Cathodic protection of existing URD systems

The corrosion control experiences of the author with underground rural distribution (URD) systems are presented. The discussion includes (1) survey testing procedures, (2) designing of cathodic protection (CP) systems, (3) criteria for selecting material, (4) installation and maintenance procedures of CP systems, and (5) an economical evaluation of CP system installations. It is the opinion of the author that impressed current systems, supplemented by galvanic sacrificial anodes, can provide economical corrosion protection for existing direct-buried copper concentric neutral wires     

循环水泵外加电流阴极保护的应用探索

金属跟电解质溶液接触时,会发生原电池反应,比较活泼的金属失去电子而被氧化,这种现象叫做电化学腐蚀,如能阻止这一电化学反应,就可以抑制金属的电化学腐蚀。外加电流阴极保护是对被保护金属结构提供直流阴极保护电流,迫使电流从阳极区流向被保护金属结构,使金属结构得到阴极极化,当极化到阴极区和阳极区的电位差为零时,腐蚀电流消失,从而抑制了腐蚀过程,达到保护金属结构的目的。     

The Control of Metallic Corrosion of Cement Plant Facilities

An overview of the fundamentals of metallic corrosion and commonly used methods for corrosion control are presented. A specific example of accelerated corrosion damage to the underground structures at a western cement manufacturing plant is provided. The installation of a cathodic protection system to prevent corrosion damage to buried structures at the plant is also described.     

电热水器内胆腐蚀机理及实施阴极保护综述

就电热水器内胆的腐蚀机理、阴极保护原理、阳极材料及规格的选择、安装方法等进行简要的综述。     

Corrosion and Grounding Systems

Corrosion that occurs in the presence of dissimilar metals in the same electrolyte, or same metal in different electrolytes, or in different concentrations of the same electrolyte, has caused numerous problems in operating electric systems. This corrosion is the result of a potential difference existing between two surfaces which forces an electric current to flow. This effect is often ignored or overlooked in electrical grounding design, with the premise that electrical system protection will be hampered by the incorporation of corrosion protection. By careful design, however, both sets of requirements can be met. Some of the principles that determine corrosion and how these conditions exist in underground systems of cement plants are reviewed. The principles of grounding design are analyzed and suggestions to improve the design to minimize corrosion are discussed.     

城市轨道交通杂散电流治理的综述与评估

杂散电流会造成电气化交通系统附近金属结构腐蚀,该现象在普遍采用直流牵引供电的城市轨道交通中尤为突出.该文分别对城市轨道交通新建线路和运营阶段的现有线路的杂散电流治理和防护措施进行讨论.对设计阶段的新建线路而言,可采用包括优化牵引变电所位置、减小轨道纵向电阻、在道床中安装杂散电流收集系统等措施.对处于运营阶段的现有线路而言,除了采取在走行轨上并联线缆或走行轨间焊接均流线等以增大回流路径截面积措施外,通过电力电子的静止变换器(如负阻变换器等)控制回流路径杂散电流的方法也是极具潜力的治理措施;上述单元可以部署在特定点,以实现对轨道电位过高或出现初期腐蚀位置处的定点治理.     

接地网外加电流阴极保护技术研究与应用

接地网腐蚀对电网安全稳定运行有较大影响.研制了一种基于模块化设计的新型接地网防腐蚀保护及监控装置,包括外加电流阴极保护单元、接地网腐蚀余量检测单元以及基于3G或WIFI的无线数据传输及远控单元.实现了接地网保护和监控的智能化,满足无人值守的要求.     

Corrosion Control in Electric Power Systems

The electrochemical mechanism of aqueous corrosion is outlined, and it is demonstrated that the process depends on a complex interaction between the material and its environment given the particular circumstances of exposure. Failure to recognize the full implications of the environment or the circumstances will often lead to unexpected corrosion failure. The technique for controlling corrosion are subdivided into material selection, coatings, electrical insulation, cathodic protection, etc. Each technique is described and explained. The need to apply a considered corrosion control package, rather than the use of a single technique, is stressed.     

接地网阴极保护法的优化控制

采用电化学方法测量镀锌钢和碳钢电极在不同的电位下电化学阻抗谱,可以确定其阴极保护参数和最佳保护电位。通过实际应用,进一步证明了采用电化学阻抗谱测试的方法来研究阴极保护的最佳保护电位,简单可行,对防止接地网的腐蚀、延长接地网的服务寿命、保证接地装置的安全运行意义重大。外加电流阴极保护法采用远程控制,有效地降低了后期的运行维护费用。     

Choices of Jacketed or Bare Concentric Neutral Cable for Effective Grounding and Corrosion Control

New types of underground corrosion have been experienced following widespread use of direct-buried cables for electric power distribution at 7.2/12.47 and 14.4/24.9kV. Alternatives that should be considered in selecting types of cable and corrosion control measures for underground electric facilities are discussed. The choices are examined in light of the permanence of other buried metal connected to the electric neutral wires, as well as possible corrosion of the copper neutral wires.     

锁相技术在FSM管道腐蚀测量中的应用

基于电位阵列的金属管道(容器)在线腐蚀检测方法称为场指纹法(field signature method,FSM).FSM是一种新型的石油、天然气管道腐蚀监测技术.它通过检测管道外部两两电极间电位差的变化,来判断管道的腐蚀情况.由于电极间的电位差极其微弱(30～60 μV),因此微弱信号的测量精度决定了腐蚀检测的精度.锁相放大技术是一种提取淹没在噪声中微弱信号的重要手段,广泛用于微弱信号检测系统中.介绍锁相放大技术的微弱信号检测电路的设计以及在FSM管道腐蚀测量系统的应用,同时针对测量信号是低频的特点,在系统中采用数字与模拟相结合的方法,大幅度提高了其测量精度以及稳定性,达到了项目的要求.     

考虑系统静态电压稳定性的电动汽车充电设备 就地控制方法研究

随着电动汽车的大规模发展,其峰值充电负荷占全网负荷的比例日益上升,给电网的静态电压稳定带来了负面影响。试图将电动汽车充电设备纳入电力系统安稳控制,从而减少这一影响。提出了电动汽车充电设备的三种控制方法：灵敏度控制方法、理想控制方法以及下垂控制方法,并对其控制效果进行了对比。三种方法都能够达到提升系统负荷裕度的目的,但其中的下垂控制方法更适合实际控制应用。将下垂控制应用到新英格兰39节点系统,在不同渗透率和不同充电速率情况下分析其对系统电压稳定性的影响。结果表明下垂控制能够明显提高系统负荷裕度,是一种有效的电动汽车充电设备就地控制方法。     

基于多方向元件的串补线路协同保护新方法

串补线路故障特征的复杂性加大了保护装置可靠动作的难度,为提高串补系统保护可靠性,提出一种多方向元件相互配合的串补线路方向保护方案。该方案利用负序电流值及故障前后的测量电流相位差判断故障类型,针对不对称短路、三相短路及负荷变动分别采用负序、工频方向及突变量电压电流相角差判断保护装置是否动作。PSCAD仿真表明,在系统发生电压反向、电流反向、经过渡电阻接地以及负荷变化等情况下该保护方案均可准确判断故障位置,从而使保护装置正确跳闸。同时,该方案不受MOV不同导通状态的影响,具有较好的保护性能。     

一种户外端子箱驱潮防腐监控新技术的研究与应用

提出了一种户外端子箱驱潮防腐集中分散监控方法,通过实时采集箱内、外温湿度、和金属腐蚀过程中,薄层电解质液膜下电化学电池的电流信息,应用大气环境金属腐蚀临界湿度、和金属结露的原理,得出加热部件、送风部件、抽湿排水部件的控制策略,达到端子箱自动驱潮防腐的目的.研制出了端子箱驱潮防腐集中分散监控系统,该系统与常规的加热除湿装置比较,既能实时监测户外端子箱内金属腐蚀行为和结露情况,又能科学地进行控制策略优化.由于采用了ACM大气电偶电化学过程监测技术,简化了不同大气环境地域污染物及金属腐蚀程度的测定工作,通过现场运行,具有良好的驱潮防腐效果,有效地延长端子箱内设备的使用寿命.     

Control batteries: power system life savers

If protective devices and relays represent the ≫OPEN "nerves” of a medium- or high-voltage electric power system, the DC control battery distribution system represents the system's “bloodstream.” The battery distribution system delivers energy the battery provides to the control circuits of AC circuit breakers and other electrically operated interrupting equipment (the “muscle” of the electric power system), allowing operation. The battery is the DC power distribution system's “heart.” Reliable control battery systems assure proper functioning of well designed, installed, and maintained power systems. Battery system failure jeopardizes a power system by eliminating the DC control power source for AC system circuit breakers and protective devices. Failure to protect DC system components also could result in disastrous consequences for the battery system itself. The author discusses battery faults, battery protection, and battery maintenance. Battery charger faults and protection are also briefly mentioned, as are load protection, and DC system protection     

电力工程防洪标准探讨

针对现行规程规范对于各类电力工程的防洪标准规定不一致或缺失的问题,根据电力工程特点,将电力工程按规划容量或电压等级划分为三个防护等级,对于同一防护等级的不同电力工程,防洪标准取为一致,以实现统一电力工程防洪标准。相应于三级防护等级,统一后的防洪重现期分别为50年、100年和大于等于100年三档;相比现行规范,本文建议的防洪标准对于部分电力工程略有提高,但总体而言更具合理性。     

直流电位补偿法抑制变压器直流偏磁的研究

根据直流系统单极大地回线方式运行时变压器的直流偏磁原理,分析比较了现有几种抑制变压器直流偏磁的措施,运用直流电位补偿法原理进行了正、负电位补偿的模拟试验。试验表明直流电位补偿法能在一定程度上抵消系统单极运行流过变压器中性点的直流电流,抑制直流偏磁。且同等条件下正电位补偿电流的利用率大于负电位,但负电位补偿能对地网起到阴极保护作用。此外,还分析了补偿装置的布置及其对周边设施的影响,分析表明直流电位补偿法在现场实施中具有可操作性。     

大型水轮发电机集电环装置环面损蚀探究

对大型水轮发电机组集电环装置环面损蚀现象进行分析,指出其主要由机械磨损、电火花腐蚀和电化学腐蚀所致。对此提出了防治和减缓集电环环面损蚀的措施：① 选择天然石墨碳刷;② 及时消除碳刷打火现象;③ 加强停运保护;④ 改善集电环室运行环境;⑤ 保持集电环环面平整。这些措施在葛洲坝水电站125 MW机组得到应用,水轮发电机滑环运行状况有所改善,因集电环环面损蚀所引起的打火及过热情况明显减少。     

阴离子膜燃料电池阴极非贵金属催化剂研究进展

与质子交换膜燃料电池相比,阴离子交换膜燃料电池不仅能显著提高阴极氧还原反应(ORR)动力学,而且可采用非贵金属催化剂大幅降低成本和减少极板腐蚀,成为新能源领域中的研究热点。对阴离子膜燃料电池中阴极非贵金属氧还原催化剂的研究进展进行了详细评述,在此基础上提出杂原子掺杂的多孔纳米碳材料和以其为载体担载合金化的非贵金属是阴离子交换膜燃料电池阴极催化剂今后的发展方向。     

环状柔直工程直流极闭锁判据及措施量计算方法

以往常规直流与柔性直流工程的结构均为端对端或多端辐射,对应的稳定控制系统采用换流变电气量和直流极非正常停运信号作为极闭锁的判据,但该方法不适合环状结构的柔性直流输电工程应用,无法可靠地识别换流器闭锁故障。文中根据张北柔直输电工程稳定控制系统研制经验,提出一种新的适用于稳定控制的直流极闭锁判据改进方法。该判据在直流轻载时将直流控制保护的特征信号作为主要判断对象,在直流极运行功率超过10%额定功率时则将直流控制保护的特征信号结合换流变电气量作为主要判断对象,改进后的判据同样适用于特高压直流输电工程与多端环网柔性直流输电工程。同时,文中提出张北柔直输电工程稳控措施量计算方法,为后续柔性直流输电工程、特高压直流输电工程应用提供了参考。理论分析及实时数字仿真系统(RTDS)实验验证了判据的可靠性。