Design of Power Supply for On-line Monitoring System of Transmission Lines

This paper uses CT to gain the energy directly from the high-voltage transmission line, to address the problem of power supply for monitoring system in high voltage side of transmission line. The draw-out power coil can induce voltage from the transmission line, using single-chip microcomputer to analog and output PMW wave to control the charging module, provides a stable 3.4 V DC voltage to the load, and solve the problem of easy saturating of core. The power supply based on this kind of draw-out power coil has undergone the overall testing, and it is verified-showing that it can properly work in a non-saturated status within the current range of 50 - 1000 A, and provide a stable output. The equipment also design protection circuit to improve the reliability to avid the impacts of the impulse current or short-circuit current. It effectively solves the problem of power supply for On-line Monitoring System of Transmission.

Long-pulse power-supply system for EAST neutral-beam injectors

The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP（Institute of Plasma Physics, Chinese Academy of Sciences）： one for the neutralbeam test stand and two for the EAST neutral-beam injectors（NBI-1 and NBI-2, respectively）. Each power supply system consists of two low voltage and high current DC power supplies for plasma generation of the ion source, and two high voltage and high current DC power supplies for the accelerator grid system. The operation range of the NB power supply is about 80 percent of the design value, which is the safe and stable operation range. At the neutral-beam test stand, a hydrogen ion beam with a beam pulse of 150 s, beam power of 1.5 MW and beam energy of 50 ke V was achieved during the long-pulse testing experiments. The result shows that the power-supply system meets the requirements of the EAST-NBIs fully and lays a basis for achieving plasma heating.

Scheme of long distance power supply for electrified railway traction network based on traction cable

Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This paper aims to study the scheme composition and power supply distance(PSD)of the scheme.Design/methodology/approach–Based on the structure of parallel traction network(referred to as“cable traction network(CTN)”),the power supply modes(PSMs)are divided into cableþdirect PSM and cableþautotransformer(AT)PSM(including Japanese mode,French mode and new mode).Taking cableþJapanese AT PSM as an example,the scheme of long distance power supply for CTN under the PSMs of co-phase and out-of-phase power supply are designed.On the basis of establishing the equivalent circuit model and the chain circuit model of CTN,taking the train working voltage as the constraint condition,and based on the power flow calculation of multiple train loads,the calculation formula and process for determining the PSD of CTN are given.The impedance and PSD of CTN under the cableþAT PSM are simulated and analyzed,and a certain line is taken as an example to compare the scheme design.Findings–Results show that the equivalent impedance of CTN under the cableþAT PSM is smaller,and the PSD is about 2.5 times of that under the AT PSM,which can effectively increase the PSD and the flexibility of external power supply location.Originality/value–The research content can effectively improve the PSD of traction power supply system and has important reference value for the engineering application of the scheme.

Design of a Bandgap Reference with a Wide Supply Voltage Range

An on-chip voltage reference with a wide supply voltage range is required by some applications,especially that of power management （PM） controller chips applied to telecommunication, automotive, lighting equipment, etc., when high power supply voltage is needed. Accordingly,a new bandgap reference with a wide supply voltage range is proposed. Due to the improved structure,it features a high power supply rejection ratio （PSRR） and high temperature stability. In addition, an auxiliary micro-power reference is introduced to support the sleep mode of the PM chip and reduce its standby power consumption. The auxiliary reference provides bias currents in normal mode and a 1.28V reference voltage in sleep mode to replace the main reference and save power. Simulation results show that the reference provides a reference volt- age of 1.27V,which has a 3.5mV drift over the temperature range from -20 to 120~C and 56t^V deviation over a supply voltage range from 3 to 40V. The PSRR is higher than 100dB for frequency below 10kHz. The circuit was completed in 1.5tzm BCD （Bipolar-CMOS-DMOS） technology. The experimental results show that all main expectations are achieved.

Application of InSAR in Surface Deformation Monitoring of Electric Power Line Selection

In the process of site selection and the facility construction in power engineering, the geological conditions of the foundation have an important impact on the displacement of completed power facilities. Usually, the conventional surface displacement has certain continuity in time and space. Therefore, in the initial stage of power line selection, the relatively stable geological conditions can greatly reduce the probability of major accidents due to ground deformation. As a new surface displacement monitoring method, InSAR can obtain the displacement monitoring results in long time series. This paper used 20 Sentinel-1A data to study the geological conditions of power line selection. Based on the fact that the vegetation coverage in the line selection area and the poor penetration of C-band data may cause serious body scattering correlation, we verified the possibility of obtaining accurate results in a long-time baseline with less influence on volume scattering decorrelation. Using this method, we obtained the surface history displacement line chart of the 220 kV power line to be erected in Laiyuan to Quanyu, Hebei Province. By analyzing 10 high coherence points on the line, we found that the largest historical surface displacement in the 18 months is less than 30mm, and the maximum cumulative deformation rate is only 12 mm/a, which meets the requirements of power line erection.

基于多导体回路法的AT供电方式长回路电容计算方法研究

提出了一种基于多导体回路法以接触网和正馈线为传输导体的电气化铁路AT供电方式牵引网长回路电容计算方法。该方法以与电荷唯一对应的回路为基本单元,对复杂多导体传输线系统开展电场描述,实现了AT供电方式牵引网长回路电容的精确计算。

Study of Lightning Damage Risk Assessment Method for Power Grid

Based on the idea of risk evaluation, the existing lightning damage risk assessment methods are reviewed and summarized in this paper. And the power grid lightning damage risk assessment system is established on the basis of lightning flashover risk evaluation methodology for transmission lines, and adopts the improved Analytic Hierarchy Process as the core algorithm. It can comprehensively evaluate the risk for transmission lines of regional grid, various sections of a line and each tower of the section, considering much more impact factors, including the running time of line, importance of grades, equipment damage, and the success rate of lightning stroke reclosing and so on. According to the calculation results of the risk assessment of the analytic hierarchy process and lightning flashover risk evaluation, the principles and methods of grade classification for power grid lightning damage risk map are studied, and give typical examples in the paper. It can describe the lightning withstanding ability much more scientifically and provide important references for the manage department of power system.

A New Fully Differential Adaptive CMOS Line Driver Using Fuzzy Controller Suitable for ADSL Modems

In this paper, a new principle for an adaptive line driver using Fuzzy logic is presented. This type of line driver can adapt its output impedance and gain, automatically to the applied load using a fuzzy logic controller (FLC). This results in automatically corrected output impedance for different cables with terminations. Also, the line driver output impedance and gain become insensitive to process and line variations. As an example, a line driver for ADSL application has been designed. The circuit operates from a 3.3 v in a 0.35 um standard CMOS technology. The power consumption of FLC is about 1 mW. The circuit dissipates 106 mW and exhibits a -62 dB THD for a 3.2-Vpp signal at 5 MHz across a 75 ohms Load. It has a relatively high -3 dB bandwidth (240 MHz) with good phase margin of about 67 degrees in a 10 pF load capacitor.

Childhood Leukemia Not Linked with ELF Magnetic Fields

The discussion whether extremely low frequency (ELF) magnetic fields (MF) are causally linked with childhood leukemia is ongoing for almost four decades. Results of epidemiologic studies have indicated such an association might exist and led to IARC’s classification of ELF MF as possibly carcinogenic (class 2B). Although in the meanwhile many epidemiologic studies and meta-analyses of selected studies are available, this did not change the situation. By a new approach of pooling all epidemiologic data, this paper shows that it is possible to come to a convincing conclusion which explains controversial results and reports dose-response relationship, and provides answers to striking facts such as that epidemiologic results on childhood leukemia are independent from field source or exposure metric of whatever kind with no specific favorite. The analysis revealed that the assumption of a causal link between ELF MF exposure and childhood leukemia is no longer plausible and hence that ELF MF’s classification as possibly carcinogenic needs revision.

地铁行业20 kVA以下UPS的离线式维修策略

针对地铁行业UPS(不间断电源)的故障量不断上升的问题,为了减少UPS的故障量,保证地铁的正常运营,提出了一种适合地铁行业的20 kVA以下UPS的离线式维修策略。首先简单介绍UPS的基本模块和工作模式;然后列举UPS的4个常发故障点,包括:电解电容、聚丙烯电容、IGBT、风扇,分析常发故障点的故障原理,预测其使用寿命;再结合地铁的实际生产环境制定UPS的维修方式;最后制定了地铁20 kVA以下UPS的离线式维修策略。将该UPS维修策略应用在广州地铁站台门专业的UPS,减少UPS的返修率和故障数量,提高UPS的维修质量,保障广州地铁的正常运营,实现预期目标。

基于PCA-OLS模型的系统等效惯量中长期预测

为综合考虑多重影响因素与系统等效惯量之间的量化关系,本文提出一种基于主成分分析-普通最小二乘法的系统等效惯量中长期预测模型。根据电网实际调度规则搭建简化的开机方式优化模型,构建系统等效惯量中长期预测历史数据集;利用主成分分析对系统等效惯量主要影响因素的多重共线性进行消除,得到主成分表达式;进行多元普通最小二乘法回归,反标准化后得到系统等效惯量解析模型。根据某电网能源发展规划数据,对未来系统惯量水平进行推演,可快速预估不同运行方式下系统等效惯量的演化趋势及非同步电源承载能力。

基于DGA技术的牵引变压器在线监测系统

为了确保高速铁路安全运行,实时监测牵引变压器运行状态,及时地发现牵引变压器内部故障具有重要的意义。文章在分析牵引供电系统运行可靠性要求和牵引变压器故障诊断要求的基础上,提出了基于DGA技术的牵引变压器在线监测的构想,并设计了相应的TTM-Ⅰ型牵引变压器在线监测系统,实现了对牵引变压器运行状态的不间断监测。现场运行数据与实验室数据的比较验证了该系统的有效性。

基于Tesla变压器和螺旋线的长脉冲发生器

提出了一种结构紧凑的长脉冲发生器,该发生器的螺旋型形成线包含有磁性材料构成的内导体棒和外屏蔽。形成线通过内置的高耦合Tesla变压器充电,变压器的初级线圈紧靠外磁芯导体,次级线圈位于螺旋中筒和外筒之间。对这种结构的螺旋线进行了特征参数的理论计算和波传输数值模拟,并进行了简单的原理验证实验。实验结果表明:这种设计是合理的、可行的。

AT供电系统接触网在线防冰电流的决策与控制

为了保障行车安全,消除接触网覆冰,针对电气化铁路AT(autotransformer)供电系统特殊的长回路和短回路结构,建立防冰系统投入后AT供电系统的电路模型.用该模型分析各AT段内防冰电流和负载电流的分布,得到保障全线防冰所需电流值;根据防冰电流与供电臂末端电压的关系,得出了牵引网压允许的防冰电流值;在此基础上,制定了以温度为目标的在线防冰电流决策流程.以某AT供电区段为例,结合实测负荷数据进行了仿真,结果表明:投入的防冰电流值至少为接触网临界防冰电流值的2倍,才能使接触线表面温度维持在0℃以上.

ADCP流速仪检定拖车驱动方案探讨

近年ADCP流速仪在国内应用不断增多，急需建设可以检定ADCP流速仪的检测平台规范水利行业产品应用。ADCP流速仪检定水槽的长、宽、深等尺寸设计，必须根据ADCP流速仪产品特点进行专门设计。相比以往检定水槽，ADCP水槽的宽度增加很多，相对应的检定拖车的跨度也会增加很多，导致检定拖车的车重增加很多，而大型检定拖车的驱动设计方案是系统设计成败的关键。根据ADCP流速仪检测特点，该文提出基于交流伺服同步电机的ADCP流速仪检定拖车混合动力驱动（4马区／2驱）设计方案：高速段（0．2～6m／s）采用四轮驱动，低速段（0．01-0．2m／s）采用2轮驱动，很好地解决工作速度段大跨度下速度准确度控制难题，满足ADCP流速仪不同速度段检定需求。

基于CAN总线的煤矿供电系统线路保护装置设计

设计了一种对煤矿供电系统输电线路进行保护的装置.该装置以32位ARM处理器MB9BF518S为控制核心,以CAN总线为通信网络,实现了对煤矿供电系统输电线路电压、电流、有功功率、无功功率等参数的测量和监控,并可以对输电线路发生的短路、过电流、低电压等故障进行有效的保护.叙述了保护装置的总体功能和基本结构,给出了信号变换电路、CAN总线接口电路和开关量输入电路的设计方案,分析了电流速断保护和反时限过流保护的保护逻辑,并给出了保护装置的部分测试数据.该保护装置结构简单、操作方便、可靠性高,能够满足煤矿供电系统对输电线路保护的要求.

基于横联线电流比原理的全并联AT牵引网故障测距装置

全并联AT(Auto-transform er)供电牵引网发生故障后,能够快速准确判断出故障类型,标定故障点位置对确保电气化铁路安全可靠运行是至关重要的。通过分析全并联AT(Auto-transform er)供电牵引网各种故障线路满足的电量方程,得到故障测距用横联线电流比原理。以典型的全并联AT供电方案为例,详细讨论了由工程实际中能测量到的电气量计算出测距公式中所需物理量的方法,提出了装置起动及数据同步原理,给出了故障测距的系统实现方案,基本上解决了各种故障类型的判断,故障点标定问题。

基于MATLAB/Simulink的客运专线牵引供电系统建模

以国内客运专线牵引供电系统为研究对象,制定牵引供电系统分解原则,按照模块化设计的方法,基于MATLAB/Simulink建立客运专线牵引供电系统的仿真模型,为用作牵引供电系统负载状态数字仿真搭建实验平台。

基于MATLAB的电力系统短路故障仿真分析

超高压输电线路和电力供配电系统对电力系统的安全稳定运行影响极大。设计使用MATLAB/Simulink电力系统工具箱搭建超高压输电线路和无限大功率供配电系统仿真模型,在仿真模型下对系统发生三相短路和不对称短路故障时的故障特征量以及出现的序分量特征量进行分析,仿真结果验证了系统模型的正确性,可以作为系统发生短路故障分析的依据。

光伏电站供电线路绝缘皮破损漏电故障无人机巡检研究

由于光伏电站供电线路存在的电磁辐射问题,对无人机巡检的飞行过程造成了一定的干扰,影响了巡检结果的有效性。为了缓解电磁干扰问题,提出了光伏电站供电线路绝缘皮破损漏电故障无人机巡检方法的研究。解析光伏电站环境下的供电线路电磁干扰强度及其衰减特性,结合巡检需求,确定无人机的视野范围,以此规划无人机巡检的路径。获取该路径下的巡检图像数据并修正其畸变问题,通过二值化处理提取识别并提取绝缘皮破损漏电范围的边缘点。在此基础上,根据线路参数计算得出漏电故障的状态参数。经过测试可知,该方法在实践应用中得出的巡检结果,所表现出的准确度更高,有效性更好,满足了光伏电站供电线路的安全运维需求。