Effect and mechanism of on-chip electrostatic discharge protection circuit under fast rising time electromagnetic pulse

The electrostatic discharge(ESD)protection circuit widely exists in the input and output ports of CMOS digital circuits,and fast rising time electromagnetic pulse(FREMP)coupled into the device not only interacts with the CMOS circuit,but also acts on the protection circuit.This paper establishes a model of on-chip CMOS electrostatic discharge protection circuit and selects square pulse as the FREMP signals.Based on multiple physical parameter models,it depicts the distribution of the lattice temperature,current density,and electric field intensity inside the device.At the same time,this paper explores the changes of the internal devices in the circuit under the injection of fast rising time electromagnetic pulse and describes the relationship between the damage amplitude threshold and the pulse width.The results show that the ESD protection circuit has potential damage risk,and the injection of FREMP leads to irreversible heat loss inside the circuit.In addition,pulse signals with different attributes will change the damage threshold of the circuit.These results provide an important reference for further evaluation of the influence of electromagnetic environment on the chip,which is helpful to carry out the reliability enhancement research of ESD protection circuit.

A Novel Discrete Branch Bidirectional Solid-State Circuit Breaker based on Mixture Device

Solid state circuit breakers(SSCBs)based on fullcontrolled devices such as IGBT and based on half-controlled devices such as thyristor have their respective advantages.The mixture device solid state circuit breaker(M-SSCB)combines the advantages together and can achieve lower loss,high efficiency,active and reliable blocking at the same time.However,the conduction loss will increase significantly when the topology expanding to a bidirectional topology because the bidirectional line commutation switch(LCS)structure composed of two groups of IGBTs in reverse series.In this paper,a novel discrete branch mixture SSCB(DBM-SSCB)is proposed,bidirectional current only flows through one IGBT that has the obvious conduction losses advantage at the same voltage and current level.Only one energy-absorbing component is shared by two discrete branches can guarantee optimal costs and volume.By calculation,the proposed DBM-SSCB can reduce the conduction loss about 30.4%in 10 k V MVDC system,while retaining other advantages of the mixture device SSCB,such as without introducing additional thyristors,charging power supply and the ability to actively interrupt bidirectional fault currents.The blocking principles and designing guidelines are presented in detail,the feasibility is verified by 500 V-18 A simulation results and scale-down experiment,the engineering calculation and simulation of 10 k V-1 k A prototype is completed and compared with other DCCBs.Experimental results and comparative analysis show that the proposed DBM-SSCB has both lower losses and significant performance advantages thus has a good engineering application prospect.

智能变电站继电保护二次虚回路失效风险动态识别技术

继电保护二次虚回路出现失效风险,会给保护功能造成隐患,影响继电保护系统安全可靠运行。为了解决该问题,提出虚回路失效风险动态识别技术,系统性预警虚回路失效风险,及时发现虚回路故障。首先,通过分析虚回路对象,梳理虚回路显性缺陷和隐性缺陷,构建二次虚回路失效风险预警技术架构。关键技术包含二次回路链路故障识别和二次回路功能故障识别。对于二次回路链路故障识别,通过装置断链告警处理、端口光功率分析、光纤损耗评估等技术监测端口,并通过判据监测异常报文。对于二次回路功能故障识别,监测保护功能有关的跳合闸回路、检修压板状态、虚回路软压板状态。最后,通过智能录波器的技术应用,验证该技术可行、方法正确。该技术为继电保护智能运维在虚回路失效风险方面提供助力,具备很好的实用价值。

基于同源录波数据比对的继电保护采样回路异常检测方法

处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检测方法。首先,利用双向编码器表征(bidirectional encoder representations from transformers,BERT)语言模型与余弦相似度算法,实现同源录波数据的通道匹配。然后,利用重采样技术和曼哈顿距离完成波形的采样频率统一与时域对齐。最后,基于动态时间规整(dynamic time warping,DTW)算法提出改进算法,并结合采样点偏移量共同设置采样回路的异常判据。算例分析表明,该方法可以完成录波数据的同源通道匹配,实现波形的一致性对齐,并且相比于传统DTW算法,改进DTW算法对异常状态识别的灵敏性和准确性更高。根据异常判据能够有效检测继电保护采样回路的异常状态,确保了智能变电站的安全可靠运行。

电源端口雷击和暂态过电压综合防护方案

介绍了电子通讯产品在易发生供电故障和易受雷击的供电环境下,电源端口雷击和暂态过电压的综合防护解决方案。该解决方案将雷击防护与暂态过电压防护有机结合,智能检测判断过电压是雷击还是暂态过电压,并及时启动防护功能,防止电源损坏等严重故障。该方案还可实现防护后自动恢复供电和远程控制供电,在复杂供电环境中保障供电安全和设备不被损坏,有很大的推广价值。

一起套管故障引起的500 kV变压器跳闸事故分析

针对某500 kV变电站一次中压侧套管故障引起的自耦变压器三侧断路器跳闸事故,结合站内保护跳闸报告及故障录波文件,对该次事故各保护动作行为正确性进行判别。对各TA电流相位进行对比,并计算差动电流、制动电流,分析确定故障点位置位于中压侧套管及套管故障点发展转移过程,并对变压器分侧差动保护不动作的原因进行详细分析,为相关技术人员提供自耦变压器中压侧近区故障的保护动作分析经验,提高电网运行管理水平。

一种微机保护收回跳闸命令的设计方案

输电线路绝大多数故障均为单相瞬时性故障,微机线路保护装置在切除故障后收回跳闸命令,自动重合闸装置对断路器重合提高供电连续性和可靠性。单相跳闸命令不收回会造成单跳失败三跳动作,保护装置将发三跳、闭锁重合闸等命令执行相关逻辑,将造成输电线路单相瞬时性故障重合闸不动作,降低了电力系统供电连续性和可靠性。微机线路保护装置正确及时收回其跳闸命令对提高电力系统供电可靠性和连续性很有必要,提出对保护装置收回跳闸命令逻辑改进,自适应一次设备运行方式,提高继电保护及安全自动装置正确动作率和电力系统供电连续性、可靠性。

一起500 kV线路保护电压二次回路异常分析及处理

电压回路是500 kV线路保护的重要回路之一。以一起500 kV线路保护电压二次回路接地线误断开事件为例,分析电压回路的原理、回路接地规范,并从回路接线、回路接地点、N600走向等方面分析本起异常事件的原因以及N线电压异常原理,并给出异常处理过程。最后针对异常原因总结后续消缺工作中的排查思路和方法,为500 kV线路保护电压二次回路异常处理提供指导。

船舶直流配电系统短路保护设计

随着节能环保理念在船舶与海工领域的发展,以及新能源在船舶上的广泛应用,直流配电系统以其高效、节能、兼容性好等优点,备受船东青睐,但由于直流断路器容量有限、价格昂贵,构造与交流断路器不同,造成直流配电系统的短路保护设计与交流系统截然不同。基于采用直流配电系统的风电安装平台短路保护设计的成功案例,分析直流断路器的构造,阐述船舶直流配电系统短路保护设计的方法以及注意要点,研究成果可为直流配电系统在船舶上的应用提供参考。

基于MAP法的线路板重金属铜氨废水处理研究

随着线路板的广泛应用,其在印刷过程中产生的铜氨废水的排放问题日益突出。铜氨废水中氨氮和铜离子对环境的危害较大,为了解决该问题,提出了一种MAP法和折点氯化法相结合的方法。该方法首先向铜氨废水中加入镁盐和磷酸盐,将氨氮转化为MAP沉淀,降低铜氨废水中氨氮的浓度,同时可以将MAP回收再利用;然后向剩余浓液中加入过量的NaClO溶液,进一步将溶液中的氨氮浓度降低,随着NaClO溶液的增加,反应液会逐渐呈碱性,而Cu^(2+)在碱性环境中会与OH-生成Cu(OH)_(2)沉淀,进而降低Cu^(2+)的浓度,从而使铜氨废水中的氨氮和Cu2+的浓度均符合《中华人民共和国环境保护法》的排放要求;最后通过纳氏试剂分光光度法和火焰原子吸收光度法检验反应后浓液中氨氮和Cu^(2+)的浓度。经过验证得知,该方法可以显著降低氨氮和Cu^(2+)的浓度。

Research on the overload protection reliability of moulded case circuit-breakers and its test device

This paper analyzed the reliability and put forward the reliability index of overload protection for moulded case circuit breaker. The success rate was adopted as its reliability index of overload protection. Based on the reliability index and the reli- ability level, the reliability examination plan was analyzed and a test device for the overload protection of moulded case cir- cuit-breaker was developed. In the reliability test of overload protection, two power sources were used, which reduced the time of conversion and regulation between two different test currents in the overload protection test, which made the characteristic test more accurate. The test device was designed on the base of a Windows system, which made its operation simple and friendly.

Study on the instantaneous protection reliability of low voltage circuit breakers

This paper outlines the significance of enhancing the instantaneous protection reliability of low voltage circuit breakers and describes their main failure modes. The instantaneous failure mechanism of low voltage circuit breakers was analyzed so that measures to improve instantaneous protection reliability can be determined. Furthermore, the theory of the instantaneous characteristics calibration device for low voltage circuit breakers and the method of eliminating the non-periodic component of test current are given in detail. Finally, the test results are presented.

A Novel Crowbar Impulse Current Circuit for Testing the Switch-Type SPD

A crowbar impulse current circuit for testing the switch-type surge protective device （SPD） is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main discharging switch, and a crowbar pseudospark switch. The active trigger technology was studied in the crowbar impulse current circuit. The circuit monitors the main discharging current and generates a trigger signal at a proper time for the crowbar pseudospark switch operation. The trigger characteristics of the main discharge switch and the crowbar pseu- dospark switch were investigated. By monitoring the preset applied capacitor voltage, the gap distance of the main discharging switch could be adjusted to ensure a discharging delay time less than 2 μs. Equipped with a surface ttashover trigger device made of high relative perimittivity dielectric material BaTiO3 （εr = 3460）, the discharge delay time of the crowbar pseudospark switch is less than 85 ns, and the minimum operating voltage is less than 1% of its self-breakdown voltage. With a storage capacitor of 9 μF , an inductor of 18 μH and a crowbar pseudospark switch, a load of 30 mΩ and an applied capacitor voltage of 40 kV, an impulse current waveform of maximum 25 kA was generated with a rise time and time to half peak value of 17.2 μs and 336μs respectively.

A New Method of Early Short Circuit Detection

To reduce the pressure on contacts and circuit breaker and realize the zone selective interlocking (ZSI) function above the instantaneous protection threshold (e.g., >10In), the short circuit current needs to be early detected. The state-of–art of early short circuit detection (ESCD) method is reviewed. Based on the equivalent model of the short circuit, a new method based on the current and its integration is proposed. The prospective current value can be detected in the early stage of the short circuit. According to the evaluation result, the short circuit current can be early forecasted with the proposed method.

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.

Process Analysis of Double Circuit Transmission Line Trip-out on the Same Tower Due to Lightning

In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.

Protection of ±500 kV HVDC Double-circuit Converter Station from Lightning Induced Overvoltage

In order to obtain reasonable schemes of arrester in converter stations, the arrester scheme of "Xiluodu-Guangdong HVDC ± 500 kV double circuit transmission" project against lighting induced overvoltage, which was designed according to the main principle of lightning protection in converter station, is discussed. A calculation of the lighting induced overvoltage in Zhaotong converter station un- der various operation modes is performed with ATP-EMTP software, then the surge arrester configuration of the converter station is decided, and the arrester protection schemes of smoothing reactor and neutral line are studied. It is concluded that additional protection is necessary because of the relatively large gap between protected disconnecting switch and arrester of metallic return transfer bus. Plus, the smoothing reactor (SR) arrester near the valve hall could be removed to improve the scheme’s economic performance.

Output Circuits of Multi-step Temperature Control System

We have finished the research and development of multi-step temperature control system.The output circuits implement the interface between the control system and oven. It receives pulsed signals for increasing or decreasing temperature from MCS-8051.The circuit diagram is shown as follows.

ESD Protection Design and Characteristic Analysis of Advanced Process Integrated Circuit

The electrostatic discharge(ESD)phenomenon is very common,in daily life,many places will appear ESD phenomenon.However,ESD is a potential hazard for integrated circuits.This paper analyzes the ESD protection design and characteristics of advanced process integrated circuits,and puts forward personal views combined with experience,hoping to bring help to the people who pay attention to the ESD protection of integrated circuits.

Research on IGBT Drive Circuit Based on 2QD30A17K-I Driver

The insulated gate bipolar transistor(IGBT) has become the most popular controllable power switching device in the design of power electronics industry.As the interface of power circuit and control circuit in power source, the IGBT drive circuit should be with short transition time and the function of isolating safely and monitoring correctly the short-circuit and over-voltage fault.This paper presents the short-circuit protection theory and relative parameter selecting rules,based on the research on 2QD30A17K-I,the representative of high voltage and high power driver.