A low-background organic-type GM tube

A low-background, organic-type small GM tube with a short tungsten wire anode of 1 cm length and a cylindrical steel cathode was constructed. Reduction on the background caused by cosmic rays and contamination is achieved by using a short, small GM tube. At the same time, the problem of low counting efficiency caused by the short tube length is overcome. The drop in the field values near the ends of the short cylindrical GM tube below the values required to produce Geiger action, which in turn causes the decrease in the counter efficiency, is corrected using two metallic balls connected to both ends of the tungsten wire anode. The optimum size of these balls corresponding to the minimum capacitance of the counter is determined using a simulation technique. Plateau curves of tubes with different-sized metallic balls are reported. Then, a plateau curve of the tube with optimum ball size is compared with that of an ordinary cylindrical GM tube having the same dimensions to evaluate the effect of using the wire anode with two metallic balls at the ends in order to improve counter performance and efficiency     

变电站接地网对附近建筑物接地网和直埋金属管道的阻性耦合分析

利用矩量法定量地分析了变电站接地网对附近建筑物接地网和地下直埋金属管道的阻性耦合，获得了建筑物及管道在不同距离不同位置情况下的阻性耦合影响曲线。研究表明：当变电站接地网与建筑物接地网的尺寸一定时，前者地电位随二者之间的距离的增加而升高；当变电站接地网与建筑物接地网之间的距离一定时，二者的电位随建筑物接地网的尺寸的增大而减小；当有管道时，情况与上相似，但当管道垂直于变电站接地网放置时，其对变电站接地网电位的影响很小。在此研究基础上，提出了相应的防护措施，可为城市变电站接地网设计和城市规划提供一定的理论依据。     

考虑大地影响的直线法测量大型地网的接地阻抗

在使用直线法测量大型变电站（厂）地网的接地阻抗时,由于地网敷设面积广泛导致周围土壤电阻率存在不均匀分布,使得测量时零电位点难以选取;另外由于电压、电流测量引线平行距离较长导致二者之间通过大地耦合得到的互感阻抗值较大,相对于地网本身的接地阻抗不能被忽略。这两方面的影响会导致直线法测量误差增大。提出一种考虑不均匀土壤电阻率和互感抗影响的大型地网接地阻抗测试新方法,通过电压极多点测量数据拟合找到准确的零电位点和对应的电阻分量值,通过对不同共线长度下的电感分量数据进行拟合计算,剔除测试数据中的互感抗分量。通过CDEGS软件进行仿真,验证了实测数据和仿真数据相差不超过5%,说明以上方法可有效地消除土壤不均匀分布及测试线互感对接地阻抗测量值的影响量,提高了测量的准确性。     

基于P-V曲线的低压减载分群配置方案

低压减载是电网防御系统的第三道防线稳控措施之一,可以经济有效地防止电压崩溃。以安徽宣城地区电网为例,研究基于P-V曲线的低压减载方案。该方案通过稳定计算分析,找到该电网可能出现的电压失稳状态,计算出其部分负荷节点的P-V曲线,按照负荷增长与电压降低之间的定量关系,将节点划分为不同集群进行配置,能有效地阻止电压持续恶化。该方法根据电压对负荷的敏感程度制定的各节点或区域低压减载方案,比起统一配置方案更有利于系统电压的恢复。     

接地网阴极保护法的优化控制

采用电化学方法测量镀锌钢和碳钢电极在不同的电位下电化学阻抗谱,可以确定其阴极保护参数和最佳保护电位。通过实际应用,进一步证明了采用电化学阻抗谱测试的方法来研究阴极保护的最佳保护电位,简单可行,对防止接地网的腐蚀、延长接地网的服务寿命、保证接地装置的安全运行意义重大。外加电流阴极保护法采用远程控制,有效地降低了后期的运行维护费用。     

复合酸掺杂聚苯胺正极材料的制备及性能

以苯胺为单体,硫酸和磺基水杨酸进行复合掺杂,电化学聚合导电聚苯胺,采用正交设计优化聚苯胺正极材料的制备工艺。采用X射线衍射、傅里叶红外光谱对导电聚苯胺电极进行了研究与表征,结果表明大分子基团的加入进一步增大了聚苯胺分子链的离域程度,提高了导电性;采用扫描电镜,电化学测试以及组成电池放电对电极表征,结果表明聚苯胺正极的最佳制备工艺条件为添加12%(质量分数)的二氧化锰,导电剂使用碳纳米管,电极制作方式采用包网模式,压制电极的压力为12 MPa,与镁合金组成海水电池,以25 mA/cm2恒电流放电,比能量为108 mWh/g。聚苯胺与二氧化锰复合使得电极的放电性能得到显著提高,电极放电比能量与氯化银电极持平。     

Neutron production rate and plasma characteristics of spherically convergent beam fusion

Experimental and simulation results of a spherical glow discharge for a portable neutron source are presented. The experimental device is a 45‐cm‐diameter, 31‐cm‐high stainless‐steel cylindrical chamber, in which a spherical mesh‐type anode 30 cm in diameter is installed. The spherical grid cathode consists of 2.0‐mm‐diameter stainless‐steel wire, which is made into an open spherical grid of 5‐cm diameter. The system is maintained at a constant pressure of 1 to 15 mTorr by feeding hydrogen or deuterium gas. The basic characteristics of breakdown voltages versus pressure and electrostatic potential profiles were measured for hydrogen discharge. Using deuterium, a steady‐state neutron production of 10⁴ s^–1 was observed at a discharge of 40 kV, 2 mA. Motions of ions and electrons in the device were simulated by using a particle code, which is one‐dimensional in coordinate system and two‐dimensional in velocity space. It was confirmed by both the measurement and simulation that a virtual anode is formed in the central part inside the grid cathode. © 2001 Scripta Technica, Electr Eng Jpn, 135(2): 1–8, 2001     

阳泉二电厂1号炉水冷壁频繁爆漏的原因及对策

对阳泉二电厂1号炉水冷壁频繁爆漏的原因进行了进一步探讨,认为1号炉水冷壁频繁爆漏是由于炉管局部超温,水冷壁管材存在应力,在炉水水质恶化的情况下,综合作用的结果。并提出了防止该炉水冷壁再次爆漏的技术措施。     

考虑特殊负荷的宁夏电网负荷建模

提出了考虑特殊负荷的实际电网电力负荷综合建模方法。对典型日负荷曲线进行分析,定义了特殊负荷与一般负荷的分类判据;根据特殊负荷生产特性,采用适用于电解铝类负荷的I+M型综合负荷模型和适用于铁合金类负荷的Z+M型综合负荷模型;最后根据分类结果和典型负荷节点的参数辨识,建立宁夏电网负荷模型。仿真结果和实际调研结果对比表明,该方法效果良好,建立的模型更接近宁夏电网实际负荷特性。     

Modification of X-ray Generator by Energy Reusing

X-ray is an important tool for charactering and analyzing materials. However, current X-ray generation is cost with low efficiency. For X-ray tube, which is mostly used in laboratories, only has an energy usage of 1% with all other energy dissipated into tremendous heats, and it needs continuous cool water flows to cool down the cathode. It generates X-ray by the bremsstrahlung of high energy electrons bombarding on the cathode target, the bremsstrahlung would contain X-ray with sufficiently high energy of the electrons. But most part of the electron energy becomes heats. In order to generate X-ray more cheaply with higher efficiency, methods about reusing the released heats during the working of the X-ray tube are brought up. Mimicking the photovoltaic effect, nonequilibrium carriers could also be injected via thermion emission when heating a metal, such injection is same to that of photonic injection which produces electromotive in a photovoltaic cell. In a photovoltaic cell the electron-hole pair generated by incident photons are nonequilibrium carriers that causes electromotive, while the thermion emission creates such electron-hole pairs via thermal excitation. Connecting metals suitable for thermion emission from the cathode into the p-n junction so that thermions as nonequilibrium carriers can be well injected into the p-n junction when the metals are heated by the cathode, with Thomson effect which enhances such injection, a thermal voltaic cell can be constructed and it can produce electricity only by heating the metals outside. Applying such thermal voltaic cell into current X-ray tube, it would produce electricity while absorbing the tremendous heats emerges when X-ray tube is working. Water flows are still used to control the temperature, but letting them boiling to keep the cathode at a temperature best for thermal voltaic cell, and the vapor may be used to drive a mini thermal power plant. In this way, the energy usage could be modified to a higher proportion. Stepwise up-conversion is possible to generate X-ray more cheaply but there are no suitable materials so far.     

光伏接入系统的小干扰稳定灵敏度分析及其应用

针对光伏并网对系统小干扰稳定的影响,提出基于随机响应面法和摄动法的阻尼比灵敏度求取方法.以光伏出力波动的随机激励作为摄动量,通过摄动法求解光伏在不同节点并网的阻尼比灵敏度;根据阻尼比灵敏度的大小筛选最佳的光伏并网节点,通过优化方法确定光伏发电的接入位置和容量,得到光伏发电的最佳接入方式.以New England 10机39节点系统和西部某省实际电力系统为例验证所提方法的有效性.     

Fluorescent lamp cold starting improvement

Three approaches to improving the efficacy and startup time of commercially available cold cathode fluorescent lamps under cold ambient conditions are evaluated in this paper: heating the tube on one side; heating the tube on two sides; and heating the circumference of the outer tube. The internal power density generated by ion bombardment of the cathode and collisions in the plasma are indirectly obtained by matching simulated axial wall temperatures with those obtained by experiment at room temperature. The estimated power density is used to evaluate the temporal evolution of the axial surface wall temperature under different ambient conditions immediately after a cold start. All simulation results have been obtained using PHOENICS, a computational fluid flow program. Experiments have shown a good correlation between the time taken for the light output to reach an acceptable value and the time taken for the inner tube cold spot to reach a temperature of 0/spl deg/C. These results have been used to estimate heating time for different heater geometries and heater powers. The study shows that the conduction of heat to the outer glass envelope is the limiting process that controls the startup time. Modest improvement in startup time can be achieved by increasing heating power or by moving the heater to the side of the lamp. However, only a heater which entirely surrounds the lamp is capable of substantially decreasing the startup time.     

电力市场中的市场力分层评价指标体系

对现有的市场力度量指标进行了补充和改进，提出了一种基于物理潮流分析的同时面向市场和面向发电公司的市场力分层评价指标体系，并将网损和区域间功率交换考虑其中，通过跟踪系统、区域、节点三个层次上的实时的市场力指标变化曲线，可以反映地理位置、网络约束、运行方式等因素对发电商行使市场力的影响，可用于辅助监管部门评价和分析电力市场中潜在的市场力水平，并对电网公司改善网络结构，缓解由于网络约束造成的市场力具有一定指导意义。     

黑启动过程中的负荷恢复

研究了黑启动中的负荷恢复与系统并网问题，将基于直角坐标的最优乘子牛顿潮流法与灵敏度技术相结合，采用连续线性规划法对负荷恢复阶段出现的N-1潮流不可行和状态越限问题建立了恢复控制的模型和算法。然后建立了负荷恢复阶段仿真各子系统频率变化过程的模型和算法，针对子系统的并网问题建立了基于连续线性规划的并网压差发电调度算法，有效地解决了并网电压差优化控制问题。用标准测试系统和实际电网的数值仿真试验证明了模型和算法的有效性。     

真空电弧截流现象的理论研究

对小电流冷阴极真空电弧的单个阴极斑点建立了以能量平衡、离子守衡为基础的数学模型,将真空电弧的电流ｉ、阴极压降ｖｃ 这些宏观参数与阴极斑点的半径ｒ、温度ｔ 及电子电流占总电流的比例ｓ,这些微观参数联系起来,并对铜和银分别研究了电弧电流对阴极斑点状态的影响,而且比较了铜和银在相同条件下阴极斑点的所有可能状态。发现对同种阴极材料电弧电流越大则阴极斑点可能的存在状态越多,在标度相同的ｒ－ ｔ 平面上存在的点越多,点堆积成的图形面积也越大。在相同的电弧电流下的不同触头材料,截流水平越低阴极斑点可能存在的状态越多,因此提出了用相同标度下ｒｔ 平面上的阴极斑点可能的存在状态面积作为衡量真空电弧相对稳定性的标准。这为比较不同触头材料截流水平相对大小提供了简便方法,有利于对低截流值触头材料的研究。     

基于资费定价的5G及光纤承载配电网业务技术经济性模型

随着5G的技术发展和行业应用,电网企业在配电网控制类业务方面逐步开始了试点验证工作。5G技术的经济性是其在电网大范围推广应用需要考虑的主要问题之一。在综合考虑配电网现场终端规模、通信需求、建设成本、运行维护成本等因素的基础上,引入与系统建设运行时间相关的资费定价模型,用以修正技术经济性计算模型,并将5G公网与光纤专网进行多维度技术经济性比较,得到2种通信技术在不同时间点、不同业务终端数量下的投资金额对比结果,为配电网控制类业务终端通信接入网技术选型提供参考依据。     

Estimation of cathode-initiated breakdown in vacuum

Cathode initiation of vacuum breakdown in DC and pulse modes is considered. New criteria and methods for evaluating the cathode initiation mechanism are proposed. They are based on consideration of relative changes in cathode surface state and electric strength. The elaborated criteria and methods have been verified with experiments results using DC and pulse modes of high-voltage treatment of electrodes. Accuracy of the proposed methods exceeds known methods precision. It is shown that optimum modes of pulsed conditioning can be used for definition of top boundary of cathode initiation mechanism applicability in DC mode.     

接地网导体腐蚀故障诊断测试方案

为了科学地确定接地网腐蚀故障诊断中的测试方案,提高诊断结果的准确度,在最大电压公理的基础上提出并证明了3个推论并指出,在给定量测位置的条件下,若要使量测电压对某条支路电阻的变化最敏感,则恒定直流电流源必须加在该支路上;当恒定直流电流源加在某条支路上时,该支路两端电压对该支路电阻的变化最敏感。提出了一种将恒定直流电流源分别加在各条本征支路两端同时量测相应本征支路两端电压的理想最优测试方案,该方案是充分的,且具有诊断结果对误差不敏感、抗干扰性强和信号大便于检测的优点;讨论了实际应用中接地引下线自身电阻的问题,并建议了一种次优测试方案。以一个60支路的实验接地网为例进行了验证,结果表明提出方法是正确的和可行的,并且能够提高接地网故障诊断的抗干扰性和准确度。     

Method to estimate long‐term change of heat and electric power daily load curves in Japan

The rapid spread of CHP systems will put pressure on the regional power system to require an examination of the power and heat output of CHP systems. When considering the countrywide potential of the CHP system, one should examine such a system in coordination with the grid power system. It is essential to calculate the heat and power demand at end‐use level. In this paper, annual heat and power demands of end‐use sectors are forecast to the year 2025 based on 20‐year data. Regression analysis is used. Estimated annual demands are divided into the seasonal hourly demands considering demand characteristics. Daily load curves of heat and power demands are determined for the Japanese end‐use sectors, and the annual changes of such demands are shown by duration curves of heat‐to‐power ratios. Moreover, the grid power daily load curves are computed numerically from the estimated heat and power demands for the manufacturing, residential, and commercial sectors. Such load curves also consider self‐generated power for the manufacturing industry and self‐consumption of the grid power. Estimating heat and power demands allows for a joint analysis between the power system and the future phasing in of CHP systems. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 18–30, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20162     

基于聚类分析的电动汽车充电负荷预测方法

准确预测电动汽车充电负荷是研究大规模电动汽车接入对电网影响的基础,现有充电负荷预测方法缺乏考虑路况拥堵因素对电动汽车荷电量的影响。提出了一种基于聚类分析的电动汽车充电负荷预测方法,在分析常规充电负荷影响因素并初步建立概率分布模型的基础上,对每段行程的行驶里程和行驶时间构成的二维出行特征数据进行聚类分析。挖掘常规统计数据无法得到的道路拥堵因素,考虑不同路况条件下道路拥堵因素对电动汽车荷电状态的影响并叠加该变量到负荷预测模型中。以北京市为例分别预测并比较分析了工作日、周末、夏季、冬季电动汽车日充电负荷曲线。计算结果表明该方法可在一定程度上提高充电负荷预测的精确度。