Table of Content

23 July 2013, Volume 46 Issue 7

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Generation Technology

Numerical Study on Gas-Solid Flow Characteristics in Loop Seal

WANG Qing-gong, YANG Hai-rui, LU Jun-fu

2013, 46(7):  1-5.  DOI: 10.11930/j.issn.1004-9649.2013.7.1.4

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Two-dimensional simulations of a pilot scale loop seal are mainly performed in this paper to reveal the viscous slip flow characteristics in negative pressure gradient. An Eulerian-Eulerian approach with constitutive relationships based on the kinetic theory of granular flow (KTGF) for dense gas-solid flows is used. By changing the fluidized-air/loose-air velocities, the particle circulation rate and the back pressure at the return leg, the flow characteristics including the distributions of particle concentration and pressure as well as the gas inverse flow phenomenon are carefully analyzed, thus the gas-solid flow structure and its variations are demonstrated. The results show that the gas inverse flow phenomenon does exist in loop seals. The higher velocity of fluidized-air or loose-air, the more bubble will come up with higher gas inverse flow rate. By increasing the particle circulation rate, particles will carry more air, resulting in the reduction of the gas inverse flow rate. By every 1 000 Pa increase of the back pressure, the packed height of the particles in the standpipe will rise by about 0.06 m and the gas reverse flow rate will also increase as a result of more flow resistance in negative pressure gradient.

Research on the Characteristics of Metal Oxide Film on Piping Inner Walls of Power Plant Boilers

HUANG Wan-qi, LI Zhi-gang, ZHANG Hong-bo, CAO Song-yan

2013, 46(7):  6-10.  DOI: 10.11930/j.issn.1004-9649.2013.7.6.4

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The formation of oxidation film on boiler tubes before and after oxygenation treatment (OT) is studied to figure out the major factors contributing to the metal surface oxide film within different temperature ranges. The characteristics of the oxide film on the economizer and water wall tubes are analyzed and compared under the conditions of feedwater all-volatile (reduction/oxidation) treatment-(AVT(R)/AVT(O)) and oxygenation treatment. The causes of metal oxidation and scale exfoliation in the high-temperature section of boilers are also explored with the data from both test bench and field testing. The results show that feeding oxygen to the water makes the metal surface form a redish brown Fe₂O₃ coating layer in the low-temperature section of the thermal system(under 300 ℃), and this layer requires continuous oxygen feeding to maintain its stability. The causes of scale exfoliation of 18Cr austenitic stainless steel in high-temperature sections are complex. Nevertheless, the temperature and the material itself are believed to be the major culprits.

Modeling of Supercritical Fossil-Fired Units for Medium- and Long-Term Analysis on Power Grids

GAO Lin, CUI Zhan-bing, WANG Wen-jun

2013, 46(7):  11-17.  DOI: 10.11930/j.issn.1004-9649.2013.7.11.6

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Many blackout accidents indicate that the medium- and long-term stability is much important for modern large-scale interconnected power grids. The proportion of supercritical(ultra supercritical) units to thermal power units grows very fast and its mathematic model is significant to the medium- and long-term stability analysis. In this paper, the physical equations presenting the dynamic characteristics of supercritical (ultra supercritical) units are derived and a simplified non-linear transfer function model is built. In addition, the model is identified and verified by the testing data of one 1 000-MW ultra supercritical unit. The results show that there are only 12 parameters in the model and the parameters can be easily obtained from the parameter identification procedures. The model and its identified parameters are accurate enough compared with the test data, which aresuitable for the medium- and long-term stability analysis of power grids.

Study for a Detailed Nuclear Power Unit Mathematical Model Based on Matlab-Simulink

TAN Jin, HUANG Yue-feng, XU Zheng

2013, 46(7):  18-23.  DOI: 10.11930/j.issn.1004-9649.2013.7.18.5

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The high-order mathematical model of nuclear power units is with complex structures, and is not suitable for applications because of massive and time-consuming simulation calculations. But the reduced mathematical model can be only used for the short-term stability analysis. So it is necessary to establish a mathematical model of the nuclear power units suitable for the mediumand long-term stability analysis of power systems. The mathematical model of the pressurized water reactor(PWR) nuclear power unit is hereby established. Based on this model, the inherent characteristics of the nuclear power unit have been analyzed. By the simulation of a single machine infinite bus(SMIB) system, the interaction between the nuclear power unit and the power system is also studied. As long as the fault is removed timely, there will be no great impact on the nuclear power units.

Research on O₂ /CO Burning Control Technology for Ultra Supercritical Boilers

SUN Wei-peng, FENG Ting-you, PANG Li-ping, ZENG Bi-qun

2013, 46(7):  24-28.  DOI: 10.11930/j.issn.1004-9649.2013.7.24.4

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In order to determine the best burning condition, by analyzing the one-month running data of a 1 036-MW unit in a power plant, it is discovered that the CO content in the flue gas is too high under high load conditions and the maximum fluctuation of the boiler efficiency is 0.6% at rated load, which leads to the increase of the coal consumption and affects the safe operation of the boiler. In boilers firing pulverized coal or mixed coal, the change of the combustion state easily causes unstable combustion, large parameter variation and boiler efficiency reduction. By analyzing the combustion characteristic curve, this paper attempts to optimize the burning conditions with the counterbalance calculation method the burning control technology and the self-adaptive optimization control technology to maximize the boiler efficiency and minimize the coal consumption at different loads.

Experimental Study of Low-Oxygen Combustion on 2 150-t/h Tangentially Fired Boilers

JIN Yun-li

2013, 46(7):  29-34.  DOI: 10.11930/j.issn.1004-9649.2013.7.29.5

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In order to provide bases for the optimization of boiler low-oxygen combustion, experiments are performed on a 2 150-t/h tangentially fired boiler to study the influence of oxygen reduction on boiler combustion. The results show that under stable conditions, there is a peak value of the furnace temperature in the change of oxygen; on the upper and lower sides of the peak, the effects of oxygen reduction on combustion and boiler operation parameters are different. As oxygen varies, NO_x emission has a peak value near the peak value of the furnace temperature, and a valley value in deep low-oxygen combustion. Decreasing oxygen can reduce NO_x emissions only if the oxygen level lies between the peak and valley values of NO_x emissions. Reducing oxygen enlarges the swirl number under steady operating conditions and the variation amplitude of swirl number in load decreasing, which easily leads to large steam temperature deviation and overheating. Oxygen reduction, which does not make obvious rise of the incomplete combustion loss, will enlarge the fluctuation range of the furnace temperature and NO_x emissions in load changes. And conversely, if the incomplete combustion loss markedly increases, the load change has little effect on the furnace temperature and NO_x emissions because of the influence of air flow on coal releasing heat.

Fast Testing of Chlorine in Coal by EDXRF Method

LIN Mu-song, SU Wei, ZHANG Hong-liang, LI Yu-chun

2013, 46(7):  35-38.  DOI: 10.11930/j.issn.1004-9649.2013.7.35.3

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For the purpose of boiler corrosion prevention and environmental protection, it is very necessary to determine the Cl^- in the coal fuels. The procedures of conventional chemical analysis in the existing national standard method are quite complicate, with low efficiency and accuracy due to many influencing factors. Therefore, the measurement of Cl^- is studied using the energy dispersion X-ray fluorescence spectrum method(EDXRF). The result of antitheses tests on standard materials and methods show that by virtue of EDXRF method the chlorine can be determined fast with, high accuracy and high precision, which reveals its a promising prospect in applications.

Discussion on Application of Hybrid Cooling Scheme in Large Wet Cooling Generating Units

YANG Zhi, LONG Guo-qing

2013, 46(7):  39-42.  DOI: 10.11930/j.issn.1004-9649.2013.7.39.3

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Generally, the design and type selection of natural draft cooling towers in large wet cooling generating units are made according to the average annual weather conditions, which leads to surplus cooling capacity in winter and insufficient cooling capacity in summer, especially in the areas where the monthly temperatures change substantially in a year. Therefore, two hybrid cooling schemes adopting both natural draft cooling towers and mechanical ventilation cooling towers are proposed for a power plant with two 660-MW coal-fired units. Comparisons between the two hybrid cooling schemes and the natural draft cooling tower are conducted. The result shows that the hybrid cooling schemes are more adaptable to load variation and need less initial investment and running cost. Moreover, in the two hybrid cooling schemes, the one with fewer mechanical ventilation cooling towers is more economical than the other one. Finally, issues in adopting the hybrid cooling schemes are put forward and analyzed.

Power System

Rules of Distributed Generator Integration to Urban Distribution Network

WANG Zheng, LIANG Wei, CHEN Si-jia, HAN Liang, WANG Shou-xiang

2013, 46(7):  43-46.  DOI: 10.11930/j.issn.1004-9649.2013.7.43.3

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In order to mitigate the adverse impact of integration of distributed generators (DGs ) to distribution systems, some rules for interconnecting DGs with electric power systems are made all over the world to guarantee the safe and effective integration of DGs. However, no definite basis are given for these rules. Therefore, case studies of Tianjin distribution networks of 35 kV high voltage, 10 kV medium voltage and 400 V low voltage are conducted, and the influences of DGs on line maximum capacity and bus voltage are calculated, through which the theoretical bases of the capacity and voltage level of DG integration are obtained, and requirements for power quality of DG integration in terms of voltage deviation, frequency deviation, harmonics, and three-phase imbalance are set up.

Simulation Proof of the IGBT Equivalent Model in the MMC Sub-Module

CHENG Xiao-xuan, LIN Zhou-hong, LIU Chong-ru, WANG Qing

2013, 46(7):  47-51.  DOI: 10.11930/j.issn.1004-9649.2013.7.47.4

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The quantity of switch elements in the RTDS small-step simulation model is strictly restricted, and there are 2 power electronic switch element IGBT in each submodule of the Modular Multilevel Converter (MMC). With the increasement of the system capacity, how to achieve the simulation of multilevel system with limited hardware sources becomes the bottleneck of the real-time simulation system. The valid establishment of IGBT equivalent model within the RTDS big-step environment has been analyzed in this paper. According to the working principle of IGBT in the submodule of MMC, the equivalent mathematic model with the switch function is adopted, which can effectively reduce the occupancy of resources and increase the simulation capacity, and the performance characteristics of IGBT can be correctly represented in the big-step environment. The applicability and correctness of the established IGBT model is proved with Matlab.

Impact Effect Research of UHV Transmission Conductor Break

OUYANG Ke-jian, HU Bo-tao, CHEN Jun-jun, LI Hong-li

2013, 46(7):  52-56.  DOI: 10.11930/j.issn.1004-9649.2013.7.52.4

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The tower-line system disconnection impact causes a huge longitudinal imbalance load of UHV transmission lines. In order to study the disconnection impact load effects, the equivalent conductor model of the tower-line system is first established through initial form-finding, and then the mechanical characteristics of the conductor break is analyzed to establish the disconnection dynamic simulation model. On this basis, the transient dynamic numerical simulation is carried out with the ANSYS software for the conductor vibration of tower-line system disconnection impact, so as to analyze the dynamic characteristics of the conductor vibration from the time and frequency domain. The results show thatthe impact effect of the conductor break is significant and the impact energy is mainly focused on high-order vertical vibration.

A New Filtering Algorithm to Enhance Veracity for Measurement of Dielctric Loss Angle

ZHAO Liang, LI Yan-qing

2013, 46(7):  57-60.  DOI: 10.11930/j.issn.1004-9649.2013.7.57.3

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To measure the dielectric loss angle(tan δ) of electrical power system, a comprehensive on-line measurement method was proposed with narrow-band half wave Fourier transformer. The original bus voltage and the end capacitor divider voltage value of capacitive equipment is calculated by band pass filter. The band pass is designed by zero, pole assignment method. Then the voltage phase angle can be calculated by the half wave Fourier transformer from the fundamental component. Finally the tanδ is got. The algorithm is shorter than the fundamental wave phase separation method for the length of data window and it has good inhibition on the DC component and even harmonics component. The results of numerical case study show that this algorithm has similar results with the traditional fundamental phase separation, but it requires a small amount of data to meet the on-line monitoring accuracy and real-time requirements.

Application of Detection Technology of SF₆ Decomposition Products to Fault Diagnoses of HVDC Bushings

XU Yang, LI Feng-feng, LIU Qi, HAO Yue-dong, OUYANG Zhen

2013, 46(7):  61-65.  DOI: 10.11930/j.issn.1004-9649.2013.7.61.4

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Detection technology of SF₆ decomposition products is an important method of electrical power equipment condition assessment and fault diagnosis along with wide usages of gas-insulated devices in power grids. However, most researches have been focused on GISs (Gas Insulated Switchgears), with a rare study on gas insulated wall-bushings and bushings at the valve-sides of converter-transfomers. According to SF₆ decomposition mechanism and detection technology and based on data of SF₆ decomposition products obtained from bushings in converter stations, regular patterns of SF₆ decomposition and its products are analysed. By two field examples, a suggestion is given that abnormal data of SF₆ decomposition shuold be systematically analysed by a comprehensive method with laboratory tests, electrical tests, electrical-ultrasonic wave detection and historical analyses. Eventually deficiencies of SF₆ decomposition-product detections are discussed.

Research on Security of Live Working on Compact 500 kV Transmission Line in Yunnan Power Grid

ZHANG Wen-ying, DENG Hua, QIAN Jing, GAO Chao, GONG Ming-yi, PANG Feng

2013, 46(7):  66-71.  DOI: 10.11930/j.issn.1004-9649.2013.7.66.5

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According to the characteristics of live working on 500 kV compact transmission lines in high altitude (less than 2 800 m) area of Yunnan Power Grid, a series of experiments have been carried out at outdoor proving ground of Kunming UHV Test & Research Base. On the basis of the calculation and analysis of switching overvoltage occurred in UHV transmission lines, the hazard rate of approach distance and complex gap of live working under the specific work position of various operation modes at high altitude area was acquired according to test results. This article proposes a novel method for determining the minimum approach distance of living work, which is based on the analysis of the variation tendency of hazard rate. This method clearly shows the relationship between hazard rate and distance, so that the optimization of verification mode for the distance of live working can be performed. The results show that it is safe and feasible to carry out live working on photogenic and lower phase conductor of 500 kV compact tangent towers in Yunnan Power Grid. Research results are able to provide reference to maintenance and live working on compact 500 kV transmission line in high altitude area.

Analysis on Characteristics of Residual Voltage in ZnO SPD Based on Natural Lightning

YAN Xu, CHEN Shao-dong, JIANG Run-zhi, YIN Na

2013, 46(7):  72-76.  DOI: 10.11930/j.issn.1004-9649.2013.7.72.4

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The waveform characteristics of residual voltage in ZnO surge protective devices (SPD) based on natural lightning is investigated. Analyzing the waveform characteristics of SPD results from 12 records of natural lightning through the variation of the line over-voltage and fast electric field. The results show that the duration of residual voltage for SPD is about 330 μs on the condition of the natural lightning, which is longer than the value of dozens of microseconds generated by the standard 8/20 μs test waveform current in the laboratory, and the piezoresistor can be melted and punctured if the current of excessive wide waveform is used . Secondly, the waveform of residual voltage in SPD with the major irregular characteristic is closely related to the lightning discharge. Furthermore, there is some inhibition effect on the over-voltage of the 50 m front-end underground line by the SPD. The inhibition effect is weak during the first return stroke, but strong during the subsequent return stroke.

Investigations on Interface Program of Series Capacitors’s Control & Protection System and Line Protection System in an EHV (UHV) Transmission Engineering

ZHANG Jian-yi, LIU Tao, GUO Guo, PEI Dong-liang, CHENG Chao-lei

2013, 46(7):  77-81.  DOI: 10.11930/j.issn.1004-9649.2013.7.77.4

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EHV series capacitors have been applied for a relatively short time in the domestic market, it is worthy to investigate problems existed in the interface of its control and protection with transmission line protection, which was exposed by engineerings. So the coordination logic between re-entering of series capacitors and reclosing of transmission lines in a power grid of EHV or UHV is analyzed. To solve the problem that series capacitors can not be quitted by local shunt reactor protection or local trip failure protection, some improved programes are proposed that series capacitors can be quitted both by 3-phase tripping contactors and distant-breakers tripping signals received by transmission line protection. To solve the problem that series capacitors in hot standby may be re-entered unexpectedly by transmission line protection when a single phase earth fault occurs, the idea of integrating overvoltage and distant-breakers tripping protection into transmission line protection is proposed. The idea of transmission line trip-failuer protection, as well as a new series- capacitor based transmission line protection, are put forward firstly.

Fault-Location Method for HVDC Transmission Lines Based on Natural Frequency

YANG Li-hong, YANG Ming-yu

2013, 46(7):  82-86.  DOI: 10.11930/j.issn.1004-9649.2013.7.82.4

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The main limitation of traveling wave fault-location method is it’s difficult to calibrate the wave correctly, but for the fault- location method based on natural frequency, the calibration is not required. Considering the characteristics of the wave speed of HVDC transmission lines, a novel fault-location method based on natural frequency is proposed, which does not require line parameters and the calculation of travaling wave speed, but analyzes the failure data of the line to get the accurate fault distance easily. The backward Prony algorithm is employed to extract the required natural frequency, which will be screened and optimized with the fuzzy clustering algorithm then. So that the rapidity and accuracy of the method will be improvedand the number of personnel involving the locating process will be reduced, thus the level of locating automation will be improved. With the combination simulations by PSCAD and Matlab, it has showed that the rapid and accurate fault-location of HVDC transmission lines can be achieved with the proposed method.

Research and Application of the Random Failure Indicators in Status Evaluation of Relay Protection

WANG Liang-yi, ZHANG Ji-hong, ZENG Zhi-an, YU Hong-xin, ZHENG Xiao-ling

2013, 46(7):  87-90.  DOI: 10.11930/j.issn.1004-9649.2013.7.87.3

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This paper, in condition of considering random failure of the relay protection, describes and analyzes the random failure indicator and the random failure rate of relay protection. The analysis shows that the random failure indicator can describe the reliability of relay protection through the exponential function. According to the actual composition of the relay protection system, the relay protection reliability model is modified and improved based on random failure indicators, and the principles for determining the random failure rate parameters are determined. In addition, by assuming that the random failure rate is constant and independent of time, a practical relay protection random failure reliability function is constructed and a calculation method of random failure reliability of equipment is proposed. This method has been used in device status evaluation and analysis of relay protection in Chongqing electric power corporation. The application results show that this method can calculate the random failure probability of the relay protection equipment under certain conditions, and identify the equipment’s health status.

Short-Term Load Forecasting for Similar Days Based on PSO-SVM and Daily Feature Vector

CHEN Chao, HUANG Guo-yong, SHAO Zong-kai, WANG Xiao-dong, FAN Yu-gang

2013, 46(7):  91-94.  DOI: 10.11930/j.issn.1004-9649.2013.7.91.3

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The human body amenity indicator was introduced to make a comprehensive analysis of the influence of the meteorological factors on power load, and three main influence factors, including week type, daily weather type and date difference, were added to constitute the daily feature vector. By using the method for calculating the similarity degree to select similar days, the PSO-SVM forecasting model was built up with the daily feature vector and load data of the similar days. An forecasting analysis of the EUNITE load prediction competition data in 2001 shows that this method has a good adaptability, and can easily select the suitable similar days, and has a high prediction accuracy and good potential for promotion.

An Investigation of Key Strategies for Reliable Automatic Power Supply Transforming in the Distribution Ring Network

OU Chang-cen, CEN Dong-mei

2013, 46(7):  95-99.  DOI: 10.11930/j.issn.1004-9649.2013.7.95.4

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Distribution network feeder automation, as an effective measure to improve the reliability of power supply, is an important part of the China’s “12th Five-Year Plan” on the construction of smart grid. Focusing on an analysis and research on the strategies of automatic power supply by transforming the local feeder automation devices which is applied universally in China, this paper points out the deficiencies in the design of the operation strategy and the dangers posed to the power system and its operation management. Furthermore, using the power grid of Zhongshan Power Supply Bureau as a typical example, a solution is proposed that devices of contact switch FA can be reformed on its operation technology for reliable automatic power supply transforming in the distribution ring network, which provides a new reference and selection for the study of the automation of distribution network feeders on its further application and development.

New Energy

Parameter Identification of DFIG Based on Trajectory Characteristic Analysis

FU Rong, SUN Wan-peng

2013, 46(7):  100-104.  DOI: 10.11930/j.issn.1004-9649.2013.7.100.4

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When investigating dynamic operating characteristics of power systems with large scale wind power integration, accurate models for structures and parameters of wind power generators are needed. Based on system identification theory, the transfer function of the double-fed induction generators (DFIG ) is derived, then the relationship between the unknown parameters and the transfer function system is constructed to analyze the identifiability of the DFIG’s parameters. The equivalent transform of reduced dimension is imposed on the DFIG-integrated system, and by analyzing the dominant image trajectory characteristics, the index of trajectory difference degree is proposed, which can be designed as an objective function to optimize the solutions to DFIG reactor parameters. Finally, some simulations are conducted with consideration of different line faults and changes in wind speed to further validate the effectiveness and feasibility of the proposed method of parameter identification for DFIGs.

Control and Simulation of a Microgrid with Different Types of Distributed Generators

ZHAO Jie, WANG Shuo, SHEN Da-li, SU Yi, LI Ji-chang

2013, 46(7):  105-110.  DOI: 10.11930/j.issn.1004-9649.2013.7.105.5

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Distributed generators in a microgrid and their loads have random characteristics. In order to study the operating perfovmancas of a microgrid, controllers with different control strategies are introduced. For instance, the P/Q control is used to realize the constant outputs of the active and reactive power, and the V/f control with droop characteristics is used to give the frequency and voltage references when in island mode. By using the Matlab/Simulink to built the microgrid simulation platform, the P/Q-V/f control strategy is proposed to realize the comprehensive control of a microgrid with the grid-connected and island operation modes, and switching between the two different modes under different external conditions, which will be the changes of sunshine intensity, wind speed and load, and the performances are simulated, which shows that the new control strategy is feasible and correct.

Study of Ancillary Service Market Mechanism for the Promotion of Wind Power Consumption in Northwest Region

ZHANG Qin, XIN Song-xu, BAI Jian-hua, LIN Qi-wei

2013, 46(7):  111-115.  DOI: 10.11930/j.issn.1004-9649.2013.7.111.4

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There are abundant resources including wind energy, water energy, coal and so on in northwest region, which is the important base of the wind power, water power and coal power. To promote the high-efficient consumption of wind power in the large-scale power base of northwest region, the further research of technology, economy and other issues is required. Overall considering the harmonious development of the wind power, water power and coal power, and combining the actual conditions in northwest region, the wind power grid connection in northwest region and the induced share mechanism of ancillary service cost and expense for the peak-load regulation have been focusedly studied. Based on the analysis of the stakeholders related to the coordinated operation of wind power, water power and coal power, the assistant service framework for the promotion of high-efficient wind power consumption is proposed. According to the principle of equity of right and obligation based on the idea“Who get benefits paid”, the cost analysis model of paid peaking service considering the wind power grid connection is proposed, and furthermore the share mechanism that the paid peaking cost be solely shared in each Province for the thermal power and centralizedly shared in the grid for the water power is established. The analysis results of the example has proved the effectiveness of the proposed method.

Information and Communication

An Expansion Scheme of CIM/E for the Expression of Substation Model

GAO Zhi-yuan, YAO Jian-guo, CAO Yang, YANG Sheng-chun, SONG Jie, TIAN Wei

2013, 46(7):  116-120.  DOI: 10.11930/j.issn.1004-9649.2013.7.116.4

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The substation model is an important foundation of power system automation technology applications. IEC 61850’s substation model description is comprehensive and detailed, but the processing efficiency is not high, and can not be applied in the dispatching systems. CIM’s substation model description is relatively simple, and CIM/XML processing efficiency is quite low. CIM/E overcomes CIM/XML’s efficiency problem, but the model is not comprehensive enough. This paper fully expands the CIM/E specification to include primary device model, secondary device model, communication model, control model, protection model and data acquisition model, so that the substation model can be comprehensively described just as IEC 61850, and be effectively verified by the prototype system. Thus the expanded CIM/E model is expected to be the public substation model description of substation and dispatching automation systems.

Hierarchical Cyber-Threat Situation Evaluation Method for Electric Power Information Network

WANG Yu-fei, XU Zhi-bo, WANG Jing

2013, 46(7):  121-125.  DOI: 10.11930/j.issn.1004-9649.2013.7.121.4

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To describe the macro safety situation of electric power information network in real-time, an hierarchical threat situation evaluation method is proposed and implemented. This method adopt the gray clustering analysis to categorize the damage degree as strong, medium, weak in total 3 types, based on which the principle layer of the analytic hierarchy process is designed. According to the evaluation index system of the structure layer of analytic hierarchy process, the weight of the cyber-threat is confirmed. And the cyber-threat situation value can be obtained by the weighted summation of each cyber-threat weight and its real-time occurrence frequency, which reports the real-time safety situation of the electric power network. The final experiment and system operation shows that, this method may effectively describe the safety situation of electric power network and be helpful for the development of safety and protection level.

Energy Conservation and Environmental Protection

Quantitative Analysis on Environmental Externality of Chinese Thermal Power Industry

JIANG Hui, ZHAO Jing-zhu, HAO Xiao-li, FAN Chun-yang

2013, 46(7):  126-132.  DOI: 10.11930/j.issn.1004-9649.2013.7.126.6

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Quantitative analyses on the environmental externality of the thermal power industry is helpful to internalize the environmental external cost and realize the target of energy saving and emission reduction as well as clean development. In this study, the emissions of sulfur dioxide, nitrogen oxides, dust and carbon dioxide generated by the industry between 1998 and 2010 are calculated, and then from the external costs of unit emission calculated with the ExternE model, the UWM model and the “top-down” method, the total external costs of the industry between 1998 and 2010 are obtained. The results suggest that in general the external costs of China’s thermal power industry have been going upwards significantly. The average environmental external cost calculated with the three methods has been raised from 298.0 billion Yuan in 1998 to 849.5 billion Yuan in 2010. The increasing trend is relatively gentle over the period of 1998-2002, rapid over the period of 2002-2007, and comparatively stable over the period of 2007-2010.

Review on Catalysts and Its Mechanisms for Catalytic Hydrogenation of Carbon Dioxide

ZHANG Zi-li, ZHAO Yi

2013, 46(7):  133-137.  DOI: 10.11930/j.issn.1004-9649.2013.7.133.4

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Researches about carbon dioxide utilization technologies will have great significances for the emission reduction of carbon dioxide from power plants. Based on the theory about catalytic hydrogenation, the mechanisms of the catalysts such as transition metals, namely copper, nickel and zinc, and noble metals including ruthenium, iridium and palladium for carbon dioxide conversion were reviewed. Current researches about the catalytic hydrogenation of CO₂ mainly focus on the studying and development of highly active catalysts, the analysis and conjecture of reaction mechanism, the improvement of productivity and selectivity, and the optimization of reaction system structure and condition, etc.. The highly active catalysts, for example thermometal alloy, and the transition metal catalyst system will be one of the primary issues in the field of CO₂ hydrogenation in the future. The reaction mechanism which is complicated with diverse catalysts in carbon dioxide conversion, is worth being researched deeply. As the development of new technics with the characteristics of economy, green and energy saving and the deep researches, it may be possible for the emission reduction and resource industry utilization of CO₂ from power plants.

Optimal Selection and Performance Analysis of MnO₂/TiO₂ for Low-Temperature De-NO_x

XU You-jia

2013, 46(7):  138-142.  DOI: 10.11930/j.issn.1004-9649.2013.7.138.4

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Under the simulated emission conditions of certain stationary source, two kinds of unsupported and one supported MnO_x catalysts were prepared and their performances on low-temperature de-NO_x were compared respectively. One catalyst named α-MnO₂/TiO₂ with high catalytic activity in low temperature was filtered out first, and then, the performance of the catalyst in the presence of H₂O and SO₂ was measured. The results show that in the environment with no H₂O or SO₂, the unsupported catalysts MnO_x and the supported catalysts MnO_x /TiO₂ all have high reactivity at temperatures between 150 ℃ and 200 ℃ with the NO_x conversion rate close to 100%. However, the performance of the MnO_x/TiO₂ catalysts deteriorates in the presence of H₂O or SO₂; especially when H₂O and SO₂ are added together, the catalytic activity drops to 22%. Therefore, there are still many limitations to the popularization of the low-temperature de-NO_x technology. Further studies are needed onthe resistance to H₂O and SO₂ in low-temperature selective catalytic reduction (SCR).

Technology and Economics

Analysis on the Operating Status of Henan Thermal Power Plants

BAI Hong-kun, QIAN Wen-ying, WEI Ying-xu, LI Gan-sheng

2013, 46(7):  143-148.  DOI: 10.11930/j.issn.1004-9649.2013.7.143.5

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The factory standard coal prices and the operating costs of Henan thermal power plants were analyzed and, it was concluded that the fuel cost determined the cost of Henan thermal power plants at present. The break-even point incoming standard coal prices of all kinds of thermal power units were estimated. A relationship model between factory standard coal prices and the current electricity price on the break-even point of thermal power plants was established, which will provide a theoretical basis for judging the operative status of thermal power plants based on the real-time coal prices.

Development Planning of Natural Gas Power Generation and Its Influence on Power System’s Peak Load Regulation and Economy

JIA De-xiang, HAN Jing

2013, 46(7):  149-152.  DOI: 10.11930/j.issn.1004-9649.2013.7.149.3

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The large-scale development of natural gas power generation in China is subject to natural gas supply, price and peak load regulation, etc. It is important to research natural gas power generation’s planning and its influence on power system and its economy. The principle and method of natural gas power generation’s planning is proposed. Based on the minimum total system cost of the power supply, with the constraints of power system’s construction ans operation, balance of power and energy, balance of natural gas demand and its supply, etc., the recommended scenario of total generation development planning scale and its structure is proposed, including natural gas power generation’s scale. Furthermore, considering natural gas power station’s preliminary work, natural gas supply and system peak load regulation, the recommended scale of natural gas power generation and its economy is proposed. The study conclusion provides the guidance for the development of the natural gas power generation in China.

Technical-Economic Analysis on Application of Energy-Saving Conductors in Transmission Lines

HUANG Peng, MO Juan, WAN Jian-cheng, ZHAO Xin-yu

2013, 46(7):  153-157.  DOI: 10.11930/j.issn.1004-9649.2013.7.153.4

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The characteristics of three kinds of energy-saving conductors including aluminum alloy cored aluminum stranded wire, steel core aluminum stranded wire of high conductivity and mid-strength of all aluminum alloy wire were introduced and a comparison was made between energy-saving conductor and the traditional steel reinforced aluminum conductor through energy-saving wire pilot project in terms of technical characteristics, economic performance, construction method, and the application scope of these new energy-saving conductors in transmission line projects. The research shows that the three types of new energy-saving conductors can be totally applied in transmission line projects by replacing ACSR, and have excellent energy saving effects.