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Effect of harmonic distortion on electric energy meters of different metrological principles

Illia DIAHOVCHENKO, Vitalii VOLOKHIN, Victoria KUROCHKINA, Michal ŠPES, Michal KOSTEREC

《能源前沿（英文）》 2019年 第13卷 第2期   页码 377-385 doi: 10.1007/s11708-018-0571-1

摘要： This paper deals with the errors of electric energy metering devices as a result of distortions in the shape of the curves of voltage and current load. It is shown and proved that the errors in energy measurements depend on the design and the algorithms used in electricity meters. There are three main types of metering devises having different principles: inductive (electro-mechanical), electronic static, and digital electronic (microprocessor). Each of these types has its measuring features. Some devices take into account all the harmonic distortions and the constant component which occur in the network while others measure the power and energy values of the fundamental harmonic only. Such traits lead to the discrepancies in the readings of commercial electric energy meters of different types. Hence, the violations in the measurement system unity occur, and a significant error can be observed in the balance of transmitted/consumed electric energy.

关键词： current     distortion     electric energy meter     harmonics     power quality    

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Preparation and properties of nano SiO2 core-shell structured additives and their nanocomposite with polypropylene

KE Yangchuan, SUN Mingzhuo, SONG Yanxin, YANG GuangFu

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 76-80 doi: 10.1007/s11705-007-0016-6

摘要： To improve the performance of traditional nucleation additives and their compatibility with other additives, as well as to solve complex problems in practical applications, SiO precursors were reactively grafted in situ with the symmetrical hydroxyl groups of the nucleation agents. With this approach, the dissymmetrical part of the nucleation agents plays an important role. As a result, the prepared composite additive the nanoparticle precursor (NPP0) produces excellent results. The NPP0-PP composite has a transparency of over 93%, haze lower than 15%, and a heat distortion temperature (HDT) of 142?C, which is more than the 110?C of the pure PP matrix. In addition, it maintains over 90% of the mechanical properties with a deformation coefficient less than 1%. This indicates a strong nanoeffect.

关键词： deformation coefficient     distortion temperature     excellent     NPP0-PP     traditional nucleation    

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Equivalent thermal conductivity of heat pipes

LU Zesheng, MA Binghui

《机械工程前沿（英文）》 2008年 第3卷 第4期   页码 462-466 doi: 10.1007/s11465-008-0087-1

摘要： In precision machining, the machining error from thermal distortion carries a high proportion of the total errors. If a precision machining tool can transfer heat fast, the thermal distortion will be reduced and the machining precision will be improved. A heat pipe working based on phase transitions of the inner working liquid transfers heat with high efficiency and is widely applied in spaceflight and chemical industries. In mechanics, applications of heat pipes are correspondingly less. When a heat pipe is applied to a hydrostatic motorized spindle, the thermal distortion cannot be solved during the heat transfer process because thermal conductivity or equivalent thermal conductivity should be provided first for special application in mechanics. An equivalent thermal conductivity model based on equivalent thermal resistances is established. Performance tests for a screen wick pipe, gravity pipe, and rotation heat pipe are done to validate the efficiency of the equivalent thermal conductivity model. The proposed model provides a calculation method for the thermal distortion analysis of heat pipes applied in the motorized spindle.

关键词： proposed     distortion analysis     hydrostatic motorized     motorized spindle     Performance    

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Performance investigation of artificial intelligence based controller for three phase four leg shunt active filter

J. JAYACHANDRAN,R. MURALI SACHITHANANDAM

《能源前沿（英文）》 2015年 第9卷 第4期   页码 446-460 doi: 10.1007/s11708-015-0378-2

摘要： In this paper, the choice of power quality compensator is a DSTATCOM which constitutes a three phase four leg voltage source converter (VSC) with a DC capacitor. The control strategy proposed for the DSTATCOM is a neural network based one cycle control (OCC). This control strategy involves neural network block, digital circuits and linear elements, which eliminates the sensors required for sensing the load current and coupling inductor current in addition to the multiplier employed in the conventional method. The calculation of harmonic and reactive currents for the reference current generation is also eliminated, thus minimizing the complexity in the control strategy. The control strategy mitigates harmonic/reactive currents, ensures balanced and sinusoidal source current from the supply mains that are nearly in phase with the supply voltage, compensates neutral current, and maintains voltage across the capacitor under unbalanced source and load conditions. The performance of the DSTATCOM with the proposed artificial neural network (ANN) controllers is validated and investigated through simulations using Matlab software. The simulation results prove the efficacy of the proposed neural network based control strategy under varying source and load conditions.

关键词： neural network     DSTATCOM     neutral current mitigation     total harmonic distortion (THD)     three phase four wire distribution system     unbalanced and/or distorted source    

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Emerging challenges to structural integrity technology for high-temperature applications

TU Shantung

《机械工程前沿（英文）》 2007年 第2卷 第4期   页码 375-387 doi: 10.1007/s11465-007-0066-y

摘要： Structural integrity technology has been widely used with great success for the design, manufacture and failure prevention of modern constructions such as chemical and petrochemical plants, power generation and energy conversion systems, as well as space and oceanic exploration. The modern needs of structural integrity technology are largely attributed to the increase of service temperature of the structures that results in the efficiency improvement in energy conversion and chemical processing technologies. Besides the needs arising from large-scale high-temperature plants, the high tech developments, such as micro chemo-mechanical systems and high-power electronics, provide new challenges to structural integrity technology. The present paper summarizes the recent technical progresses in large process plants and the aviation industry, micro chemo-mechanical systems, fuel cells, high-temperature electronics, and packaging and coating technologies. The state-of-the-art of structural integrity technology for high temperature applications is reviewed. Suggestions are provided for the improvement of current design and assessment methods.

关键词： manufacture     aviation industry     conversion     petrochemical     temperature    

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Effects of temperature on pyrolysis products of oil sludge

LIU Jianguo, SONG Wei, NIE Yongfeng

《环境科学与工程前沿（英文）》 2008年 第2卷 第1期   页码 8-14 doi: 10.1007/s11783-008-0030-z

摘要： Temperature is the determining factor of pyrolysis, which is one of the alternative technologies for oil sludge treatment. The effects of final operating temperature ranging from 350 to 550°C on pyrolysis products of oil sludge were studied in an externally-heating fixed bed reactor. With an increase of temperature, the mass fraction of solid residues, liquids, and gases in the final product is 67.00%–56.00%, 25.60%–32.35%, and 7.40%–11.65%, and their corresponding heat values are 34.4–13.8 MJ/kg, 44.41–46.6 MJ/kg, and 23.94–48.23 MJ/Nm, respectively. The mass and energy tend to shift from solid to liquid and gas phase (especially to liquid phase) during the process, and the optimum temperature for oil sludge pyrolysis is 500°C. The liquid phase is mainly composed of alkane and alkene (C–C), and the gas phase is dominantly HC and H.

关键词： sludge treatment     corresponding     Temperature     liquid     process    

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Phase separation time/temperature dependence of thermoplastics-modified thermosetting systems

ZHANG Xiujuan, XU Yuanze, YI Xiaosu

《化学科学与工程前沿（英文）》 2008年 第2卷 第3期   页码 276-285 doi: 10.1007/s11705-008-0057-5

摘要： The cure-induced phase separation processes of various thermoplastics(TP)-modified thermosetting systems which show upper critical solution temperature (UCST) or lower critical solution temperature (LCST) were studied with emphasis on the temperature dependency of the phase separation time and its potential application in the cure time-temperature processing window. We found that the phase separation time/temperature relationship follows the simple Arrhenius equation. The cure-induced phase separation activation energy (ps) generated from the linear fitting of the Arrhenius equation is irrelevant to the detection means of phase separation time. We also found that (ps) is insensitive to TP content, TP molecular weight and curing rate, but it changes with the cure reaction kinetics and the chemical environment of the systems. With the established phase separation time-temperature dependence relation, we can easily establish the whole cure time-temperature transformation (TTT) diagram with morphology information which is a useful map for the TP/TS composites processing industry.

关键词： separation time-temperature     temperature dependency     cure-induced     separation activation     temperature    

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Elevated temperature creep model of parallel wire strands

《结构与土木工程前沿（英文）》   页码 1060-1071 doi: 10.1007/s11709-023-0981-y

摘要： Parallel wire strands (PWSs), which are widely used in prestressed steel structures, are typically in high-stress states. Under fire conditions, significant creep effects occur, reducing the prestress and influencing the mechanical behavior of PWSs. As there is no existing approach to analyze their creep behavior, this study experimentally investigated the elevated temperature creep model of PWSs. A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test. It was concluded that the temperature level had a more significant effect on the creep strain than the stress level, and 450 °C was the key segment point where the creep rate varied significantly. By comparing the elevated temperature creep test results for PWSs and steel strands, it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels. The parameters in the general empirical formula, the Bailey–Norton model, and the composite time-hardening model were fitted based on the experimental results. By evaluating the accuracy and form of the models, the composite time-hardening model, which can simultaneously consider temperature, stress, and time, is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.

关键词： parallel wire strands     experimental study     elevated temperature creep model    

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Power quality investigation of a solar PV transformer-less grid- connected system fed DVR

Akhil GUPTA,Saurabh CHANANA,Tilak THAKUR

《能源前沿（英文）》 2014年 第8卷 第2期   页码 240-253 doi: 10.1007/s11708-014-0322-x

摘要： This paper presents a single stage transformer-less grid-connected solar photovoltaic (PV) system with an active and reactive power control. In the absence of active input power, the grid-tied voltage source converter (VSC) is operated in a reactive power generation mode, which powers the control circuitry, and maintains a regulated DC voltage to the VSC. A data-based maximum power point tracking (MPPT) control scheme which performs power quality control at a maximum power by reducing the total harmonic distortion (THD) in grid injected current as per IEEE-519/1547 standards is implemented. A proportional-integral (PI) controller based dynamic voltage restorer (DVR) control scheme is implemented which controls the grid side converter during single-phase to ground fault. The analysis includes the grid current THD along with the corresponding variation of the active and reactive power during the fault condition. The MPPT tracks the actual variable DC link voltage while deriving the maximum power from the solar PV array, and maintains the DC link voltage constant by changing the modulation index of the VSC. Simulation results using Matlab/Simulink are presented to demonstrate the feasibility and validations of the proposed novel MPPT and DVR control systems under different environmental conditions.

关键词： data-based maximum power point tracking (MPPT)     total harmonic distortion (THD)     proportional integral     control     voltage restorer     pulse width modulation    

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一种改进的Hilbert能量谱算法研究

杨建文,贾民平,许飞云,胡建中

《中国工程科学》 2005年 第7卷 第7期   页码 55-59

摘要：

分析了HHT中Hilbert能量谱的原理；研究了瞬时频率谱中端点效应产生的原因，将ARMA模型应用于Hilbert能量谱计算中，以旋转机械振动信号为对象，运用所提的方法对HHT中典型的本征模式函数进行仿真实验；通过与传统方法比较，证明它可以有效地改进端点效应，优化Hilbert能量谱。

关键词： Hilbert变换     端点失真     瞬时参数     本征模式函数    

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Field test on temperature field and thermal stress for prestressed concrete box-girder bridge

Baoguo CHEN, Rui DING, Junjie ZHENG, Shibiao ZHANG

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 158-164 doi: 10.1007/s11709-009-0002-9

摘要： A field test was conducted to investigate the distribution of temperature field and the variation of thermal stress for a prestressed concrete (PC) box-girder bridge. The change of hydration heat temperature consists of four periods: temperature rising period, constant temperature period, rapid temperature fall period and slow temperature fall period. The peak value of hydration heat temperature increases with the increasing casting temperature of concrete; the relation between them is approximately linear. According to field tests, the thermal stress incurred by hydration heat may induce temperature cracks on the PC box-girder. Furthermore, the nonlinear distribution of temperature gradient and the fluctuation of thermal stress induced by exposure to sunlight were also obtained based on continuous in-situ monitoring. Such results show that the prevailing Chinese Code (2004) is insufficient since it does not take into account the temperature gradient of the bottom slab. Finally, some preventive measures against temperature cracks were proposed based on related studies. The conclusions can provide valuable reference for the design and construction of PC box-girder bridges.

关键词： box-girder bridge     field test     hydration heat     temperature field     temperature gradient     thermal stress    

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A review of low-temperature plasma-assisted machining: from mechanism to application

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0734-y

摘要： Materials with high hardness, strength or plasticity have been widely used in the fields of aviation, aerospace, and military, among others. However, the poor machinability of these materials leads to large cutting forces, high cutting temperatures, serious tool wear, and chip adhesion, which affect machining quality. Low-temperature plasma contains a variety of active particles and can effectively adjust material properties, including hardness, strength, ductility, and wettability, significantly improving material machinability. In this paper, we first discuss the mechanisms and applications of low-temperature plasma-assisted machining. After introducing the characteristics, classifications, and action mechanisms of the low-temperature plasma, we describe the effects of the low-temperature plasma on different machining processes of various difficult-to-cut materials. The low-temperature plasma can be classified as hot plasma and cold plasma according to the different equilibrium states. Hot plasma improves material machinability via the thermal softening effect induced by the high temperature, whereas the main mechanisms of the cold plasma can be summarized as chemical reactions to reduce material hardness, the hydrophilization effect to improve surface wettability, and the Rehbinder effect to promote fracture. In addition, hybrid machining methods combining the merits of the low-temperature plasma and other energy fields like ultrasonic vibration, liquid nitrogen, and minimum quantity lubrication are also described and analyzed. Finally, the promising development trends of low-temperature plasma-assisted machining are presented, which include more precise control of the heat-affected zone in hot plasma-assisted machining, cold plasma-assisted polishing of metal materials, and further investigations on the reaction mechanisms between the cold plasma and other materials.

关键词： low-temperature plasma     difficult-to-cut material     machinability     hydrophilization effect     Rehbinder effect    

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Real-time tool condition monitoring method based on temperature measurement and artificial neural network

《机械工程前沿（英文）》 doi: 10.1007/s11465-021-0661-3

摘要： Tool failures in machining processes often cause severe damages of workpieces and lead to large quantities of loss, making tool condition monitoring an important, urgent issue. However, problems such as practicability still remain in actual machining. Here, a real-time tool condition monitoring method integrated in an in situ fiber optic temperature measuring apparatus is proposed. A thermal simulation is conducted to investigate how the fluctuating cutting heats affect the measuring temperatures, and an intermittent cutting experiment is carried out, verifying that the apparatus can capture the rapid but slight temperature undulations. Fourier transform is carried out. The spectrum features are then selected and input into the artificial neural network for classification, and a caution is given if the tool is worn. A learning rate adaption algorithm is introduced, greatly reducing the dependence on initial parameters, making training convenient and flexible. The accuracy stays 90% and higher in variable argument processes. Furthermore, an application program with a graphical user interface is constructed to present real-time results, confirming the practicality.

关键词： tool condition monitoring     cutting temperature     neural network     learning rate adaption    

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Effects of pressure and temperature on fixed-site carrier membrane for CO 2 separation from natural gas

Meng WANG, Dongxiao YANG, Zhi WANG, Jixiao WANG, Shichang WANG,

《化学科学与工程前沿（英文）》 2010年 第4卷 第2期   页码 127-132 doi: 10.1007/s11705-009-0231-4

摘要： In this paper, the effect of testing temperature on the performance of fixed carrier membrane for CO separation were studied. The blend composite membranes were developed respectively with a blend of PEI-PVA (polyetheleneimine-polyvinyl alcohol) as separation layer and PS (polysulfone) ultrafiltration membranes as the substrates. The permselectivity of the membranes was measured with CO/CH mixed gas. The effect of testing temperature on membrane separation performance was investigated. The results showed that both the permeances of CO and CH decreased with the increase of temperature, and the permeances decreased more quickly under low pressure than those under high pressure. At the feed pressure of 0.11MPa, the CO/ CH selectivity of PEI-PVA/PS blend composite membrane reduced along with temperature increment. Under the feed pressure of 0.21MPa, as well as 1.11MPa, the selectivity decreased with the increase of temperature.

关键词： temperature increment     high pressure     permselectivity     separation performance     temperature    

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A simple digital control algorithm for three phase shunt active filter: simulation and experimentation

Subbaraman SRINATH, Chandan KUMAR, M. P. SELVAN

《能源前沿（英文）》 2014年 第8卷 第1期   页码 119-128 doi: 10.1007/s11708-013-0288-0

摘要： A novel and simple control algorithm using digital signal processor (DSP) has been proposed and realized for a three phase shunt active filter (SAF). The simulation and prototype construction of SAF is conducted to compensate the reactive power and harmonics in a distribution system. The major feature of the proposed algorithm is that it does not require unit vector templates and any transformations for the reference current generation of SAF. This reduces the computational complexity and makes the control flexible and faster. The simulation is conducted in MATLAB/SIMULINK while DSP TMS320LF2407 is employed in the digital implementation of hysteresis current control (HCC) for experimentation. The hardware results correlate with the simulation results in reducing the total harmonic distortion (THD) of the source current and achieving unity power factor.

关键词： shunt active filter (SAF)     power quality     voltage source inverter (VSI)     digital signal processor (DSP)     total harmonic distortion (THD)     power factor improvement    

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标题 作者 时间 类型 操作

Effect of harmonic distortion on electric energy meters of different metrological principles

Illia DIAHOVCHENKO, Vitalii VOLOKHIN, Victoria KUROCHKINA, Michal ŠPES, Michal KOSTEREC

期刊论文

Preparation and properties of nano SiO2 core-shell structured additives and their nanocomposite with polypropylene

KE Yangchuan, SUN Mingzhuo, SONG Yanxin, YANG GuangFu

期刊论文

Equivalent thermal conductivity of heat pipes

LU Zesheng, MA Binghui

期刊论文

Performance investigation of artificial intelligence based controller for three phase four leg shunt active filter

J. JAYACHANDRAN,R. MURALI SACHITHANANDAM

期刊论文

Emerging challenges to structural integrity technology for high-temperature applications

TU Shantung

期刊论文

Effects of temperature on pyrolysis products of oil sludge

LIU Jianguo, SONG Wei, NIE Yongfeng

期刊论文

Phase separation time/temperature dependence of thermoplastics-modified thermosetting systems

ZHANG Xiujuan, XU Yuanze, YI Xiaosu

期刊论文

Elevated temperature creep model of parallel wire strands

期刊论文

Power quality investigation of a solar PV transformer-less grid- connected system fed DVR

Akhil GUPTA,Saurabh CHANANA,Tilak THAKUR

期刊论文

一种改进的Hilbert能量谱算法研究

杨建文,贾民平,许飞云,胡建中

期刊论文

Field test on temperature field and thermal stress for prestressed concrete box-girder bridge

Baoguo CHEN, Rui DING, Junjie ZHENG, Shibiao ZHANG

期刊论文

A review of low-temperature plasma-assisted machining: from mechanism to application

期刊论文

Real-time tool condition monitoring method based on temperature measurement and artificial neural network

期刊论文

Effects of pressure and temperature on fixed-site carrier membrane for CO 2 separation from natural gas

Meng WANG, Dongxiao YANG, Zhi WANG, Jixiao WANG, Shichang WANG,

期刊论文

A simple digital control algorithm for three phase shunt active filter: simulation and experimentation

Subbaraman SRINATH, Chandan KUMAR, M. P. SELVAN

期刊论文