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Table of Content

    25 April 2019, Volume 41 Issue 4
    Stress analysis on rigid hanger of steam pipeline
    SONG Zhanbing1,FAN Peipei2,WEI Jiang1,LIU Baolin1,LI Gen2,CHONG Daotong2
    2019, 41(4):  1-5. 
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    The deformation and stress concentration of steam piping hanger are important to the safety of pipeline and equipment in the rmal power plants. Finite element analysis is adopted to conduct 3D modeling of steam piping rigid hanger for a 300MW coalfired generating unit. Steady state research is carried out under rated working condition and transient processes of varying load rates are studied. The temperature field, thermalstructural coupled stress field and deformation distribution of the rigid hanger are obtained from the studies.The results indicate that the maximum equivalent stress of the rigid hanger is up to 190.1MPa under rated working condition,and the stress concentration mainly occurs at pipe clamps,supports and bolts.When the load changes rapidly,the equivalent stresses of bolts and pipes change greatly,reaching 109.0MPa and 122.1MPa respectively.The equivalent stresses of pipe clamps,hanger rods and supports changes lightly.Changing load acceleration has little effect on the range of equivalent stress variation.
    Analysis and optimization test for 660MW supercritical unit under slidingpressure operation
    CHEN Shuilin1,ZHANG Xiaolei2,WU Shun1
    2019, 41(4):  6-9. 
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    With the continuous improvement of economic level and living standard, the demand for electricity is gradually rising, and the total load of power grid is increasing, which increases the disparity between peak loads and valley loads. The demand for peak load regulating is more urgent. At present, the effective operation mode of steam turbine under low load is slidingpressure operation, which is more economic and more coalsaving. It is of great significance to study the lowload operation mode of steam turbines in order to reduce the energy consumption. Through slidingpressure test, the initial load point of slidingpressure operation and the initial pressure of constantpressure operation are determined. The relationship between the load and the main steam pressure in front of the engine is given to guide the economic operation of the unit.
    Design and implementation of crossarea interactive channels for data stream in the master station of distribution system
    CAO Yinxiang,LI Junda
    2019, 41(4):  10-13. 
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    To solve the difficulty in crossarea interactive channels for data stream, a highefficiency, compatible, and freely deployed standarding interface adapter is proposed based on information exchange bus comply with IEC 61968, as interactive channels for data stream. By serializing use cases, designing data structure and function interface, the interactive channel can be instantiated with gSoap toolkit. On the basis of technical standard for bus, a complete experimental scheme is designed and executed to verify and optimize the bus and the adapter.
    Research on visual control of smart substation SCD file version
    WANG Ruibiao1,ZHENG Wenbin2
    2019, 41(4):  14-18. 
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    Substation configuration description (SCD) files describe the instance configurations and communication parameters of all intelligent electronic device (IED) in the station, communication configurations between IED, and virtual terminal connection information. In the debugging, reconstruction and expansion of smart substations, SCD files will be changed. But there is currently no convenient, intuitive and effective method to controlling SCD files. By analyzing the present situation of SCD file version control, a visual control function is developed on the intelligent station configuration tool. After verification of qualified SCD, all published SCD file tables are displayed. At the same time, the detailed differences in the content of different versions of SCD files can be reviewed, which achieves visual control of SCD file versions.
    Design and implementation of generator/transformer protection device MMI and communication management unit
    CUI Dianbin
    2019, 41(4):  19-23. 
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    With the development of digital power plant, it brings higher requirements for the MMI, communication function and performance of relay protection devices. Based on the comprehensive analysis of the generator/transformer  protection device MMI and communication management unit, a design scheme that includes chip AM3352 and embedded realtime operating system QNX is proposed.The design scheme is expounded from software/hardware platform selection, software architecture, software process design, etc.
    RB test and optimization of primary air fan in 600MW supercritical W flame boiler
    GE Jusheng
    2019, 41(4):  24-28. 
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    Taking a 600MW supercritical W flame boiler coalfired unit as the research object,in view of its specific structure characteristics and operation mode,an RB control strategy for primary air fan is designed.It introduces the operating process of primary air fan in RB test,and makes a detailed analysis on the changes of  main parameters which includes furnace pressure,main steam temperature and reheat steam temperature during the test.The control strategy is optimized according to the problems founded in the first primary air fan RB test,then another primary air fan RB test was carried out.The test results show that the optimized control strategy has good application effect and the unit operation stably,the fluctuation range of the main parameters is obviously improved compared with that of the first RB test.The results can provide a beneficial reference for the application of primary air fan RB test with same type.
    Realtime operation monitoring of thermal power units based on big data platform
    FENG Zelei,WU Meifeng
    2019, 41(4):  29-32. 
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    The power generation group is responsible for the realtime operation status of the unit, especially the abnormal status, which is an important part of daily management. Taking the online monitoring technology to develop the unit status management module, realtime supervision and management on the startstop and derated output of thermal power units are carried out. The realtime tracking provides accurate time of unit state switching. Compared with manual supervision, online monitoring is of a lower underreporting rate,better determination accuracy and reduced information processing time. Through mining historical data, suitable eigenvalues and derated output model are developed, and the automatic monitoring of derated output events is realized, which solves the problems that the data is difficult to collect within manual recognition and the boundary of the active derating output  is blurred. A closedloop management is made up by online analysis and expert verification, which facilitates the immediate supervision on equipment and provides data support for business decisions.
    Influence analysis of ungrounded neutral system on distance protection
    KANG Feng,QI Yinian,ZHANG Wei,LIU Qinghai
    2019, 41(4):  33-37. 
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    Operation mode and structural changes of power systems have little influence on distance protection whose protection range is relatively stable. It is widely used in the relay protection of power transmission lines.The influence of the ungrounded neutral system on the distance protection is mainly described.Firstly, based on the basic principle of the distance protection of the ungrounded neutral system, it is found out that the discrimination of positive sequence component directly affects the action of distance protection, and then the failure of the ungrounded system.The characteristics of ungrounded system faults are analyzed, and combined with the quadrilateral characteristics of the distance protection relay, an improved distance protection scheme for blocking the discrimination of positivesequence voltage direction component is proposed. Finally, the correctness of the scheme is verified by the simulation test  of the realtime digital simulator(RTDS).
    Antiswaying measures for PZQ1400 flattop tower crane slewing mechanism
    SHI Xiaofei,WANG Pengge
    2019, 41(4):  38-40. 
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    Largescale flattop tower cranes are widely used in largescale construction projects of thermal power, hydropower and nuclear power. It is very important to diminish the swaying of large flattop tower crane slewing mechanism for the safe and accurate lifting. The causes of the swaying of the large flattop tower crane slewing mechanism are analyzed. Two antisway measures taken by the PZQ1400 and the parameter adjustment process onsite are introduced. Finally,a favorable braking effect is achieved, and the swaying of large flattop tower crane slewing mechanism is diminished effectively.
    Experiment on the influence of biomass gasification syngas on the load of coalfired power plant
    CHEN Xuanlong1,LIU Sanju2,YANG Tao2
    2019, 41(4):  41-46. 
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    Taking Huadian Hubei Power Generation Company Limited as an example,the constant load and coal consumption tests on biomass gasification coupled coalfired unit power generation system are carried out. It is found out that the gas composition of biomass gasification syngas is stable,combustible gas mass fraction is around 30%, the mass fractions of CH4 and H2 are steady at 5%,and mass fraction of CO is about 18%. In the test, coalfired units have absorbed the influence of syngas on the pollutants, SO2 and NOx,in the flue gas. When syngas enters the furnace, the mass concentration of SO2 and NOx are below 35mg/m3 and 40mg/m3 respectively, which satisfies the ultra clean emission standard.The biomass gasification syngas has an enhancing effect on the combustion of the coalfired power plant. The biomass gasification syngas generates power efficiently through the coalfired unit, which can reduce the coal consumption of coalfired power plant.
    Analysis on influence of air conditioning water balance in buildingtype distributed energy station
    GU Zhixiang1,LIU Jie2,KONG Fei2,LIU Yubin2,HONG Bo2,JI Yufei2
    2019, 41(4):  47-50. 
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    There is unbalance on the the primary side and the secondary side of the air conditioning water system in a buildingtype distributed energy system of Huadian Industrial Park. The refrigeration load and efficiency of waste heat lithiumbromide refrigerator,electric refrigerator and directfired lithiumbromide refrigerator under balanced and unbalanced air conditioning water on the primary and secondary side are compared.The operating costs and benefits of energy stations under two conditions are also compared.The results show that the balance of air conditioning water system is important to improve thermal efficiency,improve operation efficiency, reduce power supply for station, etc.
    Calculation method of array spacing for mountain PV project
    WANG Chunlin1,2,YUAN Yun1,SHI Yu’an1,GAO Dan2
    2019, 41(4):  51-55. 
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    Studying the relationship between the spacing of PV arrays in mountainous areas, the gradient and the direction of slopes, improvement can be made on the base of mathematical calculation model of the spacing for plain PV arrays, and a mathematical model calculation method suitable for the spacing for PV arrays in mountainous PV projects is obtained. Through this method, the regularity of PV array spacing varying with the slope direction is obtained under different slope conditions. This method is not only conducive to a comprehensive understanding on the PV array spacing of mountain PV projects with different topographies, but alsoconducive to a more accurate assessment of the availability of terrains with different direction, which can provide a practical and effective assistant for the future site selection for mountain PV project at a early stage and the economic optimization at design stage.
    Analysis on improved adjustment strategy for adjustable fixed bracket system
    WU Shaojing,ZHOU Changyou,CHEN Bin,LU Gang
    2019, 41(4):  56-58. 
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    The traditional fixed adjustable bracket system uses a fixed adjustment strategy throughout its life cycle which means the number of adjustment time per year is unchanged in the whole life cycle. However, because of the degradation of PV panels and the increase of manual adjustment cost, the traditional method is not the optimal strategy. Based on the discounted profit and loss model, it analyzes and determines the reasonable adjustment method with the best economy based no the data of Golmud Project of Hefei Sunshine New Energy Technology Company Limited.The results show that adjusting 4 times per year in the first 8 years and adjusting 3 times per year in the following years of the whole life cycle can optimize the benefits.
    Thermal design and test verification of the evaporator for ORC power generating system
    SUN Hui,XU Xue,LIU Shujun,WEI Yufang,YIN Ruixiang,MAO Lianfei,HU Busong
    2019, 41(4):  59-63. 
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    There is difference between the heat transfer coefficient of the phase transformation zone and that of the single phrase zone in the evaporator of steam waste heat type organic Rankine cycle (ORC) power generation system.There may be errors in calculating the heat transfer area using conventional design methods.The heat transfer area of the evaporator can be calculated by the basic method of heat transfer, and the heat transfer performance can be evaluated based on the test data.The results show that the evaporator could meet the heat transfer requirements of the system. It can provide reference for the design of evaporator in ORC power generating system.
    Research on comprehensive dust control technology of coal handling system in thermal power plants
    ZHANG Chengguo1,WANG Jian2
    2019, 41(4):  63-65. 
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    Targeting at the unqualification of dust concentration of coal handling system in coalfired power plants, the causes of dust generation in coal handling system are analyzed which are air flow in guiding grooves and vibration of belts. According to environmental conditions and coalburning characteristics, the technical scheme for guiding groove, water sprayer and coal dropping pipe is proposed. The transformation has achieved good dustremoval results and provides reference for the comprehensive treatment of dust in the coal handling system of thermal power plants.
    Application of adjacent boiler heating technology in 1000MW ultrasupercritical thermal power units
    JIA Lifeng
    2019, 41(4):  66-67. 
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    During the cold startup of a 1000MW ultrasupercritical thermal power unit in Huadian Laizhou Power Generation Company Limited, adjacent boiler heating technology is used to heat feed water of No.2 high pressure heater in hot flushing and boiler warming process, which can boost the flushing water temperature, shorten the hot flushing time and accelerate the warming of boiler. The technology can save auxiliary machinery power consumption and reduce the emission remarkably. Its environmental benefits and economic benefits are good.
    Analysis and treatment of 390H generator shaft current abnormity
    JIANG Xiaofeng, NIU Zhifeng
    2019, 41(4):  68-70. 
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    The hazards and monitoring methods of generator shaft current are introduced.Through the analysis and troubleshooting of the generator shaft current abnormality,the initial causes of the shaft current abnormality which are the generator side shaft end and the excitation shell air seal rubbing, and the journal electric corrosion at the grounding brush are obtained.After the rubbing phenomenon disappears,the metal material remaining at the shaft end is shortcircuited with the oil seal,causing the shaft current to appear at the cold start;at the same time,the grounding brush is poorly contacted due to the journal erosion at the grounding brush,making the shaft current difficult to be completely eliminated. Targeted treatment for different reasons provide reference for generator operation and maintenance.
    Zibo Thermoelectric WESP water system optimization
    LI Qiang
    2019, 41(4):  71-73. 
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    With the increasingly strict national environmentprotection policy, the ultralow emission transformation of coalfired units has been completed. After the ultralow emission transformation of No.6 unit (330MW) in Huadian Zibo Thermal Power Company Limited, a series of problems occurred in the design, construction and material selection, resulting in unstable operation of the wet electrostatic precipitator(WESP),low reliability of water system operation and risks in exceeding the environmentprotection standard. In response to the existing problems, solutions such as renovating the spray pipe, optimizing the filter program, and accurate measuring of the indicator are proposed. After implementation of the scheme, the operational reliability of the WESP water system in No.6 unit can be improved, and the experience of ultralow emission transformation of coalfired units are provided.
    Exploration on feed water flow control at initial stage of startup of a 600MW supercritical boiler
    WANG Xiaojun
    2019, 41(4):  74-75. 
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    At initial stage of boiler startup (before grid connecting),the temperature rise of boiler heating surface has to be controlled, the superheater surface temperature has to be controllable, and superheat steam temperature should be controlled.Large piece of oxide scale will fall off because of large variation of superheater temperature or overtemperature. The fallen oxide scale will block the superheater within one week after the boiler startup,which could cause overtemperature and tube burst. Disengaging the boiler feed water lowflow protection and controlling the feed water flow between 350~574t/h can effectively solve the problem of frequent burst pipe in boilers.
    Implementation of lean cost management in thermal power infrastructure projects
    YAN Tao,HE Shengli
    2019, 41(4):  76-80. 
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    Thermal power generation project has the characteristics of long construction cycle and large investment. Cost management, as a systematic work, runs through the whole construction process. The management level of cost is also a miniature of project management level.The key cost management is to be objective, impartial and careful at the different stages of the whole process management. Accordingly,it focuses on experience in engineering design, calling for tenders and phrased settlement of cost management from the perspective of lean management. In the aspect of engineering design, through the reward and punishment for the design institute, with the help of mature experience,the optimization of design, reducing the times of modification can be achieved, so as to control the cost. At the stage of bidding, it focuses on the experience in bidding planning, list preparation and price limit setting, so as to offer an objective and fair bidding and to lay a foundation for the smooth implementation of the project. In terms of phrased settlement, the key is to closely link up the cost with the onsite progress, and cooperate with the other parts in phrased settlement, so as to achieve a winwin situation.