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Table of Content

    25 January 2019, Volume 41 Issue 1
    Research on electrical and structural characteristics of a newtype 220kV inverted “Y” string transmission tower with double circuit lines
    PAN Feng1,JIANG Wendong2,SONG Gang1,CAI Yong2
    2019, 41(1):  1-8. 
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    To determine the pole and tower position for transmission line in mountainous areas, weight span/wind span (Kv) is one of the important limiting factors of pole and tower. While designing transmission line in mountainous areas, there are often cases where the weight span and wind span are not large enough, and the Kv value is small, which can be solved raising tower height, adopting a tower with a smaller Kv value, or adopting a tension support as breaking measure. The three methods above will increase the engineering quantity, and a newtype inverted “Y” string transmission tower is introduced to solve this problem. It can be used in the areas with small Kv. In the case of strong wind, ice coating, broken wire and other working conditions, the stress of the insulator is analyzed, and reasonable design of fitting strings is proposed. The finite element model is established, and the natural vibration coefficients are obtained and compared with that of conventional towers. Based on the time domain method, the distribution characteristics of wind vibration coefficients are studied, and the recommended values of the wind vibration coefficients for tower bodies and cross arms of inverted “Y” tower are put forward. Finally, the comparative analysis of the economic performance of the inverted “Y” string tower is carried out. Through the research, the electrical and structural characteristics of the inverted “Y” towers are revealed, and the results can be used as a reference for the design of transmission towers.
    Study on steady state change calculation of natural circulation parameters
    ZHOU Tao1,2,3,ZHU Liangyu1,2,CHEN Jie1,2,ZHANG Jialei1,2,HUANG Yanping4
    2019, 41(1):  9-12. 
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    The parameters of natural circulation in steady state play an important role in improving the capacity of natural circulation. The change law of natural circulation flow and other parameters in steady state are studied. Given related parameters, the effective pressure head can be adjusted by changing the outlet temperature of the cooling section.After updating the related physical property parameters, the change laws of natural circulation flow rate, pressure head and cooling power of the each cooling section under different parameters are analyzed. The results show the coolant density and specific enthalpy at the outlet of cooling section increase gradually with the increase of the coolant temperature at the outlet of cooling section. The increase of power in heating section will cause the increase of natural circulation flow rate.The results provide reference for improving the natural circulation capacity and further research.
    Discrete value algorithm of cosine function based on table lookup interpolation
    YE Pinyong1,WU Yinfu1,SHAO Zongwei1,GUAN Jiyong1,CHEN Xinzhi2,ZHOU Zhaoqing2
    2019, 41(1):  13-16. 
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    Field programmable gate array (FPGA) is widely used in smart grid related relay protection and automation equipment for its flexibility, reliability and integration. Due to the prominent contradiction between the calculation accuracy and the storage capacity, the commonly used table lookup method has no advantage in calculating the cosine function discrete value in the FPGA chip which has limited storage space. Therefore, an algorithm which combines the table lookup with the Lagrange interpolation is proposed. Combining the advantages of the two algorithms, the output delay and resource consumption of the algorithm are optimized on the premise of ensuring the accuracy. The design of the algorithm and hardware verification is completed on Xilinx’s Artix7 chip.
    Finite element conjoint analysis of the blade operating mechanism for large Kaplan turbine
    REN Shangjie,LIU Siliang
    2019, 41(1):  17-20. 
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    The blade operating mechanism is an important assembly of Kaplan turbine, which is used to transfer the force from piston and adjust the angle of blade. In general calculation,a single component of the operating mechanism is analyzed separately, while deformation coordination between the components is ignored,which result in the calculated stress is larger than the fact. By means of conjoint analysis, the finite element method is used to calculate the overall blade operating mechanism, and the stress distribution of each component can be obtained accurately. It can be a better guide for structural design and improve the economy of the design.
    Economic analysis on design and operation of pad mounted transformer integrated with awning in photovoltaic station
    CHEN Jianguo1,ZHANG Guomin1,MA Hui1,HAN Bing2,ZHUO Gang1,FENG Hui1
    2019, 41(1):  21-26. 
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    Pad mounted transformer is an important equipment for photovoltaic power plants which can boost the low voltage AC of photovoltaic inverter to high voltage AC. Considering the operating characteristics of largescale photovoltaic power plants and the limited land area, it put forward an arrangement of photovoltaic modules on top of the pad mounted transformer for integrated power generation. It can generate power by using solar energy while meeting the shading function. Taking a 20MW PV plant as an example, detailed analysis and calculation of the project’s system efficiency, output characteristics, and project investment income are made.The results show that the installation of photovoltaic panels on the top of pad mounted transformer can reduce the winding temperature by around 20℃, and the return on investment is expected to be 17% under current electricity price. Comprehensively shows that the program has greater practical value.
    Flow field optimization and energy saving based on antinoise fan pipes
    LI Xiaofei1,ZHANG Zan1,XIE Jiankun2,WEN Xiaoming2,LIU Yuqing2
    2019, 41(1):  27-31. 
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    The vertical blast pipe has certain flow field design defect which results in the increase of draft loss. However, the muffler installed to reduce the noise accelerates the power consumption of fan. Improved design of fan pipes combines antinoise and flow field optimization, which makes pipe itself has a certain muffling performance. The energy saving of fan is achieved by improving the flow field of the pipe and reducing the draft loss. Numerical analysis and demonstration project application show that after the antinoise and flow field optimization of the fan pipe, the muffling energysaving pipe can achieve the muffling effect as ordinary mufflers,and increase the efficiency of the fan by more than 10%. This pipe has the advantages of simple structure,good environmental adaptability,low maintenance cost,excellent application and promotion prospects.
    Application research of air staging technology based on CFD
    LIU Peiqi,LIU Xiaomeng,ZHU Yue
    2019, 41(1):  32-35. 
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    Based on Fluent software, the numerical simulation of the combustion process of 450t/h pulverized coalfired boiler is carried out. The simulation results show that the different air ratios of main combustion zones have a great influence on the oxygen content at furnace exit, smoke temperature and NOx concentration. Properly reducing the air volume in the main combustion zone can effectively reduce the NOx emission concentration at the furnace exit.The CO concentration and exhaust gas temperature at furnace exit rises slightly at the same time.
    Research and design of power generation capacity evaluation for coalfired power plants
    TANG Guodong1,WANG Zhongbao1,DING Jian1,WANG Qun1,XIE Xiaopeng2,WU Mingxin2
    2019, 41(1):  36-39. 
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    Taking the power generation capacity evaluation for coalfired power plants as the research object, it focuses on the equipment selection, model construction and evaluation process of unit health assessment and unit load capacity evaluation. The design concept, function structure design, main function design and innovation point of the system are introduced. The system provides powerful support for grid dispatching and realtime operation management of power plants.
    Axial clearance calculation and differential expansion analysis of Dongfang Turbine Company Limited X300P turbine
    LIU Guanjun
    2019, 41(1):  40-44. 
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    To cut down the power consumption level of a unit, No.2 turbine in a power plant upgraded its parameter.After the transformation, there were problems of large HP/IP cylinders differential expansion and worsening adaptability to varied load. Accordingly,it calculated and analyzed various clearances in flow passage of HP/IP cylinders, according to the structure and actual operating parameter of turbines.The parts that are prone to rubbing were found out. After analyzing the reason of differential expansion,suggestion and warnings for designing and manufacturing during reforming are put forward.
    Optimization of operational and cleaning method of predesalination system in thermal power plants
    XIA Yu,ZHANG Song,TAO Qihua
    2019, 41(1):  45-49. 
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    To solve the problem of low water production rate in predesalination system of a power generation company, measures for equipment maintenance, system operation mode adjustment and cleaning mode adjustment are proposed after analyzing the water quality and equipment operation mode. The methods effectively improve the water production rate in predesalination system and its cleaning effect. The silting density index in reverse osmosis system is reduced. The safety and economy of the predesalination system is enhanced.
    Cause analysis and preventive measures for high dispersion of 9FA turbine exhaust gas
    WANG Liangming
    2019, 41(1):  50-54. 
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    It analyzes the reasons for the high dispersion of turbine exhaust gas during the operation of GE 9FA gas turbine, and proposes countermeasures to improve the operation and maintenance level of the unit to avoid the tripping protection triggered by high dispersion of exhaust gas.It reduces the damage risk of the hot channel components of the gas turbine, and significantly improve the safety of power generation.
    Measures to increase the operational rate of AVC system in thermal power plants
    ZHANG Yunbin,CHAI Haichao,WANG Xinhe
    2019, 41(1):  55-58. 
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    为提高火力发电厂自动电压控制(AVC)系统的投入率,通过分析AVC系统,从AVC下位机数据采集、AVC下位机与受控对象、AVC系统逻辑优化、AVC系统通信4个环节着手,提出了相应的改造措施,增加了AVC系统的可靠性与稳定性,提高了AVC系统的投入率。
    Analysis on processing technology of large stopwater grooves
    LI Yuqiong,WAN Yueying,HUANG Peibing
    2019, 41(1):  59-61. 
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    According to the results of multiple process experiments, by optimizing the cutter clamping method and milling cutter model, milling cutters with different diameterwere selected at different processing stages, and finally scientific processing technology is developed. The processing quality of the large stopwater groove of the seat ring on the top of tailwater emergency gate groove in the pumping storage power station is successfully guaranteed.
    Feasibility research of periodical exhaust steam recovery system in coalfiled units
    QUE Yanping,NING Yuqing
    2019, 41(1):  62-63. 
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    To minimize the heat loss and working medium loss of periodical exhaust gas in coalfiled units, a feasibility research of an energysaving technology for periodical exhaust steam recovering into lowpressure heaters by jet mixing heater was taken on a 300MW unit.The results show that a unit installed periodical exhaust steam recovery system can save 10781 tons of water per year and the amount of heat recovered each year is equivalent to the calorific value of 981 tons of standard coal. It has high economic benefits.
    The research on turbine control mode of feed water pump in high back pressure heating reformation
    YU Shuhui
    2019, 41(1):  64-66. 
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    In the high back pressure heating reformation of No.2 unit in Huadian Qingdao Power Generation Company Limited, a control mode for feed water pump turbine is taken, in which high pressure regulating valve is used to control the prepressure of low pressure regulating valve, and low pressure regulating valve is used to control rotation ratio. The key technology of the high pressure regulating valve control reformation of the micro electrohydraulic control system (MEH) is introduced, and the operating condition after the transformation is tested and analyzed. The good results after the transformation prove the rationality and effectiveness of the transformation.
    Cause analysis on opencircuit of CT secondary circuit for measuring at generator end
    ZHOU Linlin,WANG Kebin,YU Yi
    2019, 41(1):  67-68. 
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    It introduces the classification of current transformer and the open circuit hazard of secondary circuit. Combined with the open circuit event of current transformer secondary circuit at generator end of a 330MW unit in a power plant, the reason why the current transformer is prone to secondary open circuit is summarized. The precautions for solving such events are provided as reference for the operation and maintenance of current transformers with the same type.
    Development of Chinese voice and visual alarm based on system state in service
    CHEN Hao,YU Lifan
    2019, 41(1):  69-71. 
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    Voice and visual alarm plays a vital role for the safety of power plants. An effective alarm system can help the operation attendant detect the deviation of the system timely, adjust the running parameters of the system as soon as possible and reduce unplanned shutdown caused by improper operation and equipment failure. Taking the 6FA gas generator of Hangzhou Huadian Xiasha Cogeneration Company Limited as an example, a Chinese voice distributed control system (DCS) for alarming based on the unit state in service is put into practice. The idea, implementation process and system debugging situation are introduced. Operational practice shows that the alarm performs well.
    Unit tripping risk analysis hidden behind the failure of deaerator admission check valve
    FENG Guangming
    2019, 41(1):  72-73. 
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    By analyzing the tripping of a thermal power unit, it theoretically negates the inevitability of tripping led by shorttime high/low voltage bypass fault opening. Combined with the further analysis on site, it is confirmed that the failure of the deaerator admission check valve was the direct cause of the unit tripping. After the valve fails, it can be opened by the frontandback pressure difference, but it cannot play the role of backstop. Once the unit is greatly reduced in load, it will bring water shock to the water pump turbine,which causes the unit tripping.
    Application of adjacent boiler heating startup technology for 1000MW ultrasupercritical units
    LIU Bin,SHAO Changnuan
    2019, 41(1):  74-76. 
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    1000MW ultrasupercritical turbine units generally adopt high pressure cylinder starting mode. During the startup of the turbine, the exhaust temperature of the high pressure cylinder is low, the reheat steam is cold, the pipe of the hot section is long , bearings at 2 ends of the medium pressure cylinder vibrate acutely, which results in the extension of startup time. By reforming adjacent boiler heating system, steam of adjacent boiler can directly get into the high pressure cylinder through the cold section pipe, which achieves the purpose of fully preheating the high pressure cylinder and uniformly heating the medium pressure cylinder. Therefore, the lifetime of the unit can be extended, the reheater can be protected, the starting time can be shortened, and the starting cost can be reduced.
    Research and analysis on boilers status quo of lignite mixed burning and its effect
    LIU Zhongxuan,NING Xinyu,WANG Yashun,CHENG Shi,ZHENG Mincong
    2019, 41(1):  77-79. 
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    It summarizes the current sources of mixed burning lignite, the capacity of mixed burning and the type of boiler of domestic power plants.It analyzes the effects of lignitemixedburning on boilers. Based on the experimental data,it explains the effects of lignitemixed burning on pulverizer drying capacity, boiler efficiency, furnace temperature, desuperheater water, service power rate and other parameters.