Table of Content

18 October 2014, Volume 47 Issue 10

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Power System-Column of UHVDC Transmission

Full-Scale Test for Cruciform Angle Tower Applied in ±800 kV Double-Circuit Transmission Lines on the Same Tower

HAN Jun-ke

2014, 47(10):  1-6.  DOI: 10.11930/j.issn.1004-9649.2014.10.1.5

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Cruciform angle tower SJ30102 is the first full-scale test tower for ±800 kV UHV DC double-circuit in China. The total height and weight of the tower are 75.5 m and 176.8 t respectively. The test tower SJ30102 successfully passed the load test with seven conditions including wind, installation, ice coating, broken conductors and etc. Under the condition that the overload reaches 134% of the designed limit in case of 45 degrees gale, the cruciform angle tower failed with compression. The test results show that the calculated axial forces of main materials matches well with the tested results, which shows that the calcualtion model is reasonable. The calculated stability bearing capacity of cruciform angle tower matches well with the measured stable stress with consideration of filler plate arrangement form, which shows that the calculating method is accurate and the stability bearing capacity calculation method of cruciform angle tower in DL/T 5154-2012 is over-conservative. The linear filler plate arrangement form can reduce the tower weighs by about 3% and the calculation method for filler plate and bolts is safe and reliable. The new connection form between the main and the diagonal materials of cruciform angle tower can improve the cooperative working performance of two limb angle steels with good stress evenness.

Structural Design of Buildings and Structures on Converter Transformer Area of ±800 kV Converter Station in South Hami

ZHANG Yu-ming, YING Jie, CHANG Wei, ZHANG Mi, WANG Wei

2014, 47(10):  7-8.  DOI: 10.11930/j.issn.1004-9649.2014.10.7.1

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Converter transformer area is the core area in ±800 kV UHVDC converter station, and it is also the focus and difficult part for the station design. According to the engineering technical conditions of the Hami ±800 kV converter station project, the structural design characteristics of the main buildings and structures in the converter transformer area are introduced. On the basis of the experiences in design, construction and operation of the ±800 kV converter stations that have been put into operation in China, the structure type selection and implementation scheme for the mian buildings in the ±800 kV converter transformer area, including the valve hall, cable interlayer in control building, insulated room for air cooler, converter transformer foundation and railroad foundation, and the incoming-line frame for the converter transformer are summarized in the principle of advanced technology, reasonable economy, safe, reliable and convenient construction, which can be used as a guidance and reference for the structural design of the future UHVDC converter stations.

Study on Layout of AC Filter Switchyard of UHVDC Converter Station

ZHANG Xian-wei, PENG Kai-jun

2014, 47(10):  15-18.  DOI: 10.11930/j.issn.1004-9649.2014.10.15.3

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AC filters and shunt capacitors are important and indispensable parts of UHVDC converter stations. Rational layout of AC filter switchyard, especially AC filter bank switchyard, plays a decisive role in controlling the total land area and project cost of UHVDC converter station. Technical and economic comparison is made on the traditional crisscross shaped AC filter layout and its two improved schemes. It is concluded that the optimized scheme A needs a smaller land area and has good adaptability; the optimized scheme B needs the smallest land area and has the lowest cost, but has a poor adaptability, and it can only be used in the area without using pantograph disconnector. So the scheme A is recommended.

Calculation of the Surface Electric Field and Checking of the Corona Onset Field Intensity on the Fittings Inside UHVDC Valve Hall

LIU Ze-hong, DING Yong-fu, WANG Zu-li, ZHANG Yan-bing, XU Guang-hui, JIN Shuo, HU Long-fei, ZHU Lin

2014, 47(10):  19-23.  DOI: 10.11930/j.issn.1004-9649.2014.10.19.4

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To check the corona onset field intensity on the surface of fittings inside valve hall, by taking a ±800 kV UHV converter station as an example, a 3D whole model is built for the valve hall with the external software and inputted into ANSYS for pre-processing. The electric field distribution in the high voltage valve hall under various working conditions within a cycle is obtained by the electrostatic field instantaneous load method according to the voltage waveforms simulated by PSCAD software. Accurate calculation of the electric field in some concerned areas is realized by using the sub-model method. The corona discharge on the surface of tubular fittings and spherical fittings is also checked throuth comparing the calculation results with the empirical equation and experimental data. In the checking process, the fittings with irregular shapes are processed equivalently. The checking results indicate that the fittings selected for the valve hall have a certain margin in corona control, which can meet the safety requirement. The research result can provide a good reference for designing fittings inside UHVDC valve hall.

Research on Electromagnetic Environment of ±1 100 kV UHVDC Transmission Lines

BAI Xiao-lu, LI Jian, CHEN Yuan, HUANG Yu-cheng

2014, 47(10):  24-29.  DOI: 10.11930/j.issn.1004-9649.2014.10.24.5

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Study of the electromagnetic environment of UHVDC transmission lines is very important for construction of UHVDC transmission lines in China. Several methods, including charge simulation method, finite element method and formula of CISPR and EPRI, are used to calculate the relevant parameters, such as total electric field, ion current density, magnetic field intensity, radio interference and audible noise. The calculation is based on the limits of electromagnetic environment of ±1 100 kV UHVDC transmission lines and the given initial conditions. The research result shows that the audible noise is the controlling factor for selecting conductor types. Various conductor types are recommended according to different pole intervals and altitudes in this paper and the minimum ground clearance of different conductor types are also given.

Calculation and Analysis on Corona Onset Voltage of Double-Circuit UHVDC Overhead Transmission Lines

LI Yong-ming, LIU Ju-feng, Xu Lu-wen, Qin Hao-hao, Hu Yu-yao

2014, 47(10):  30-35.  DOI: 10.11930/j.issn.1004-9649.2014.10.30.5

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To study the characteristics of corona onset voltage of double-circuit UHVDC overhead transmission lines, a computation model is established in this paper based on the gas discharge theory and with consideration of the power line's arrangement and the stranded conductor's actual structure. According to the different mechanism of positive and negative corona onset, the corona onset voltages of each pole's sub-conductor are calculated on the basis of solving the surface space electric field of stranded conductor by using the optimized charge simulation method. The impacts of the line arrangement, air temperature, air pressure and parameters of stranded conductors on corona onset voltage are analyzed and discussed. The results show that the value of corona onset voltage is much higher for the -+/-+ line arrangement. In addition, the increase of conductor radius, air pressure and bundle number can significantly raise the corona onset voltage. The height of line to ground, anode-cathode distance, the height difference between upper line to lower line and the bundle spacing can also affect the corona onset voltages to varying degrees. When the stranding ratio of the stranded conductor is close to zero, the corresponding corona onset voltage will also be close to the one of the smooth conductor.

Research on Insulation Coordination for ±800 kV UHVDC Double-Circuit Transmission Lines

ZHANG Liu-chun, YIN Yu, GE Dong, DING Yu-jian

2014, 47(10):  36-39.  DOI: 10.11930/j.issn.1004-9649.2014.10.36.3

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With the constant construction of UHV power grid, the available transmission corridors for planning UHV transmission lines is limited. To improve the efficiency of existing transmission corridors, it is necessary to research the transmission technology for ±800 kV double-circuit transmission lines on the same tower. An analysis is made on the insulation coordination of converter station and transmission line. In converter station, the adopted insulation level is same as the conventional one. For the ±800 kV double-circuit transmission lines on the same tower, the line parameters may vary due to the effect of the mutual inductance between lines, which could influence the overvoltage level. The suspension mode of V-shaped insulator string adopted in the ±800 kV double-circuit transmission lines is extremely different from the one adopted in the ±800 kV single-circuit transmission lines. Based on the researched results of overvoltage and the discharge characteristics experiment of the real tower in the project of double-circuit transmission lines, the insulation coordination has been investigated. For the ±800 kV double-circuit transmission lines, the minimum air gap is recommended.

Identification of UHVDC Transmission Line Lightning Disturbance Based on Morphology

CHEN Shi-long, CAO Rui-rui, BI Gui-hong, LI Xing-wang, RONG Jun-xiang

2014, 47(10):  40-46.  DOI: 10.11930/j.issn.1004-9649.2014.10.40.6

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Study on the transient characteristics of the electric signal is significant to the development of transient-based protection and its reliability improvement when the overhead transmission lines are disturbed by the direct lightning stroke. The multi-scale decomposition of mathematical morphology can decompose the complex signal into different sections with physical significance, and highlight the local features of the waveform. The mathematical morphology is used to make a multi-scale decomposition of the transient currents resulted from the non-fault lightning stroke, fault lightning stroke and line short circuit of the ±800 kV UHVDC transmission lines. The spectrum energies from the high and low frequency bands are extracted respectively. According the ratio of the maximum amplitudes of the waveforms in the second scale to the sixth scale of the first head of the current, the fault lightning stroke and the line short circuit can be distinguished. Extensive simulations demonstrate that the approach is correct and effective.

Impacts of Weak AC System on the Commissioning and Operation of UHVDC Transmission Project

WANG Hua-wei, HAN Min-xiao, ZHANG Jian, GUO Xiao-jiang, WU Yani, YANG Wan-kai, LIU Yao, SONG Rui-hua

2014, 47(10):  47-51.  DOI: 10.11930/j.issn.1004-9649.2014.10.47.4

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Ultra-high voltage direct current(UHVDC ) system is characterized by large transmission capacity, high reactive power consumption and complex control system, while a weak AC sending system has much simple grid structure and power source composition. Consequently, the DC fault or disturbance can bring many problems to the power grid. An analysis is made on some problems of the weak AC system of UHVDC, such as safety and stabilization of power system, DC startup and power ramping & decreasing, overvoltage, and coordination between generators and power grid. Based on the commissioning of Xiang-Shang UHVDC project, some issues that needs to be addressed and corresponding controlling strategies are proposed for commissioning of UHVDC project with weak AC system, including optimization of commissioning items, operation mode of power system and stability control measures, voltage/reactive power control, and protection configuration of DC lines. Meanwhile, some other phenomena occuring during operation of the UHVDC with weak AC system are analyzed. The conclusions made in this paper can be a reference for planning, construction and operation of UHVDC project.

Power System

A Disturbance Evaluation Model of Power Quality Based on Backward Cloud Theory

XU Bai-yu, WANG Ling, LI Ding, SHENG Chao, MA Ming

2014, 47(10):  52-56.  DOI: 10.11930/j.issn.1004-9649.2014.10.52.4

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The boundary value of disturbance classification levels is fuzzy and random. And the cloud model is an uncertain transformation model describing the qualitative concept and quantitative processing. By fully considering these characteristics and combining the advantages of cloud model such as uncertainty reasoning characteristics and matter element analysis theory, a synthetic disturbance evaluation model is proposed based on the theory of backward cloud matter element. The standard model is established with backward cloud generator for synthetic disturbance evaluation of power quality, and the model is constantly updated through real-time data analysis, which makes the disturbance evaluation model more realtime. According to the characteristics of the disturbance evaluation of power quality, the weights of all the indices in power quality synthetic evaluation are obtained by integrating three methods, including the analytic hierarchy process method, the grey cluster method and the entropy method, which makes the disturbance evaluation result more credible. The superiority and effectiveness of the model are demonstrated by using the results of the actual numerical tests in the IF furnace of metal factory and the traction substations.

FEM Analysis on the Lateral Icing of the 500 kV Composite Insulators

CHEN Yan, YANG Lin, LIU Guo-te

2014, 47(10):  57-63.  DOI: 10.11930/j.issn.1004-9649.2014.10.57.6

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Glaze icing has serious impacts on the safety of the transmission lines, and the icicles produced by glaze distorts the potential and electric field on the insulators. In order to study the impacts of the lateral icing on the potential and electric field distribution along composite insulators, the ANSYS software is used to establish a finite element model for the icing of the 500 kV composite insulators. According to the phenomenon that the icicles grow laterally on the insulator both in the field and laboratory, the impacts of various icing patterns on the potential and electric field distributions is analyzed with the simulation model under different conditions, including changing the length, angles and locations of the lateral icicles, and the lateral and vertical icing appearing in the same time. The simulation results show that under the glaze condition, the change of the length and locations of the lateral icicles has little impact on the potential and electric field distribution along the icing composite insulator.With the decrease of the vertical angle of lateral icicles, the potential and electric field distributions on the surface of composite insulators distorts increasingly. It is concluded that the vertical icicles have a major impacts on the potential and electric field distribution along the composite insulator.

Study on Distribution Coefficient Characteristics of Wind Load with 0-360 °Angles for Power Transmission Lines

PAN Feng, GAO Zhi-lin, WANG Yi-wen, NIE Jian-bo, YING Jian-guo

2014, 47(10):  64-70.  DOI: 10.11930/j.issn.1004-9649.2014.10.64.6

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Accurate calculation of wind loads on power lines is critical in designing transmission towers. Selection of the distribution coefficients of angle wind loads directly affects the rationality of design specifications. The calculation principles of linear wind load in general design conditions (0.5Φ₁=0.5Φ₂=0) are analyzed in this paper, and the distribution coefficients corresponding to winds with angles of 0-90 degrees are obtained. Moreover, the calculation formula for distribution coefficient of winds with angles of 0-360 degrees is also derived based on an analysis of the wind angle and line angle. The front and back side wind load distribution coefficients for different allocation ratios(i.e., 0.5Φ₁=0.5Φ₂, 0.5L₁∶0.5L₂=5∶5, 4∶6, 3∶7) are calculated, respectively, and their characteristics are analyzed and a comparison study is made. The study result reveals the characteristics of wind load distribution coefficient of transmission lines and can be used as a reference for designing transmission towers.

Vibration Amplitudes and Tensions of Conductors during Galloping in Transmission Tower-Line System

ZAO Li, YAN Bo, LÜ Xin, LIANG Ming

2014, 47(10):  71-76.  DOI: 10.11930/j.issn.1004-9649.2014.10.71.5

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The finite element models of three typical transmission tower-line systems are set up by means of ABAQUS software, and the galloping processes are numerically simulated, based on which the vibration amplitudes and tensions of the conductors in different span and different phase during galloping are obtained. Based on the comparison of the numerical results with those determined by the theoretical simplified and empirical formulas, it is found that the simplified formula presented by Hunt and Richards is suitable for galloping amplitude estimation of dead-end span; the empirical formula presented by Lilien and Havard is suitable for galloping amplitude estimation of suspension span, and the simplified formula by Baenziger is suitable for dynamic tension estimation of conductors in both dead-end and suspension spans. Moreover, the stresses in the dead-end towers are larger than those in the suspension towers. The max stresses in the conductors and dead-end towers exceed the allowable stress of materials under some wind speed, which may cause the rupture of conductors and damage of towers.

Simulation Study on Electric Field Intensity of UHV Overhead Transmission Lines with Different Arrangements

BAI Long-sheng, CHANG Mei-sheng, CAO Dong-dong

2014, 47(10):  77-81.  DOI: 10.11930/j.issn.1004-9649.2014.10.77.4

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In order to lower the surface EFI of the sub-conductor and reduce the corridor width of overhead transmission lines, a simulation study is conducted. Firstly, a model is established with FEM to calculate the EFI on and around the surface of overhead transmission lines. Secondly, the FEM is used to calculate the average EFI on the surface of the maximum phase conductor under unsymmetrical configuration, the maximum EFI at the level of one meter to the ground under the line, and the corridor width. Finally, it is found though a comparative data analysis that the horizontal elliptical configuration of sub-conductors is superior to the circular configuration. The simulation results show that the horizontal elliptical configuration of eight-bundle conductors with inverted triangular layout can reduce the average EFI on the surfaces of the maximum phase conductor, the maximum EFI at the level of one meter to the ground under the line, and the corridor width. When used in overhead transmission lines, this configuration can reduce the corona loss and the level of radio interference and audible noise as well as the tower height.

Interpretation of General Specification of Relaying Protection and Security Automatic Equipment- New Edition

WU Bei, ZHONG Ze-zhang

2014, 47(10):  82-85.  DOI: 10.11930/j.issn.1004-9649.2014.10.82.3

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In order to improve the technical performance of relay protection products, enhance the standardization design level and meet the requirements of relay protection product in design, test and operation management, the DL/T 478—2013(General Specification of Relaying Protection and Security Automatic Equipment) has been released and implemented. In view of the revised and supplementary content of the new standard, the reason for all previous revisions and technical background are introduced in detail, and the main principle is pointed that standard improvement should follow technology development. The supplementary requirements for improving performance, safety and test rule in the new edition are analyzed, which can help relay protection designers and management personels to well- understand and accurately implement the current standard.

Analysis on Trajectory-correction Sensitivity Adapted to Dynamic VAR Configuration of UHV AC and DC Interconnected Power Grid

ZHONG Sheng, TIAN Xin, WANG Hui-lai, ZHANG Chang, YAO Yong

2014, 47(10):  86-91.  DOI: 10.11930/j.issn.1004-9649.2014.10.86.5

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With the deepening development of UHV AC and DC interconnected power grid, the requirement of power system for voltage and reactive power regulation is becoming higher and higher. As a result, the application of FACTS will hold out a cheerful prospect. However, there is still a lack of effective approaches which are suitable for engineering application and guiding dynamic reactive power compensation. A trajectory-correction sensitivity analytical method is proposed accordingly, which is based on static sensitivity, time domain simulation and trajectory sensitivity, and combines the dynamic analysis and static analysis. The method can reflect the comprehensive effect of dynamic reactive compensation and provide a quantitative index for the optimization of the dynamic reactive power compensation. Through the instance of IEEE39 bus systems and UHV AC and DC interconnected power system, the rationality and validity of the method is verified.

Generation Technology

Retrofit with Low NO_x Combustion Technique and Performance Optimization Test for a 1 000-MW Ultra Supercritical Boiler

ZOU Lei, YUE Jun-feng, CHEN Yong-sheng, LIANG Shao-hua, XU Yi-ran, ZHANG En-xian

2014, 47(10):  92-97.  DOI: 10.11930/j.issn.1004-9649.2014.10.92.5

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The technical retrofit adopting low NO_x combustion technology was carried out for a 1 000-MW ultra supercritical boiler to reduce the NO_x emissions. After the retrofit, the NO_x emission mass concentration was down by 42%, while the CO emission mass concentration and the carbon content of fly ash were higher. Therefore, based on the analysis of the variation of the combustion conditions before and after the retrofit, the combustion adjustment test was conducted, in which the boiler combustion and NO_x emission characteristics under different working conditions were studied by changing the oxygen volumetric fraction at the economizer exit, the secondary air distribution mode, the OFA flow rate and the SOFA flow rate. The test results show that the CO emission mass concentration has been dropped to less than 100 mg/m³ and the carbon content of fly ash has been down below 1% under high boiler load after the combustion adjustment.

Experimental Research on the Impacts of Zhundong Coal Blending Waste Silicon Powder on Sodium Transformation and Ash Fusion

WEI Bo, WANG Xue-bin, ZHANG Li-meng, TAN Hou-zhang, XU Tong-mo

2014, 47(10):  98-102.  DOI: 10.11930/j.issn.1004-9649.2014.10.98.4

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The Zhundong Wucaiwan coal is blended with the waste silicon powder and combusted to study the ash fusion and sodium transformation characteristics of the coal. The experiment results show that, the sodium content of the ash increases substantially when the waste silicon powder is added to the coal. With the blending ratio of the waste silicon powder increasing, the sodium fixation rate rises accordingly. Meanwhile, the characteristic temperature of the ash tends to go up first and then down. The X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses indicate that the waste silicon powder causes the CaSO₄ in the Zhundong Wucaiwan coal to decompose at lower temperatures and produce a large amount of CaO which is apt to form eutectic hedenbergite. This is the major reason for the ash fusion temperature decrease. However, when the blending ratio reaches as much as 9%, crystobolite will become the dominant component and can act as the backbone of the ash, which leads to the increase of ash fusion temperature.

Impact of Inlet Air Heating Mode on Thermal Performance of Rotary Air Preheaters

CHEN Xun, DUAN Xue-nong, CHEN Yi-ping, ZHU Guang-ming, WANG Dun-dun

2014, 47(10):  103-109.  DOI: 10.11930/j.issn.1004-9649.2014.10.103.6

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Under the circumstances of different inlet air heating modes for thermal units with rotary air preheaters using flue gas denitrification, in order to perform the comparison and analysis on the outlet gas and air temperatures, the wall temperature of the heat storage element, and the influencing trend and variation patterns of the acid corrosion area and ammonium bisulfate deposition area , the thermodynamic properties of the air preheater are calculated. Based on the thermodynamic model, the calculation are done on the air preheaters of a 600-MW power plant, with hot air recirculation mode and inlet air heating mode respectively. The results show that in the hot air recirculation mode, with the hot air recirculation ratio increasing, the average outlet wall temperature of the cold-section thermal storage element goes up, while that of the hot-section thermal storage element goes down. Meanwhile, with the acid corrosion area in the cold section shrinking, the ammonium bisulfate deposition area ascends, which intensifies ash clogging in the air preheater. In the steam air heater mode, the average outlet wall temperatures of the heat storage elements at both the hot and cold sections increase, and the acid corrosion and ammonium bisulfate buildup areas descend simultaneously. Thus, for the air heater of thermal power units using flue gas denitrification technology and high-sulphur coal, the calculations for thermal check should be conducted for winter peak load scenarios, and the inlet air heating by steam air heater is more preferable to be applied in practice.

Analysis and Prevention of SCR DeNO_x-Caused Air Preheater Clogging

HUI Run-tang, WEI Fei, WANG Bao-de, YANG Ai-yong

2014, 47(10):  110-112.  DOI: 10.11930/j.issn.1004-9649.2014.10.110.2

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The selective catalytic reduction(SCR) is commonly used for flue gas denitrification in coal-fired power plants. Corrosion and clogging tend to happen in the air preheaters after the SCR denitrification device is installed. In the case study of a power plant, the analysis of the impacts of the SCR denitrication device on the air preheater is conducted and some measures against the corrosion and clogging are proposed accordingly. To control the pressure difference of the air preheater no longer increasing, the ammonia is stopped spraying into the SCR denitrification device during low load operation while it is reduced during normal load operation. In addition, the heat exchange part of the air preheater heater is changed to an enameled one during the boiler shutdown. In more than a year of operation since then, the pressure difference has been normal and no severe clogging has ever happened.

Discussion of Bottom Ash Handling System Selection

HU Zhen-jun

2014, 47(10):  113-116.  DOI: 10.11930/j.issn.1004-9649.2014.10.113.3

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The dry bottom ash handling system affects the slagging and boiler efficiency. This paper analyzes the influencing factors of the slagging and boiler efficiency and proposes the measures to reduce the negative effects of the dry bottom ash handling system. Meanwhile the effects of slagging property coal on the wet slag system are analyzed. The study indicates that more attention should be paid to the furnace design, heat exchanger arrangement and combustion management to avoid boiler slagging. For boilers burning easy slagging property coal, effective measures should be taken to ensure the safe operation of the bottom ash handling system, whether dry or wet, and reduce the negative impacts on boiler combustion. The selection of the bottom ash handling system should follow the DL/T5142 Technical Code for the Design of Ash Handling System of Fossil-Fired Power Plant and the combustion of easy slagging property coal should not be the only reason for abandoning the dry bottom ash handling system.

Research and Application on Low-Low Temperature Electrostatic Precipitator Technology

ZHAO Hai-bao, LI Jian-guo, HE Yu-zhong, YAO Yu-ping

2014, 47(10):  117-121.  DOI: 10.11930/j.issn.1004-9649.2014.10.117.4

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As a new dust removal technology, the low-low temperature electrostatic precipitator (LLT-ESP) has the advantages of low energy consumption and high SO₃ removal efficiency and has become the mainstream method in flue gas treatment in Japan. However, studies on the LLT-ESP performance are few in China. In this paper, the analysis on the coal adaptability, acid dew point, D/S ratio (the concentration ratio of PM to SO₃ solution as H₂SO₄), dust re-entrainment and off-line rapping technique is conducted and the D/S ratio formula is proposed. The influencing amplitude of D/S ratio on the corrosion and dust removal efficiency of typical LLT-ESP and the application of combining mobile electrode with LLT-ESP are studied. At the end, some of the most representative LLT-ESPs which will be launched in China are introduced.

Development of Ceramal Compound Grinding Roller and Refiner Plate of Medium Speed Mill

QIAN Bing, SUN Shu-gang, ZHU Yu, NI Hong-jun, SONG Han-chao, ZHOU Cheng

2014, 47(10):  122-125.  DOI: 10.11930/j.issn.1004-9649.2014.10.122.3

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Grinding roller and refiner plate are the core components of the coal mill, which is one of the most important equipments in the thermal power plants. In this paper, the operating condition and principle of the grinding roller and refiner plate are analyzed. In addition the current situation of ceramal compound roller and refiner plate manufacture is elaborated. And the new techniques for the preparation of the ceramal compound roller and refiner plate are introduced. In contrast with the products using the conventional techniques, the service life of those manufactured with the new techniques almost doubles, and the grinding efficiency is also greatly improved, which shows significant direct and indirect economic benefits.

Analysis and Treatment on Seawater Leaking into the Lubricating Oil System of 1 000-MW Steam Turbine

CHEN Su-hong, YU Nai-hai

2014, 47(10):  126-129.  DOI: 10.11930/j.issn.1004-9649.2014.10.126.3

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In this paper, aiming at the problem of seawater leaking into the lubricating oil system and affecting the safe operation of a 1 000-MW unit due to the oil cooler leakage in the coastal area of Shandong Province, the analysis is conducted and the corresponding treatment measure adopting the centrifugal oil filter and the cartridge oil filter to get rid of the water from the oil is proposed. Meanwhile, the dissolving elution method is proposed to determine the chlorine ion content in the oil, which helps to make a judgement on whether the seawater entrained in the oil is cleaned. With the oil filter processing, the moisture content of turbine oil falls from 24 414 mg/L to 10.1 mg/L, while the chloride ion content is from 155 mg/L down to the undetected. The practice proves that the oil filter processing can make the heavily seawater polluted lubricating oil return to normal in a short time, which can ensure the safe operation of the unit and avoid malignant accidents.

Study on Computed Radiographic Sensitivity Testing Technique

HUA Xiong-fei, WANG Bin, ZHONG Hua, FANG Song-li, LU Xi-zhi, YE Feng

2014, 47(10):  130-133.  DOI: 10.11930/j.issn.1004-9649.2014.10.130.3

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The study on the sensitivity testing technique for the computed radiography(CR) is conducted with a specially-designed testing block. A large number of experiments have shown that the testing block can well verify the difference between the CR displaying of object details and determine the effect of various CR parameters on the sensitivity of CR images. Moreover, the sensitivity tests are performed respectively by using the image quality indicator(IQI) of the hole type, the wire type and the double wire type, as well as the testing block. The results show that the sensitivity distinguishing ability of the testing block is superior to that of the above mentioned IQIs.

Energy Conservation and Environmental Protection

Study on Operation Optimization and Retrofit of Non-Bypass FGD System of Fossil Fuel Power Plants

LI Xing-hua, ZHAO Cai-hong, NIU Yong-jun, HE Yu-dong

2014, 47(10):  134-136.  DOI: 10.11930/j.issn.1004-9649.2014.10.134.2

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Non-bypass FGD systems require the start-up and shut-down process synchronous with the primary turbines, which imposes higher demands for its security and reliability. In this paper the researches are mainly conducted on the operational optimization measures and improvement schemes after the removal of FGD bypass. Moreover, the optimization scheme and retrofit principle are proposed for the flue gas system, absorption tower, absorbent slurry preparation system, gypsum dewatering system, accident evacuation system, electrical system and thermal control system. Finally, it is suggested that the FGD system should be included as part of the “primary turbine” set, and the operation reliability of the desulfurization equipment should be improved to ensure the safe operation of the generating units.

The RB Control of Booster-Fan (with Bypass) of a 350-MW Supercritical Unit

WANG Xiao-yong, ZHAO Zhi-dan, GUO San-hu

2014, 47(10):  137-141.  DOI: 10.11930/j.issn.1004-9649.2014.10.137.4

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The national environmental protection authority requires that the large FGD bypass shall be removed from thermal power generation projects. In the FGD system of one 350-MW supercritical unit with single booster-fan, the boiler will be forced to shut down due to the boiler main fuel trip(MFT) in the case of booster-fan trip. In order to ensure the unit long-term secure operation and reduce the number of unplanned outages, the original large FGD bypass is removed while a bypass for the booster-fan is built. At the time of booster-fan faults, the booster-fan bypass will be opened quickly and the booster-fan runback(RB) will be triggered simultaneously. Through the improvement of booster-fan control strategy and the successful RB tests at different loads, the unsafe hidden issues in boiler operation are resolved with satisfactory results.

New Energy

Upgrade of the PV Power Prediction System and Implementation of the Key Technologies

CUI Yang, CHEN Zhen-hong, CHEN Chi, TANG Jun, GU Chun

2014, 47(10):  142-147.  DOI: 10.11930/j.issn.1004-9649.2014.10.142.5

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The “Solar Power Generation Forecasting System V2.0” was developed in early 2012. As the national energy industry standard- the “Functional Specification for Photovoltaic Power Prediction System” (2014) is to be issued soon, it's necessary to upgrade this system to further perfect its function and improve its suitability. The upgrade mainly consists the following respects. Firstly, the B/S technical architecture is added to achieve the network publishing of forecasting products through Silverlight 4.0. Secondly, the combined forecast method is included in the upgrade to integrate various forecasting methods as to improve the forecast accuracy. Thirdly, the Google Earth will be incorporated to show the geographic information of plant which can enhance the display performance of the system. Finally, the upgrade strengthens the standardized management of data and divides the system by power generation units. The upgraded system has been applied to several PV power plants and it will help to effectively schedule the photovoltaic power generation and improve the power generation efficiency.

Pricing Mechanism and Economic Analysis of Wind-PV-ES Hybrid Project

YOU Pei-pei

2014, 47(10):  148-151.  DOI: 10.11930/j.issn.1004-9649.2014.10.148.3

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In this paper, the selection of technical solutions and the cost of Wind-PV-ES hybrid project are analyzed. The applicability of the existing tariff policy for the selected typical Wind-PV-ES hybrid project and the feasible pricing methods are discussed. Besides, the project's economy under different pricing methods is investigated and the influence of construction cost and electricity pricing on the project's economy is quantitatively analyzed by using sensitivity analysis method. The pricing mechanism for Wind-PV-ES hybrid project is also proposed. From the results, it can be concluded that package pricing can be used to the whole project in short term. While in long term, in order to ensure the price policy's incentive and promote fairness and efficiency, separate pricing should be used for the Wind-PV-ES hybrid project and the energy storage price policy should be introduced.

Analysis on the Situations and Reasons of Wind Power Operation and Consumption in Northeast China

XIE Guo-hui, FAN Hao

2014, 47(10):  152-155.  DOI: 10.11930/j.issn.1004-9649.2014.10.152.3

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The wind power operation and consumption situation was stable overall in 2013 in China while wind power consumption problem is becoming increasingly severe in recent years in Northeast China. Some crucial indices used in evaluating the current situations of wind power operation in Northeast China, including proportions of the wind power capacity and the local accommodation, wind power growth rate and the system load, wind power capacity and the flexible power capacity are put forward. The direct and fundamental reasons for wind power curtailment are analyzed based on the evaluation on the status quo of wind power operation in Northeast China. The results indicate that the unbalance between large-scale wind power development and local accommodation capability is the direct reason and disunified wind power planning and imperfect incentive policies are the fundamental reasons. Speeding up the constructions of inter-regional transmission lines to deliver the wind power to the load center is the effective way to promote the wind power utilization in Northeast China.

Pricing Mechanism and Economic Analysis of Heating Supply by Wind Power

WANG Cai-xia, LI Qiong-hui, XIE Guo-hui

2014, 47(10):  156-160.  DOI: 10.11930/j.issn.1004-9649.2014.10.156.4

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Pricing mechanism of heating supply by wind power and its economic factors were analyzed by a case study. The results show that, based on the current unit-heating price, heating demand and heat station investment, treating heat station and wind farm as a whole has better economics than treating the heat station alone. Moreover, with a given condition of unit-heating price, heaing demand and heat station investment, the maximum electricity price that can be afford by a heat station should be controlled in a certain range to make the project profitable. Subsidizing for the investment of a heat station could be used to ensure the profit of the projects of heating supply by wind power.