Results of operation and current safety performance of nuclear facilities located in the Russian Federation

After the NPP radiation accidents in Russia and Japan, a safety statu of Russian nuclear power plants causes concern. A repeated life time extension of power unit reactor plants, designed at the dawn of the nuclear power engineering in the Soviet Union, power augmentation of the plants to 104–109%, operation of power units in a daily power mode in the range of 100-70-100%, the use of untypical for NPP remixed nuclear fuel without a careful study of the results of its application (at least after two operating periods of the research nuclear installations), the aging of operating personnel, and many other management actions of the State Corporation “Rosatom”, should attract the attention of the Federal Service for Ecological, Technical and Atomic Supervision (RosTekhNadzor), but this doesn’t happen.The paper considers safety issues of nuclear power plants operating in the Russian Federation. The authors collected statistical information on violations in NPP operation over the past 25 years, which shows that even after repeated relaxation over this period of time of safety regulation requirements in nuclear industry and highly expensive NPP modernization, the latter have not become more safe, and the statistics confirms this. At a lower utilization factor high-power pressure-tube reactors RBMK-1000, compared to light water reactors VVER-440 and 1000, have a greater number of violations and that after annual overhauls. A number of direct and root causes of NPP mulfunctions is still high and remains stable for decades. The paper reveals bottlenecks in ensuring nuclear and radiation safety of nuclear facilities. Main outstanding issues on the storage of spent nuclear fuel are defined. Information on emissions and discharges of radioactive substances, as well as fullness of storages of solid and liquid radioactive waste, located at the NPP sites are presented. Russian NPPs stress test results are submitted, as well as data on the coming removal from operation of NPP units is analyzed.     

The application of the current-comparator technique ininstrumentation and measurement equipment for the calibration ofnon-conventional instrument transformers with non-standard rated outputs

An overview of the development of instrumentation and measurement techniques at the National Research Council of Canada, based on current comparator technology, for calibration of nonconventional instrument transformers with nonstandard rated outputs, is presented. The instruments include: (1) a wide-dynamic-range transimpedance amplifier for operation of input currents from 1 A to 1000 A with means for modifying the in-phase and quadrature components of the output voltage (rated 10 V) within a ±10% range; (2) a high-voltage high-current transconductance amplifier with output current ranges of 10 A, 100 A, and 1000 A; and (3) a voltage ratio standard also with means for modifying the in-phase and quadrature components of the output voltage (rated 100 V) within a ±10% range. The current comparator technique is used to obtain accuracies of better than 20 parts per million in both magnitude and phase of the associated outputs of these instruments     

一起母线保护不正确动作情况的分析

该文通过对华能大连电厂一次母线故障时BUS1 0 0 0母线保护动作情况的分析 ,找出了BUS1 0 0 0母线保护不正确动作的原因 ,总结了事故教训 ,并提出了改进措施     

Effect of humidity on the breakdown characteristics of air in uniform field for the very low frequency (VLF) band

The paper reports about the role of humidity and frequency on the electrical breakdown of air in uniform field gaps. Experiments were conducted on Rogowski profile electrodes with gap lengths ranging from 5 to 53 mm at power frequency (60 Hz) and frequencies in the range of 18-50 kHz, corresponding to the VLF/LF bands used for long-range communication. The results show that breakdown voltage at VLF decreases with humidity, opposite to that observed at 60 Hz. Breakdown mechanisms for explaining this important phenomenon are proposed. A correction factor to calculate breakdown voltage as a function of humidity for VLF is presented.     

类钙钛矿复合氧化物La_(2-x)Sr_xNiO_4的合成及电学性能

采用柠檬酸硝酸盐燃烧法合成了La2-xSrxNiO4(LSN)阴极材料,并系统地研究了LSN的热膨胀性能、电子电导率,并考察了基于Ce1.8Sm0.2O1.9(SDC)电解质的LSN电极极化性能.结果表明,自燃烧产物经1 000℃煅烧2 h形成了单一的K2NiF4结构,25～800℃范围内,LSN材料的热膨胀系数在13.7×10-6～14.3×10-6K-1. La1.4Sr0.6NiO4电子电导率最高,为151.5～155.7 S/cm(600～800 ℃).极化测试结果显示,未掺杂的LSN具有最小的极化电阻(0.48Ω·cm2,800℃),电流密度为0.3 A/cm2时,过电位约为0.083 V.     

Sensorless-control of the synchronous reluctance motor

In this paper a sensorless closed-loop speed control for the synchronous reluctance motor is presented. The sensorless control is based on the torque vector control algorithm. It has been implemented using a high-speed digital processor DSP96002. Experimental results for a 120 W axially-laminated synchronous reluctance motor are presented and compared with operation with a speed sensor and simulations. A base speed range of 400-1500 RPM has been achieved. The top speed was extended to 2750 RPM using flux-weakening. The drive can be applied a full-load step-change within this speed range without losing synchronism     

Design and fully digital control of parallel active filters forthyristor rectifiers to comply with IEC-1000-3-2 standards

This paper presents the implementation of a digitally controlled parallel active filter for a thyristor rectifier with inductive load. Using a state-of-the-art digital signal processor (DSP) platform (ADSP21020 and ADMC200), a fully digital control of the system, based on the dead-beat control of inverter currents and space vector modulation, is implemented. The intrinsic calculation delay of the dead-beat algorithm is shown to represent a serious hurdle for the achievement of a satisfactory compensation quality. In particular, meeting the IEC 1000-3-2 standards for class A equipment appears to be quite difficult, especially in the high-frequency range. This paper investigates the effects of the input passive filters and power converter design on the system's performance and describes the implementation of the digital control by means of the specified hardware. Experimental results are finally given to evaluate the achieved performance     

锂离子动力电池脉冲功率特性的研究

对自行研制的17Ah高功率型锂离子动力电池室温下的脉冲功率特性进行了研究。采用控制电流和控制功率脉冲充放电的方法研究电池在50%SOC下的脉冲充放电特性,然后以控制电流脉冲充放电模式循环,研究电池容量和功率的衰减规律。结果显示,电池在控制电流脉冲充放电模式下的功率变化范围为-500～338W,能量效率为96.2%;在控制功率脉冲充放电模式下的电流变化范围为-51.7～39.4A,容量效率为93.7%。电池以控制电流脉冲充放电模式循环1.7万次(2833h)后容量衰减了7.9%,放电功率衰减了13.1%。发现循环过程中容量和功率的衰减都呈现出先快后慢的衰减规律,功率的衰减主要发生在前1000次循环。     

Fast valve power loss evaluation method for modular multi-level converter operating at high-frequency

There is no common accepted way for calculating the valve power loss of modular multilevel converter (MMC). The method based on analytical calculation is inaccurate to address the switching power loss while the method based on detailed electro-magnetic simulation is of low speed. To solve this problem, an accurate valve power loss evaluation method of MMC based on the detailed equivalent simulation model of MMC is proposed. A fast power loss evaluation method is then proposed by linking the PSCAD/EMTDC and Matlab files. Detailed valve power loss analysis of a 201-level 500MW MMC operating at 50Hz~1000Hz is then presented. Relationship between the valve power loss, power transfer level and operating frequencies are presented and fitted. Research results of this paper can be used as guidance for the application of medium and high frequency MMC.     

高功率薄型金属双极板PEM燃料电池堆研究

对高功率车用薄型金属双极板PEM燃料电池堆模块进行测试研究.电池堆模块可在空气压力110～300 kPa条件下工作,表现出良好的高、低压兼容特性.当空气压力300 kPa,电池堆温度70℃,工作电流350 A时,电池堆输出功率可达27.2 kW,其质量和体积比功率分别为777 W/kg和1 015 W/L.单电池电压方差求和计算结果显示,在工作电流50～120A的窗口区间内,单池电压具有相对最好的均匀一致性.在320A(约为1 A/cm2)放电电流下,使用纯氢/氧气的电池堆输出功率比使用氢/空气高出约10%.空气相对湿度影响测试结果,电池堆较低功率下,空气的相对湿度80%～100%为佳;而当高功率下,空气相对湿度80%为佳.另外,对4单体薄型金属双极板燃料电池短堆进行耐久性测试,累计超过2 900 h,平均单池电压衰减率约为10 mV/1000 h.     

新型单相无源功率因数校正整流器的电路拓扑、工作原理和设计分析

电磁兼容标准是强制性的,因此满足特定的电磁兼容标准是功率因数校正技术研究的重要内容.无源功率因数校正技术具有简单及成本低的优点,在小功率应用场合具有广阔的前景.然而当功率大于300W时,现有的基本LC滤波器电路需要添加笨重的电感.本文提出一种LC滤波器类型新的无源功率因数校正电路,它以满足新的电磁兼容标准为前提,新电路简单且电感尺寸为原来的一半.介绍电路拓扑和工作原理、设计分析、计算机仿真和样机实验验证.     

Electron-atom collision cross sections in argon: an analysis and comments

Experimental data on electron-atom collision cross sections in argon published during the period 1980-2002 are compiled and reviewed, with 123 references. Total, integral elastic, differential, excitation and ionization cross sections in the energy range 0-1000 eV are considered separately. A comparison between various measurements and, between various semi-empirical formulas are given. Improved formulas previously unpublished are also given where required. The sigma rule (the total cross section is the sum of partial cross sections) holds good in argon to an accuracy of /spl plusmn/5% in the energy range 12-1000 eV. A recommended set is provided.     

Four-quadrant and zero-speed sensorless control of a switched reluctance motor

A four-quadrant sensorless controller for switched reluctance motor (SRM) drives is presented in this paper. The drive system with appropriate turn-on and turn-off angles for each operating quadrant delivers excellent dynamic performance over a wide speed range including zero speed. The problems associated with practical implementation especially at low and zero speeds have been addressed and overcome with engineering solutions. Experimental results for a 1-kW SRM obtained on a dSPACE-based system are presented along with useful guidelines for practical implementation.     

A 40 M–1000 MHz 77.2‐dB spurious free dynamic range CMOS RF variable gain amplifier for digital TV tuner ICs

In this paper, a 40 M–1000 MHz 77.2‐dB spurious free dynamic range (SFDR) CMOS RF variable gain amplifier (VGA) has been presented for digital TV tuner applications. The proposed RFVGA adopts a wideband operational‐amplifier‐based VGA and a wideband buffer with differential multiple gated transistor linearization method for wideband operation and high linearity. The SFDR of the proposed RFVGA is also analyzed in detail. Fabricated in a 0.13‐µm CMOS process, the RFVGA provides 31‐dB gain range with 1‐dB gain step, a minimum noise figure of 7.5 dB at a maximum gain of 27 dB, and maximum in‐band output‐referred third‐order intercept point of 27.7 dBm, while drawing an average current of 27.8 mA with a supply voltage of 3.3 V. The chip core area is 0.54 mm × 0.4 mm. Copyright © 2014 John Wiley & Sons, Ltd.     

PM-assisted reluctance synchronous motor/generator (PM-RSM) for mild hybrid vehicles: electromagnetic design

This paper introduces the conceptual design and finite-element method analysis of a permanent-magnet-assisted reluctance synchronous motor/generator for mild hybrid vehicles where a large constant power speed range (6:1) is required and machine volume, converter peak kVA, and battery size are the main constraints. Careful flux-barrier and permanent-magnet sizing, high magnetic saturation, and current density are the main requirements for maximum torque production with constraint volume. A specific tangential force density of 4.33 N/cm/sup 2/ is obtained. Rated (continuous) power-battery limited is 2.5 kW at 42 V dc, from 1000 to 6000 r/min. The peak torque of 140 N/spl middot/m is obtained at 202 A (rms/phase) and can be secured up to 500 r/min. Peak power is still 7.85 kW at 6000 r/min at 42 V dc with an efficiency of 90%. Preliminary results on a prototype are also available.     

A low-power,low-data-rate efficient ADC with hybrid exponential-linear transfer curve for bio-potential recording systems

A digital-ramp hybrid exponential-linear analog-to-digital converter (ADC) is presented in this paper, which is attractive, where a high dynamic range (DR) is required. It is especially applicable for sampling neural (bio-potential) signals, as most of the neural signal data are concentrated on higher side of the amplitude range. By the exponential quantization function for low signal amplitudes, the background noise that disperses in lower amplitudes will be reduced. For higher signal amplitudes, the exponential function optionally switches to linear function at an adjustable voltage threshold, to reduce required number of bits for those high amplitudes, as well. As a result of this exponential-linear hybrid operation, the total data rate and the power required for data transmission are decreased. A prototype 8-bit counter-based exponential ADC is designed and simulated in 0.18-μm complementary metal-oxide-semiconductor (CMOS). The 20-KS/s ADC achieves a DR of 66 dB, occupies 0.036 mm² area, and consumes 6.4-μW power from a 1.8-V supply. Integral nonlinearity (INL) and differential nonlinearity (DNL) that are redefined to be compatible with nonlinear ADCs are 3.2 and 0.88 least significant bits (LSBs), respectively.     

Influence of supply voltage frequency and magnitude on PD pulse parameters

A study on the influence of supply voltage magnitude and frequency on partial discharge (PD) pulse shapes is presented in this paper. Ultrawide band (UWB) timeresolved PD pulse measurements were carried out on artificial PD defects using test voltage frequency range of 10 ? 400 Hz and voltage range of 2 - 11 kV. The manner in which the PD pulse shape responded to changes in the test voltage characteristics depended on the defect type. The observations can be interpreted using the generally agreed theory of PD mechanisms. The knowledge generated in this work is valuable in the interpretation and comparison of PD measurements made at different voltages and frequencies. It also contributes to development of PD defect classification techniques based on the correlation between test voltage frequency and time-resolved PD.     

Modeling of natural acoustic frequencies of a gas-turbine plant combustion chamber

The paper presents results of determination of natural acoustic frequencies of a gas-turbine plant annular combustion chamber model using 3D-simulation. At the beginning, a calculation procedure for determining natural acoustic frequencies of the gas-turbine plant combustion chamber was worked out. The effect of spatial inhomogeneity of the flow parameters (fluid composition, pressure, temperature) arising in combustion and some geometrical parameters (cooling holes of the flame tube walls) on the calculation results is studied. It is found that the change of the fluid composition in combustion affects the acoustic velocity not more than 5%; therefore, the air with a volume variable temperature can be taken as a working fluid in the calculation of natural acoustic frequencies. It is also shown that the cooling holes of the flame tube walls with diameter less than 2 mm can be neglected in the determination of the acoustic modes in the frequency range of up to 1000 Hz. This reduces the number of the grid-model elements by a factor of six in comparison with a model that considers all of the holes. Furthermore, a method of export of spatial inhomogeneity of the flow parameters from a CFD solver sector model to the annular combustion chamber model in a modal solver is presented. As a result of the obtained model calculation, acoustic modes of the combustion chamber in the frequency range of up to 1000 Hz are determined. For a standard engine condition, a potentially dangerous acoustic mode with a frequency close to the ripple frequency of the precessing vortex core, which is formed behind the burner device of this combustion chamber, is detected.     

电压稳定裕度对参数灵敏度求解的新方法

针对与鞍结分岔相关的电压稳定裕度对参数的灵敏度计算问题，该文提出了一种解线性方程组求灵敏度的新方法。与以往方法不同的是：该方法无需求解鞍结分岔点处潮流雅可比矩阵零特征值对应的左特征向量，而只需求解一个左端系数阵为扩展潮流雅可比矩阵的线性方程组。由于避免了左特征向量的迭代求解，因此该方法简单实用，计算量小，适于在线静态电压稳定分析的使用。另外文中还对另一种普遍存在的分岔形式--限值诱导分岔的特点与灵敏度计算作了探讨。在EPRI 1000母线系统算例下的计算表明，本文方法切实可行并具有较高的精度。