Table of Content

18 September 2014, Volume 47 Issue 9

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Plant Automation

Experimental Study on Enhancing the Quality of AGC and Primary Frequency Regulation Based on Heat System Accumulation

WANG Jian-qiang, ZHENG Wei-jian, TONG Xiao-zhong, GU Wei-fei

2014, 47(9):  1-5.  DOI: 10.11930/j.issn.1004-9649.2014.9.1.4

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In this paper, the analysis on the load control performance and response is conducted in combination with the requirements of automatic generator control (AGC) and primary frequency regulation (PFR) according to the present situation of subcritical units. Through the calculation on the heat accumulation capacity of the heating pipes, the availability of the heat accumulation is gained based on the requirements of AGC and PFR load response and the load response amplitude and lasting time are obtained. Therefore, tests and the analysis on the test data are carried out on the practical heating units, from which the initial study results are concluded.

Optimization on Control Logics of Siemens DEH System for 1 000-MW Steam Turbines

WANG Hui

2014, 47(9):  6-10.  DOI: 10.11930/j.issn.1004-9649.2014.9.6.4

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In order to improve the reliability of the control system for 1 000-MW ultra-supercritical steam turbines which are jointly designed and manufactured by Shanghai Turbine Company Ltd and Siemens, the faults of the digital electro-hydraulic (DEH) system occurred in routine operations are analyzed and summarized. The solenoid valve tripping control logic, fast valving protection logic, main steam pressure control switching logic, long load shedding logic, instantaneous load shedding logic, turbine speed control logic and switching logic after bypass opening are optimized without changing the original design ideas and protection principles. Therefore, the potential troubles, such as the EH oil low pressure tripping caused by the trip solenoid valve disconnection and the(long) load shedding caused by grid load fluctuation, are eliminated. Moreover, these optimized logics are also adopted by the 1 000-MW units installed later and used as the reference for the units of the same type.

Optimization on Recirculation Control of Feedwater Pump System in the Power Plant

YUE Jian-hua, XIE Jian-min, ZHU Yan-hai, MA Tian-ting, HU Yi-qun, MA Ji-ming

2014, 47(9):  11-17.  DOI: 10.11930/j.issn.1004-9649.2014.9.11.6

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The feedwater pump is one of the most important auxiliary equipments of thermal power plants. It constitutes the water supply system which is essential to the unit safe and economic operation. In order to improve the secure and economic operation level of the water supply system, in combination with the analysis of the related fault mechanism, the optimized control strategy of the feedwater pump recirculation system is put forward after systematic research and testings. This optimized strategy is established according to the relationship between the speed and flow of the feedwater pump on the basis of the new PID control with three-layer coordinated controls. The implementation of the optimized PID closed-loop control strategy can not only improve the security of the unit, but also reduce the energy consumption of the recirculation system as well as the valve repair costs. The security and economics of the system with optimized control is verified through testing.

Solutions to Generation Output Constrained by Power Line Transmission Capabilities

YANG Zhen-li

2014, 47(9):  18-24.  DOI: 10.11930/j.issn.1004-9649.2014.9.18.6

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Due to the change of the power transmission network infrastructure, to be compliant with the N-1 principle in“Power System Security and Stability Guideline”, the Unit 3 in Zhoushan Power Plant has to reduce its MW generation from the original full load down to only 215 MW. In order to maximize the output power, a joint control mode integrated with the steam turbine, boiler and outgoing line together is adopted, which solves the dilemma of unit MW output limitation. In this paper, the study on the line overload determination via electrical signals and also the fast load-shedding control are introduced. The electrical overload signal is triggered by hardware configuration and logic optimization. Instructions are issued to trip the unit from the electrical dynamic monitoring control equipment when fast load-shedding scheme fails. The engineering application is put into practice, which shows great improvement of the utilization rate of the transmission line capacities.

Application of Correlated Variable Verification Method in Enhancing Reliabilities of Thermal Control Protection and Interactions

JIA Chang-wu

2014, 47(9):  25-28.  DOI: 10.11930/j.issn.1004-9649.2014.9.25.3

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In this paper, according to“25 Requirements for Prevention of Major Power Production Accidents” and “Guidance on Improving Thermal Control Protection and Automatic Device Reliability for China Datang Corporation”, key protections and interaction signals shall be determined through“two out of three” or“ two out of two” logics to improve their reliabilities. However, it is difficult for the process variables to meet the requirements by adding measurement spots on site. As a result, some correlated process variables are attempted as the signals for verification. Through the internal relationship between these signals, appropriate alarm value set for reference is added to the logics. Without any extra measuring spots or equipment, the reliabilities of protection and interaction are improved. This method is proved to be a convenient way to improve the protection reliabilities for the sites where no more measuring spots can be added.

Analysis and Measures on Reducing Impacts of SCR Flue Gas Denitrification System on Air Preheater

TU Shi-feng, ZHANG Wei-jun, YE Guo-man

2014, 47(9):  29-34.  DOI: 10.11930/j.issn.1004-9649.2014.9.29.5

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Along with the state’s environmental protection standards becoming increasingly stringent, coal-fired units are required to install denitrification devices to ensure that the flue gas NO_x emission concentration complies with the environmental standards. In this paper, aiming at the frequent scaling and blocking of the air preheater due to the ammonia slipping after the denitrification devices being put into use, the intelligent optimization system is proposed for the SCR denitrafication device to improve the control quality of the denitrafication control system through the budget function of the multi-input and multi-output model, which can reasonably control the ammonia injection volume and reduce the amount of ammonia slip on the premise of meeting the environmental standards. In addition, when slight air preheater fouling blockage occurs, the original online program control soot blowing mode is changed to the manual directed soot blowing mode which focuses on the fouling areas to reduce the risk of blocking the air preheater. The two measures effectively reduce the occurrence of the air preheater blocking problem caused by the operation of the denitrafication device.

Generation Technology

Research on Peak Regulation Capability of 300-MW Combined Heat and Power plant

XU Tong, ZHOU Yun, WANG Xin-lei

2014, 47(9):  35-41.  DOI: 10.11930/j.issn.1004-9649.2014.9.35.6

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There have been prominent contradictions between wind power and combined heat and power plant in the heating areas of Northern China. In order to improve load peak regulation of power grid and wind power accommodation, a calculation model and corresponding software were developed to study the peaking capability of combined heat and power plant by using thermal balance method, equivalent enthalpy drop method and Frugal formula. The maximum power generation and minimum power generation for 300-MW and 350 MW combined heat and power plant under the conditions of different steam extracting mount and steam extracting pressure were calculated by taking into account the influences of steam-water loss on peak regulation capability. The conclusion will be beneficial to take full advantages of the peak regulation capability of existing combined heat and power plant and promote wind power accommodation in northern heating areas.

Cause Analysis and Treatment on Bearing Pad Fault of 650-MW Steam Turbines

WANG Bin, YU Yong

2014, 47(9):  42-45.  DOI: 10.11930/j.issn.1004-9649.2014.9.42.3

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Bearing ablation directly affects the safe operation of steam turbines. In this article the analysis on bearing ablation of three 650 MW steam turbines in China Resources Power(Changshu) Co., Ltd. is conducted. It is concluded from the analysis that the main cause of bearing ablation is the sludge deposition generated from turbine oil aging. When the turbine oil is regenerated, the problems of oil aging and bearing ablation are solved. Since the turbine oil quality has direct effects on the safe and stable operation of the unit, more attention should be given to turbine oil aging and measures on regular operation maintenance of turbine oil are proposed.

Configuration and Type Selection Optimization of Low-Pressure Drain Pump for Conventional Island of AP1000 Nuclear Power Plants

LI Qiang

2014, 47(9):  46-51.  DOI: 10.11930/j.issn.1004-9649.2014.9.46.5

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Different configuration schemes of the low-pressure (LP) drain pump of conventional island (CI) in nuclear power plants affect the reliability and economy of the LP heater drain system. In order to optimize the system performance, by analyzing the existing domestic codes and comparing the LP drain pump configuration schemes for the reactors of different types in China and aboard, the rationality of three-pump configuration is proposed from the economic aspect in consideration of the initial investment of the LP drain pump and its associated system and the operation cost. According to the preliminary selection result and the characteristic curve of the LP drain pump, through economic analysis, the flow and head of the LP drain pump are optimized and it is proposed that the flow of the LP drain pump should be selected according to the rated load condition. The optimization of the head selection reduces the operation cost.

Cause Analysis on Abnormal Rupture of LP Cylinder Rupture Disc of Nuclear Power Plant

GE Lian-wei

2014, 47(9):  52-55.  DOI: 10.11930/j.issn.1004-9649.2014.9.52.3

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Data information is collected on the failure characteristics of abnormal rupture of the rupture disc of low-pressure(LP) cylinder release valve. In combination with the working conditions of LP cylinder, the macro crack analysis, microscopic fracture analysis and material composition analysis are conducted. Meanwhile, the mechanical performance test, metallurgical test and blast simulation test are also carried out. The results demonstrate that the crack of the lead-made rupture disc shall be categorized as fatigue fracture, resulting from the creep sensitivity of pure lead material. Therefore, suggestions such as shortening the replacing time interval of the rupture disc are put forward.

Study on Pump Tripping Classification of Water Intake and Drainage Scheme of an EPR Power Plant

SI Heng-yuan

2014, 47(9):  56-59.  DOI: 10.11930/j.issn.1004-9649.2014.9.56.3

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The advanced European pressurized water reactor (EPR) technology is adopted by a domestic nuclear power plant. However, due to the difference of site condition, the water intake and drainage scheme with seawater pool in closed circulation is adopted in the design of the heat sink for emergency conditions, which is different from that of the reference power plant. According to the principles of EPR safety classification and the idea of classifying items based on their functions, the pump tripping function of the circulating water system (CRF) and auxiliary cooling water system(SEN) are classified both in functions and equipments. The associated safety requirements are also proposed. The analysis shows that the safety classification of the original design shall be improved to ensure the safe operation of the nuclear power plant.

Power System

Power Transformer Fault Diagnosis Based on IGSO Optimization Algorithm

HUANG Xin-bo, SONG Tong, WANG Ya-na, LI Wen-jun-zi

2014, 47(9):  60-65.  DOI: 10.11930/j.issn.1004-9649.2014.9.60.5

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In view of the problems existing in power transformer fault diagnosis, such as the code boundary is too absolute and the accuracy is low, a new power transformer fault diagnosis method is proposed, which applies the self-adaptive search improved glowworm swarm optimization(IGSO) to optimize the LM neural network. The method adopts the firefly individuals as the neural network’s weights and thresholds and the mean square error function of neural network as the individuals’ fitness function, and uses the IGSO to obtain the optimal weights and thresholds of the LM neural network. In the meantime, the fuzzy theory is used to handle the boundary of the improved three ratio method, and the obtained characteristic gas ratio code is used as the network model input, which has the advantages to remove the redundant information and overcome the absoluteness of code boundary. In the end, the LM neural network model of GSO algorithm is established based on self-adaptive search, and the transformer fault data is inputted for simulation. A comparison of the simulation results of the Bias regularization neural network model and the particle swarm model shows that the method has good classification performance with an accuracy rate of 88.57%.

Positioning of Transformer Core Loosening Based on the Vibration Signals

SHEN Pei-feng, ZHAO Hong-fei, LI Kai, XU Hong-hua, WANG Chun-ning, MA Hong-zhong

2014, 47(9):  66-70.  DOI: 10.11930/j.issn.1004-9649.2014.9.66.4

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In order to diagnose and locate the core loose failure of oil-immersed power transformer, this paper studies the vibration signals measured on the surface of the transformer tank. Firstly, the characteristics of vibration signals with different locations of the tank surface is theoretically analyzed under the condition of no-load operation of transformers and the variation of the vibration signals of the transformer tank surface before and after core loosening is discussed. And then experiment on an oil-immersed transformer is carried out and the variation of characteristic frequency of the vibration signals before and after core loosening is analyzed. Experimental results show that the value of fundamental component amplitude of the vibration signal is in linear with the value of the square of no-load voltage. When one phase core of the three phases A, B, C loosens, the fundamental frequency component amplitude of the vibration signal increases with the degree of core loosening of the corresponding position measuring point above the phase iron core. And the vibration amplitude of the other two points firstly decreases and then increases. The core loose fault can be diagnosed and located according to this principle.

The Application of Improved Particle BP Neural Network for Substation Noise Control

JIANG Hong-yu, MA Hong-zhong, LIANG Huan, JIANG Ning, LI Kai

2014, 47(9):  71-76.  DOI: 10.11930/j.issn.1004-9649.2014.9.71.5

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In order to overcome the shortcomings of existing adaptive noise filtering algorithms for substation noise control, such as poor adaptive ability and slow convergence speed etc., a new intelligent filter algorithm is proposed based on the error back propagation neural network (BPNN) of particle swarm optimization (PSO). In view of the existing problems of PSO, including difficult reconciliation of local and global search, and the population diversity loss, an improved strategy is used, which uses the particle’s“close” degree to adaptively adjust particle inertia factor and mutat ion rate. The improved particle swarm optimization algorithm is used to replace the gradient descent algorithm for real-time optimization of the weights and thresholds of BPNN, and rapid noise reduction. The gradient descent algorithm is then used for further optimization of the weights and thresholds of BPNN, and as a result, the noise is further subdued. By using the noise signal of a substation transformer for simulation of the sound source, the proposed algorithm, PSO-BPNN algorithm and BPNN algorithm are respectively applied to suppress the sound source. The results show that the performance of the proposed algorithm is superior to the performance of the other two algorithms, and the transformer noise reduction system is improved notably.

Analysis on Power Loss Characteristics and Efficiency of Energy-Saving Technologies of Overhead Grounding Wires

PENG Xiang-yang, MAO Xian-yin, HU Wei

2014, 47(9):  77-82.  DOI: 10.11930/j.issn.1004-9649.2014.9.77.5

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With scale expanding of power grids and length increasing of transmission lines, the power loss of overhead ground wires has become an increasingly prominent problem. Therefore, the power loss characteristics of ground wires through field measurement and computer simulation, and the quantitative data and laws of induced current of 110~500 kV typical single, double circuit transmission line were studied, and a variety of energy-saving measures for overhead ground wire, such as single point grounding, segmentation, transposition, coordinate transposition with overhead conductors and grounding wires, etc., were proposed, which have been applied to Guangdong power grid. It is shown that the energy-saving technologies can make overhead ground wires lossless operation and achieve enormous economic and social benefits basically. In addition, investment costs and economic benefits of energy-saving projects in Guangdong Power Grid and China Southern Power Grid were analyzed, which is of great significance to green power grid construction.

Estimation of Soil Thermal Parameters Based on Surface Temperature of Underground Cables and Prediction of Cable Rating

CHEN Xi-ping, ZHANG Long, LIU Bin, SUN Zhen-quan, LI Hong-jie

2014, 47(9):  83-87.  DOI: 10.11930/j.issn.1004-9649.2014.9.83.4

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Numerous power utilities are installed with advanced distributed temperature sensing (DTS) systems to measure the temperature of underground cables. However, two problems needs to be solved for full application of the advanced DTS. The first is to calculate the conductor’s temperature according to the measured cable surface temperature by DTS; the second is to predict the maximum allowable load under the condition of emergency overloading. This paper presents a novel technique for solving the above two problems, the basic principle of which is based on the estimation of soil thermal parameters by matching the computed thermal field with the measured thermal field. Two methods, i.e., the finite-element method(FEM) and the gradient-based optimization method, needs to be used for the proposed technique. It is found through comparing the calculated results and measured results that the predicted values are consistent with the measured values, which verifies the technique’s effectiveness and can provide a basis for dynamic assessment of ampacity.

Study on the Dielectric Response Diagnostic Techniques for Oil-Immersed Transformer Insulation Damp

WANG Wen-huan, CHENG Jin, LIU You-wei

2014, 47(9):  88-93.  DOI: 10.11930/j.issn.1004-9649.2014.9.88.5

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It has been a problem to accurately diagnose the moisture level of transformers under field conditions. Therefore, the effects of temperature and moisture content on the dielectric response are analyzed by the dielectric response testing on transformers and oiled paper model. The results show that with the increase of temperature,the dielectric response curve moves to the high-frequency area in frequency axis, while with the increase of moisture content,the dielectric response curve pans up in the longitudinal axis. In addition, the minimal value of the complex capacitance’s imaginary part changes insignificantly with the change of temperature; but it increases in exponential form with the increase of moisture content. This conclusion can provide a basis for accurate diagnosis of the moisture level.

Comparative Study on Melting Ice with High Frequency AC and DC Short Circuit Method

ZHONG Hong-zhou, LIU Ming-guang, ZHANG Xue-Liang

2014, 47(9):  94-99.  DOI: 10.11930/j.issn.1004-9649.2014.9.94.5

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It is a feasible method to use the joule heat generated by the current through power lines to melt ice. Therefore, the AC current with a frequency of 1 kHz is suggested to be used for melting ice, which means by using the current-skin-effect produced by the high frequency current through the transmission line, the equivalent resistance in the unit length of transmission line will be increased. Compared with the DC current, in the same electric shed, the AC current will generate two times of joule heat in a short period of time,which will shorten the melting time and reduce the economic loss. Moreover, a serial-connected type of high frequency and high voltage power device is designed and simulated by Matlab. The results show that the alternating current with 1 kHz high-frequency is applicable to melting ice in power systems of 35 kV and below, which can provide a reference for melting ice in low-voltage distribution systems.

Simulating Reappearing of an Actual Fault in Large-Scale AC/DC Power System Based on PSCAD/EMTDC

XIONG Qing, XI Liang, ZHOU Bao-rong, ZHAO Yong, HONG Chao, XIA Cheng-jun

2014, 47(9):  100-106.  DOI: 10.11930/j.issn.1004-9649.2014.9.100.6

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Aimed at analyzing the actual short-circuit fault on the Beijiao-Zengcheng line which led to simultaneous commutation failures in 5 DC lines of China Southern Power Grid, the electromagnetic transient simulation model including detailed DC models was built according to the equivalent model of the actual grid based on the electromagnetic transient simulation software PSCAD/EMTDC. In order to ensure fast and accurate modeling to reflect real failure process, the main difficulties were analyzed and corresponding solutions during the large-scale AC/DC power system modeling process were also proposed, in which some engineering solving methods, such as the modeling scale, DC system modeling, user-defined model, accurate and fast modeling of large-scale system, etc., were defined. On this basis, the fault was simulated successfully by using the PSCAD/EMTDC model, which reproduced the actual failure process. By comparing the simulation results with the actual recorded wave results, it was demonstrated that the modeling method is practical and effective to make the grid model accurate and reliable and able to truly reflect the actual dynamics of the system. With the model, the fault scan of Guangdong 500kV important sites was carried out to determine the fault areas those may cause simultaneous commutation failures in 5 DC lines.

Application Research of Zero Power Protection for Thermal Power Plants

WU Peng-yue, YANG Bo, WANG Hai-tao, SUN Gang-hu, PENG Jin-ning

2014, 47(9):  107-111.  DOI: 10.11930/j.issn.1004-9649.2014.9.107.4

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At present, the logic of power load unbalance is widely used in DEH control system of large thermal power generation unit to prevent the unit from considerable oscillation and tripping when the power output channel is interrupted. However, the logic relies heavily on the active power transmitter, and its weak ability of anti-interference is easy to cause the unit’s maloperation. To solve this problem, based on the actual fault cases, the speed control mode before unit’s grid connected operation and load control mode after unit’s grid connected operation were studied, in which the advantages of zero power protection such as accurate judgment, fast operating and strong anti-interference ability when load interruption happens were analyzed and verified. Moreover, the tripping way and the necessity of zero power protection were also discussed and it was recommended to configure zero power protection in the thermal power unit.

Analysis of Differential Protection Characteristic for On-Load-Tap-Changer Transformer of UHV

LI Yan-jun, ZHOU Chun-xia, XIAO Yuan-qing, GUO Xiao

2014, 47(9):  112-117.  DOI: 10.11930/j.issn.1004-9649.2014.9.112.5

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In order to investigate the differential protection characteristics for on-load-tap-changer transformers of UHV, the basic performances of differential transformer protection and its unbalanced differential current were studied, by which it is found that the conventional protection of on-load-tap-changer transformers may have a potential risk during the transformer tap adjustment. Through the further analysis of the influencing factors on the characteristics of unbalanced differential current, suggestions about the selection of rated current of differential protection for on-load-tap-changer transformers were proposed. In addition, the differential current distribution during the transformer tap adjustment is obtained by the simulation and the setting strategy is accordingly provided, which is also validated by the simulation.

Sensitivity Checking of Wye/Delta Converter Transformer Differential Protection in DC Converter Station

HAO Jun-fang

2014, 47(9):  118-121.  DOI: 10.11930/j.issn.1004-9649.2014.9.118.3

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By taking the wye/delta converter transformer in Pu’er converter station in Nuozhadu-Guangdong ±800 kV DC Transmission Project as an example, the calculating settings and sensitivity checking of differential protection are discussed. A 12-pulse inverter DC transmission model is established by MATLAB for simulation of the AB phase-to-phase fault on the valve side of wye/delta converter transformer, and the testing data and waveforms from the XUJI GROUP’s converter transformer protective device-RTDS in CSG’s project are used for proof. A comprehensive analysis indicate that, for HVDC systems ,since tube A is used in the differential protection of the wye/delta converter transformer, the sensitivity should be calculated according to the three-phase short-circuit on the valve side of wye/delta converter transformer under the system’s minimum operating mode rather than the conventional phase-to-phase short-circuit.

Information and Communication

Broadband Power Line Carrier OFDM Channel Estimation

SUN Zeng-you, LING Xia, LI Huan-huan, TENG Zhi-jun

2014, 47(9):  122-125.  DOI: 10.11930/j.issn.1004-9649.2014.9.122.3

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OFDM is an effective modulation technology to realize high-speed data transmission on power lines. The time-frequency selectivity of power line channel will lead to frequency shift of the OFDM system, which also yields ICI. To master the channel characteristics accurately, the broadband power line carrier OFDM channel estimation based on DPSS-BEM is proposed in this paper. In this method, the power line channel is modeled with using two-dimensional DPSS-BEM and regarded as the linear weighting of two-dimensional orthogonal components. The channel variation during OFDM symbol is treated as the variety of weights, and the training information from pilots and the least squares method are used to estimate weights to complete channel estimation.The simulation results show that the method can effectively track the changes of power line channel, obviously improve the normalized mean square error and bit error rate performance.

Application of IEC 61850 Communication Technology to Power Plant

LU Yan-lin, FU Sheng-ming, ZHANG Li-hua, ZHANG Hui-xin

2014, 47(9):  126-131.  DOI: 10.11930/j.issn.1004-9649.2014.9.126.5

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IEC 61850 communication technology is widely used in smart grid. However, no IEC 61850 communication standard has been enacted for fossil fuel power plant yet. Based on an investigation of the contents of IEC 61850 and its application in smart substation, the feasibility is analyzed for application of the IEC 61850 in control, protection and status monitoring of switchyard, generator units and auxiliary power system of the fossil fuel power plant, and its current application situation is introduced. In the end, the implementation plan and suggestions are proposed for application of the IEC 61850 communication technology in the fossil fuel power plant.

Image Processing and Recognition Technology for Transmission Line Icing

LUO Chao-xiang, WAN Huan-jian, LUO Wen-bo, JIANG Lan

2014, 47(9):  132-136.  DOI: 10.11930/j.issn.1004-9649.2014.9.132.4

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Accurate and reliable identification of ice thickness on a conductor is one of the key technologies of transmission line icing on-line monitoring, by which the conductor de-icing work can be guided effectively. According to the intuitionistic and reliable characteristics of remote imaging and its data, and based on digital video image processing technology of ice thickness identification and calculation, the layout boundary of the conductor can be identified in terms of graying processing, binearization, morphological pre-processing and Radon transform based linear detection. Meanwhile, the thickness of ice can be calculated with the differences of the image pixels before and after conductor icing. Comparing with the existing method, the proposed method shows the promised improvement of ice thickness calculation. Finally, the direction of the further optimization of transmission line icing recognition techniques was proposed.

Smart Grid

Tripping Time Characteristics in Smart Substation Process Level Network

BU Qiang-sheng, YUAN Yu-bo, GONG Xin-yue, GAO Lei

2014, 47(9):  137-142.  DOI: 10.11930/j.issn.1004-9649.2014.9.137.5

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The process layer network has a direct impact on the security and reliable operation of smart substation. Research on the performances of different network modes can provide an essential reference for the selection of process layer network mode. Firstly, the characteristics of different network modes are introduced, including direct sampling and tripping, network sampling and network tripping. The application principle of VLAN and priority level is elaborated. Then, the protection operation time under different network modes and network conditions is tested in detail. At last, an analysis is made on the characteristics of the process layer tripping time. The testing results show that the direct tripping time is stable; the network tripping time increases with the increase of the network traffic; and the discreteness is relatively large.

Study on GOOSE Isolation Measures in Smart Substation Relay Protection

HOU Wei-hong, QIU Yu-tao, WU Zhen-jie, WU Jing

2014, 47(9):  143-148.  DOI: 10.11930/j.issn.1004-9649.2014.9.143.5

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In order to solve the implementation problems of GOOSE isolation measures, this paper analyzes the mechanism of different GOOSE isolation techniques and their features in Smart Substation, and studies the maintenance mechanism and the soft strap principle. According to the reliability of the existing isolation techniques, it is proposed that the safety measures of GOOSE in Smart Substation should consist of at least two isolation techniques with different principles. Finally, by taking the isolation maintenance of a 220 kV transmission line for case study, the implementation principles of the Smart Substation safety measures is introduced and the isolation measures of the operating and maintenance equipment are described, which can provide a reference for the implementation of GOOSE safety measures.

Energy Conservation and Environmental Protection

Comparative Study on Ammonia Slip Measurement of SCR Denitrafication Equipment in Power Plant

PAN Dong, NIU Guo-ping, DING Jia-yi

2014, 47(9):  149-152.  DOI: 10.11930/j.issn.1004-9649.2014.9.149.3

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According to the practical situation of the SCR denitrafication equipment of power plants, the comparative study on three ammonia slip measurement methods, including indophenol blue spectrophotometric method, Nessler’s reagent spectrophotometry method and ion selective electrode method, is conducted. The result shows that the three methods can all be applied to the measurement of ammonia slip of flue gas from the SCR denitration equipments in the power plants. Among the three methods, the ion selective electrode method has the most excellent anti-dust ability, while the Nessler’s reagent spectrophotometry method has the most stable result. The two methods are recommended for practical application.

The Strategy on Reduction of SCR Minimum Operation Load

YANG Qing-shan, LIAO Yong-jin

2014, 47(9):  153-155.  DOI: 10.11930/j.issn.1004-9649.2014.9.153.2

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Generally, the gas temperature at the outlet of boiler economizer cannot meet the operation requirement of the SCR denitrification device when the generator loading is low. In this paper, the flue gas bypass type or limited flow type economizer with low temperature heat exchanger is proposed to solve the problem based on the analysis of existing bypass type economizer. In this way, the stable and efficient operation of the denitrification device can be realized without lowering down the boiler efficiency in the event of low loads. Moreover, for those boilers with high gas exhaust temperature, adopting the limited flow type economizer and low temperature heat exchanger can not only effectively reduce the boiler gas exhaust temperature, but also improve the efficiency of the boiler.

Research for Thermal Power Enterprises on Emissions Trading Based NO_x Emission Control Actions

WANG Yi, JIANG Hui, FU Xiao, WU Gang

2014, 47(9):  156-159.  DOI: 10.11930/j.issn.1004-9649.2014.9.156.3

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Due to the tremendous effort involved in the NO_x control of thermal power industry in China, establishing the emissions trading system will be helpful to achieve the NO_x control goals on schedule. According to the actual situation of Chinese thermal power industry, this paper constructs a calculation model of the costs and benefits of NO_x control for thermal power plants, and deduces the calculation model of NO_x control optimal removal capacity, which can provide a theoretical basis for the strategic action choice of thermal power plants in the emissions trading. Finally, in this paper some proposals are put forward on completing the denitrification electricity policies.