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Table of Content

    25 April 2017, Volume 39 Issue 4
    Busbar abnormal great number detection method based on virtual difference current technology
    TANG Zhiguo,ZHOU Xiaobo,CHEN Qi,WANG Yongxu,CHEN Hongyan
    2017, 39(4):  1-3. 
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    With the application of intelligent substation and localized protection, the probability of sampling abnormal great number is increasing. This required higher reliability of busbar protection. This paper introduced a new approach to recognize abnormal sampling. By linear interpolation, the virtual busbar protection difference current could be calculated. To compare actual and calculated difference current, fault and abnormal great number could be accurately distinguished. This method was approved by simulation, and is able to effectively eliminate the effect of sampling abnormal great number on busbar protection, and increase busbar protection reliability.
    Features and mechanism of interturn short circuit fault by energizing noload transformer
    GUO Xiao, XING Wu, HU Bing, WANG Zhe
    2017, 39(4):  4-7. 
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    When interturn short circuit fault by energizing noload transformer occurs, the threephase current differential protection is blocked by blocking criteria, and it causes the singlephase interturn short circuit fault could not be rapidly removed, which threats the safe operation of transformer. Through establishing the equivalent model of interturn short circuit fault, this paper deduced the analytical expression of magnetic flux of exciting windings and analyzed the influences of system impedance and number of faulted turns on fault features. It concluded that the larger system impedance and number of faulted turns, the more difficult the inrush current occurs. Using the PSCAD software, the correctness of the conclusion was verified, and it provided a theoretical basis for the selection of blocking criteria and blocking schemes of differential protection.
    A study of differential protection of variablefrequency motor and its applications
    ZHANG Yanlin, WANG Peng, HAN Yingjie, FAN Yusheng, LIU Zheng
    2017, 39(4):  8-10. 
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    As the application of frequency converter in auxiliary power, the requirements of frequency conversion transformation of highvoltage motors and variable frequency differential protection are increasing. Taking the frequency conversion transformation of condensate pump motor as an example,this paper introduced the transformation scheme of differential protection and the nonpower frequency tracking sampling value differential algorithm it adopted, and verified its sampling performance and protection reliability by experiments, which provided a reference for the differential protection transformation of a highvoltage variablefrequency motor.
    Coalfired boiler performance test points installation standardization study
    LI Guangwei
    2017, 39(4):  11-14. 
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    The standardization installation of test points impacted the accuracy of thermal power plant unit boiler performance test. This paper summarized the experience of boiler performance tests, discussed installation standardization and methods to enhance the test accuracy of flue gas ingredient, ash, temperature, pressure, flow rate and other parameters. This provided solid foundation for energy saving and environmental protection.
    Simulation study of fan blade shimmy control to reduce wind turbine fault rate
    ZHAN Peng, GUO Jinxue, CHEN Xiaoming
    2017, 39(4):  15-18. 
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    Wind power industry has been rapidly increasing in recent years. With the warranty of wind turbine expired, operation maintenance is critical, especially the fan blade shimmy was already one of the main causes of wind turbine unit failure. To solve the problem of fan blade shimmy, minimum and maximum linear quadratic Guass optimal control theory was indicated. This method using EulerianLagrange equation of the vibration of the fan blade system mathematical model is established, and the minimum and maximum LQG controller scheme design. The simulation results show that the controller has good control effect to blade shimmy, reach the wind generator to reduce failure rate, to enhance the efficiency of the wind power generating units.
    Heat supply unit online monitoring method study and application
    MA Pengbo1, JIA Peng1, WANG Fengxian2, ZHANG Zhao1, WANG Bo1, LIU Fusheng1, XIE Mingming1
    2017, 39(4):  19-23. 
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    This paper introduced the system composition of thermal power heat supply unit, heater supply unit monitoring method and coal consumption online calculation method. Online monitoring calculating methods of thermal power plant heat supply unit steam extraction, heat exchange station, water pipeline and heat supply system was analyzed. The accuracy of a supercritical unit generating coal consumption online calculating system was verified. Combined with online monitoring data, provided by a power group, authors determined that heat supply unit online monitoring system is able to satisfy the requirement of power generation dispatching, economical analysis and heat supply system monitoring.
    Corrosion leakage mechanism analysis of super heater tubes for refuse incineration power plant
    LI Li1,SONG Jinghui2
    2017, 39(4):  24-27. 
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    In order to solve the frequently occurred leakage problem of super heater in the actual production process of refuse incinerator, this paper conducted a comprehensive analysis of the corroded tube of a certain refuse incineration power plant using the scanning electron microscope with energy disperse spectroscopy (SEMEDS), ion chromatograph (IC), Xray fluorescence (XRF) and Xray diffraction (XRD), discussed its corrosion mechanism, and proposed some suggestions on how to prevent the corrosion leakage of super heater. The study shows that gaseous chlorine corrosion and alkali metal ash deposit corrosion are the root causes of corrosion leakage of super heater tubes. For gaseous chlorine corrosion, the HCl and Cl2 produced by refuse incineration could spread to the metal lining of tube wall and corrode it under oxidizing atmosphere, and together with the SO2 in flue gas, the synergistic effect would accelerate the corrosion and form some corrosion pits, which may lead to a leakage eventually. For alkali metal ash deposit corrosion, the alkali metal compound produced by refuse incineration deposits at the outside of tube wall, and the SO2 in flue gas could react with alkali metal compounds to form alkali metal sulfates, which could corrode the tube wall under oxidizing atmosphere. Besides, part of the alkali metal chlorides in ash deposition could corrode the ferruginous oxide film under oxidizing atmosphere, which also could accelerate the corrosion of tube wall.
    Practice of noise reduction transformation for a heat recovery boiler in gas power plant
    YU Weigen,YAO Yong
    2017, 39(4):  28-29. 
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    For a vertical heat recovery boiler in a certain gas turbine power plant, it has problems of big noise and prominent lowfrequency noise, and because of its compact arrangement, the conventional measure of overall sound insulation enclosure could not be implemented. This paper studied the lowfrequency noise of boiler of this type, identified its source, developed a new noise reduction device according to the analysis result, and applied it in practice. The application result shows that the device could significantly reduce the lowfrequency noise of boiler and improve the surrounding noise environment.
    600MW supercritical unit interconnection control valve fullyopened incident analysis and treatment
    WU Xueli1,WANG Weitao2
    2017, 39(4):  30-31. 
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    This paper took Hubei Huadian Xiangyang Power Plant Company Limited MAXDNA control system digital electric hydraulic (DEH) as study objective, summarized the incident of control valve fullyopened by mistake while synchronization. Rapid treatment measures were indicated. Which could be referred to treat similar incident.
    Application analysis of silicon carbide ceramics in boiler turbulent combustor
    LI Zhigang, WANG Lei
    2017, 39(4):  32-33. 
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    The problem of abrasion is existing in large scale power plant boiler combustor operation. This problem changed the air distribution, increased the adjustment difficulty of burning process, increased the primaryair flow rate, and ultimately increased the NOx density. By analyzing the causes of combustor abrasion, and comparing the application condition of aluminum oxide ceramics and silicon carbide ceramics, to use silicon carbide ceramics as antiabrasion material is able to solve the problem of anticorrosion liner detachment and combustor abrasion.
    Analysis of ETS reform of Luohe Power Plant
    WANG Hao, WU Hao
    2017, 39(4):  34-35. 
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    This paper introduced Huadian Luohe Power Plant Company Limited steam turbine emergency trip system (ETS) improvement reconstruction. Based on the control philosophy, original PLC control system was instead by General Electric Energy Group Xinhua Control Engineering Company Limited’s OC6000e system, and integrated into decentralized control system (DCS) network.Controldisplay integration was realized. Reliability and expandability of ETS was significantly improved.
    High sulfur anthracite supercritical Wflame boiler movable blade adjustable axial induced fan bladejam and draft prevention and treatment
    ZHUO Renchun
    2017, 39(4):  38-39. 
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    For supercritical Wflame boiler that firing high sulfur anthracite, the axial induced fan blade jam and shift is an existing problem. After analyzing this problem, a series prevention and treating measures was indicated. This problem was effectively controlled.
    660MW unit blendedcombustion inferior coal adjusting analysis
    KUANG Zheng, KONG Fanxu,GUO Yiyong
    2017, 39(4):  40-41. 
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    Due to serious competition, more and more large capacity power plants prefer to blendedcombustion inferior coal for lower cost. During blendedcombustion, the operation safety, load and pressure shall be ensured to avoid coalwater unbalance. This paper discussed the assurance measurements, especially the operation safety while peak load and underload.
    Economical analysis of gas boiler exhaust steam exhaust
    TANG Mingfeng, WU Minjie
    2017, 39(4):  42-43. 
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    In order to improve the economic operation of the gas boiler deaerator, by adjusting the deaerator steam heating mode and regulation mechanism, thereby effectively reducing the exhaust loss of the deaerator, greatly saves the operation cost. After optimization, the deaerator exhaust loss is reduced, Operational cost on gas reduced 730000 yuan per year.
    Analysis of 4~20mA redundant current output in DCS
    WU Shenghua, TIAN Haibo
    2017, 39(4):  44-45. 
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    Introduces the distributed control system (DCS) 4~20mA current output circuit principle, on the basis of the introduced three kinds of the realization of 4~20mA current redundant output method, according to their respective advantages and disadvantages are analyzed.
    Reason analyses and treatments of the derailing problem of main harrow tensioning wheel and the unsoldering problem of oil cylinder base of a reclaimer
    YANG Gongxiao, MA Qian
    2017, 39(4):  46-47. 
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    A reclaimer in strip material yard is a type of environmentally friendly large mechanical equipment and the tensioning condition of chains would directly influence its normal operation. According to the calculation formulas of pretightening force and minimum pretightening force, the type selection of tension cylinder could be conducted, including the appropriate cylinder diameter and cylinder pressure. Through analyzing, this paper considered that the main reason of the derailing problem of main harrow tensioning wheel and the unsoldering problem of oil cylinder base is misoperation. After that, this paper provided corresponding solutions for the above problems.
    600MW unit high pressure reheater startup pipeline vibration analysis and treatment
    HUANG Xiaojun
    2017, 39(4):  48-49. 
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    To save startup energy and shorten boiler startup time, high pressure reheater was put into operation in advance in startup stage. Due to small water flow and full cold state, dewater pipeline usually serious vibrates during startup. After analyzing vibration causes, technical improvement was carried out accordingly. Vibration of high pressure reheater in startup stage was eliminated.
    Reason analysis of high exhausted gas temperature of a boiler and its countermeasures
    WANG Donghui
    2017, 39(4):  50-55. 
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    The change of exhausted gas temperature has a great influence on boiler efficiency. After the 600MW direct aircooled lignitefired subcritical unit of Baiyinhua Jinshan Power Generation Company Limited put into operation, there exist a problem of high exhausted gas temperature. This paper deeply analyzed the main reason of high exhausted gas temperature, and adopted some measures, such as adjusting oxygen volume, optimizing coal pulverizing system and adjusting combustion, etc. Then it conducted a technical transformation of economizer. After the transformation, the exhausted gas temperature reached the design value basically.
    600MW unit flue gas waste heat ladderform utilization energy saving effects comparison
    HAN Xianfei1, ZENG Hao2, ZENG Yujuan2, BAI Jinde3, SUN Huailin2
    2017, 39(4):  56-59. 
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    With the development of coalfired power plant flue gas waste heat recovery technology, flue gas temperature of low temperature economizer is limited to 130~150. According to the level of flue gas heat step utilization using principle, operation data of 600MW unit of Guodian Duyun Power Plant Company Limited of the existing scheme combined process of medium temperature economizer of low temperature economizer the preliminary design, based on the equivalent enthalpy drop method of traditional economic calculation, the results show that the technology of the energy saving effect is remarkable.
    600MW supercritical unit water consumption reduction reconstruction practice
    WU Xiaohui
    2017, 39(4):  60-62. 
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    This paper introduced the condition of the supercritical unit of Huadian Changsha Power Plant. A series of reconstruction plan which included water purification, desalination and water consumption reduction of precision processing system was indicated. This paper introduces the implementation process and analyzes the effect and the corresponding economic benefits.After implementation, good results have been achieved. The scheme is to provide reference for the corresponding transformation of the same type of power plant.
    HG-1025/17.45-YM28 subcritical boiler ultralow emission improvement
    YANG Xuhao
    2017, 39(4):  63-65. 
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    Per national environmental protection requirements, ultralow emission improvement of Huadian Energy Company Limited Mudanjiang Second Power Plant was carried out.This paper briefly introduced the improvement of desulfurization, denitration and dust removal system. After improvement, unit pollutant density was significantly reduced. Beside environmental achievement, corporation benefits were increased by environmental protection price. This paper also indicated specific treatment for the booster fan overflow after improvement.
    Influence of denitration transformation on air preheater of supercritical unit and its countermeasures
    XU Qi, PAN Mengmeng, LI Qiaoqiao
    2017, 39(4):  66-67. 
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    Taking the denitration transformation of No.4 supercritical unit of a certain power plant in China as an example, this paper analyzed the influence of denitration transformation on air preheater, proposed some feasible countermeasures for the problems, and provided some reasonable experience for the future denitration transformations of similar coalfired power units.
    A comparative analysis of mixed burning cost of lignite
    ZHANG Fang, FANG Jin, ZHOU Jiang
    2017, 39(4):  68-70. 
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    Through calculating the calorific value loss in the storage period of lignite and the coal consumption loss in the mixed burning process, this paper converted the pros and cons after mixed burning of lignite into purchase cost of standard coal and compared it with common bituminous coal. After that, it analyzed the profit boundary point of mixed burning lignite from an economic point of view.
    Wind turbine generator yawing correction analysis method study
    ZHANG Wei, LEI Yang, ZHANG Zhongquan
    2017, 39(4):  71-73. 
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    Yawing system is one of the key systems of wind turbine generator. The error of yawing system will affect the energy generated. A yawing correction analysis method based on operation data was indicated. This method is based on wind direction angle interval model, built on Betz’s law. By inputting the wind speed, wind angle, power rate, generator speed and other data collected by SCADA into this model, power rate curve will be calculated. After comparing and analyzing, the unit yawing error was indicated. This method was applied on a wind power plant in Yunnan Mengzi, and approved by comparing with airborne laser radar anemoscope.
    Study on the selection method of direct normal irradiance design points for tower molten salt solar thermal power generation
    GAO Song
    2017, 39(4):  74-76. 
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    According to the technical features of tower solar thermal power generation, taking the 50MW installation capacity as a computation model, and on the basis of solar energy resource conditions of a certain area, different direct normal irradiances (DNI) are chosen as the design points, and together with different solar multiples (SM) and thermal storage times, several allocation plans are formed. Taking the same annual utilization hours as boundary condition and taking the minimum unit price as optimization target, this paper simulated and filtered the allocation plans. The results shows that different annual power generating requirements need different allocation plans. Even in same area, different annual power generating capacities need different design points. The design points is a necessary condition to confirm the day lighting area at concentrated field under a certain SM, and through the optimization design of spotlight, heat absorption, heat storage and generating unit capacity, the day lighting area at concentrated field could be confirmed. At last, the confirmation of design point could provide a reference for the equipment selection in the design of spotlight and heat storage systems.