Protective Measures for Space Environment of Time-honored Brands——With Xi'an City as a Study Case

Based on the field survey and analysis of representative traditional time-honored shops in Xi'an City,specific measures for protecting their space environment were put forward,and the sustainable preservation and development pattern of such intangible cultural heritages in the future urban development was established.

Solution Scheme for Time Synchronization of Current Differential Protection between Digital Substations

In digital substations with power transformers, the key to implementation of line differential protection is synchronization of electrical quantities at both two sides. System framework of current differential protection for lines between digital substations is analyzed briefly, as well as the necessity of demand for time synchronization. Principle of time synchronization based on GPS and IEEE1588 PTP (Precision Time Protocol) are introduced. Time synchronization of current differential protection between digital substations based on IEC61850 is discussed. This paper puts forward two solution schemes of time synchronization, analyzes their advantages and disadvantages respectively, and points out that the development direction of time synchronization of differential protection between digital substations is IEEE1588 PTP.

The Research of Intelligent Substation Time Synchronization System and the Influence of Its Fault to Relay Protection

The intelligent substation realizes the digitization of information in the whole substation and thus time synchronization system becomes more and more important. This paper introduces time synchronization technology of intelligent substation and puts forward the principles for designing intelligent substation time synchronization system. According to some relay protection malfunction examples caused by time synchronization system fault, analyze the influence of time synchronization system fault to relay protection and correspondingly put forward some improving measures.

Analysis of travel time, sources of water and well protection zones with groundwater models

This study compares numerical models with analytical solutions in computing travel times and radius of protection zones for a pumping well located in an unconfined aquifer with uniform recharge and in a semi-confined aquifer. Numerical models were capable of delineating protection zones using particle tracking method in both cases. However, protection zones defined by travel time criterion can only protect small percent of source water to the well; large percent of source water is not protected which may pose a risk of pollution of source water to the well. The case study of Leggeloo well field in the Netherlands indicates that although a well field protection area was enforced in 1980 s, elevated nitrate concentration has been monitored in the abstracted water since 1990 s. The analysis of protection areas shows that the current protection area only protects 37.4% of recharge water to the well field. A large protection area must be adopted in order to safeguard the sustainable water supply for the local community.

The Game Analysis of Environmental Protection at Scenic Spots

Game model of environmental protection at scenic spots is established in this paper in order to carry out analysis of the equilibrium between one-time game and infinitely repeated game, disclose the reasons why the environment of scenic spots are destroyed, and propose the countermeasures to ensure the equilibrium of the game. The study also reveals that during the one-time game between tourists and tour operators, it is tour operators' dominant strategy not to control environmental pollution that leads to the destruction of environment at scenic spots. While, during the infinitely repeated game between tourists and tour operators, the realization of Pareto optimality equilibrium (The strategy of tourist is traveling, and the strategy of tour operators are controlling environmental pollution) is dependent upon the choice of players (tourists or operators) of triggering strategy (traveling or controlling environmental pollution). The supervision of the government upon operators can force them to control environmental pollution, which can consequently improve the efficiency of equilibrium in the game, and promote environmental protection at tourism scenic spots and sustainable development of tourism.

浅析基于Time-WORM技术的视频监控数据保护解决方案

从安全防范的角度来说,视频监控系统最大的价值在于为各种事故责任的鉴定提供最直观的证据——真实的视频资料,在视频监控系统中安全、有效地保护这些关键数据极其重要。基于Time-WORM技术数据保护解决方案,可以实现在规定时间段内,任何人、病毒等都无法对最新的视频文件进行删除或破坏,确保在规定时间内视频文件的绝对安全性,保护监控系统的视频数据,使其在安防领域发挥重要作用。

Comparative Identification of Wellhead Protection Areas for Municipal Supply Wells in Gaza

Groundwater is the only source of fresh water in Gaza Strip while its inhabitants and its water consumption increased rapidly. This study aims at preserving and protecting the groundwater from any pollutants caused by 141 industrial installations through the work of delineation of Wellhead Protection Areas (WHPA) for 47 Municipal Supply Wells in Gaza Governorate boundaries. WHPA has been determined in three different methods: Calculated Fixed-Radius Method (CFR), Analytical Method (AM), and Wellhead Analytic Ele-ment Model (WhAEM2000) which is currently used by the United States Environmental Protection Agency (EPA). These methods mainly depend on the time it takes groundwater to travel a specified horizontal dis-tance. Three well zones were delineated for each municipal production well, the first zone is 50 days time of travel (TOT), the second zone is 2 years TOT and the third zone is 5 years TOT. Different values of the ra-dius of WHPA of each well were obtained using the three methods. Consequently, several industrial installa-tions were laid inside the WHPA according to the radius values. The results show that CFR method is the weakest method because it does not take into account regional groundwater flow, causing a hydraulic gradi-ent. WHPAs identified by these methods may be either too large or too small, resulting in wellhead overpro-tection or under protection. Analytical Method incorporates hydrogeologic characteristics of the aquifer, groundwater flow, and hydrogeologic boundaries into the model. Often produces a WHPA that is smaller than the one produced using CRF. WhAEM2000 method is the best method because it uses a hydrogeologi-cal computer model of groundwater flow and it provides a more accurate delineation of the WHPA. It often produces a smaller area to manage than other methods. The study concluded that all industrial installations located in the WHPA should be carefully checked and investigated by governmental authorities. Mitigation measures for pollutants and licenses for the establishment of any new industrial installations could be based on the delineation of WHPAs using the previously mentioned methods.

A New Analyzing Method of Single Event Latch-Up Protection Circuit Based on Current Comparing and Its Performance Verification

Single event latch-up (SEL) is a significant issue for electronics design in space application, which would cause large currents in electronic devices, and may lead to burning out of devices. A new monitoring circuit based on current-comparing method is designed to protect the electronics away from SEL’s damage in radiation environment. The response time of protection circuit has been analyzed. The signal simulation results indicated that the operating time of the SEL protection circuit is dependent on the action time of current comparator and system application recovery time. The function of the monitoring circuit protection device away from SEL’s damage has validated through experiment at last.

Fault diagnosis and protection of motors in coal shearer

Symmetrical components method is employed in analysis of the characteristic motor faults.Motor protection method is put forward based on detecting positive sequence,negative sequence and zero sequence current.And problems of lack of motor overload capacity in existing mining motor protection system,impact of dynamic current on stage and definite-time delay operation and inaccuracy of criterion phase failure protection are analyzed.The unbalanced faults protection and inverse-time overload protection,which can make protection time change with the current movement,are proposed.The above problems can be solved,and the reliability and intelligent of coal shearer are improved.

Study of Discharging Characteristics of Hollow Cathode Surge Protective Gap

A hollow cathode surge protective gap （HCSPG） was designed, and the discharge characteristics was investigated in an air and nitrogen gas environment. For both the gap spacing D and the hole diameter Ф of HCSPG of 3 mm, the voltage protective value Up of HCSPG is about 3.5 kV and its converting time tc exceeds 100 ns at an air pressure from 10 Pa to 100 Pa. The maximum converting time tc from glow to arc discharging reaches 1600 ns at an air pressure of 100 Pa, while the minimum converting time tc is 120 ns at 10 Pa. For a triggered HCSPG, Up is reduced to about 1.6 kV while the converting time is 120 ns with a semiconductor trigger device and 50 ns with a dielectric porcelain trigger device under an air pressure of 100 Pa.

含逆变型分布式电源和储能系统的配电网反时限过流保护定值优化方法

高比例逆变型分布式电源(IIDG)和储能系统(ESS)接入配电网,导致传统反时限过流保护存在误动或拒动问题。在IIDG和ESS故障等值模型的基础上,分析IIDG和ESS对传统配电网反时限过流保护特性的影响;以保护选择性要求为约束条件,建立以速动性和灵敏性为优化目标的反时限过流保护多目标优化模型;基于标准多目标粒子群优化算法,引入自适应惯性权重、学习因子、网格密度与柯西变异因子,提出一种含IIDG和ESS的配电网反时限过流保护定值优化方案,并结合基于层次分析法和客观赋权法综合权重的理想逼近法对模型进行求解。通过PSCAD/EMTDC仿真验证了保护优化模型和求解方法的有效性与优越性。

Impact Analyses of Wind Farm on Performances of Transmission Line Relay Protection

A simulation system for power grid with concentrated large-scale wind farm integration is established based on the electro-magnetic transient model of wind turbine equipped with doubly-fed induction generator (DFIG),which is built by real-time digital simulator (RTDS).Using the hardware communication interface of RTDS,a closed-loop testing experiment is accomplished to study the impacts of large-scale wind farms on the existing relay protection devices for wind farm outgoing transmission line.This paper points out problems existing in current relay protection devices as follows:fault phase selector can select unwanted phase due to the changes of fault features caused by special network connection of wind farms;blocking condition for distance protections needs to be re-examined due to the weak power-feed characteristics of wind farms;and power frequency parameter based relay protection devices cannot accurately operate due to the special transient voltage and current characteristics of wind farms during fault period.Results lay the foundation for improving the performances of the existing relay protection device and developing new principle relay protection.

一种应用于TDMA无线传感网的低能耗同步机制

为了降低时分多址网络中时钟同步所导致的节点能耗,根据节点晶振器件的潜在漂移,提出了一种应用于星型无线传感网的低能耗同步机制。该机制中整个时间轴由长帧组成,每个长帧包含一个同步帧与多个子帧,每个子帧由所有子节点绑定的子时隙构成。根节点在长帧开始时发送同步帧,使得所有子节点时钟同步。每个子时隙增加了相应的保护间隔,有效地避免子节点之间因时钟漂移导致时隙间相互影响,从而最大限度地增加长帧中的子帧数量,降低子节点唤醒进行同步的频率。与传统的TDMA每个子帧均需同步相比,从接收同步帧角度来讲,大幅度减少了子节点能耗。最后,假定晶振频率误差为正态分布的情况下,利用MATLAB进行仿真,验证了该低能耗同步模型公式的正确性,并将仿真情况在CC1310器件构建的星型网上进行了应用验证。

三种复方植物精油驱蚊效果实验室观察研究

养殖场中滋生的大量蚊蝇可以在畜禽之间和人畜之间传播蚊媒病毒,不仅会对养殖场造成经济损失,而且还会严重威胁人类健康。本试验为了观察三种复方植物精油在实验室驱蚊的效果。我们根据国标GB/T 13917.9-2009规定的攻击力试验方法,通过使用小鼠模型来测定三种复方植物精油对白纹伊蚊的驱避时效。本试验结果显示在该试验中,以白纹伊蚊作为本次试验蚊虫,两种驱蚊花露水在2 h以内对昆明小鼠有效保护率在70%以上;复方植物精油(APEX)在2 h内对昆明小鼠的有效保护率达到40%;通过调整植物精油成分,复方植物精油(APEX-1)对昆明小鼠有效保护时间为2 h,而且在4 h内有效保护率均可达到80%以上;复方植物精油(APEX-2)型对昆明小鼠有效保护时间为2 h,而且在4 h内有效保护率均可达到90%以上。结果表明,复方植物精油(APEX)是一种有效的蚊蝇驱避剂,通过调整植物精油成分后,有效保护率达到80%以上,其高效绿色环保的优势在养殖场蚊蝇驱避方面有较大应用前景。

Monitor System for Protection Device Based on Embedded RTOS

For the purpose of the monitor system in digital protection, the embedded real-time operating system (RTOS) and the embedded GUI (Graphical User Interface) is introduced to design the monitor system. Combining the necessity and the application value of the operation system, the choice of embedded Linux and Qt/Embedded is completely viable for the monitor system in digital protection for generator-transformer sets. The design with embedded Linux and embedded GUI enriches system information, increases developing efficiency and improve the generality.

基于动作时限曲线拟合思想的含DG型配电网后备保护新方法

分布式电源(distributed generation,DG)的接入可能会改变电力系统的短路电流特性,从而影响到反时限过流保护的选择性和配合关系。为此,提出一种基于动作时限曲线拟合思想的含DG型配电网后备保护新方法。从配电网主保护和后备保护的动作时间差入手,建立曲线拟合模型,并运用梯度下降法对反时限过流保护的动作时限曲线进行优化。通过在优化整定计算中考虑保护的选择性以及DG接入所带来的影响,使优化参数适用于配电网中各分段位置。然后,在配电网中设置两相、三相短路故障,并根据故障位置、类型进行整定参数再调整,最终得到参数的全局最优解。基于PSCAD/EMTDC仿真软件进行仿真分析,验证了所提方法的有效性和实用性。

从绍兴书圣故里南入口的时代变迁看古城更新保护

绍兴书圣故里街区是国内完整保存的具有二千余年城市肌理的历史街区。随着城市化进程,沿萧山街河南侧的书圣故里南入口地块近三十年经历了巨大的变化。从低矮的民居演变到绍兴有名的杂货一条街,再到20世纪90年代绍兴第一高楼王朝大酒店和新华书店在这里树立,城市风貌的变化在这里尤为激烈。随着时代的变迁,这些影响古城风貌的高层建筑被拆除,书圣故里的南入口又被重新打开。南入口的建筑与风貌被重新赋予了符合历史和时代的新含义,通过绍兴书圣故里南入口的历史溯源和建筑风貌再塑,从古城空间、高度、视线、历史溯源等多重角度的研究成为了古城历史风貌区的保护和更新的重要基础。通过对绍兴书圣故里南入口整体打造思路的分析,为古城历史街区的研究和更新保护做出了一个鲜活的案例。

300MW机组小机TSI系统升级改造

TSI监控保护系统是保证汽轮发电机组安全运行的关键设备,能够持续、准确地监控机组在不同运行阶段的参数变化,如转速、轴位移、膨胀、振动等。当检测到轴向位移、轴承振动或转速等参数超出限制时,TSI系统会及时报警,提醒操作人员并判断是否需要紧急停机,保护汽轮机,防止汽机转子和轴承损坏事故发生,以防止设备损坏。文章对300 MW机组小机TSI系统升级改造进行了介绍。

提升抗时延抖动和数据异常性能的配电网故障自同步5G差动保护方案

配电网5G差动保护信道的来回时延不等导致传统同步算法无法应用,需要增加额外的同步装置。另外,5G信道存在时延抖动和数据异常等问题会对保护的可靠性产生影响。针对这些问题,首先提出了基于变频插值的故障自同步法,在保护装置启动后利用插值法处理故障前特定时刻数据窗来实现同步误差校正。以此为基础,分析保护可能面临的异常数据特征,提出了考虑舍去极值的Hausdorff故障判别算法。最后设计了一种能够提升抗时延抖动和数据异常性能的配电网故障自同步5G差动保护方案。在PSCAD对方案进行仿真验证,结果表明所提方案能够在不增设额外同步装置的前提下有效提升抗时延抖动和数据异常的性能,保证发生各类故障和存在大噪声时的保护可靠性。该方案可为配电网5G差动保护的可靠性提供保障。

Reliable Remote Relay Protection in Smart Grid

As the false trips of remote protection relays are among the main reasons behind cascading blackouts, it is critical to design reliable relay protection. Even though common protection schemes on traditional power systems have been investigated for a few decades, cascading failures in recent years indicate more research needed in this area. Consequently, researchers have proposed agent-based methods on the Smart Grid （SG） to address this issue. However, these existing agent-based methods simply use TCP protocol without considering real-time communication requirements （such as bandwidth and delay）. To deal with this issue, several methods for efficient network resource management are proposed. Furthermore, these existing methods do not consider the potential issues in practical communication networks, which may result in delay violation and trigger relay false trips. We have discussed simple backup solutions in the previous work. In this paper, in addition to network efficiency, we focus on improving the system reliability by exploring known power system information and minimizing the chances of false trips of important remote relays, e.g., defining power line priorities based on their importance. Moreover, to further improve the. system reliability, we also in- vestigate the peer-to-peer protection approaches to address the single point of failure of centralized control center.