Fast thermal cycling-enhanced electromigration in power metallization

Multilevel interconnects used in power ICs are susceptible to short circuit failure due to a combination of fast thermal cycling and electromigration stresses. In this paper, we present a study of electromigration-induced extrusion short-circuit failure in a standard two level metallization currently used in power ICs and in particular the effect of fast thermal cycling on the subsequent electromigration lifetime. A special test chip was designed, in which the electromigration test structure is integrated with a heating element and a diode as temperature sensor in order to generate fast temperature swings and to monitor them. Experimental results showed that with the introduction of fast thermal cycling as a preconditioning, the electromigration lifetime is significantly reduced. We observed that the reduction of the electromigration lifetime depends on the stress time, temperature range and the minimum temperature. Electromigration simulations using a two-dimensional simulator confirm the extrusion short circuit as failure mechanism.     

Reliability and failure analysis of Sn-Ag-Cu solder interconnections for PSGA packages on Ni/Au surface finish

The reliability and failure modes of eutectic Sn-Ag-Cu solder joints were studied and compared to eutectic Sn-Pb-Ag ones. Two different failure modes occur: brittle fracture and fatigue. The results show that with a Ni/Au surface finish the reliability of Sn-Ag-Cu solder is much better than that of Sn-Pb-Ag solder. First, when the joint is deformed at high thermomechanical strain, the chance of brittle fracture at the Ni-Au interface is significantly reduced when using Sn-Ag-Cu solder. The reason is a reduced formation of the brittle (Au, Ni)Sn/sub 4/ intermetallic at the UBM interface, responsible for the brittle fracture mode. Second, after deformation at low thermomechanical strain, both solders fail due to solder fatigue, but the Sn-Ag-Cu shows a better lifetime. This better reliability of the Sn-Ag-Cu solder is attributed to a new solder fatigue mechanism: the crack propagates through the bulk of the solder in a web-fashion way, linking the Au-containing particles formed in the volume. This is beneficial for the joint reliability as it hinders the crack propagation.     

Backtracking search optimization based economic environmental power dispatch problems

This paper presents the solution for a nonlinear constrained multi objective of the economic and emission load dispatch (EELD) problem of thermal generators of power systems by means of the backtracking search optimization technique. Emission substance like NO_X, power demand equality constraint and operating limit constraint are considered here. The aim of backtracking search optimization (BSA) is to find a global solution under the influence of two new crossover and mutation operations. BSA has capability to deal with multimodal problems due to its powerful exploration and exploitation capability. BSA is out of excessive sensitivity to control parameters as it has single control parameter. The performance of BSA is compared with existing newly developed optimization techniques in terms quality of solution obtained, computational efficiency and robustness for multi objective problems.     

An evaluation method for power transfer capability enhanced by lightning countermeasures

Various countermeasures are taken against lightning faults in power transmission lines to decrease their occurrence and improve transmission reliability. However, how much they enhance the power transfer capability has not yet been quantitatively evaluated. The conventional deterministic approach, which is widely used in power system planning methodology, is inadequate to deal with this issue. This paper proposes a new method for numerically defining the power transfer capability enhanced by countermeasures against lightning. The proposed method is based on a probabilistic approach in which several fault patterns are taken into consideration with their occurrence frequency and maximum transferable power. This paper also gives an example application of the proposed method to a model trunk transmission system. The effect of a third overhead ground wire on the increase of transfer capability of a 500 kV transmission line has been quantitatively evaluated.     

基于自调节小波变换的电力系统扰动信号检测

根据电力系统及其发生扰动故障时所具有的特点,提出了基于自调节小波变换的电力系统扰动信号检测方法。该方法既充分利用了小波变换的优点,又克服了在电力系统信号分析中傅里叶算法和传统小波算法的不足。此外,在电力系统运行和保护中,该方法具有简单、可靠等特点,便于形成实时软件,对于提高电力系统扰动信号检测水平和保护性能具有重要意义。     

相间功率控制器(IPC)在电力系统中的应用

发展迅速的柔性交流输电及其控制器技术(FACTS)已被国内外普遍认为是新型有效的输电技术。除了其技术概念和技术规范取得新进展外,控制器技术也在快速发展着。其中的相间功率控制器IPC(Interphase Power Controller)能有效地控制线路潮流,提高线路输送功率或用于设备增容,限制短路电流。从IPC的基本原理和结构出发,研究了IPC的主要系统应用及在国外的研究和应用情况,IPC在未来互联电网中的可能工程布点,着重对IPC在联网中的可能应用进行了研究,并得出初步的结论。     

An efficient faults calculation method taking into account mutually coupled lines of power systems

It is necessary to take into account the effects of mutual couplings when unbalanced faults are to be calculated in transient stability study. When the method based on symmetrical coordinates is applied to faults calculation, it has been necessary in the conventional method to construct the zero sequence network, the configuration of which is more complex than other networks so far. Then, the application of faults calculation including mutual couplings to the analysis on the bulk power system model has been considerably difficult for a long time. This report presents a newly developed method to calculate the effects of mutual coupling in multifaults calculation under the same configuration and with no change for all sequence networks. The validity of the proposed method was verified through the application of transient stability analysis for power system models.     

基于超级电容的智能电能表长寿命后备电源设计

智能电能表的进一步发展要求在外部供电电源中断后具有一定时间的远程通信能力,以便电能表数据的备份与停电等重要事件上报。作为常规后备电源的电池与电解电容都存在弊端,前者使用寿命较低,后者容量太小。文章首先用超级电容寿命估计理论论述了满足新一代电能表16年设计寿命的可行性,给出了满足寿命要求的超级电容备用电源充电电路设计,并解决了储能电容的待机能力,最后针对微功耗电路难以用常规仪器测量的现实,使用Spice模拟电路仿真工具分析了电路功能,并进行了实际电路试验,验证了电路方案的可行性。文章对市电供电的智能互联仪表设备的备用电源设计具有一定的借鉴意义。     

An adaptive digital processor for power efficiency enhancement in hybrid supply modulators

A novel digital envelope modulator for envelope tracking radio frequency power amplifier is presented in this paper. The proposed modulator consists of a parallel combination of linear class AB and switching class D power amplifiers that are controlled digitally. In the previous analog architectures, the requirements needed for the AB operational amplifier such as high‐current driving capability, high bandwidth and large output swing is usually obtainable at high overall static power dissipation. The digitally controlled power opamp presented here not only provides the aforementioned requirements but also reduces power dissipation compared with previous work. Furthermore, the digital control of the modulator makes it adaptive to the input signal variations in comparison with conventional analog parallel hybrid envelope modulators. The digital processor of the modulator is evaluated with a 45‐nm complementary metal oxide semiconductor technology. The overall power consumption of the digital processor is around 142 mW at 1.5‐GHz clock frequency. As an application, the designed digital class AB is incorporated in a complete envelope modulator architecture. The overall efficiency of the modulator, including the digital processor power consumption, is around 82% at an average 32 dBm output power for a 5‐MHz input signal. Copyright © 2015 John Wiley & Sons, Ltd.     

BGA焊点的质量控制

球栅阵列(BGA)是现代组装技术的新概念,它的出现促进SMT(表面贴装技术)与SMD(表面贴装元器件)的发展和革新,并将成为高密度、高性能、多功能及高I／O数封装的最佳选择。本文将结合实际工作中的一些体会和经验,就BGA焊点的接收标准、缺陷表现及可靠性等问题展开论述,特别对有争议的一种缺陷空洞进行较为详细透彻的分析,并提出一些改善BGA焊点质量的工艺改进的建议。     

基于常规电力的核电发展经济性研究

核电作为能源的一种形式,在资源相对有限的条件下,其经济性评价不能仅衡量核电项目本身,以电力市场的大环境评价核电的经济性有着现实的必要性。在现行市场条件下,通过百万级核电机组与煤电机组贴现净利润和现金流的比较,核电40a经济运行期的整体效益存在一定的经济优势,而煤电的短期盈利能力比较强。良好的现金流和成本控制能力是判断企业持续经营的前提,基于核电的长期效益和煤电的短期盈利能力,常规电力集团参与核电发展是解决核电短期现金流和常规电力长期成本控制的有效途径,核电与常规电力作为投资组合运营可以化解资源约束,低风险实现核电产业规模化。     

A multi-task automatic generation control for power regulation

The conventional model of a power system control area used for automatic generation control (AGC) is crucially extended to include individual power producers. Taking into account the influence of the power network, a systematic method of obtaining a detailed model of a control area is presented. It is proved that within the framework of the model developed, both frequency control as well as regulation of the power of individual power stations becomes possible. To this end, new advanced optimal control methods are used for the design of suitable proportional–integral (PI) controllers. Using the proposed model and the new control strategy, the application of automatic generation control and its effectiveness is extensively studied and evaluated on a 6-bus illustrative power system example; furthermore, the method is tested on the New England power system, which is commonly used as a large test system.     

高渗透率光伏参与电力系统调频研究综述

光伏发电的波动性和随机性会造成高渗透率光伏发电系统输出功率随机波动,进而加重了电网频率调节负担。同时高比例光伏发电接入系统,会替代部分常规机组,进一步削弱了电网调频能力。针对高比例光伏并网对电网频率稳定带来的全新挑战,分析了光伏发电接入系统对电网频率稳定性的影响机理。介绍了当前光伏发电参与系统频率调节的技术路线。最后,结合当前我国电网和新能源发展实际情况,展望了今后需要进一步关注的问题。     

Hierarchical economic dispatch for multi-area power systems

In a multi-area power system, power exchange through tie lines such that the overall cost of the system operation is a minimum is a major economic dispatch problem. In this paper, techniques and methods are presented for solving the economic dispatch problem of radially interconnected power systems. The proposed method, based on a multi-area approach, uses an hierarchical control concept to improve the computation efficiency and accuracy; it has certain advantages over the conventional single-area approach. Theoretical formulations are derived and discussed from a simple power transfer concept. An efficient algorithm is organized. Numerical examples have been tested for a fictitious three-area system. The simulation results strongly support the proposed method with real-time application capability.     

城市配电网电缆接头温升在线监测系统研究

结合城市配电网地埋电力电缆接头点多、量大、分布较广等特点,设计了一种基于CAN-BUS总线分布测量和GSM/GPRS无线通讯的城市配电网电缆接头温升在线监测系统,并对该系统的综合设计方案、逻辑架构组成、现场分散采集系统,以及上位机管理站网络化动态检测平台的功能作用进行了详细分析。结果表明:该系统解决了地埋电力电缆运行中接头温升故障率较高且监测不方便等问题,提高了设备可靠运行水平。     

Transmision capability enhancement using power electronics technologies for the future power system in Japan

Many power system stabilization measures realized by the upgrading transmission lines, generator controls, and power system controls and protections have been developed and utilized toward increasing transmission capability of power systems in Japan. With restriction of transmission routes and power system deregulation, it is now inevitable that transmission capability will be increased to sustain such power system reliability. Various remarkable power electronic technologies such as self-commutated SVC are being introduced toward improving power system stability. It is expected that these will also be employed in power flow control to avoid faults from cascading throughout the entire power system. This paper describes the present researches related to the application of power electronics to power systems in CRIEPI, including the recent results of the research carried out in cooperation with ten Electric Power Companies subsidized by MITI. Specifically: (1) analytical studies in power system enhancement by self-commutated SVC, thyrister controlled series capacitance (TCSC), and unified power flow controller (UPFC); (2) analytical studies on transmission capability increase of the interconnected power system applying the HVDC system with self-commutated converters; and (3) experimental studies of the self-commutated converter for continuous operation of converters at AC system faults.     

Recursive implementation of MUSIC algorithm to minimize power system disturbances

This paper exhibits new recursive implementation of the root-MUSIC algorithm in power system applications in order to extract the instantaneous power disturbances, which emanate from the arc furnace. The MUSIC algorithm is selected because it has an outstanding capability to estimate and track the frequencies of all types of distortion such as harmonics and interharmonics. The utilized algorithm has been newly developed so as to recursively track the instantaneous disturbances in the arc furnace current and consequently mitigate them. The suggested development of the recursive root-MUSIC is compared with the ESPRIT in order to prove that the adopted technique outperforms the high-resolution common techniques in a noisy or non-noisy environment. The instantaneous disturbance is formed by an innovative formulation of the recursive notch filter. Moreover, the experimental results are given to prove the practicality of the proposed concepts and techniques.     

On the construction of power quality control systems

Some aspects of the construction of power quality control systems in power supply systems are discussed. The basic requirements for quality factors of electric power are determined, the conditions of joint parallel operation of energy consumers are considered, and analysis of traditional ways of solving the emerging problems is carried out. The advantages and disadvantages of power quality control systems related to the capabilities of new technologies with application of high-power semiconductor switching devices (GTO and IGCT thyristors, MOSFET and IGBT transistors) are considered. The application of computer technology in power quality control systems makes it possible to use rather complicated and effective algorithms of numerical processing of signals and significantly increase the accuracy of correction of disturbances in electric networks. The advantages and disadvantages of industrial plants constructed in the form of a controlled reactor with a dc magnetic bias and a reactor with a thyristor key are considered. Two types of devices to compensate for possible disadvantages are identified: devices using fully controlled keys and devices ones using artificial commutation and incompletely controlled power keys. A brief analysis of the known methods of electric power quality control is implemented. Recommendations for the establishment of power quality control systems are suggested in which the parameters of software depend on the solution algorithm of a posed problem, while the algorithm itself depends on the method of control and mathematical laws on which it is based. The method of control determines the structure of the power quality control system, while the software determines the basic operations of information processing, their quantity, the scheme of data processing, the volume data flows, etc.     

压电振动能量收集的拓频方法及阻抗分析

利用能量收集技术来为装置供电,比有线布网供电和电池供电节约成本,同时便于设备的无线部署和长期运营维护。振动能量作为自然界中最常见的机械能之一,收集振动能量可以促进装置微小型化。现有的振动能量收集技术主要利用了装置与环境振动产生共振,因此能量收集的频率带宽仅在共振频率附近的小范围内,这限制了技术的应用场景。文中基于目前的机械和电气等各种拓展振动能量收集技术,分析了电气方法的频率响应特性。此外,相位可变开关电感电路作为电气拓频方法,比同步开关电感电路具有更宽的振动频率响应,使得在环境振动频率远离共振频率时,整体装置保持高水平的能量收集效率和能力。     

基于双CPU 的电力监控器的设计

随着电力工业的发展,电力供应的可靠性和电能质量越来越多地受到关注,对电力参数的检测也提出了更高的要求。研制了以单片机与DSP双CPU并行处理技术为基础的电力监控装置。该装置采用交流直接采样技术,充分利用87C196CB单片机的硬件资源和DSP强大的运算能力,并尽可能采用软件代替硬件,具有可靠性高、数据刷新速度快、关键信息不丢失等特点。还配置有串行通信接口和CAN现场总线接口,可方便地与计算机或其它电力监控装置通信,该电力监控器可以代替多种电力测量仪表、功率因数表及负荷控制器等实现电力系统的远程监控功能。