A New Adaptive Technique for Enhancement of Zone-2 Settings of Distance Relay

This paper presents a technique that increases the second-zone coverage of distance relays without causing overreach problems. The technique is based on the impedance seen by distance relays when faults are simulated on the reach of zone-1 relays. The approach checks the relay operation for the maximum as well as the minimum generation outputs of the power system. The proposed technique can be used for different reach setting for zone-1. Results show that it is possible to increase the coverage provided by zone-2 distance relays without causing coordination problems with the primary relays that protect the lines emanating from the remote bus. The proposed method is modified for use in an adaptive protection system. It is shown that further improvements can be achieved when settings are calculated using the proposed method and the prevailing system conditions. The proposed method and its adaptive version were applied to a part of the Power system. The simulation of the system is done by using PSCAD-EMTDC software. The simulated results are observed and compared with the conventional and proposed technique.

Ultrasonic distance sensors-An overview and trends

Nowadays ultrasonic distance sensors are widely used in automobiles,robotics and in industrial automation.Some functional principles of usable transducers for airborne ultrasonic distance measurements are shown.As every sensor principle,ultrasonic distance sensors have pros and cons which lead to some problems and challenges de-scribed below.For the main challenges(crosstalk and blind zone) some trends and solutions are presented.

Characteristics of fault zones and their control on remaining oil distribution at the fault edge: a case study from the northern Xingshugang Anticline in the Daqing Oilfield, China

Most major oil zones in the Daqing Oilfield have reached a later,high water cut stage,but oil recovery is still only approximately 35%,and 50%of reserves remain to be recovered.The remaining oil is primarily distributed at the edge of faults,in poor sand bodies,and in insufficiently injected and produced areas.Therefore,the edge of faults is a major target for remaining oil enrichment and potential tapping.Based on the dynamic change of production from development wells determined by the injection-recovery relationship at the edge of faults,we analyzed the control of structural features of faults on remaining oil enrichment at the edge.Our results show that the macroscopic structural features and their geometric relationship with sand bodies controlled remaining oil enrichment zones like the edges of NNE-striking faults,the footwalls of antithetic faults,the hard linkage segments（two faults had linked together with each other to form a bigger through-going fault）,the tips of faults,and the oblique anticlines of soft linkages.Fault edges formed two types of forward microamplitude structures：（1） the tilted uplift of footwalls controlled by inverse fault sections and（2） the hanging-wall horizontal anticlines controlled by synthetic fault points.The remaining oil distribution was controlled by microamplitude structures.Consequently,such zones as the tilted uplift of the footwall of the NNW-striking antithetic faults with a fault throw larger than 40 m,the hard linkage segments,the tips of faults,and the oblique anticlines of soft linkage were favorable for tapping the remaining oil potential.Multi-target directional drilling was used for remaining oil development at fault edges.Reasonable fault spacing was determined on the basis of fault combinations and width of the shattered zone.Well core and log data revealed that the width of the shattered zone on the side of the fault core was less than 15 m in general;therefore,the distance from a fault to the development target should be larger than 15 m.Vertically segmented growth faults should take the separation of the lateral overlap of faults into account.Therefore,the safe distance of remaining oil well deployment at the fault edge should be larger than the sum of the width of shattered zone in faults and the separation of growth faults by vertical segmentation.

Analysis of strain variation in cross shear zone of plate during snake hot rolling

In order to study the distribution of equivalent and shear strain of aluminum alloy plate during snake hot rolling, several coupled thermo-mechanical finite element models(FEM) are established. Effects of speed ratio and offset distance on strain distribution of the plate are analyzed. The length of cross shear zone is defined to have a better understanding of the deformation characteristic in cross shear zone, which is the essential difference from symmetrical rolling in deformation zone. The results show that the equivalent strain and shear strain of lower part both increase with the increase of speed ratio, while the upper part decreases; the equivalent strain through the whole thickness decreases with ascending offset distance, while the shear strain of lower part increases. The length of cross shear zone quickly increases with ascending speed ratio and slightly decreases with ascending offset distance. The "positive" and "negative" cross shear zones are formed with the increase of speed ratio and offset distance, respectively. The value of the sensitivity coefficient of speed ratio is an order of magnitude bigger than the offset distance. However, the shear strain at center point increases with the ascending speed ratio and offset distance for different mechanism. As speed ratio increases, the asymmetry of the distribution of equivalent is becoming larger and the shear strain is generated in the same direction in cross shear zone. The FEM results agree well with experimental results.

Low velocity zone of upper mantle and its effect on PdSwr phase related to 670 kmdiscontinuity

This paper studied some properties of PdSwr phase related to 670 km discontinuities in detail, and theoretically processed a preliminary analysis to this phase. We discussed the relationships between the incident angle ih of PdSwr phase with its path, epicentral distance, travel-time and relative amplitude due to low velocity zone (LVZ) of upper mantle, and preliminarily pointed out the main characters of PdSwr phase recorded in seismogram. The PdSwr phase is concentrated in range of 13.5~96.5. When epicentral distance is greater than 33, the start point of PdSwr phase is relatively well distinguishable and could thus be determined more easily. When the epicentral distance is between 13.5 to 33, the triplication of PdSwr's travel-time curve could be slightly distinguished due to the low velocity zone and 220 km seismic velocity discontirluity of upper mantle. The relevant observed PdSwr phase should be in a more complex pattern and it should be more difficult to determine its start point

A New Algorithm for Black-start Zone Partitioning Based on Fuzzy Clustering Analysis

On the process of power system black start after an accident, it can help to optimize the resources allocation and accelerate the recovery process that decomposing the power system into several independent partitions for parallel recovery. On the basis of adequate consideration of fuzziness of black-start zone partitioning, a new algorithm based on fuzzy clustering analysis is presented. Characteristic indexes are extracted fully and accurately. The raw data matrix is made up of the electrical distance between every nodes and blackstart resources. Closure transfer method is utilized to get the dynamic clustering. The availability and feasibility of the proposed algorithm are verified on the New-England 39 bus system at last.

Zone 3 Relay Blocking Scheme to Prevent Cascaded Events

Defense systems are needed to prevent catastrophic failures of a power grid due to cascaded events. Cascaded events can be attributed to improper operations of protective relays. The most challenging problem for the design and implementation of a defense system is the performance in accuracy and speed in a real time environment. Protective devices are normally designed to operate fast in order to isolate the fault（s）. This paper proposes a new methodology to distinguish line overloads from actual faults for distance relays. In order to distinguish between line flow transfers from a line outage and an actual fault, the line outage distribution factor （LQDF） and generation shift factor （GSF） based power flow estimation method, and a secure peer to peer （P2P） communication structure are adopted. Computer simulations of cascaded events for a 6-bus system and the Korean power grid have been performed to establish the feasibility of the proposed scheme.

水电工程主厂房防火防烟分区划分的探讨

鉴于《水电工程设计防火规范》修编过程中,对主厂房防火分区、防烟分区和疏散距离存在不同认识,本文从防火设计的基本理念出发,分析了水电工程的特殊性,同时采用性能化设计数模理论,确定了规范中防火分区、防烟分区面积,以及疏散通道长度的依据,探讨了水电工程的特点,为特殊工程防火设计规范编制提供参考。

基于元胞自动机的城市快速路长距离交织区运行仿真

为了研究城市快速路长距离交织区对交通流运行特性的影响,建立多车道元胞自动机模型.根据长距离交织区内不同位置的换道车辆,考虑其各自换道行为和换道需求强度,引入3种不同换道规则,并对长距离交织区进行分段设定.基于动态安全间距、车流管理策略双重要素,构建不同管理策略下的多车道元胞模型.仿真结果表明,长距离交织区内的强制性驶出换道行为容易引发局部拥堵,形成出入口瓶颈.虽然双虚线型策略能够提供更多驶出车辆换道机会,但随着占有率的增加,这种优势逐渐减弱,相比之下,虚实线型策略更加合理.虚实线型策略-主路优先机制保证主路驶出车辆换道路权,不可避免会牺牲部分辅路通行效率.考虑到辅路的间断交通流特性,虚实线型策略1(先出后入)仍具备一定的实施价值.

基于优化DeepLabv3+的智能化高速铁路安全区域划分算法研究

针对目前电气化铁路沿线复杂背景下铁路安全区域划分均需采用实际固定标准件为参照物且区域划分范围小等问题,提出一种无需参照物的高速铁路安全区域划分算法.首先基于无人机所采集图像中的相关参数计算出相应的GSD(地面采样间距)参数,然后利用加入ECA-Net模块的DeepLabv3+模型对图像中的轨道进行精确分割.通过边缘检测、开运算、概率霍夫变换等一系列图像处理操作,提取出构成轨道的关键像素点,并运用最小二乘法进行轨道拟合,得出轨道数学表达式.最后,结合数学算法和GSD参数以及轨道数学表达式,完成安全区域的划分.实验结果表明,所提算法测量精度高达90%以上,无需选取固定参照物,适应性强、鲁棒性高,具有较高的实用性和可靠性.

双反射与透射结合的激光引信扫描系统

针对激光引信周向扫描系统光束发散角大且存在扫描盲区的问题,设计了一种基于双反射与透射结合的激光引信扫描系统。阐述了系统结构尺寸的约束并通过光线追踪分别对系统扫描过程中光束发散角和扫描角度进行了仿真,并研究了超环面和六棱台镜面的面型参数调整与光束发散角、扫描角度之间的影响。仿真结果表明:通过控制光阑位置可以实现单窗口的扫描角度达61°,六窗口组合可实现无盲区扫描;通过调整反射面参数来矫正透射场曲可实现全扫描角度光束最大发散角为0.034°;扫描路线会出现波浪式起伏,需要进一步匹配收发视场实现远距离无盲区扫描。该系统为激光引信远距离周向探测提供了技术支撑。

近距离煤层重复采动覆岩破坏规律及“两带”发育高度分析

为研究近距离煤层重复采动下覆岩破坏规律与“两带”发育高度,预防工作面开采过程中由导水漏风通道引起的工作面顶板漏水、采空区自燃等各种安全事故,以鄂尔多斯市某煤矿为工程背景,采用井下窥视法和数值模拟对近距离煤层开采后覆岩破坏规律以及“两带”发育高度进行分析,揭示了规律形成的原因。研究结果表明:在近距离煤层重复采动影响下,“两带”发育高度远超过上煤层开采,下煤层推进80 m时裂隙带最大发育高度为88 m,与地表贯通形成导水漏风通道;初次采动与重复采动时的裂采比分别为19.33、29.33;裂隙带的发育呈台阶式上升,阶段间的变化表现为激跳形式;覆岩的破坏表现为“拱形→帽形→马鞍形→外O内蝶形”;数值模拟及拟合公式所预测的“两带”发育高度与实测值之间误差率为1%左右,验证了预测的准确性,可为相似工作面的开采以及相似工程提供借鉴。

近距离煤层群联合开采火区“三位一体”治理技术

针对近距离煤层群开采期间的自然发火防治难题,以新维煤矿2110、3108工作面断层区域火点处置为例,通过实验研究与现场实践相结合的手段,开展隐蔽火点的探测与综合治理技术研究。3号煤层自然发火模拟实验结果表明:CO、C_(2)H_(4)体积分数与煤温呈二次函数关系,可用于煤层自然发火预测预报;氧气体积分数的降低可以有效抑制煤自燃氧化进程,氧气体积分数为7%时最为明显,因此将其设为3号煤层自然发火的临界氧气体积分数。通过自燃隐患分析结合钻孔探查划定了3110轨道巷以西长80 m、宽10 m的F9断层区域为自然发火隐患区域,并提出以注浆降温为先导,以注胶堵漏为核心,以注氮阻爆为手段的液-胶-气“三位一体”的火区治理思路,累计向隐患区域注浆180 t、注胶504 m^(3),2110工作面采空区注氮流量保持在810 m^(3)/h,实现了火区的有效治理,保障了2个工作面的顺利启封与安全回采。

HBS-LNSB Ⅲ 型旋流燃烧器回流区和着火距离的试验研究

针对某煤粉燃烧器的回流区和着火距离进行了试验研究。试验考查了中心风量、外二次风量、内二次风量以及内二次风旋流强度对回流区大小的影响规律,结果发现内二次风量的变化对回流区宽度的影响最大,中心风量对回流区与燃烧器的轴向距离影响最大。试验结果为不同煤种燃烧时的燃烧器配风选择提供依据。通过对各影响因素下煤粉着火距离的研究发现,针对着火距离短的易燃煤种,为了避免燃烧器喷口烧损,提高中心风量以及一次风速是最有效的措施。由于低负荷下炉内整体温度水平低,煤粉着火距离变长,可以适当提高易燃煤种的掺烧比例。对于着火温度较高的煤种,中心风量、内外二次风量的变化对于其着火距离均有明显的规律性,内二次风旋流强度的影响需要综合考虑旋流强度带来的风量变化的影响。不同煤种着火距离的工业试验为旋流燃烧器的配风选择提供了指导。煤种发生较大变化时应进行回流区与着火距离的工业试验,为燃烧器配风找到最优选择。

采空区下近距离煤层开采导水裂隙带发育规律研究

导水裂隙带是煤层顶板水源涌入工作面的主要通道之一,掌握覆岩“三带”发育情况对于矿井水害治理具有重要意义。东峰煤矿8号、9号煤层属于典型的近距离煤层,且顶板灰岩含水层是主要涌水水源,因此采用相似模型、现场实测手段进行9号煤层开采覆岩“三带”发育规律的研究。相似模拟研究表明9号煤层开采会引起上覆岩层进一步垮落,裂隙带发育范围为30~58 m,双端封堵测漏法实测研究表明裂隙带发育范围为28.7~55.5 m,测试结果可为9号煤层开采涌水量的预测和治理提供参考依据;相似模拟结果与实测结果基本吻合,相似模拟可较准确的预测重复采动影响下覆岩运移规律。

缓倾斜近距离煤层群重复开采“两带”高度研究

以四川省石屏一矿缓倾斜近距离开采工作面为工程背景,针对重复开采中缓倾斜近距离煤层的“两带”高度发育问题,采用FLAC^(3D)数值模拟与经验公式计算的方法进行研究。对工作面开采之后引起上覆岩层塑性区的变化特征进行了分析;确定了重复采动下“两带”的高度;并与经验公式进行对比验证;得出在重复采动情况下“两带”高度并不是简单的相加,而是存在一种叠加效应。通过该研究,进一步探索了缓倾斜近距离煤层群重复开采情况下“两带”高度的发育问题,为缓倾斜近距离煤层群安全开采提供了依据。

深井岩巷空顶区失稳及安全空顶距研究

为解决深井岩巷掘进过程中空顶区冒顶、片帮的安全问题,以吕家坨矿-950四采区回风道为工程背景,综合采用理论分析与数值模拟相结合的方法开展研究。运用卡斯特纳公式计算了巷道开挖之后塑性区半径为3.19 m,以此为基础建立了一端简支一端固支的空顶区岩梁力学模型,推导出了最大空顶距表达式。研究结果表明,-950四采区回风道的安全空顶距为2.6 m;运用GDEM模拟分析了不同工况下围岩的应力和损伤情况,模拟结果表明前方岩壁的支撑作用要明显高于后路锚杆对顶板的支撑作用,Ⅲ型工况下围岩的应力和损伤情况与Ⅱ型工况相差不大,考虑炮孔深度受限,空顶距为2.4 m时较为合适。

基于视认距离的隧道入口段亮度折减系数研究

为保障隧道入口段的行车安全,从驾驶员视认特性出发,定量研究被试者视认距离和亮度折减系数、运行速度、障碍物位置之间的关系。被试者在不同条件下进行隧道实车试验,采用障碍物的视认距离作为隧道入口段安全性指标,建立两种亮度环境下的被试者视认距离与亮度折减系数、运行速度、障碍物位置之间的回归模型。以入口段最小视认距离大于相应车速下的安全停车视距为条件,计算得到安全的亮度折减系数阈值,结果高于我国现行规范的参考值。该研究方法和结论对高速公路隧道入口段的照明设计具有参考价值。

大型长距离输水灌区工程测量技术研究

针对大型长距离输水灌区工程测量的重点和难点,从控制网建立、地形图测绘两个关键节点,探析如何利用现代化测绘技术(平面控制网观测利用北斗导航卫星技术、利用自编水准数据处理小软件提高高程控制网建立的效率,地形图测绘采用低空无人机航测、激光雷达测量技术,外业调绘加载高精度大地水准面模型提高高程测量精度等)快速、高效、高质量完成测量任务。

高地应力软岩隧道超前平行导洞开挖对主洞影响:以玉龙雪山隧道工程为例

为研究高地应力软岩隧道超前平行导洞开挖对主洞影响,依托玉龙雪山隧道工程,基于现场长期监测数据,结合有限差分程序FLAC3D建立数值分析模型,研究超前平导对主洞围岩应力、围岩位移和塑性区分布的影响,探明主洞与平导间最优间距。研究结果表明:主洞开挖过程中,当掌子面超过监测面3.63倍主洞宽度的距离后,监测面拱顶沉降、上收敛、中收敛和下收敛值占最终变形值的80%以上,围岩变形稳定后上收敛值和中收敛值均大于拱顶沉降;平导超前开挖可有效改善主洞围岩应力环境,主洞与平导间距较大时,围岩应力改善效果不佳,随着二者间距逐渐减小,围岩应力改善效果逐渐增强,但主洞与平导间距过小时,二者开挖产生的塑性区会贯通,综合考虑,确定主洞与导洞最优间距为3.5倍导洞宽度;主洞拱顶沉降值和仰拱隆起值随着主洞与平导间距的减小而增大,左右拱腰水平位移值随着主洞与平导间距的减小先减小后增大。