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1.
A new principle and scheme of a Feeder Automation based system protection using the channel of communication is proposed. The conjoint protection devices exchanging fault signal with direction information and the fault can be cleared instantly. These information can hel Pto isolate the fault zone and restructure the network rapidly. The recover is used for instantaneous faults. The optical MODEM disjoins the SCADA communication and Boolean signals functions using coding technology. So the fault flags can be exchanged rapidly peer-to-peer and special optical cables are not needed. Frames between optical MODEM are sent automatically. This scheme presented is successful through physical simulation experiment and has operated for about two years in a real distribution network. 相似文献
2.
XIAO Yong~ 《保鲜与加工》2004,(11):30-33
The scheme of rapid protection will be possibly implemented by using the channel of communication, as the communication network of distribution power system being increasingly perfect and particular foundation of optical cable. The feeder protection based on communication can quickly and selectively isolate fault section and restructure the distribution network. This method is the direction of distribution automation. The action principles of feeder protection using blocking and allowing signals of directional over-current are analyzed. The directional over-current protection utilizing blocking signals is suitablefor distribution automation. The scheme can locate the fault section and instantly separate it. When feeder terminal unit (FTU) fails to act or communicate is interrupted, the feeder protection in the substation can backup. 相似文献
3.
光储微电网混合储能系统的控制策略及开关优化 总被引：1，自引：0，他引：1
传统光储微电网混合储能系统控制策略将蓄电池视为容量无限大的理想元件,而实际上蓄电池容量有限,当蓄电池剩余电量达到阈值无法正常工作时传统控制策略将不适用。在二阶低通滤波法的基础上提出一种光储微电网混合储能系统的新型控制策略,同时考虑超级电容与蓄电池的剩余电量,根据储能元件的荷电状态调整储能元件输出电流参考值,维持储能元件剩余电量,但在极端天气情况下,仍需与储能元件保护开关相配合。由于采用传统储能元件保护开关的储能系统需独立的充放电电路,存在成本较高、充放电不连续等问题,因此,对储能元件的保护开关进行了改进,利用开关与二极管并联使其具有4种工作状态,在储能元件剩余电量达到阈值时,可自动恢复电量,降低了成本,提高了并网输出电能质量。最后结合新型控制策略与改进的保护开关,提出整体的混合储能系统控制方案,并用Matlab/Simulink对其进行仿真验证,结果证明了所提方法的正确性与可行性。 相似文献
4.
To solve the problem that the existing method of extracting fault components is easily affected by power system swing,a new methed has been proposed in this paper,which can be used in high speed protection of transmission lines. This proped method ean greatly decrease unbal-ance outputs under power swing condilions without frequency tracking circuits,therefore it can make the protection using fault compnents operate correctly. 相似文献
5.
The governing system of hydraulic turbine generator plays an important role in power system. It is significant to find out the faults of governing system and remove them quickly. This paper sets up a new fault diagnosis model of the hydraulic turbine generator governing system with the advanced ANN (artificial neural net). This 17-in-13-out model consists of three layers. It is proved that this model can find the fault accurately. 相似文献
6.
Petri网逆网在主轴故障诊断中的应用 总被引：2，自引：0，他引：2
比较了成熟期27个梨品种的果胶含量、半乳糖醛酸含量、果肉硬度和可溶性固形物含量,并分析果胶含量与果实品质特性的相关性。结果表明,不同梨品种间的果肉硬度、可溶性固形物、果胶、半乳糖醛酸含量4个指标的差异性都达到极显著水平(P0.01),果肉硬度均值为2.76 kg·cm-2,F值为47.03;半乳糖醛酸含量为0.64%~1.73%,F值为89.24,品种间差异最大;可溶性固形物含量为9.41%~15.19%,F值为17.66,品种间差异最小;果胶含量为0.23%~1.02%,与可溶性固形物和半乳糖醛酸含量呈极显著正相关(P0.01),Pearson相关系数分别为0.618和0.680。 相似文献
7.
8.
This paper presents a method which can accurately calculate the fault voltages and currents of the transposed and untransposed transmission lines.It can be applied to the simulation of protection relay analysis and fault location and so on.The principle of method is clear,the computational precision is high and usage is simple. 相似文献
9.
《Journal of Landscape Research》2017,(1)
The Historic Conservation District(HCD) is an important target for urban heritage protection in China. The spatial characteristics of its road system,formed before the appearance of automobile,do not adapt to the car traffic. In the context of very rapid motorization in Chinese cities,the increase in car traffic brings an inevitable trouble for the protection of HCDs. Road widening and pedestrianization are two popular solutions to this problem in current practices; however,both of them may lead to negative consequences. Inspired by the development of Zone 30 in European cities,this paper firstly cleared up first some misunderstandings of the concept of traffic calming,then taking the inner city of Paris as an example,explained how traffic calming measures can be implemented in HCDs and what effects will be generated. Finally,it discussed the possible application of traffic calming measures in HCDs projects in China and pointed out the specific situations of Chinese cities to which the planners should pay more attention. 相似文献
10.
以绿豆为主要原料,研究了速食绿豆粉的加工工艺。结果表明,采用VC(95 mg/kg)+柠檬酸(30 mg/kg)+CaCl2(185 mg/kg)+醋酸锌(100 mg/kg)作护色剂,以3倍加水量在40℃下恒温浸泡4 h后,沸水煮制10 min,快速闪蒸30 min,在90～100℃下烘干3 h,速冷、研磨、过筛分级,制得的速食绿豆粉复水性好,用沸水冲泡后即可食用,是一种原汁原味、方便快速、易于保存、便于携带、利于消费者食用的速食食品。 相似文献
11.
A type of handhold computer that has been researched successfully is introduced as the application case and practical usage effect about fault tolerance technology in the machine. At the meantime, it can be as a usage for reference while the same type of machine brings in fault tolerance technology in order to increase its reliability. So, it has greater availability and extended character. 相似文献
12.
Novel method for fault line selection in arc suppression coils system using transient energy 总被引：1，自引：0，他引：1
In order to overcome low sensitivity of the protection based on transient components when the faulty voltage passes zero, regarding arc suppression coill branch as a healthy feeder line, using the relation of its transient energy and all feeders of transient energy amounting to zero, this paper presents an improved fault line selection method in arc suppression coils system using transient energy. This method has no requirements of detection fault close angle and pre setting, has a good anti interference ability and adaptability to various faults occurred in the systems with arc suppression coils. Large amount of digital simulation results show that the proposed method is effective and reliable. 相似文献
13.
以板蓝根为原料,在一定条件下泡制白酒,制得板蓝根多糖保健酒。采用苯酚—硫酸法测得泡制酒中板蓝根多糖含量在一定范围内随泡制时间、温度、料液比有正比关系。用自然干燥的板蓝根粉粒室温下泡制7~28 d,酒中板蓝根多糖质量浓度为40~60 g/L;适度加热处理的板蓝根比未处理或处理不当的板蓝根粉粒的室温下泡制酒中的多糖含量高;在适度加热条件下泡制板蓝根白酒,多糖溶出快、含量高。试验表明,泡制板蓝根多糖酒可用100℃下加热3 h或自然干燥的板蓝根粉粒直接进行,用石油醚和体积分数为95%的乙醇充分浸提后的板蓝根粉粒泡制白酒,虽然多糖含量降低,但该工艺模拟了用板蓝根制药残渣泡制多糖保健酒的技术路线,可充分利用板蓝根生药资源,并有效地保持多糖活性。适宜条件下泡制的板蓝根多糖保健酒橙黄清澈,具有板蓝根特有的清香和微苦滋味。 相似文献
14.
A. E. Zeilinga 《Euphytica》1956,5(2):171-174
Summary As a final test for colchicine-induced tetraploid plants the cytological method is most reliable. However, cytological testing can only be done in satisfactory manner if a large series of preparations can be prepared in a relatively short time.It is shown how, after some simplifications and improvements with LA Cour's acetic orcein staining, a trained person can in about one and a half hours prepare a series of 30 preparations which keep for one month or longer.Staining and maceration are done on the slide; the material is squashed and mounted in acetic Fast Green. Fast Green enhances the contrast and the preparations mounted in this solution do not deteriorate so quickly as when mounted in orcein solution. 相似文献
15.
种快速提取棉花干种子基因组 DNA 的新方 法简 总被引：1，自引：1，他引：0
利用SSR(Simple sequence repeats)分子标记技术,能够快速有效地进行杂交棉纯度鉴定。为了攻克SSR分子标记技术中存在的技术难关,本文专门对棉花干种子胚的基因组DNA提取方法进行了研究。利用该方法,只需要2次加液、1次离心,从基因组DNA提取到SSR-PCR扩增,最后电泳,进行谱带分析,整个过程仅需4.5～5 h。本方法成本低、速度快、操作简单,适用于批量化DNA的提取,且整个提取过程无毒、无污染,是一种资源节约型和环境友好型的高效提取方法,适用于大批量样本的SSR分子标记鉴定工作。 相似文献
16.
A novel method for power transmission line monitoring and fault diagnosis is proposed based on non linear frequency response analysis. The power line carrier signal has been used for on line monitoring of power transmission line. As the non linear frequency response function describes the system inherent characterization, different frequency response patterns corresponding to different operation states of transmission line can be established. Based on the analysis of transmission line characteristics of fault modes, various fault features can be extracted, thereby achieve online monitoring and fault diagnosis on transmission line. Simulation experiments show the effectiveness of the proposed method. 相似文献
17.
As the self weight of cable affects mechanical behavior obviously with the inerease of span length.FRP (fiber reinforced polymer) cable that has the lighter weight than the conventional cables has advantage for long span structures.The analysis of single cable is the fundamental theory for the design of cable structures.Based on different considerations of gravity loads.the solutions of the single cable on gravity loads have three sets of solutions: parabola solution.catenary solution and elastic catenary solution.And the equations for the three sets of solutions are derived by taking the end tension force of cable as the control parameter.The comparison between FRP cables and steel cables is conducted by elastic catenary solution.and the results show that the lager span structure can be realized by FRP cables.The precision for the parabola solution and catenary solution is compared for stay cables and horizontal cables.and the proper ranges of both approximate methods are proposed.Based on the above methods.the ultimate span length of FRP cable and steel cable are analyzed.It is concluded that the ultimate span of FRP cable is 4.4 times larger than that of steel cable. 相似文献
18.
Lu Jiping Ye Yilin 《保鲜与加工》1988,(4)
So far, the accuracy of the existing methods of fault location based on calculating the impedance at only one terminal of lines is certainly affected by the variation of the system impedance at the remote end. In accordance with parallel lines' special characteristics, this paper presents a method that can calculate the system impedance of the remote end when one of the two lines has fault, so that the effect of its variation can be eliminated completely. This method has been tested by the computer digital simulation, and the results are very satisfactory. 相似文献
19.
The turbogenerator vibration faults have the character of variety. Many faults often occur synchronously. This paper introduces a diagnosing model based on parsimonious covering theory and probability. A model for turtogenerator's fault diagnosis is proposed. The availability of this method is proved by two fault diagnosis examples of turbogenerator. The results show that the model proposed can be used for multi_fault diagnosis together. It may make up shortage for some of expert systems and neural networks in some aspect. From the practice,this model has higher reliability and practicability. 相似文献
20.
Yao Zaoxin Ye Yilin 《保鲜与加工》1990,(4):14-22
In accordance with the characteristic of digital relay and fault locatoin four methods of phase selection on fault component are presented in this paper.These methods are simple in principle, reliable in action, and immune from load flow,system oscillation.Hardly affected by fault location, source impedance and fault resistance, they can select fault phase reliably for any power system and fault type.As phase selection schemes, they can be used for perfect digital relay. 相似文献