Table of Content

25 July 2017, Volume 39 Issue 7

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Statically indeterminate structure support stress calculation

SU Ruijie, SHAN Xiuyang, LI Xin

2017, 39(7):  1-3. 

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Take statically indeterminate structure support as study objective, mechanical model was designed. Based on static equilibrium equation, the stress and deformation of on the analysis of the support under the premise of using force and displacement condition of deformation coordination and supplement the physical relationship between deformation equation, the force situation of solving differential equations and obtain support. The calculation method is consistent with the result of simulation analysis, and the deviation is within the allowable range. The calculation method is compared with the traditional estimation method, which is more widely used and more accurate.

Steel rope stress and structural stability calculation while steel trestle integral lifting

HUANG Peibing, CHEN Yaxiu, WAN Yueying

2017, 39(7):  4-6. 

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In large scale steel structure lifting, steel rope stress and structural stability calculation was usually ignored by engineers. Which significantly increased the safety risk. This paper took steel trestle integral lifting as example, detailed introduced the procedure of steel rope stress and structural stability calculation.

Boiler heat surface small diameter pipe ultrasonic phased array inspection technology study

WANG Dong, WANG Ye, LIU Wensheng, JIA Shaowei, WANG Jingwei, ZHU Guobin

2017, 39(7):  7-10. 

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Based on the principle of ultrasonic phased array inspection technology, combined with the character of heat surface small diameter pipe butt weld, the specific ultrasonic phased array inspection transducer and wedge was developed. Two dimensions image inspection for small diameter pipe was realized based on PHASCAN portable ultrasonic phased array device. Artificial defects of 51mm×4mm small diameter pipe was chosen for verification. This technology is rapid, intuitional, and effective. This will ensure the safety of boiler operation and prevent pipe booster.

Cabinet shock resistant performance study based on response spectrum method

DAI Tingzhen, GU Jinshu, GAO Xuebin

2017, 39(7):  7-10. 

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This paper introduced the process of an intelligent power grid secondary cabinet modal analysis by ANSYS Workbench to study its dynamic characteristic, and then carry out the shock resistant study by response spectrum method. The weak points of cabinet were indicated by simulation. After improvement, deformation and stress,and eventually shock resistant performance was improved. This paper provided an effective and convenient shock resistant design method, and provided data for electrical equipment earthquake test.

Comparison of different operating methods of centralized heat supply pipeline

LUAN Tianhua

2017, 39(7):  15-19. 

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Based on the centralized heat supply system of a certain area, the hydraulic calculation method for dendritic and ring pipeline was introduced. Circulating resistance of dendritic and ring pipeline was calculated and compared based on different work condition. It was indicated that ring pipeline take advantages than dendritic pipeline on operation energy consumption and reliability in certain work condition. Which has certain value for promotion and implementation.

EMTPbased interconnection cable lightning overvoltage affecting factors analysis

WANG Xuxu1，ZHENG Xianlong2，GUO Jing3

2017, 39(7):  20-23. 

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Based on electromagnetic transient program(EMTP) simulation model， lightning current waveform，cable alignment，cable length，impulse grounding resistance，and the relationship of cable end load and cable lightning overvoltage was studied. The result indicated that steeper the wave front is，greater the overvoltage is. The lightning overvoltage is relatively small if cable is horizontally aligned. Lightning overvoltage is maximum if the cable length is 3000m. Cable aligned in same length will reduce lightning overvoltage. Impulse grounding resistant and soil resistant can barely affect the lightning overvoltage. Bigger the load is，greater the cable lightning overvoltage is. The cable lightning overvoltage is greater if load is capacitive or inductive.

Regional power grid degree of balance evaluation model and method

WEN Xiaoqiang

2017, 39(7):  24-27. 

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The concept of reginal degree of balance was introduced.The model for balance degree evaluation was build based on grey association analysis method. Combination weighting approach of subjective and objective was carried out. The resource improvement friendship degree of five provincial power grid was evaluated. A model was built to testify the correctness of balance degree model. The result indicated that it could indicated the reginal balance degreed under different operation condition. And it featured with commonality and operability.

A power plant’s 350MW boiler combustion test adjustment and anticoking test study

BAI Hongsen, GUO Jincheng, HU Zhen

2017, 39(7):  28-31. 

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To solve the problem of boiler coking and NOxoveremission, a series of tests was carried out. The boiler operation status and cause of serious coking was accurately indicated. By improvement adjustment, boiler opertaion and NOxemission was optimized. Constant coking was solved. Boiler combustion adjustment and anticoking test achieved expectation.

The design and implementation of differential protection based on current differential harmonic content

KANG Feng，WANG Runyi，ZHANG Wei，LIU Qinghai，YANG Qingsong

2017, 39(7):  32-35. 

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Accurately determine current transformer (CT) saturation caused by internal or external fault will increase the reliability of differential protection. After analyzing cause of CT saturation and current differential waveform，a differential protection plan was indicated based on current differential harmonic content. CT is able to accurately transmit secondary current at zero passage. By analyzing the current differential harmonic content，the fault is in or out of the protection range will be determined. The simulation proved that，after applying this protection plan， external fault CT saturation will interlock differential protection effectively. Internal fault CT saturation will release differential protection rapidly.

Cause analysis of low temperature of reheated steam at low load of boiler and reconstruction of combustor

WANG Lipeng, WANG Lei, QIN Qi, LAN Xiaocun, JI Ya

2017, 39(7):  36-38. 

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Based on a domestic 350MW boiler low reheat steam temperature at low load, by investigating and combustion adjusting tests, it was determined that operation adjustment would not solve this problem, and combustor improvement reconstruction is necessary. The plan that to reduce furnace heat absorption and upper flue gas swirling was indicated. After improvement, reheat steam temperature was significantly raised at low load. Situation of combustion and slugging was improved. Unit NOx emission mass concentration was reduced. The combustion adjusting tests after improvement provided instruction cards for operation crew. Unit economy and safety was enhanced.

Main transformer nonelectric quantity protection actionbymistake causes analysis and prevention measurements

BAI Guogang

2017, 39(7):  39-41. 

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Based on the accident of a power plant unit No.9 nonplaned outage, by test analysis and inspection, the integrated converter in winding temperature controller was found burn, and caused winding temperature raising and nonelectric protection action. After main transformer outlet tripped, unit stopped. Based on relative standards, the prevention and treatment measurements were indicated after nonelectric protection trip switch was outofservice, to prevent nonplaned outage.

Distribution automation system intelligent device communicating function rapid construction

ZHANG Hang, KANG Zhenquan, WANG Zhenyue

2017, 39(7):  42-43. 

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Based on the problem that distribution automation system intelligent devices have to be reprogrammed for different embedded software of hardware environment, or different application, a rapid communicating function developing method for embedded device was introduced. Plugin type communicating service frame,communicating process plugin,communicating media plugin and communicating protocol plugin were designed. The modelling process of configuration tool was described. Rapid communicating construction and online update was realized.

Bali Power Plant dual internal watercooled generator rotor splash water analysis and treatment

LI Yanfeng

2017, 39(7):  44-45. 

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Based on the treatment of Bali Power Plant generator No.2 rotor discharging support water splash, the cause of water splash was analyzed. Improvement was carried out. Experience was summarized, which could be referred by similar projects.

Puding Power Generation Company 10kV distribution transformer reconstruction

WANG Wen

2017, 39(7):  46-47. 

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The development process and production status of amorphous alloy transformer was introduced. The feature of Yyn0 wiring and Dyn11 wiring, and the advantage of amorphous alloy transformer were analyzed. The reconstruction was summarized. The future of amorphous alloy transformer research, produce and application was discussed.

Super (ultra) critical unit low load MFT cause analysis and improvement strategy

YUAN Shitong

2017, 39(7):  48-51. 

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The incident that main fuel trip (MFT) of two units of supercritical units, which was caused by feed pump recirculating valve opened while varying condition operating, was analyzed. A proportionalintegralderivative (PID) control strategy was designed. If feed pump inlet flow rate is higher than protection value, recirculating valve is automatically controlled by PID. If feed pump inlet flow rate is low to protection value, recirculating valve is controlled by valve position function. This significantly reduced the effect of recirculating valve on feed water flow rate, and enhanced the safety of units operating in low load.

The incident of 220kV circuit lightning conductor heat cause analysis and treatment

XIAO Mingwei

2017, 39(7):  52-53. 

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Base on the overheat of connection point of high voltage transmission line lightning conductor incomer and transformer gatetype frame, far infrared technology was adopted and diagnosed a heating defect of connection metal fitting. The causation and creation condition of heating was analyzed. The onsite treatment and result of heat defect was introduced. Advices for transmission line lightning conductor insulation joint design was introduced. Which could be referred by similar situation.

Vertical condensate pump motor overvibration cause analysis and treatment

CAO Jingfang, WU Changhao, LI Menglin

2017, 39(7):  54-56. 

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A power plant’s unit No.5 condensate pump motor B is overvibrating while switch operation. By vibration analysis, overvibration is caused by heavy wear of rubber bearing and shaft sleeve. Treatment measurements were carried out accordingly. Motor overvibration was eliminated.

S109FA unit main steam pressure abnormal raising cause analysis and treatment

YANG Xutao

2017, 39(7):  57-58. 

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Based on an incident of S109FA unit main steam pressure abnormal raising， the flow passage damage situation by foreign matter was introduced. The main cause of combined cycle units steam turbine flow passage failure was identified. Specific inspection  measures was  introduced.

The optimization and transformation for control circuit of air preheater

SUN Yan,ZHAO Xiaohui

2017, 39(7):  59-61. 

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This paper introduces the principle of Huadian Laizhou Power Generation Company Limited air preheater control circuit, air preheater accident analysis and the problems existing in the control loop.At the same time,puts forward the solution of pneumatic motor circuit, DC power supply circuit and PLC control circuit,which can optimize these circuit.It can be improving the reliability and safety of the air preheater by transformating control circuit of air preheater.

Gassteam combined cycle unit bypass system logic improvement

WAN Zhiyong

2017, 39(7):  62-63. 

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9FA class gassteam combined cycle unit has problems of startup slow and poor economy. After analyzing unit bypass system logic, the economy was enhanced by improving bypass system operation logic.

Flue gas wet type desulfurization gypsum dewater system improvement and implementation

LIU Kaihui, LIU Liwei, NIE Haitao

2017, 39(7):  64-66. 

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Gypsum dewater system is critical for the stability of wet type desulfurization system, especially on ensuring absorber slurry quality, material balancing and byproduct comprehensively utilization.This paper introduced the process and common fault of gypsum dewater system. Based on the reconstruction of Sanmenxia Huayang Power Plant 1000MW unit wet type desulfurization gypsum dewater system,  the alignment  improvement  was introduced. Which could be referred by similar upgrading reconstruction.

Aircooled unit auxiliaries circulating water cooling method selection analysis

WANG Lei, HE Ruixue

2017, 39(7):  67-70. 

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Base on a power plant 2×300MW direct air cooling unit in Shanxi Province, the selection and comparison of mechanical air wet type cooling tower, air cooler and evaporative condenser was carried out. One reliable and economic plan was indicated. Which could be referred by similar auxiliary circulating water system.

350MW unit electricbag precipitator trip cause analysis and treatment

FU Sicong

2017, 39(7):  71-72. 

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Stable operating dust removal and ash conveying system is precondition of ultralow emission. The incident of a power plant’s 350WM unit electricbag precipitator trip was introduced and analyzed. The main cause was determined as ash hopper deposition. Treatments were indicated from mechanical, electrical and control aspects. The stability of precipitator and dust removal system was ensured.

600MW coalfired unit SCR ammonia spraying improving adjustment test study

Gongtao, LIAN Ke, JIANG Jiaxu, ZHU Yue

2017, 39(7):  73-76. 

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Based on a power plant 600MW coalfired unit denitration project, the harm of ammonia escape, criterion of selective catalytic reduction (SCR) system ammonia spraying improving test and procedure and method of ammonia spraying improving adjustment was introduced. By ammonia spraying improving adjustment test, the NOx mass density of side A and side B outlet was reduced from 60.8% and 28.9% to 13.5% and 8.8%. Ammonia escape mass density reduced by 63.4% and 53.8%. Reactor outlet NOx mass density distribution was improved. Ammonia escape mass density was controlled. The safety and economy of unit operation was enhanced.