the point electrode and one of the two rods, and how many between it and the other rod. By moving the point electrode in a direction at right angles to the axes of the rods, but at the same height above them, this ratio could be varied. In order to get reasonable consistency it was necessary to run 1000 trials in the simulation for each point electrode position. Different ratios were obtained for different assumptions as to the magnitude of the random element in the section-by-section prediction. A series of experiments with an analogous electrode system gave good agreement in terms of the percentage strikes to a given rod versus the position of the point electrode.     

低压电弧短路电流计算

根据大量低压电弧短路实验的结果，用概率统计方法导出低压电弧短路时的电弧电压模型及电弧短路电流的计算公式。用这些公式计算的最小电弧短路电流与实验结果吻合。因此，这些公式可用于低压继电保护装置的整定计算，以确保在发生电弧短路时继电保护能可靠动作。     

Transmission loss allocation in a deregulated electrical energy market

This paper presents a new method for transmission loss allocation in a deregulated electrical power market. The proposed method is based on physical flow through transmission lines. The contributions of individual loads to the line flows are used as basis for allocating transmission losses to different loads. With minimum assumptions, that sound to be reasonable and cannot be rejected, a novel loss allocation formula is derived. The assumptions made are: a number of currents sharing a transmission line distribute themselves over the cross section in the same manner; that distribution causes the minimum possible power loss.Application of the proposed method is straightforward. It requires only a solved power flow and any simple algorithm for power flow tracing. Both active and reactive powers are considered in the loss allocation procedure. Results of application show the accuracy of the proposed method compared with the commonly used procedures.     

含压缩空气储能的能源互联微网型系统优化配置

首先构建了含分布式光伏、压缩空气储能（compressed air energy storage, CAES）、需求侧响应、燃气轮机等设备的能源互联微网型系统模型。在此基础上以安装成本、能耗成本和需求侧响应成本等构成的年运行费用最低为优化目标,分析对比不同场景下分布式光伏电池组数量、能源互联微网中设备的配置情况及CAES、需求侧响应和电动汽车入网（vehicle to grid, V2G）技术对设备容量配置和微网中各类成本的影响。特别的,考虑了CAES透平机透平压力、透平温度、需求侧响应比例等参数及有无V2G对微网系统影响。算例结果表明,所提模型能合理化能源互联微网中设备容量配置和降低能源互联微网年运行费用。     

Fault arc propagation on cables for space applications in vacuum,oxygen-enriched air and air

Investigations of fault are propagation on spacecraft cables under specific conditions, e.g. vacuum, normal and oxygen enriched atmospheres have been performed. Typical patterns of fault arc extinction have been identified and their consequences with respect to causes of damages are discussed. The results indicate that for a given test current and test voltage the behavior of the arc and the damages caused in a cable bundle depend strongly on the kind of insulation material, cable size and design, as well as on the environmental conditions. For some cables the arc propagation effects are increased at higher oxygen partial pressure and significantly increased under vacuum. In many cases vacuum has turned out to be an important worst-case parameter. It was found that the amount of damage assessed by post-test measurements increases substantially, if the value of the test current grows. More than 250 tests have been performed for test currents in the range of 6 to 30 A at the test voltage of 125 V dc     

带气隙铁氧体磁芯变压器模型及仿真分析

结合实际测得的铁氧体磁化曲线和损耗曲线,有利于提高变压器模型的仿真准确度。采用磁场分析软件Magnet分别对无气隙铁氧体磁芯变压器、有气隙铁氧体磁芯变压器和气隙-铁氧体等效材料磁芯变压器模型进行了仿真研究。对不同电压下三种模型的特性进行了分析与研究。仿真结果表明两种有气隙铁氧体模型均可对磁场分布进行有效计算。两种模型的建立为不同的需求提供了建模基础。     

Particle-triggered pre-breakdown phenomena in atmospheric air gap under AC voltage

Corona discharge mechanism and breakdown voltage characteristics of air gaps in the presence of metallic particles were investigated including the relationship between the corona discharge mechanism and the phase resolved partial discharge patterns. These results are of interest for detection of foreign particles in gas insulated systems (GIS). The results with different shaped particles show that the corona mechanism depends on the particle shape and applied voltage. Moreover the corona discharges on both sides of the particle interfere with each other by inflow of charge carriers into the particle. The breakdown voltage is a minimum when the particle is in the vicinity of the electrode due to active interference of coronas. The phase-charge characteristics as the phase resolved partial discharge patterns vary with the particle shape. This suggests that the corona discharge mechanisms for all types of particles should be considered in the particle-detection method for GIS based on the phase resolved partial discharge patterns.     

大气压空气辉光放电

重点论述了大气压下辉光放电的研究现状、诊断方法和放电机理,探讨了大气压下空气间隙(>2mm)实现辉光放电的可行性,提出用降低放电电场强度的方法有可能实现大气压下较大空气间隙辉光放电.