自动化技术在电力系统运行中的应用

随着我国科学技术的不断变革和发展,电力系统在运行的过程当中也经过了许多不同的阶段,电力行业也在不断的进步和发展,在当前的发展背景下,为保障人民用电的安全性以及可靠性,大多数的电力企业都引入了先进的自动化技术,不断更新相关的设备,以及系统保障当前的电力系统,在运行的过程当中能够更加顺利。而当前的信息时代背景也为电力系统的运行和发展提供了更多的可能性,将自动化技术和电力系统进行结合,是一种发展和突破,也是当前电力行业在发展过程当中,依赖性较高的一项关键性技术。将电力系统与电气自动化技术相结合,能够从根本上对整体的系统流程以及操作等进行精简,还能够减少整体资源的投入,减少一定的浪费,而且还能够确保电力系统在运行的过程当中更加稳定和安全。因此研究自动化技术在电力系统运行中的应用具有十分重要的作用。本文主要从电力系统中的自动化技术特点入手,明确了电气自动化技术的作用,然后将电力系统运行中的电气自动化技术的相关应用进行了阐述和分析,希望能够为相关的研究人员提供一定的参考价值.

In-situ investigation of atmospheric corrosion behavior of bronze under thin electrolyte layers using electrochemical technique

The atmospheric corrosion behavior of bronze under thin electrolyte layer （TEL） with different thicknesses was monitored using cathodic polarization curves, open circuit potential （OCP） and electrochemical impedance spectroscopy （EIS）. Cathodic polarization result indicates that the cathodic limiting current density increases with decreasing the TEL thickness. EIS result shows that the corrosion rate increases with decreasing the TEL thickness at the initial stage because the corrosion is dominated by the cathodic process, whereas after long immersion time, the corrosion degree with the TEL thickness is in the sequence of 150 μm 〉 310 μm〉 10μm ≈ bulk solution 〉 57 μm. The measurements of OCP and EIS present in-situ electrochemical corrosion information and their results are in good agreement with that of physical characterizations.

庆祝《农业工程学报》创刊三十周年

《农业工程学报》是由中国科协主管、中国农业工程学会主办的学术性期刊,半月刊,国内外发行。编委会主任罗锡文,编委会常务副主任兼主编朱明。《农业工程学报》荣获"中国科协精品科技期刊工程项目"期刊、"百种中国杰出学术期刊"、"中国精品科技期刊"、"中国期刊方阵双效期刊"等称号,是中文核心期刊、中国科技核心期刊、CSCD(中国科学引文数据库)核心收录期刊、RCCSE中国权威学术期刊。主要栏目包括:综合研究·关键技术、争鸣与讨论、农业装备工程与机械化、农业水土工程、农业信息与电气技术、农业生物环境与能源工程、土地整理工程、农产品加工工程。

Copper corrosion in hot and dry atmosphere environment in Turpan, China

The atmospheric corrosion behavior of pure copper exposed for three years in Turpan, China, which is a typical hot and dry atmosphere environment, was investigated using mass-loss tests, morphology observations, composition analyses, and electrochemical techniques. The results indicated that the annual corrosion rate of pure copper was approximately 2.90 μm/a. An uneven distribution of corrosion products was observed by scanning electron microscopy; this uneven distribution was attributed to the dehydration process during wet–dry and cold–hot cycles, and the compositions mainly consisted of cuprite （Cu2O） and atacamite （Cu2Cl（OH）3）. Electrochemical measurements showed that deposits on copper improved its resistance to corrosion and the protectiveness decreased with increasing temperature. On the other hand, results obtained using the scanning vibrating electrode technique showed that the porous and uneven structure of the deposit layer generated a spatial separation of cathodic and anodic reaction sites, which accelerated the corrosion process in wet and rainy weather.

寒冬下的企业变革

受宏观经济形势的影响、外部竞争的加剧以及一些特殊危机(例如“非典”)的出现,在这多重危机的挑战下,当前许多企业正面临着一个严酷的寒冬。

An Investigation into Regenerative Braking Control Strategy for Hybrid Electric Vehicle

Energy regeneration during braking is an important technique for hybrid electric vehicle (HEV) to improve their fuel economy and extend their driving range. Due to the effect of regenerative braking torque which is added by electric motor, the braking torque distribution between front and rear axles should be changed and the control logic of anti-lock braking system (ABS) ought to be adjusted according to the regenerative braking torque. This paper put forward a braking control strategy for hybrid electric vehicle; the control strategy is implemented with eight DOFs (Degree-of-Freedom) nonlinear vehicle forward simulation model which is built under the environment of Matlab/Simulink. Based on target wheel slip ratio, a fuzzy logic approach was applied to maintain the optimal target slip ratio so that best compromise between hydraulic torque and regenerative torque can be obtained for the vehicle.

Zero-voltage switching converter absorbing parasitic parameters for super high frequency induction heating

This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive and capacitive parasitic components in the converter. The switch devices operate in a zero-voltage soft-switching mode. Consequently, the high voltage and high current spikes caused by parasitic inductors or capacitors oscillation do not occur in this circuit, and the high power loss caused by high frequency switching can be greatly reduced. A large value inductor is adopted between the input capacitor and the switches, thus, this novel converter shares the benefits of both voltage-type and current-type circuits simultaneously, and there are no needs of dead time between two switches. The working principles in different modes are introduced. Results of simulation and experiments operated at around 1 MHz frequency verify the validity of parasitic components absorption and show that this convener is competent for super high frequency applications.

Eco-friendly corrosion inhibitor from Pennisetum purpureum biomass and synergistic intensifiers for mild steel

Extracts of elephant grass （Penniseturn purpureum） blended with some intensifier halides like ammonium chloride （AMC） and potassium iodide （PTI） were investigated as corrosion inhibitor for mild steel. The corrosion process was monitored in 3.5% HCI by mass loss and electrochemical techniques at 30, 40, 50, 60 and 90 ℃. Addition of AMC and PTI increased the inhibition efficiency with the highest inhibition efficiency obtained with PTI blend- ed extract. The blends behaved as mixed type inhibitors and were spontaneously adsorbed on mild steel surface in exothermic nature. Synergistic parameters of the intensifier ions revealed cooperative effect. Kinetic data treatment indicated increase in energy barrier by intensifier ions. The results demonstrate that elephant grass extract blended with halide ions can act as alternative ecofriendly inhibitor for mild steel at elevated temperatures.

Decision-tree induction from self-mapping space based on web

An improved decision tree method for web information retrieval with self-mapping attributes is proposed.The self-mapping tree has a value of self-mapping attribute in its internal node,and information based on dissimilarity between a pair of mapping sequences.This method selects self-mapping which exists between data by exhaustive search based on relation and attribute information.Experimental results confirm that the improved method constructs comprehensive and accurate decision tree.Moreover,an example shows that the self-mapping decision tree is promising for data mining and knowledge discovery.

Online fault recognition of electric power cable in coal mine based on the minimum risk neural network

Firstly,the concepts of the traveling wave entropy and the feature function of traveling wave entropy were defined.Then the statistic characters of the traveling wave entropy feature function,mean value and variance were analyzed after the zero-order component of the traveling wave of online cable was selected to serve as the observed object.Finally,the new recognition algorithm of minimum risk neural network was pre- sented.The simulation experiments show that the recognitions of the early fault states can be completed correctly by using the proposed recognition algorithm.The classes of cable faults include in 1-phase ground faults,and the 2-phase short circuit faults or ground faults and the 3-phase short circuit faults or ground faults,open circuit.The fault resistance range is 1×10^(-1)～1×10~9Ω.

A novel current-sharing scheme based on magamp

The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advan-tages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation (PWM) instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica-tion, a new current-sharing (CS) scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.

The Effect of Sparger Geometry on Gas Bubble Flow Behaviors Using Electrical Resistance Tomography

By electrical resistance tomography (ERT) the cross sectional profiles of gas hold-up in a φ56mm bubble column are obtained with four designs of gas sparger. The effect of sparger geometry on the bubble distribution is re-vealed by applying a sensitivity conjugated gradients reconstruction method (SCG). Experimental results show that over-all hold-up obtained by ERT is generally in good agreement with those measured with the pressure transducer and the ERT system produces informative evidence that the radial profiles of hold-up is very similar to the sparger design in the lower section of bubble column. Meanwhile, the rise velocity of bubble swarm and the Sauter mean bubble size are evaluated using ERT based on dynamic gas disengagement theory. The experimental results are in good agreement with correlations and conventional estimation obtained using pressure transmitter methods.

Economic Comparison of Three Gas Separation Technologies for CO2 Capture from Power Plant Flue Gas

Three gas separation technologies,chemical absorption,membrane separation and pressure swing adsorption,are usually applied for CO2 capture from flue gas in coal-fired power plants.In this work,the costs of the three technologies are analyzed and compared.The cost for chemical absorption is mainly from $30 to $60 per ton(based on CO2 avoided),while the minimum value is $10 per ton(based on CO2 avoided).As for membrane separation and pressure swing adsorption,the costs are $50 to $78 and $40 to $63 per ton(based on CO2 avoided),respectively.Measures are proposed to reduce the cost of the three technologies.For CO2 capture and storage process,the CO2 recovery and purity should be greater than 90%.Based on the cost,recovery,and purity,it seems that chemical absorption is currently the most cost-effective technology for CO2 capture from flue gas from power plants.However,membrane gas separation is the most promising alternative approach in the future,provided that membrane performance is further improved.

Life Cycle Assessment,Estimation and Comparison of Greenhouse Gas Mitigation Potential of New Energy Power Generation in China

From the perspective of life cycle assessment （LCA）, the development, construction, and operation of all kinds of new energy power generation technologies release greenhouse gas （GHG） emissions. This sparks concerns about the lowcarbon nature of the new energy power generation technologies. Based on national and international literature review, this paper estimates and compares the GHG emission factors of traditional thermal power generation and new energy power generation technologies in China with the LCA approach. The GHG mitigation potential of new energy power generation technologies as substitution for traditional thermal power generation in China was evaluated, according to the objectives of new energy power generation of the national development planning. The results show that the GHG emission factors of new energy power generation axe much lower than that of traditional thermal power generation even with LCA accounting, and the GHG mitigation potential of new energy substitution is huge.

Properties of Surface Film on X70 Pipeline Steel in CO_3^(2-)-/HCO_3^- Environment

The electrochemical behavior of X70 pipeline steel in (0.5mol·L-1 Na2CO3+1 mol·L-1 NaHCO3) solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to analyze the composition and microstructure of the surface film. The results showed that there were two anodic peaks at -600 mV and -350 mV. The surface film formed at -600 mV mainly consisted of ferrous carbonates and ferrous hydroxycarbonates. It had a small reaction resistance. It was metastable and possessed poor protective property. Numerous pits and microcracks existed on the film, which could be the active paths for the initiation of stress corrosion cracking. The surface film formed at -350 mV, mainly consisted of ferric oxides. It has high reaction resistance and offered good protection for the substrate.

Safety and effective developing nuclear power to realize green and low-carbon development

This paper analyzes the role of nuclear power of China's energy structure and industry system. Comparing with other renewable energy the nuclear power chain has very low greenhouse gas emission, so it will play more important role in China's low-carbon economy. The paper also discussed the necessity of nuclear power development to achieve emission reduction, energy structure adjustment, nuclear power safety,environmental protection, enhancement of nuclear power technology, nuclear waste treatment, and disposal, as well as nuclear power plant decommissioning. Based on the safety record and situation of the existing power plants in China, the current status of the development of world nuclear power technology, and the features of the independently designed advanced power plants in China, this paper aims to demonstrate the safety of nuclear power. A nuclear power plant will not cause harm either to the environment and nor to the public according to the real data of radioactivity release, which are obtained from an operational nuclear plant. The development of nuclear power technology can enhance the safety of nuclear power. Further, this paper discusses issues related to the nuclear fuel cycle, the treatment, and disposal strategies of nuclear waste, and the decommissioning of a nuclear power plant, all of which are issues of public concern.

A Novel Technology for Generation of Electricity and Cold by Using Energy Potential of Transmission Line＇s High Pressure Gas

The main objective of this paper is to develop a novel technology for combined generation of electricity and cold by using energy potential of transmission line＇s high pressure gas. For this purpose, the reduction of high pressure of the gas in gas distribution station instead of useless expansion throttling process is suggested to realize by adiabatic expansion, which is executed in a gas expanding turbine. Herewith, the gas distribution station is turned into energy and cold generating plant. Simultaneous operation of energy and cold generating plant is described. A method and appropriate formulas for determination of design characteristics of considered plant are suggested. A new method for reveres order of calculation and design of the cold store based on the use of expanded cold gas as cooling agent is developed. Calculations and analysis prove high energy efficiency of suggested technology, the wide use of which will provide significant production of cheap electricity and cold and as well as reduction of fossil fuel consumption.

Climate technology promotion in the Republic of Korea

The implementation of climate technologies and their commercialization ultimately depends on the success of their research and development(R&D) projects. In the Republic of Korea(ROK), twenty-seven climate technologies were selected to boost the greening of existing industries and to develop new green industries to promote a sustainable climate technology development strategy. Rechargeable battery technology, carbon capture and storage(CCS) technology, smart grids, and sewage treatment are all research areas expected to have tangible outcomes in the forthcoming years. As such, they were included in a comprehensive R&D plan for climate technology advancement, which places an emphasis on climate technology development and commercialization strategy. In this study, the R&D plan of the ROK is reviewed by examining its six core climate technology programs: solar cells, fuel cells, bioenergy, rechargeable battery technology, information technology(IT) applications for the power sector, and CCS technology in detail. The climate policy in the ROK aims to find new economic growth engines and to develop new business opportunities while actively participating in international efforts to combat climate change.

In-Vessel Melt Retention of Pressurized Water Reactors: Historical Review and Future Research Needs

After the first concrete was poured on December 9, 2012 at the Shidao Bay site in Rongcheng, Shandong Province, China, the construction of the reactor building for the world＇s first high-temperature gas- cooled reactor pebble-bed module （HTR-PM） demonstration power plant was completed in June, 2015. Installation of the main equipment then began, and the power plant is currently progressing well to- ward connecting to the grid at the end of 2017. The thermal power of a single HTR-PM reactor module is 250 MW,h, the helium temperatures at the reactor core inlet/outlet are 250/750 ℃, and a steam of 13.25 MPa/567 ~C is produced at the steam generator outlet. Two HTR-PM reactor modules are connect- ed to a steam turbine to form a 210 MW nuclear power plant. Due to China＇s industrial capability, we were able to overcome great difficulties, manufacture first-of-a-kind equipment, and realize series ma- jor technological innovations. We have achieved successful results in many aspects, including planning and implementing R＆D, establishing an industrial partnership, manufacturing equipment, fuel produc- tion, licensing, site preparation, and balancing safety and economics; these obtained experiences may also be referenced by the global nuclear community.

Clean Coal Technology and Market in China

This paper briefs the current clean production and consumption levels of coal in China and the pollution harmbrought to the atmospheric environment, present status and orientation of clean coal technology development in Chinacoal industry, progress and perspective of clean coal power generation technology in China, as well as application andmarket of flue gas desulphurization technology in coal-fired power plants.[