Table of Content

25 September 2015, Volume 37 Issue 9

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Computation of the closest critical point based on open source software InterPSS

MA Longyi1，CAO Min2，FU Zhihong3，WANG Haona1

2015, 37(9):  1-4. 

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Abstract:A new method for finding the closest critical point is introduced based on the open source power system analysis software InterPSS.
With the API (application programming interface) provided by InterPSS,the extended program for load model was written with Java language, which can interface with InterPSS flow computation program and can solve the limit power in a certain direction.Based on this,with the actual factors about the load increased,a model for calculating the closest critical point is proposed.Analysis of 118 bus node system and practical example system show that the extended method conforms to the realizing process and the analysis outcomes coincide with those of the actual
project.

Transformation design of underframe for tower crane

ZHANG Xiaobing

2015, 37(9):  5-7. 

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Abstract:For the shortcomings of stationary base of traditional tower crane, this paper used the steel beam typed underframe instead of pile cap
typed base to transform the crane.The results of calculations show that the straight beam of transformed underframe and the original ring beam can meet the strength and integral rigidity requirements well.Practices show that the steel beam typed underframe has many advantages and the transformation has high feasibility and practicality.

Research on data pre processing to improve the accuracy of load forecasting

TAO Li1，ZHU Xiaoguang2

2015, 37(9):  8-10. 

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Abstract:The higher prediction accuracy is,the more helpful is to improve the availability of facilities and the validity of economic dispatches.
Through the load characteristics analysis of Huaiyin area in 2013,the effects of load characteristics and different data pre processing methods are analyzed.The results show that stabilizing the abnormal data is the most directive and efficient method.The original data of daily amount of samples had little effect on the predicted results.The prediction accuracy will be improved greatly when the load forecasting of the working days after major holidays is predicted by deleting the original data in the weekends and major holidays Adjustment of data sequence of the same day types can also be appropriate to increase the prediction accuracy when load is stable in spring and autumn.

Improvement of Siemens’s continuous emission monitoring system

LIN Zaofa， DENG Guangnan

2015, 37(9):  11-12. 

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Abstract:The Siemens’s continuous emission monitoring system (CEMS) of Fujian Huadian Zhangping Power Company Limited has
problems, such as SO2 density displayed incorrect, high zero drift and etc. After improvement of calibration system, condenser drainage system and purge system, the operation stability and accuracy of CEMS was significantly increased. The operation safety and stability of whole unit was secured.

Pretreatment of zero injecting and reliability assessment for power system based on recursive convolution

ZHANG Zece, SHEN Tianshi, ZOU Yuntao

2015, 37(9):  13-16. 

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Abstract:The nature of reliability assessment for power system is to quantize the electrical adequacy of a single node.It is equivalent to do
convolution operation between the two random variables:the power generation capacity and the load.However,the operation units need to be determined whether they are off sequence when doing the convolution between the outage tables,and that makes the complex arithmetic
logic even more complex after adding the determinant logic.This paper proposed a method that can avoid the discrimination of off sequence to improve the outage table: pretreatment of zero injecting.It also proved the recursive convolution would be more efficient after the pretreatment of zeroinjecting by using the actual example.This pretreatment method for the outage table provided an idea to simplify the program logic and reduce the computation,which has certain guiding effects on the reliability assessment for power system.

Study on unsuitability of water intake by top cover as technical water supply of unit

ZHANG Qi

2015, 37(9):  17-18. 

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Abstract:There exists much problem for water intake by top cover as technical water supply in operation practice,successful application is less in domestic.The study did analysis to unsuitability of water intake by top cover as technical water supply for the new input 600MW  large scale water turbine,which provided reference or design selection of technical water supply of future new built large scale generating unit.

Design and application of safety system in the Three Gorges Project ship lift

LIU Bingfeng1, QIN Wenyu2

2015, 37(9):  19-21. 

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Abstract:Concerning such characteristics as the large tonnage,the high hoisting height and the fast amplitude of upstream and downstream water level,the Three Gorges Project ship lift is currently the largest ship lift in terms of its technical difficulty and scale in the world.This paper gives an overview of safety system and its application in the Three Gorges Project ship lift,followed by the analysis of system equipment selection,fault classification and control flow.It is concluded that the application of safety system ensures the stable operation of the Three Gorges Project ship lift and greatly improves the overall system reliability as well.

The performance diagnosis model of a rotary air preheater and its application analysis

WANG Chengliang

2015, 37(9):  22-24. 

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Abstract:According to the survey results of rotary air preheaters in large capacity thermal power units,the performances of more than 80% of rotary air preheaters appear different degree of deterioration and that caused the decreasing of unit output.This paper built the performance diagnosis model and found the reason that caused the performance decreasing of a rotary air preheater,and then it proposed preventive measures to ensure the safe running of an air preheater,which were proved effective by living examples.

Expert system for fault diagnosis of hydroelectric generating unit based on knowledge base

MAO Cheng1, LIU Hongwen2, LI Xiaojun1, WU Jinhui2, PAN Hua1, WANG Jianghuai2, QIAN Huadong2

2015, 37(9):  25-28. 

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Abstract:According to the operation characteristic of hydropower units,the knowledge base of expert system for fault diagnosis is formed by gathering the fault features and the reasons of the faults occurred during the operation of the hydropower unit.This fault diagnosis system is completed through real time database,historical database and the configuration function of the Cybercontrol software platform and Java
programming language,thus to provide operation and maintenance of hydropower units.

Bus rapid CT break detection based on current variation

KANG Feng，ZHOU Xiaobo，TANG Zhiguo

2015, 37(9):  29-32. 

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Abstract:In order to detect the current transformer(CT) disconnection quickly and accurately and at the smae time to improve the reliability of the
protection bus,the wave about the CT break and bus failure were analyzed.A project was put forward based on the characteristics of the current variation.This scheme combines the Fourier algorithm with sampling point algorithm,which not only maintains the advantage of the Fourier algorithm,but also increase the velocity of the sampling point algorithm.The CT disconnection can be judged in a short time.The scheme can ensure that the bus can’t be falsely tripped under the CT disconnection and line break can’t be misjudged at the bus failure.

Reason analysis of the abnormally increased motor bearing temperature for induced draught fan of 1000 MW power unit

ZHOU Liming

2015, 37(9):  33-34. 

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Abstract:Taking Shenhua Guangdong Guohua Yudean Taishan Power Generation Company Limited as an example,this paper analyzed the reason of the abnormally increased motor bearing temperature for axial flow fan after the runback (RB) experiment.It is considered that the motor shaft shoulders have great problems when the fan working under special conditions and the root cause is the heat expansion impediment phenomenon of the motor shafting.After some treatments,the hidden danger is thoroughly eliminated,and which ensures the safe and steady operation of the induced draught fan under any conditions.

Analysis and treatment of the overlarge direct current resistance of rotor for a large turbo generator

LIN Zhenyu

2015, 37(9):  35-37. 

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Abstract:In the preventative test of No.4 turbo generator for Guangdong Zhuhai Jinwan Power Generation Company Limited, the direct current resistance of rotor is measured out of limit. This paper takes advantage of the direct current resistance differences among different rotation angles of rotor to determine the fault location, and result shows that main reason of the overlarge direct current resistance is the looseness of connection parts of conductive lever.

Analysis and treatment to the steam turbine of the 600MW ultra supercritical power

BING Hankun,GUO Jialei,CHEN Hao,PANG Le

2015, 37(9):  38-39. 

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Abstract:Taking a 600MW ultra supercritical coal power unit as an example, the bearing bush excessive vibration caused by the rotor bending of the steam turbine is analyzed and the exact solutions are given, which provides the basis forsolving the same type troubles by increasing the rotor weight at the both ends.

Reason analysis and its preventive measures for thermal protection miss operation of 660MW power unit

WANG Shipeng, ZHAO Jin

2015, 37(9):  40-41. 

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Abstract:This paper introduced the application of thermal protection logic in 660MW power unit, combined relevant data of thermal protection missoperation, summarized the experience of protection logic, analyzed the reason of thermal protection missoperation and proposed corresponding preventive measures that improved the reliability of thermal protection.

Improvement of 680 MW unit booster fan variable blade system

TAO Liwei

2015, 37(9):  42-43. 

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Abstract:To solve the gas desulfurization system booster fan variable rotor blade system fails to automatically start while 680 MW unit peak regulation,the author adopted the feedback signal as feed forward signal to improve the single circuit booster fan variable rotor blade system, and indicated the setting principle of rotor blade varying parameters.After improvement,the booster fan variable rotor blade system starts automatically while peak regulation.

Accuracy analysis of the vacuum tightness test results of direct aircooled generating unit

BAI Feng

2015, 37(9):  44-47. 

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Abstract:According to the regulations of DL/T 1290—2013: Test Method on Vacuum Tightness of Direct Aircooled Generating Unit, a vacuum tightness test must be carried out at fixed period in the operation of a steam turbine in order to check the tightness of the unit vacuum system. For direct aircooled generating unit, the cooling effect of a condenser is greatly influenced by environment factors because the cooling
medium of condenser is air. Similarly, the test results are also greatly influenced by environment factors when doing a vacuum tightness test. This paper introduced the test method on vacuum tightness of direct aircooled generating unit, and analyzed the major factors which affect test results. Then the accuracy of test results is evaluated and a judgment method of vacuum system leakage through unit operation parameters is proposed.

Technology Research on the 300 MW NCB heating turbine

DONG Lijuan, ZHANG Runpan

2015, 37(9):  48-50. 

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Abstract:The advantages,disadvantages and technical key points of the large and medium sized units and the commonly used back pressure steam turbines in the combined heat and power generation in China are analyzed.By comparing the technical and economical performance of the extraction condensing turbine and the NCB turbine.The author conclude that the NCB turbine can further reduce the cold end loss than the extraction condensing turbine in the area with sufficient heat load.

Calculation for short circuit current of 380V low voltage fourcore power cable

WANG Lu

2015, 37(9):  51-52. 

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Abstract:Due to most 380 V plant power system power center (PC) and motor control center (MCC) are TN-S grounding,the standard short circuit current curve in existing design handbook cannot satisfy the practical demand.This paper provided methods to calculate the short circuit current of 380 V four core power cable from PC to MCC of plant power system.Based on these methods,the relationship between short circuit current and cable length was indicated,which can be applied for relay protection value setting and sensitivity verification.

Heat economy study on low pressure heater drainage system

KANG Xudong1, CAI Tianshui2

2015, 37(9):  53-54. 

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Abstract:Most extraction and recycle system of thermal power generation unit adopted surface heater.The dewatering method negatively affected the heat economy.Based on equivalent heat drop method and projects practice,this paper studied on combined dewatering,and indicated that low pressure heater dewatering system installed with dewatering pump or dewatering cooler would provide higher heat economy than drained waterartesian flow.This paper also evaluated the advantages and disadvantages of these two combined dewatering method.

Analysis and selection of the ultraclean emissions technology route for coal fired power units

XU Ping

2015, 37(9):  55-58. 

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Abstract:This paper analyzed the current control situation of the pollutant emissions from coal fired power units in China, discussed the
principles of the ultraclean emissions using wet desulphurization technology for coal fired power units and its practical application situation, analyzed the economic efficiency of wet desulphurization echnology, and provided suggestions for the selection of the ultraclean emissions using wet desulphurization technology.

Analysis of ultralow emissions transformation for Zhangqiu Power Generation Company Limited

REN Shangkun, HE Weiguo, SHENG Hu, LI Haiping

2015, 37(9):  59-60. 

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Abstract:With the implementation of new national environmental protection policy,it is imperative to promote the ultra low emissions transformation technology for coal fired power units in order to reach the national emission standard of nitrogen oxides,soot and sulfur dioxide, etc. Huadian Zhangqiu Power Generation Company Limited adopts the high efficiency synergistic removal technology to transform  the denitration,dedusting and desulfurization systems of No.3 power unit.After the transformation,the emission concentrations of major pollutants can meet the emission standards of natural gas generating unit,and provided a successful example for the promotion of ultralow emissions programs.

Cause analysis and preventive measures for the collapsed bed of the dry desulfurization absorption tower

HUANG Peiyang1,2，ZHANG Chen2，XIAO Xiong2，GAO Jianqiang2

2015, 37(9):  61-62. 

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Abstract:The flue gas desulphurization system and its procedure process of the CFB in the No.3 unit of a power plant are introduced. Based on the data collected from the operation of the dry desulfurization system,the main causes for the collapsed bed of the absorption tower are analyzed. The results manifest that the main reasons are the low flux of fluegas and its low temperatures. Preventive measures are put forward to prevent CFB absorbing bed collapse.

The determination of adjustment schemes of electrical auxiliary system for environment protection alteration

TAN Pengzhan

2015, 37(9):  63-64. 

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Abstract:According to the national environmental protection requirements, Tianjin Junliangcheng Power Generation Company Limited needs to
reconstruct the desulfurization and denitrification systems of No.5 to No.10 power units. Aimed at the condition of large variety of auxiliary power
capacity, this paper proposed two reconstruction schemes, compared the two schemes, and finally determined the reconstruction scheme.

Keywords:wet stack;GD-APC corrosion resistant coating;failure analysis

WANG Jie1,QIU Zhibin2,WANG Heng1,YUAN Lin2

2015, 37(9):  65-67. 

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Abstract:The GD-APC hybrid polymeric corrosion resistance coatings drop off after one year operation in the stack of 2×600 MW hypercritical coal power units in a power plant of Guizhou province.The coating chips are analyzed through macro structure microscope,energy spectrum analysis microscope and scanning electron microscope.The main reasons are that the fume gas temperature changes abruptly and the construction is not strictly under the control of the construction procedures.At last,advice is give about the design,construction and operation stage.

Overview of air receivers used for solar thermal power generation

WANG Pei，LIU Deyou，XU Chang，GUO Su

2015, 37(9):  68-71. 

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Abstract:Compared with the tube receivers,the tower solar thermal electric power system has the characteristics of the simple structure, high working parameters, high efficiency,easy maintenance and so on.The heat transfer process mainly occurs in the porous media of the air receiver.The incident radiation heats the porous media, then the air will be heated by convection.In this paper,the principle,characteristic,classification and the development status of the air receiver are introduced.The characteristics of the heat transfer by radiation convection with the air as the heat medium in the different air heater are discussed, and the development direction of the air receiver is also given in this paper.

Heat consumption and simulation of power outdoor cabinets based on clear sky solar radiation model

YU Chunlin, TONG Xingxing

2015, 37(9):  72-74. 

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Abstract:With the further development of intelligent substations construction,a large quantity of intelligent equipment is locally mounted in outdoor cabinets.Due to higher requirements on protection grade of outdoor cabinets,their inner space is relatively airtight,and their internal ambient temperature is liable to be affected by heat consumption of internal devices and external solar radiation.On the basis of the research on clear sky solar radiation model in a certain region of Nanjing,solar heat gain of outdoor cabinets is calculated.A rational way of ventilation and heat dissipation is designed based on the calculated result in conjunction with the simulation of ICEPAK software,providing guarantees for the reliable operation of intelligent equipment in the cabinets.

Analysis on application of pipe bending technology in nuclear power station

WANG Lei, WANG Zengchen, CHENG Chao, HUANG Wenqiang

2015, 37(9):  75-76. 

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Abstract:The main process of pipe bending and its application in nuclear power plant were introduced. The advantages of the pipe bending technology conparing with elbow were analyzed. Under condition of enough arrangement space, it was recommended to adopt pipe bending process preferentially. The design and acceptance check requirements for pipe bending process in standards RCC-M and ASME were compared, and the comparison shows that the related requirements of the standard RCC-M are more comprehensive and specific, and to adopt RCC-M preferentially is suggested.