Study on DeviceNet communication mechanism and its application in protection measurement and control system

To fit in with the developing requirement of int and communication of protective relays, a protection egrated functions of protection measurement, control measurement and control system based on DeviceNet fieldbus is designed. The communication mechanism of DeviceNet is studied and data trigger modes, communication connection, message types and other key technologies are analyzed. The object modeling and device description of the device are realized too. Results of network test, dynamic simulation and test in the field indicate that this system can accomplish all the communication tasks in real time and can make precise response to every kind of faults of the motor, transformer, line and capacitor. Moreover, this system has higher measurement precision and better control capability.

Advancement in Wide Area Monitoring Protection and Control Using PMU’s Model in MATLAB/SIMULINK

A big step forward to improve power system monitoring and performance, continued load growth without a corresponding increase in transmission resources has resulted in reduced operational margins for many power systems worldwide and has led to operation of power systems closer to their stability limits and to power exchange in new patterns. These issues, as well as the on-going worldwide trend towards deregulation of the entire industry on the one hand and the increased need for accurate and better network monitoring on the other hand, force power utilities exposed to this pressure to demand new solutions for wide area monitoring, protection and control. Wide-area monitoring, protection, and control require communicating the specific-node information to a remote station but all information should be time synchronized so that to neutralize the time difference between information. It gives a complete simultaneous snap shot of the power system. The conventional system is not able to satisfy the time-synchronized requirement of power system. Phasor Measurement Unit (PMU) is enabler of time-synchronized measurement, it communicate the synchronized local information to remote station.

Theoretical and experimental assessment of a novel method to establish the complete measurement range of the calorimeter and its limit of detection and quantification

For determining the accuracy of a calorimeter over the instrument’s entire measuring range,a novel method has been established.For this new approach,(a)benzoic acid(C_(6)H_(5)CO_(2)H) as a certified reference material(CRM),(b)SiO_(2) and(c)a mixture of CRM benzoic acid and SiO_(2) have been used.To illustrate the essential difference between 1)the novel analytical method for control of the entire measurement range and 2)the calorimeter calibration,both applications of benzoic acid(BA)have been demonstrated.An experimental result showed that BA was successfully used to check the whole calorimeter measurement range.The results also showed that the same new method was successfully applied to determine the limit of detection and quantification.A new instrument testing process and a new measurement technique have thus been established.In this way,the cost of using CRM to control the accuracy of measuring the entire measuring range of the calorimeter,as shown in this paper,is minimized.The requirements of the ISO/IEC 17025:2017 standard are satisfied.ISO/IEC 17025:2017,together with ISO 9001:2015(quality management systems),ISO 14001:2015(relate to environmental protection)and ISO45001:2018(occupational safety),constitute an integrated quality system by which a testing laboratory may also accredit.

Control Measures for Protected Strawberry Cultivation in Continuous Overcast and Hazy Days

Continuous overcast and hazy days are common for the winter in Hebei Province,these disastrous weathers have tremendous negative effect on the production of protected strawberry cultivation,for leading to the problems such as degrading photosynthesis of leaves,poor pollination and fertilization,more malformed fruits,low percentage of fertile fruits,delayed maturation of fruits,degraded quality and yield,and aggravated diseases.In view of the disastrous weathers and problems,the authors put forward the measures for the management of protected strawberry cultivation in continuous overcast and hazy days,to provide technical support for strawberry farmers.

基于Android的测控装置人机界面的设计与开发

针对目前测控装置采用比较简单的图形软件进行界面开发不适应技术发展要求的情况,提出了利用Google的Android作为测控装置人机界面的软件开发平台,在Android的系统框架上实现测控装置的人机界面。阐述了如何对Android现有的系统框架进行裁剪和调整,使得系统更加符合测控装置人机界面的要求。利用Android提供的组件设计了测控装置人机界面的各个功能模块(规约模块、逻辑模块和CAN模块等),使得模块设计更加合理,模块之间的耦合性更小。设计了基于OMAP3530的测控装置人机界面,结果表明基于Android的测控人机界面功能更加丰富,操作更加友好,易于升级和维护,能较好地满足用户的需求。

Development of a Stabilized Pan/Tilt Platform and the State of the Art

In the context of this paper, a small scale, medium precision, stabilized pan/tilt platform is developed as a prototype, which is used to compare various stabilization algorithms experimentally. The overall performance of the system depends on rigid body dynamics, structural dynamics, servo control loops, stabilization control algorithm, sensor fusion algorithm and sensory feedback such as from the IMU （inertial measurement unit）. In the case that the response bandwidth of the overall system is high enough, the same hardware can also achieve active vibration isolation. All of these design aspects are investigated in the paper via numerical models and with their experimental verification.

基于PXI和Teststand的模拟保护卡件自动测试工装设计

核反应堆的模拟保护系统具有较高的可靠性,运用脉冲试验,可使其具有充分的在役测试能力。作为模拟保护系统的组成部分,卡件具有模拟计算功能和逻辑运算功能。针对常规卡件测试耗时、费力等弊端,设计一套基于PXI和Teststand的自动化测试工装。通过对自动化测试原理和测试资源的分析,实现了硬件设备的选型,以及对开关网络、接线和系统结构的设计;以Teststand软件和LabVIEW语言为软件编程环境,完成测试流程的设计。借助一块辅助电路板,将工装自身的电源和多用表短接,实现了工装的自动化检测,确保工装在使用前处于完好可用状态。测试结果表明,卡件的测试时间为人工的1/5,卡件的测试质量达到了100%。

有效避免ABB UNITROL 6800励磁系统故障导致机组跳闸的方案

ABB UNITROL 6800拥有多重冗余和多CPU配置,通道最大可达三通道。整个控制系统配有两套恒机端电压控制(AVR)、两套恒励磁电流控制(FCR)和一套备用恒励磁电流控制(BFCR),高冗余度的设计和彼此间的合理切换大大地提高了机组运行的安全性和可靠性,但ABB UNITROL 6800励磁系统测量板(CCM)本身存在一个概率极小的故障,且动作权限最高,一旦发生,将直接导致机组跳闸。介绍了一种有效避免因CCM板故障导致机组跳闸的优化方案。

Quantum State Preparation and Protection by Measurement-Based Feedback Control Against Decoherence

We consider an open quantum system subjected to a noise channel under measurement-based feedback control and two prototypical classes of decoherence channels are considered： phase damping and generalized amplitude damping. Based on quantum trajectory theory, we obtain an extended master equation for the dynamics of the reduced system in the presence of feedback control. For a qubit system we analytically solve this master equation and obtain the solution of the state vector dynamics. Then we propose an effective feedback control scheme for preparing an arbitrary quantum pure state. We also study how to protect two nonorthogonai states effectively, and find that projective measurement with unbiazed basis is not optimal for this task, while weak measurement with biased basis could realize the best protection of two nonorthogonal states. Furthermore, the inefficiencies in the feedback process are also discussed

基于故障主动控制的海上风电交流汇集线路时域距离保护

海上风机通过电缆线路与海上模块化多电平换流器(MMC)相连接,构成海上风电交流汇集系统。由于海上风电交流汇集线路双端均为电力电子设备,基于双端通信的差动保护存在一定风险;其短路电流幅值受限、相位受控且具有大量谐波分量,基于工频量的距离保护可靠性较低。鉴于此,该文提出一种故障主动控制下计及分布电容影响的时域距离保护方案。首先,提出降压限流控制策略,以避免海上MMC换流器在严重故障下的误闭锁;其次,为放大海上换流器故障特征并解决双端故障电流的相位差异导致单端距离保护性能下降的问题,利用海上MMC换流器的故障主动控制能力,通过锁相环调制特定频率的负序故障分量,该特定频率分量仅存在于换流器与故障点之间,从而避免了风机故障电流的影响;再次,充分考虑电缆分布电容的影响,基于线路π型模型推导故障微分方程,结合最小二乘法求解故障距离,并构造保护判据;最后,基于PSCAD/EMTDC仿真平台验证了所提方案的可行性及有效性。

某海洋石油平台天然气回收改造项目投产前期职业病危害影响变化及防护分析

通过对某海上油田中心平台天然气回收改造项目投产前期职业病危害因素变化进行预分析,提出职业病危害的关键控制点和指导性防护措施,以期满足职业卫生要求。经过职业卫生类比调查、检测、推算,预估改造后职业病危害因素的浓度/强度,进而预测拟采取的职业病防护措施的防护效果。该项目类比检测的有毒化学物质浓度均符合国家职业卫生标准,类比推算的个体噪声水平均较改造前提高,其中1个个体噪声接触水平预测不符合国家标准;该项目职业病危害因素中,化学因素影响变化不明显。该项目所采取的防护措施有一定防护效果,经有效治理及对其他不足之处加以改善后,符合国家职业病防治方面法律、法规、标准的要求。

城际铁路盾构下穿既有铁路施工技术及影响分析

盾构隧道下穿既有铁路施工会扰动周边地层,进而引发周边地层损失和土体固结沉降,应采取可靠的工程措施来确保隧道上方既有铁路运营安全。依托某新建城际铁路盾构隧道下穿既有铁路工程,通过对国内类似工程的广泛调研,阐述盾构隧道下穿既有铁路的变形控制标准,提出“既有铁路线路加固、铁路限速通行、加强盾构施工控制及监控量测,地层跟踪注浆加固,信息化施工、盾构隧道结构和防水加强、铁路轨道应急调整”的综合性铁路安全保护措施。同时,为深入研究盾构隧道下穿施工对既有铁路的影响,采用三维有限元数值分析方法进行模型假设和施工过程模拟,得出轨道最大沉降为3.62 mm。并通过施工过程中及工后既有铁路设备设施监控量测数据,验证提出的铁路安保措施和数值分析结果的可靠性,实测轨道最大沉降为2.98 mm。结果表明,盾构隧道下穿既有铁路满足规范变形控制及相关技术管理要求,现场监控量测数据与有限元数值分析结果吻合,工程措施得当,施工对地层扰动较小,既有铁路设备、设施均处于安全可控状态。

超临界火电机组升降负荷的压力偏差控制研究

针对超临界火电机组运行过程中频繁启动和停止、快速升降负荷,以及一次风压的波动等导致的压力偏差问题,研究了一种超临界火电机组升降负荷的压力偏差控制技术。利用广义回归神经网络,计算超临界火电机组蒸汽流量值。通过流量与压力之间的转换,将蒸汽流量值转换为实际蒸汽压力值。计算实际蒸汽压力值与可容忍压力限值之间差值,得到压力偏差。以压力偏差为输入,利用改进的比例积分微分(PID)控制器得到控制量。结合升降负荷压力偏差的调整过程,实现对超临界火电机组升降负荷过程中的压力偏差控制。试验结果表明:所提技术应用后,两种工况下的机组升降负荷压力偏差一直控制在阈值1.5 MPa之下。该研究实现了超临界火电机组升降负荷过程中的压力偏差控制效果优化。

Fault Detection Based on Hierarchical Cluster Analysis in Wide Area Backup Protection System

In wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be discriminated quickly and defined exactly. In our study, global information will be introduced into the backup protection system. By analyzing and computing real-time PMU measurements, basing on cluster analysis theory, we are using mainly hierarchical cluster analysis to search after the statistical laws of electrical quantities' marked changes. Then we carry out fast and exact detection of fault components and fault sections, and finally accomplish fault isolation. The facts show that the fault detection of fault component (fault section) can be performed successfully by hierarchical cluster analysis and calculation. The results of hierarchical cluster analysis are accurate and reliable, and the dendrograms of hierarchical cluster analysis are in intuition.

Reliability of Substation Protection System Based on IEC61850

Although the new technology of protection and automation system of substation based on IEC61850 standard has developed rapidly in China,reliability measures depending on this technology need to be further researched.By taking advantage of convenient information sharing,two kinds of new schemes,shared backup protection unit(SBPU)and signal backup(SB),have been proposed to solve the failure problem of protective devices and current/voltage transducers respectively,and the working principle of these two schemes are also described.Furthermore,the key technologies of on-line diagnosis of protective devices'failure and on-line status diagnosis of optical or electronic current/voltage transducers to realize the two schemes are proposed.

Analysis on Structural Control of Coal Distribution in the Northern Qaidam Basin,NW China

The distribution of the Jurassic coal measures in the northern Qaidam Basin is obviously controlled by the regional structures. Based on the existing data of coalfield exploration and combined with the analysis of coalfield basement structures, features of the main faults, and the distribution of coal measures, this paper brings forward a scheme of coalfield tectonic divisional units and the definition of the coal-controlling structural styles in the northern Qaidam Basin. The structure control of the distribution of coal measures is further discussed. Several stages of regional tectonic activities since the Indosinian has led to the distribution of coal measures into the characteristics of zonation from the north to south and block from east to west. The results indicate that the structural deformations are the most intense in the front of the three uplifted belts, which are characterized by the combination of thrusts. The coal measures are uplifted to the shallow formations, and are easy to be exploited, but the scale of mines is small because of serious damages by the coal distribution. On the contrary, the stress and strain are weak in the three depressions, with the coal-controlling structural styles being mainly the thrust-fold and thrust-monocline combinations. The distribution of coals in the depressions is relatively stable. The shallower part of the depression will become the key areas for exploration and development of coal resources in the northern Qaidam Basin.

An Improved Torque Sensorless Speed Control Method for Electric Assisted Bicycle With Consideration of Coordinate Conversion

In this paper,we propose an improved torque sensorless speed control method for electric assisted bicycle,this method considers the coordinate conversion.A low-pass filter is designed in disturbance observer to estimate and compensate the variable disturbance during cycling.A DC motor provides assisted power driving,the assistance method is based on the realtime wheel angular velocity and coordinate system transformation.The effect of observer is proved,and the proposed method guarantees stability under disturbances.It is also compared to the existing methods and their performances are illustrated through simulations.The proposed method improves the performance both in rapidity and stability.

基于变形影响的基坑邻近建筑保护措施研究

城市土地资源的紧张促进了城市地下空间的开发,同时,大量的基坑工程紧邻既有建构筑物,为工程建设带来极大的挑战。随着深基坑的设计理念由“强度控制”转变为“变形控制”,周围既有建筑的保护成为基坑工程中的重点问题。为确保深基坑邻近建筑的安全,综合大量文献资料,总结了深基坑施工引起的建筑变形特征、来源、影响因素和预测方法,基于建筑变形影响因素对目前建筑保护的主要措施和手段进行了分析整理,探讨了各项措施的适应性,结合基坑工程的勘察、建筑保护方案设计、基坑工程施工和信息化施工监测提出了基坑邻近建筑保护综合体系,以期为相关工程和研究提供参考与建议。

江苏省平原水网区河湖生态水位确定探索与实践

保障河湖生态流量,事关江河湖泊健康。本文在分析江苏平原水网区域特点的基础上,选择生态水位作为河湖生态流量的表征指标,根据水利部确定的江苏省26条全国生态流量保障重点河湖名录,科学选定控制断面,采用1990—2020年水文序列资料,选用Qp法分析计算90%、95%、99%保证率下的水位,同步对比分析近10年最枯月水位、最低通航保证水位,最终确定了26条河湖的生态水位。通过制定保障措施方案、开展监测预警评估、强化统一调度管理等措施,全面保障区域河湖生态水位,为平原水网地区河湖生态水位的确定与保障提供了经验。

新生儿重症监护病房肺炎克雷伯菌医院感染暴发事件的调查与防控

目的调查一起在新生儿重症监护病房(NICU)发生的肺炎克雷伯菌(KP)医院感染暴发事件,评价控制措施实施效果,为医院感染防控提供依据。方法采用流行病学调查和环境卫生学监测方法对2020年6-8月在NICU检出KP的患者进行原因分析并采取控制措施。结果14例检出KP的患者中,9例医院感染,KP引发的医院感染例次率高于3-5月(P<0.05)。84份环境卫生学标本,2份标本检出KP。采取综合性与针对性控制措施后,复查未检出KP,9-11月医院感染例次率显著下降(P<0.05)。结论本次事件推测为外源性的KP定植于电热烧水器托盘,经由医务人员手或水杯等物品直接或间接接触传播。通过查找感染源,采取集束化、针对性干预策略,有效控制医院感染的蔓延。