Table of Content

31 March 2014, Volume 47 Issue 3

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Orginal Article

Application of Energy Storage Technology and Its Prospect in Power System

YE Ji-lei, XUE Jin-hua, WU Fu-bao, YANG Bo

2014, 47(3):  1-5.  DOI: 10.11930/j.issn.1004-9649.2014.3.1.4

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The use of energy storage(ES) technology in power system is increasingly recognized. A comprehensive investigation and analysis of the use of ES in power system will help to understand the current status of the ES development and the constrain factors for its development, and analyze its future market prospect and development trend. The paper described the power system characteristics of several countries or regions, such as the SGCC of China, the PJM of USA, the RTE of France, and the National Grid of Britain. The ES demand of various countries was analyzed in terms of power load, power structure and renewable energy planning. The technical development and cost features of ES were summarized and the future trends about ES research and development were also proposed.

The Study of the Frequency Adjustment Characteristics of Wind Power Uniting Thermal Power Outgoing System

WANG Qing, YANG Yue, MA Shi-ying, XU Yong-hai

2014, 47(3):  6-13.  DOI: 10.11930/j.issn.1004-9649.2014.3.6.7

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Wind power uniting thermal power outgoing is an important characteristic of China's western wind power development. In this paper, taking a typical significance wind power uniting fire power simplified system as an example, the interaction between wind power and thermal power is analyzed profoundly. Taking into account speed droop, feed-forward coefficient and servomechanism constant, the primary frequency regulation of thermal power units is analyzed under wind power fluctuation. The power system frequency control strategy of thermal power dealt with mass wind turbine off-grid is proposed to enhance mechanical power emergently. By monitoring the amount of off-grid wind turbines and thermal power spinning reserve capacity, the mechanical power of thermal power units enhanced emergently is calculated. Thus the CCS of thermal units from normal AGC control is switched to emergency power control. The frequency fluctuations are reduced and the stability of the system frequency is improved. The response characteristics of different types of wind turbines are compared in consideration of interruption and short-circuit fault of export power grid. The theory of solid-speed wind turbine removed by over-speed protection because of its speed instability is analyzed deeply under short-circuit fault.

Analysis on Local Consumption and Peaking Issues of 5 Million Kilowatts PV in Hexi Area of Gansu Province

YAO Tian-liang, ZHENG Xin, YANG De-zhou, XU Min

2014, 47(3):  14-18.  DOI: 10.11930/j.issn.1004-9649.2014.3.14.4

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Four areas of Gansu Hexi get admits for more than 5 million kilowatts photovoltaic (PV) in 2012, the problems of grid access and consumption for large-scale PV currently become the most important hinder issue to the rapid development of PV. Based on analysis of actual situation of grid load development, grid planning and transportation capacity, this paper proposes a new idea about dispersive access and local consumption between PV constructive capacity and regional new loads, analyzes the power output characteristics of Hexi PV, calculates and analyzes the max PV acceptable space of Jiajiu, Zhangye, Jinchang and Wuwei local grid. The analysis is given on peaking characteristics and peaking program based on PV output and load characteristics.

stablish of Online Monitoring and Remote Diagnosis Centre on Overall Conditions of wind turbine-Generators

ZHOU Ji-wei, ZHANG Bo, WANG Dong, ZHANG Lin

2014, 47(3):  19-23.  DOI: 10.11930/j.issn.1004-9649.2014.3.19.4

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With applications of monitoring systems for wind turbine vibration conditions, mechanical drive vibration signals can be analyzed, but the monitoring methods are too unitary, in which the wind turbine overall conditions cannot be monitored. So a comprehensive monitoring method is proposed, in which other parameters can be monitored also, such as blade strain, oil wear particle, generator electrical parameters and wind turbine performance parameters. The overall condition online monitoring system of wind turbine generators is developed and the remote diagnosis centre is set up, by which the goal of the wind farms with few people or unattended can be reached.

A Power Prediction Model of PV System With Hybrid Energy Storage

LIANG Shi-chun, ZHANG Xiao-dong, LIN Pei-feng, NIU Meng

2014, 47(3):  24-27.  DOI: 10.11930/j.issn.1004-9649.2014.3.24.3

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After adding prefect photovoltaic power prediction algorithm,the photovoltaic power generation system with hybrid energy storage,which is optimized,can let the photovoltaic power and invert power to keep balance in a short period of time.Then it can reduce the number of storage units frequently depth charging and discharging and prolong the service life of the storage unit and raise the utilization rate of the energy of the system.The existing prediction algorithm of photovoltaic power,which includes BP neural network,similar day typical of the trend and least squares support vector machine etc,has some shortcomings which the utility is not strong and smooth effect is not good.This paper proposes a pratical short-time photovoltaic power prediction mathematical model which is based on the trend of moving average model,the model is based on the historical datas as input,then manipulation datas to get the predicted value.Through the experiment under weather environment of the cloudy, the photovoltaic power prediction algorithm,which can timely tracking and smoothing PV fluctuation,also reduce the storage unit's capacity,is verified.

The Research on the Impact of the Frequency Stability of Isolated Net Caused by the Large Scale Wind power Grid Integration

ZHOU Zhuan, YAO Xiu-ping, CHANG Xi-qiang, WANG Heng

2014, 47(3):  28-32.  DOI: 10.11930/j.issn.1004-9649.2014.3.28.4

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With large scale wind power accessed to power grid, wind power impacts power grid more and more obviously. Based on the output characteristics of wind farm and wind farm power grid brought by the match problem of security and stability control equipment. This paper adopts PSASP program for simulation and analsis of Altai region in xinjiang power grid, considering wind power output characteristics and load characteristics to impact isolated net running in the transient process and security and stability control device, through the comparative analysis in different wind speed and different load cases after cooperation with all kinds of security and stability control device for the effect on the stability of the isolated net frequency, the results show that after the large-scale wind power connected to the electricity grid, wind power output characteristics and load characteristic in mutual cooperation, which affect the security and stability control equipment and isolated net frequency stability. Combined with wind turbine output characteristics and load characteristics influence on security and stability control device to cooperate, put forward on a method and action sequence of the safety and stability control device for power grid containing wind farm. In this paper, it has an important reference value to the contain of large-scale wind power connected to the power grid safe and stable operation.

Research on a new MPPT control strategy of PV system

JIN Xiao-hu, CHEN Hua, FENG Tao

2014, 47(3):  33-36.  DOI: 10.11930/j.issn.1004-9649.2014.3.33.3

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Based on the platform of Matlab/Simulink,a generic simulation model of PV battery is built. Then a MPPT control strategy of PV system based on intermediate value of step length method combined with neural network is proposed. When the environment or the load changes suddenly,the BP neural network will provide the initial duty ration. After that,by using the intermediate value of step length method with small-step,the system will get to the MPP finally. In the end, by using neural network module, the simulation results show that the control strategy proposed in this paper can track the MPP fast and accurately with a good static performance.

Optimal Dispatch Model of Power Systems Integrated with Large-scale Wind Power

WANG Kun, LI Lin-chuan, SUN Qian

2014, 47(3):  37-41.  DOI: 10.11930/j.issn.1004-9649.2014.3.37.4

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In order to study influences of large scale of wind power on electric power system operation in generation market, a new thermal-unit commitment model is proposed considering wind power extreme fluctuation, that is taking the minimum equivalent load as the bidding capacity to determine the start-up thermal-unit, then checking whether the preliminary boot mode can meet the maximum equivalent load, if not, curtailing wind power at the minimum equivalent load moment to increase the bidding capacity. This process is repeated until the maximum equivalent load is met. An optimal model with the goal of minimizing the generation cost is put forward, and constrained cost variable method and interior point method are used to solve the OPF model. The example shows the effectiveness and feasibility of the model and algorithm.

Bifurcation Analysis on Voltage of Power System with Doubly Fed Induction Generator

YUAN Yi-tao, KANG Ji-tao, WU Xiao-gang, LI Ya-hui

2014, 47(3):  42-47.  DOI: 10.11930/j.issn.1004-9649.2014.3.42.5

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The power flow of the grid will be changed by the wind power connected with it. For studying its impact on voltage stability,a dynamic model is built for wind power system with doubly fed iduction generator(DFIG), and a new approach to deal with the rotor control voltage of DFIG is proposed, in which DFIG's steady state rotor control voltage is used as rotor control voltage and this value is changed with the change of state of system. The equilibrium solution manifold of power system is tracked under variable load parameter, the influence of load parameter on wind power system is analysed based on bifurcation theory. The simulation showed that the difference of voltage stability analysis between different wind turbine model, and the proposed new approach is feasible.

Analysis and Comparison to the Correction Method of Boiler Thermal Efficiency Based on GB 10184-88 Codes

LI Yong, HAN Wei, WANG Yan-hong

2014, 47(3):  48-54.  DOI: 10.11930/j.issn.1004-9649.2014.3.48.6

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Boiler thermal efficiency is an important indicator to evaluate the economic efficiency of thermal power unit in operation. When a parameter changes, the existing correction method of boiler thermal efficiency is inconvenient to analyze its influence to the boiler thermal efficiency, and it is also inconvenient to analyze the reason and location which cause the reduction of the boiler thermal efficiency in operation. A new correction method which combined differential deviation method with first order Taylor formula was proposed to revise the various losses and boiler thermal efficiency, and comparison and analysis of correction calculation method were also conducted between the innovative correction method and the Chinese Utility Boiler Performance Test Code GB 10184—88. Taking a 1025 t/h boiler for example, various losses and boiler thermal efficiency were calculated under two different test conditions, The results show that the difference of the losses and boiler thermal efficiency calculated on differential modification method and GB 10184—88 codes is tiny after modification, so this method can be applied into the engineering practice.

Analysis and treatment on vibration fault on 600 MW steam turbine

LI Yu-chun, CAI Qiang

2014, 47(3):  55-58.  DOI: 10.11930/j.issn.1004-9649.2014.3.55.3

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The shaft vibration of NO.3 bearing suddenly raised from 80 μm to 240 μm in an imported 600 MW supercritical power plant. At the same time, the temperature of NO.2 bearing raised to 106 ℃. The excessive vibration and temperature have already threaded the safety of the unit. In order to find out the cause of the vibration fault, several experiments were carried out on the unit, including changing the oil hydraulic, load and vacuum of the condenser. Experimental results show that the forward reasoning method is valid for finding out the cause of vibration and the example provided in this paper is useful for analyzing similar vibration fault in supercritical power plant.

Influence of Low NOx Combustion Technology Reformation on Tangentially-Fired Boiler Heat Distribution

JIN Yun-li

2014, 47(3):  59-64.  DOI: 10.11930/j.issn.1004-9649.2014.3.59.5

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Based on debugging and testing data, the issues of low main steam temperature and low reheat steam temperature existing in the tangentially-fired boilers after low NOx combustion reform are analyzed, which concludes that the boiler heat distribution moving towards the water walls after the reform is the main cause for the excessively low main steam and reheat steam temperatures. Moreover, the heat distribution shifting is caused by the new separated over-fire air(SOFA) that increases the oxygen content of burn-out zone, leading to a significant rise of burning rate. Meanwhile the secondary air flow redistribution caused by SOFA makes the burning rate in the primary combustion zone shift from smooth change to rapid change with oxygen content. After the reformation of low NOx combustion technology, the primary combustion zone and the burn-out zone both lie in the rapidly changing range of the burning rate with oxygen content. In this range, the change of oxygen content will have significant effect on boiler heat distribution, and consequently, some key parameters including the steam temperature and pressure and the water level in the drum fluctuates widely.

Optimization of TOFD Detection for Generator Retaining Ring with Inner Wall Defect

DAI Zhen, LI Wei, HAO Xiao-jun, LIU Hong-quan, JING Shang-qian

2014, 47(3):  65-68.  DOI: 10.11930/j.issn.1004-9649.2014.3.65.3

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Probes for ultrasonic time of flight diffraction (TOFD) are considered to be conventional, such as 45°, 60° and 70°. Austenitic steel is widely used in generator retaining ring. Coarse grain size and large thickness play an aggravating role in acoustic wave attenuation. Inner wall defect can not be detected accurately even 45° probe is used. In order to optimize the detection process, the 20° probe is proposed based on analysing of the characteristic of acoustic wave. Through TOFD detection of inner wall with natural crack, the optimal frequency (2.25MHz) is determined. And artificial defect detection is in good agreement with actual fact by the optimal frequency. So the optimum detection process is 20° probe, 2.25MHz, transducer diameter of 12mm. And beam is focused on inner wall of generator retaining ring. By optimization detection process, inner wall artificial defect with height of 2mm can be effectively distinguished in generator retaining ring with thickness of 50mm.

Economic Benefit Analysis and Control Logic of Condensate Throttling

QIAN Neng, JIN Sheng-xiang, WANG Qi, ZHAO Yan, WANG Liu-hu

2014, 47(3):  69-73.  DOI: 10.11930/j.issn.1004-9649.2014.3.69.4

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Load adjustment of power plants with the condensate throttling can reduce the throttle loss of governing stage and improve the operation economy and security, without the loss of response performance. This article identifies the condensate flow-load’s transfer function of certain 600 MW plant by analyzing condensate throttling dynamic model, and give out a fuzzy adaptive control algorithm, based on which the control system works well in field operation. The result shows that the max range of condensate throttling is about 800 t/h under secure conditions. The response time for load is 10 s, and the load amplitude of the response is 9 MW. Grid assessment indicators value KP increases about 10%, and efficiencies of HP increase 1.42%, 1.20% and 0.99% on load point 400, 450 and 500 MW, which decease average coal consumption by 1.77, 1.26, 0.91 g/(kW·h), indicating the economy benefits and improvement in load control of condensate throttling.

The research on the saturated electricity demand of North China Grid

YAO Yu-fang, CHEN Li-ping, SHEN Wei-dong

2014, 47(3):  74-79.  DOI: 10.11930/j.issn.1004-9649.2014.3.74.5

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This research analyzed the trend of electricity consumption growth in different developing stages for different countries, confirmed the growth rate of electricity demand from high to low during the economy developing process in developed countries, and having the fact of saturated electricity demand; established a indicator evaluation system for forecasting regional saturated electricity demand; analyzed many factors during the industrialization process of six provinces in North China grid, such as economy development, industrial structure, labor structure, urbanization rate, consumption mode, per capita income level in consideration of the situation of North China; calculated the time and the quantity scopes of the saturated electricity demand by using the system dynamics model.

A coordinated generation and reserve dispatching model considering unit commitment risk

XUE Zhi-ying, ZHOU Ming, LI Geng-yin

2014, 47(3):  80-84.  DOI: 10.11930/j.issn.1004-9649.2014.3.80.4

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This paper aimed at the coordinated dispatching problem of generation and operating reserve. A dispatching model considering unit commitment risk was built. Calculation method based on the conditional expectation was proposed to control both the probability and degree of load lost accident. The approaches to deal with wind power integration and dispatching energy storage load were discussed. Simulation test proves the simpleness, correctness and feasibility of the above method by comparison with other method introduce in our references. The results show that the method can also solve the physical index which stands for the shortage of available generation capacity. And it has the obvious advantage of calculation speed which makes it of great practical value in power systems unit commitment problem.

Simulation Research of Short-circuited Fault Detection with Micro-grid in Islanded Operation

ZHOU Jian-ping, XU Si-cong

2014, 47(3):  85-89.  DOI: 10.11930/j.issn.1004-9649.2014.3.85.4

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Micro-grid with distributed generation is modeled and simulated with Matlab/Simulink. Simulation experiments are made when operating mode of micro-grid is switched from the islanded mode to the grid-connected mode. The simulation results demonstrate the effectiveness of the built micro-grid simulation model. Short-circuited fault is simulated in micro-grid's islanded operation by adding the three-phase fault module to the above simulation model. Db wavelet is selected to detect the voltage of short-circuited fault. The simulation results show that db wavelet can accurately detect the singularity of the short-circuited fault signal, which provides support for improving the power quality of the micro-grid.

Comparison of Stability Factors of Axial Compressive Members in Transmission Towers in Design Codes

HAN Jun-ke, ZHANG Chun-lei, YANG Jing-bo

2014, 47(3):  90-95.  DOI: 10.11930/j.issn.1004-9649.2014.3.90.5

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Stability is a very important problem in transmission towers. Taking the stability factor of axial compressive members in transmission towers as the research object, this paper presents stability factors of axial compressive members specified in American tower design guidelines (ASCE10-97), the British tower design specification (BS 8100-3) and European overhead transmission line of over 45 kV design specification (EN50431-1), and make a comparison with technical regulation of design for tower and pole structures of overhead transmission line(DL/T 5154—2002). The results show that stability factors of axial compressive members do not consider the influence of section classification in ASCE10-97, while DL/T 5154—2002, BS 8100-3 and EN 50431-1 considers the influence of section classification on stability factor curves; for the stability factor of hot-rolled angle steel members in transmission towers, ASCE10-97 is greater than DL/T 5154, while BS 8100-3 and EN 50431-1 almost equals to DL/T 5154—2002; for stability factor of cold-formed steel tube members, ASCE10-97 is greater than DL/T 5154—2002, BS 8100-3 almost equals to DL/T 5154—2002, and EN 50431-1 is the lowest.

Experiment Study on Reinforcement of 500kV Guyed Transmission Tower

ZHAO Qiang, WANG De-hong

2014, 47(3):  96-100.  DOI: 10.11930/j.issn.1004-9649.2014.3.96.4

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Guyed transmission tower is a common form used to high voltage transmission lines. According to the maintenance and operation record, there are deformation phenomenon appears in tower component of junctions between the upper crossarm and cable, which seriously threatened the safety of transmission line. The non-linear finite element model for the 87LM21towers which are widely used in Dong-Chang-Ha transmission lines is built with ANSYS software. The mechanical properties under three kinds of wind conditions were analyzed and some mechanical properties of guyed transmission tower under calm wind are obtained. The reason why the tower cannot meet the requirements in practice was found, and two reinforcement schemes were proposed, then an experiment of 87LM21 tower under static wind load wascarried out. The mechanical properties of guyed transmission tower were more explicit. At the same time, the rationality of tower model and the result of numerical analysis are verified, and the feasibility of the reinforcement schemes was proved.

Simulation and Analysis of Short-Circuit Impact Test of Series Capacitors

LI Zhi-gang, DONG Fang-zhou, LI Yu, CAI Wei, LIU Liang, WEI Ran, LU Jing

2014, 47(3):  101-106.  DOI: 10.11930/j.issn.1004-9649.2014.3.101.5

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Currently, series capacitors as a series compensation device run unsteadily, which leads faults happen frequently. According to the parallel capacitor test standard, many tests are carried out such as the partial discharge test, the dielectric loss test, AC withstand voltage test, which can't fully reflect the quality of the capacitor. In order to the inspection of the series capacitor overload capacity, it is necessary to simulate series compensation capacitor short-time over voltage condition when short circuit fault happens. After the analysis of the various solutions, it ensures the use of parallel resonant energy storage test loop. Finally it clears about the influence of various parameters in the test loop on the test results by means of the simulation and puts forward the optimal parameter collocation scheme, which provides qualitative theory guidance for the specific tests in the next step.

ATP-EMTP Based Simulation on Auxiliary Ground Wire in High-voltage Cables

ZHU Wen-wei, LIANG Ai-wu

2014, 47(3):  107-110.  DOI: 10.11930/j.issn.1004-9649.2014.3.107.3

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In order to study the effect of auxiliary ground wires in high-voltage cables, single-circuit power cables and double-circuit power cables with or without an auxiliary ground wire are modeled by ATP-EMTP simulation software under the conditions of typical laying mode, normal operating current and single phase short circuit current. According to requirements of regulations, the effect of an auxiliary ground wire to inhibit induced voltage is analyzed under the conditions of normal operation and single phase short circuit. The feasibility of double circuits sharing an auxiliary ground wire and taking metal sheath of parallel cables as auxiliary ground wires is studied. Suggestion is given to auxiliary ground wire laying to reduce power loss when normally operating.

Simulation of Inner-Potential Difference of Grounding Grid

ZHANG Ting, ZHANG Xiao-liang

2014, 47(3):  111-115.  DOI: 10.11930/j.issn.1004-9649.2014.3.111.4

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With the increasing of power system capacity, the grounding short-circuit current that is withstanded by grounding grids of substations becomes higher and higher. The inner-potential difference may cause damage to cable and secondary equipment. A simulation model is presented in this paper. The grounding simulation software CDEGS is used to obtain the inner-potential difference under different conditions. The simulation results show that the lower soil resistivity leads to higher inner-potential difference, and the inner-potential difference of a cooper conductor is lower than the steel one’s; the larger grounding grid has the higher inner-potential difference. When inner-potential difference is greater than 1.4 kV, the cross-section of the steel conductor should be increased, or the coppered steel grounding grid should be chosen.

A new tuning method of arc suppression coil based on the zero-sequence voltage fixed phase and compared amplitude

MIAO Xiao-peng, WEN Zhen-jiang, LI Xiao-bo, ZHAO Guo-dong

2014, 47(3):  116-119.  DOI: 10.11930/j.issn.1004-9649.2014.3.116.3

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In order to facilitate the measurement of the parameters to ground in the neutral point arc suppression coil grounding system ,a new tuning method of arc suppression coil based on the zero-sequence voltage fixed phase and compared amplitude is proposed. In this method, the arc suppression coil and resistor are added in the distribution network neutral point, before incorporating the resistor, the zero-sequence voltage phase can be measured firstly; after incorporating the resistor, the arc suppression coil inductance value will be further adjusted to make sure that the zero-sequence voltage phase of the neutral point is identical. The total capacitance and the total resistance to the ground in the power distribution network can be accurately obtained by using the formula with the measured zero-sequence voltage amplitude. Finally, the Matlab simulation model is built to verify the tuning method. It proves that this method has the advantages of simple operation, high accuracy etc.; and it has good compensation effect on the arc suppression coil tuning.

The Application Comparison of TCSC and SVC in Sub-Synchronous of Power System

WU Xiao-gang, LEI Fan, YUAN Yi-tao, KANG Ji-tao

2014, 47(3):  120-124.  DOI: 10.11930/j.issn.1004-9649.2014.3.120.4

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Aimsat the problem of Sub-synchronous resonance(oscillation) caused by series compensated transmission of power system, based on the standard IEEE sub-synchronous resonance test systems, The inhibitory effect of TCSC and SVC was researched exhaustive and thorough by test signal method and time domain simulation method. The research shows: TCSC and SVC both can effectively inhibit the sub-synchronous resonance, but because they belong to the series and parallel devices, so the own characteristics are different. When in the same capacity case, the inhibitory effect of TCSC was better than SVC as well as the enhance capabilities of electrical damping; in the same inhibitory effect case, the capacity of TCSC was required less than SVC; however, the investment was higher. The harmonics that injected into grid by TCSC and SVC were both odd harmonics, and the 3,5,7 times were main component. The latter part of the operation and maintenance was in a high degree of automation and targeted maintenance should be set based on the weak link of the device.

Study on Partial Discharge Detection in GIS under AC Voltage and DC Voltage

MA Hong-ming, ZHOU Nian-rong, XIAO Dan, TAN Xiang-yu, LI Jing-rui

2014, 47(3):  125-129.  DOI: 10.11930/j.issn.1004-9649.2014.3.125.4

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In order to explore an effective method for detecting the typical defects of metal conductive particles in GIS, using the simulation GIS to establish a set of partial discharge detection platform under AC voltage and DC voltage. Application of the ERA and the UT to carry out the measurement of partial discharge signals, then access to a large number of experimental data and maps and comparative analysis. We propose a method by analyzing for detecting the typical defects of metal conductive particles using partial discharge detection under positive DC voltage. This detection method is the most effective to the typical defects of metal conductive particles. It can discover the typical defects in time and has a little damage to the insulating properties of GIS, so that it has important application value.

The Decomposition Analysis of Residential Electricity Consumption in China

ZHU Kai, YIN Hai-tao

2014, 47(3):  130-134.  DOI: 10.11930/j.issn.1004-9649.2014.3.130.4

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Electricity consumption plays an important role in Resource conservation and environmental protection. Using LMDI method and decomposition analysis, this paper identifies four key factors including demographic effects, urbanization, social atomization and electricity consumption intensity that contribute to the increase of residential electricity consumption(REC). Results show that increased electricity consumption intensity is the primary driver for REC increment across the country. While demographic, urbanization and social atomization do not have a strong explanation power for the current REC growth, their impacts tend to increase. Besides, we found there are significant differences about the influences of the four factors among four major economic regions.

Washing Survey and Technical Economic Analysis of China Thermal Coal

HUI He-long, ZHU Feng-hao, HUANG Qi-li, WANG Shu-juan, SHUXin-qian, XU Xu-chang

2014, 47(3):  135-139.  DOI: 10.11930/j.issn.1004-9649.2014.3.135.4

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Based on the survey of washing conditions and characteristics in application in power plants of thermal coal in China, this paper revealed the existing circumstances and some problems during the washing of thermal coal. Then, a preliminary technical and economic ananlysis in 'coal-electricity-transportion' was given combined with the composition of cost of the three parts. Furthermore, a kind of 'quality-priced method' was proposed due to the clean degree of coal. It is hoped that this paper will plays a role in promoting the development of washing of themal coal in our country.

Available Hours,Lossing Hours and Their Application in Technical-Economic Evaluation of Power Transmission

LIANG Han-qing, LIANG Xu-ming, WU-xiong

2014, 47(3):  140-145.  DOI: 10.11930/j.issn.1004-9649.2014.3.140.5

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In order to obtain the investment of the Power Transmission and Transformation project, it normally need to estimate yearly mean transmission capacity and the relating line resistance loss in operation. In this paper, it led some results of relationship between the available hours and lossing hours in AC and DC transmission via the theoretical derivation and studing the actual data, proceed to the next step discuss the and impact of these relationship in project technical-economic analysis, and finally peovided advises in constructing power transmission and transformation project based on different boundary conditions.

The Empirical Analysis on the Electricity Auction Market of East China Power Grid

LI Xiao-gang, YANG Li-bing, ZOU bin, WANG Xiao-jun

2014, 47(3):  146-151.  DOI: 10.11930/j.issn.1004-9649.2014.3.146.5

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based the data of the electricity auction market of Easr China Power Grid, the factors impact on the selling electricity price, such as the power generation cost, the Benchmark Electricity Price, the relationship between supply and demand, and the potential market power, are sequenced according to their grey correlation coefficient. The results showed that the most influential factor is the power generation cost, then the Benchmark Electricity Price, the third is the relationship between supply and demand and the minimal impact is the potential market power. Further, the correlation coefficient between the electricity prices in different periods, as well as power generation bidding price and the above factors to be tested, they show the same relationship. All these results indicate that the market has the role of discovering cost and regulating supply and demand, and there is almost not the room for generation to exercise their potential market power.

Analysis and Control meaaures for Gypsum rain of Wet Flue Gas Desulfurization

GUO Yan-peng, PAN Dan-pin, YANG Lin-jun

2014, 47(3):  152-154.  DOI: 10.11930/j.issn.1004-9649.2014.3.152.2

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After the uninstalling of gas-gas heater from limestone-gypsum wet desulfurization technology of coal-fired power plants,gypsum rain become serious,and adversely affect the environment.This paper deeply analyzes the sources,forming process and influencing factors of gypsum rain,introduces several common solutions which have certain industrial application value. Combined with the engineering case, the advantages and disadvantages of each solution are discussed,which provide experience for actual WFGD system transformation in coal-fired power plants.Also pointed out it's good for air pollution controlthat the current desulfurization process optimization and develop new wet electrostalic precipitator suited to China's national conditions.

Investigations on the strategy of changing of catalyst of SCR systems

LI De-bo, LIAO Yong-jing, XU Qi-sheng, YANG Qing-shan

2014, 47(3):  155-159.  DOI: 10.11930/j.issn.1004-9649.2014.3.155.4

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SCR is widely used in the power plants for the reducing of NOx. In addition, the cost of catalyst is so high. Researches on the management of the catalyst for SCR systems are conducted by us. This research concentrates on the changing method for the catalyst, strategy for the changing of the catalyst, models for the changing of catalyzer considering the economical effect. Our research on the strategy of changing of catalyst of SCR systems is very important for catching up with foreign countries on the managing strategy on the catalyst. In addition, this research is important for the running of SCR systems in our country, which is both science and technology value.