Table of Content

18 November 2012, Volume 45 Issue 11

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Special Conlribulion

Research and Practice of Wind Power Dispatch Based on International Advanced Experience

LI Ming-jie

2012, 45(11):  1-6.  DOI: 10.11930/j.issn.1004-9649.2012.11.1.5

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With the rapid development of wind power in China, it is the most difficult challenges for grid operation organization to increase wind power utilization rate and to improve the safety level of the system. This paper analyzed the international wind power dispatching technology such as Europe and America. The true difficult points of Chinese electrical system for operating large-scale wind power are presented. Moreover, the wind power dispatching optimization technology is studied. Thereafter, the wind power dispatching supporting systems are constructed in the SGCC management range to aid the dispatching decision. The system includes real-time supervision, wind power forecasting, day-ahead schedule, real-time control and heat supply monitoring. The practice in the SGCC management range indicates that all of the methods improve the wind power ratio in the system greatly.

Research on Key Indexes Comparison of Wind Power Utilization Level

BAI Jian-hua， ZHANG Qin， XIN Song-xu， XIE Guo-hui

2012, 45(11):  7-12.  DOI: 10.11930/j.issn.1004-9649.2012.11.7.5

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In order to reasonably evaluate wind power development status and perform comprehensive comparison of wind power utilization level，the comparison system with various indexes are constructed. Firstly，an overview of the status quo development of wind power in China is briefly introduced，and the basic conditions and utilization level of the development of wind power at home and abroad are clarified. Moreover，with system integrated optimization model，future wind power utilization level comparison is considered. The analytic results show that: wind power utilization level need to be scientifically measured from multiple aspects and the coordination development level between wind power and power system is the key factor. Increasing power system planning and operation level is the key to finally realize wind power scientific and effective development.

Lessons Learnt from Grid Planning in Europe

Kaare Sandholt

2012, 45(11):  13-17.  DOI: 10.11930/j.issn.1004-9649.2012.11.13.4

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During the last ten years planning for grid expansion has developed considerably in Europe. The development has been driven by the changes in the ownership of the power sector due to liberalisation of the sector, but also driven by the rapid introduction of renewable energy technology as a new and important source for power in the future. The new grid planning process has successfully addressed some of the major challenges regarding grid expansion in Europe, while others still are unsolved and even more challenging today than years ago. It is obvious that China and Europe in many ways face the same types of challenges and a strengthened cooperation on these issues would benefit both sides.

Generalion Technology

Study on Optimization of Low Load Operation for Supercritical 600-MW Steam Turbines

FAN Xin, QIN Jian-ming, LIU Jing-yu, ZHOU Zhi-ping, LI Ming

2012, 45(11):  18-21.  DOI: 10.11930/j.issn.1004-9649.2012.11.18.3

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The optimization of low load operation for a supercritical 600-MW steam turbine made by Dongfang Steam Turbine Co. Ltd. is presented to improve the economics of the unit under the low load condition. According to the unit practical operation status and its own characteristics, first the sequence valve control mode is adopted through optimizing the management curve for the HP control valve, and then the optimized control curve of sliding pressure operation is gained by optimizing the sliding pressure operation. The tests for comparison between the thermal efficiency before and after the optimization are performed, which indicates that the optimized operation mode can effectively improve the unit economics under the low load condition.

Research on Main-Turbine-Driven Feed-Water Pump for 1 000-MW Wet Cooling Units

ZHU Jin, FU Huan-xing, MA Ai-ping

2012, 45(11):  22-27.  DOI: 10.11930/j.issn.1004-9649.2012.11.22.5

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The mode of boiler feed-water pump adopting main turbine drive is introduced and discussed, and the technical and economic performance is compared between the feed-water pumps adopting main turbine drive and small turbine drive for 1 000-MW ultra-supercritical wet cooling units. The results show that it is feasible from the technical point that main turbine drive is adopted by feed-water pumps. For 1 000-MW ultra-supercritical wet cooling power units, the thermal economics of main turbine drive is better than that of small turbine drive. Although the initial cost of main turbine drive is higher than that of small turbine drive, it could be recovered through the accumulated savings in operating costs over the twenty-year life cycle of the power plant. With the reduction of coal resources, the advantages of main turbine drive for boiler feed-water pumps could become more and more significant.

Optimization of Water Treatment System for Combined Power, Water and Heat Generation Units

LIU Zhi-jiang

2012, 45(11):  28-31.  DOI: 10.11930/j.issn.1004-9649.2012.11.28.3

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Taking one 600-MW combined power, water and heat generation unit for example, the characteristics of the water treatment process including boiler make-up water, condensate water and boiler feed water are introduced. According to the problems such as the over-long desalination regeneration cycle, the high condensed water dissolved oxygen content and water-vapor system containing hydrazine, related technical innovations are carried out as follows. First, since the raw water of the water treatment system is the condensate generated from the seawater desalination system, its quality is equivalent to the desalting water. Therefore, it can be desalinated by a bypass system. Second, the way of replenishment is modified in which the positions of the replenishment and the pump seal return water are changed from the original condenser hot well to the condenser throat with the atomizing nozzle being added at the throat. Third, the water treatment conditions are changed, i.e., changing the feed water treatment method from AVT(R) to AVT(O) for subcritical boilers and from AVT(R) to OT for supercritical boilers with the hydrazine treatment stopped in the combined power, water and heat generation unit. After taking the above optimization procedures, the problems of the original system are solved.

Retrofit of Heating Surfaces for DG2070/17.5-Ⅱ6 Type Boiler

FANG Zhan-ling

2012, 45(11):  32-35.  DOI: 10.11930/j.issn.1004-9649.2012.11.32.3

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To decrease the extra large amount of desuperheating water in the superheaters and reheaters of the subcritical natural-circulating boiler of the Model DG2070/17.5-Ⅱ6 which severely affects the security and economics of the unit, a feasible plan is put forward based on the analysis on the structural characteristics of the heat recovery surfaces, which includes reducing the heating area of the low-temperature superheaters and the low-temperature reheaters, and increasing the heating area of the economizer adequately. The plan is put into practice at a power plant, which indicates that the amount of the desuperheating water in the superheaters and the reheaters is decreased by a big margin with the security and economics of the boilers being improved.

Application of Preload Factor to Eliminating Unstable Vibration of Tilting Pad Bearings

HE Guo-an, CHANG Yi, ZHANG Xue-yan, TANG Ren-zong

2012, 45(11):  36-40.  DOI: 10.11930/j.issn.1004-9649.2012.11.36.4

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Tilting pad bearings are commonly adopted by large turbo-generator units, but unstable forced vibration and oil film whirling often happen to them in practical operation. For solving the unstable vibration of tilting pad bearings, the influences of the preload factor on the oil film stiffness coefficient, damping coefficient and temperature rise are studied with the finite difference method. The study discovers the relationship between the performance of the bearings and the preload factor. With the adjustment of preload factor, the unstable vibration fault of tilting pad bearings is eliminated.

Power Syslem

Economic Comparative Study on Coal Transportation and Power Transmission to Henan

BAI Hong-kun1, LI Gan-sheng2, WANG Yan2

2012, 45(11):  41-46.  DOI: 10.11930/j.issn.1004-9649.2012.11.41.5

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Henan, as a large energy resources province, has become a net energy-import province in the late of“Eleventh Five-Year”(2006-2010). Under the increasingly serious energy situation, large amount of external energy needs to be imported for Henan province to realize its Central Plains economy zone strategy and satisfy the its rapid economic development. Coal consumption accounts for 88% of the province′s total energy consumption. An economic comparative study is conducted on the coal transportation and power transmission from six major coal-producing areas to Henan, and it is suggested that the main power source for Henan should be from such low-price areas as Xinjiang and Inner Mongolia regions, and it is concluded that power transmission are more economic than coal transportation, the ultra high voltage transmission is superior in electricity price for Henan province.

Influences of the UHVDC Project from Hami to Zhengzhou on Central China Power Grid

ZHONG Sheng, GUO Xiang-guo, TIAN Xin, LI Tai-jun

2012, 45(11):  47-51.  DOI: 10.11930/j.issn.1004-9649.2012.11.47.4

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The UHVDC project from Hami to Zhengzhou is China′s first dedicated DC Project for wind power and thermal power transmission, and the first large capacity project transmitting power to Central China power grid. Its construction will significantly affect the peak-regulation ability, security and stability of the receiving-end grid. The requirements of large capacity DC transmission for the receiving-end gird are proposed. The receiving-end location of Hami-Zhengzhou project is verified through regional electricity balance calculation and grid structure analysis, which is selected in the east of Zhengzhou City. Power system operation simulation proves that the peak-regulation ability of Central China grid can meet the requirements of the DC transmission. But the simulation calculation for grid security and stability indicates that the AC interconnection lines between North China grid and Central China grid are weak. Therefore the AC interconnection section needs to be strengthened or the section′s transmission capacity needs to be lowered for security and stability of the power grid.

Transformer Fault Diagnosis Based on C-SVC and Cross-validation Algorithm

ZHANG Yan, WU Ling

2012, 45(11):  52-55.  DOI: 10.11930/j.issn.1004-9649.2012.11.52.3

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A novel method for power transformer fault diagnosis based on the C-SVC(support vector classification with the optimized penalty parameter C) and cross-validation algorithm is presented, which can monitor and detect latent transformer faults timely and accurately. The training and testing sets of the C-SVC algorithm are built upon the data about the dissolved gases including hydrogen, methyl hydride, ethane, aethylenum and acetylene produced from transformer faults. Through the optimizing process of the penalty parameter and kernel function parameter γ in the training set, the optimal support vector machine model can be gotten, with which the classification of data in the testing set can be conducted to determine fault features. The method has been validated by many practical examples to be feasible and efficient with high fault diagnosis accuracy.

Application of Power Grid Holographic Digital Map in Preliminary Design Review of Transmission Projects

YAN Ping, XU Zi-zhi, SHANG Hao-liang, GAN Yu, ZHANG Jing-jing

2012, 45(11):  56-59.  DOI: 10.11930/j.issn.1004-9649.2012.11.56.3

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As one of the important modules in the engineering design review platform, power grid holographic digital map provides a new technical solution which integrates three-dimensional display of engineering preliminary design scheme, multi-source thematic information display and multimedia player. Based on the application and construction of this new technical program, relevant business background is introduced, and relevant technical principle and main technical points are analyzed, including data construct principle, technical architecture, platform structures, business process and other aspects. The system is proved effective in the test running of the review platform in Stare Grid Corporation and it realizes to use spatial information to build a three-dimensional review scene, and will plays an active and important role in improving the efficiency and accuracy of engineering design review.

Image Variation Parameter Recognition of Electrical Power Equipment Based on SIFT Feature Matching

YU Ping, DONG Bao-guo

2012, 45(11):  60-64.  DOI: 10.11930/j.issn.1004-9649.2012.11.60.4

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In video monitoring system of substation, in-process video inspection is used to detect abnormalities in timely so as to avoid failures. Changes in certain parameters of the image constitute an important basis in identifying the changes in image status. A power installation image change parameter identification algorithm based on SIFT, OTSU and RANSAC feature matching was presented. Firstly, a SIFT feature matching was performed on the sample image and monitoring image. Then the interference matching feature points were eliminated in combination with OTSU, and the RANSAC random sampling agreement algorithm was used to eliminate the wrong matching feature point. Finally, two important parameters including the variation angle and zoom coefficient of power installation image were identified based on the matching result. As is proved in the simulation test, this algorithm features simplicity and high precision and it can be used in recognizing the electric power tower inclination angle and meterneedle rotation angle. Meanwhile it can be used in recognizing the zoom coefficient in video inspection as well.

Nonlinear Dynamic Response Analysis of the Transmission Tower-Line System under Earthquake

HOU Jing-peng, CHEN Jia-bao, LEI Jun-fang

2012, 45(11):  65-69.  DOI: 10.11930/j.issn.1004-9649.2012.11.65.4

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With the 5A-ZM4 cat-head transmission tower as an example, a finite element model of transmission tower-line system consisting of two towers and three lines is established by using ANASYS software. The dynamic characteristics of natural frequencies and vibration modes of the system are calculated and the influencing factors are analyzed. Based on 3 typical seismic records of Tianjin wave, EI-Centro wave and Shanghai artificial seismic wave, the peak values of the accelerations are scaled up to consider the nonlinear behaviors and plastic limit of transmission towers. The results show that the largest displacements on top of the tower are mainly concentrated between H/200-H/100 (H is the height of tower) in the nonlinear ultimate limit state under earthquake; and that the bars between the second and the third diaphragms of the tower fall first into elastic-plastic limit state and produce large plastic deformation, indicating a strong nonlinear characteristics of the system.

Improvement of Separation System for Dissolved Gas in Transformer Oil

WEN De-bin, LI Kai, JIANG Hui

2012, 45(11):  70-73.  DOI: 10.11930/j.issn.1004-9649.2012.11.70.3

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In order to improve the reliability of the transformer oil chromatographic on-line monitoring system, in view of the problems of oil and gas, gas mixture separation device, an improved gas-oil dissociation device is developed. The device consists of a vacuum degassing system and an automatic injection system involving temperature control and electromagnetic valve control. Test results show that the device is effective in transformer oil chromatograph on-line monitoring. The degassing of the vacuum degassing system takes less time; within 20 minutes the gas-oil dissociation can reach saturation state. Its size is as small as(100 mm×100 mm×100 mm). It also shows a high separating efficiency. Within 20 minutes the gas mixture degassing rate can reach up to 97.3%, and many fault-characterized gases can be quickly degassed, such as CH₄, C₂H₆, C₂H₄, C₂H₂, H₂ and CO. In June of 2011, the device was successfully commissioned in a substation for high-speed railway passenger special line traction. Since then, it has been working stably and met the demand of field testing.

New Energy

Study on Maximum Power Point Tracking Control Strategy in PV Systems

LUAN Jun-shan, FENG Tao, CHEN Hua

2012, 45(11):  74-77.  DOI: 10.11930/j.issn.1004-9649.2012.11.74.3

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Based on the simulation platform of matlab/simulink, a generic simulation model of photovoltaic(PV) battery is built. The principles, pros and cons as well as the applications of two traditional methods on maximum power point tracking (MPPT) control strategy, i.e., perturb & observe method and inc-cond method are analyzed. In addition, a fuzzy control strategy based on the perturb & observe method is proposed according to the nonlinear output characteristics of PV arrays. The simulation results show that the fuzzy control strategy can fast track the maximum power point with good static performance when the ambience changes.

Evaluation System for the Impact of Wind Farm Terrains on the Performance of Wind Turbine Generators

QIN Rui, DONG Kai-song, LI Zhen, SHEN Wei-cheng, YANG Ping

2012, 45(11):  78-81.  DOI: 10.11930/j.issn.1004-9649.2012.11.78.3

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Wind farm terrains are one of the major factors affecting the performance of wind turbine generators. For the sake of a better understanding of the relationship between the terrains and the generator performance, an evaluation system is developed. With a given wind farm as the test site, the functionalities of the evaluation system, such as primary data interpretation and calculation, terrain surveying and mapping, are demonstrated. Through the analysis of the test data, the impacts of the terrain on the performance of the wind turbine generators mounted are evaluated, which could provide an important reference for post-evaluation of wind farm planning as well as accurate operation scheduling of wind turbine generators.

Information and Communcation

Research and Application of Automatic Relay Algorithm for 10-kV Distribution Network Powerline Communication

XIE Zhi-yuan, WU Xiao-yan, HU Zheng-wei, GONG Zhen-gang

2012, 45(11):  82-85.  DOI: 10.11930/j.issn.1004-9649.2012.11.82.3

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In order to dynamically adapt to the changes in power line environment, communicate effectively and reliably and meet the increasing demand for power line carrier communications, an automatic relay distribution line carrier communication method is developed to improve the existing artificial fixed relay based on statistics. The algorithm process and detailed procedures are presented. By virtue of Matlab the algorithm process is simulated through an example. The simulation analysis is carried out with the information of each relay path provided. The signal-to-noise ratio of all paths is compared and a diagram of different optimal path simulation is also drawn. The simulation results show that the algorithm is easy to be implemented, and the automatic relay could be achieved effectively.

Research on Time Synchronization Mode in Process Level of Smart Substation

HAN Ben-shuai, SUN Zhong-wei, CUI Hai-peng, LIN Ze-yuan, ZHANG Tao

2012, 45(11):  86-90.  DOI: 10.11930/j.issn.1004-9649.2012.11.86.4

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There are two kinds of time synchronization modes in the process level of smart substation, including IRIG-B and IEC61588, and significant controversy exists about which mode should be used. The time synchronization systems of smart substation in State Grid Corporation and China Southern Power Grid Corporation are studied, and the performance index, reliability and economy of the two modes are analyzed. The feasibility of the IEC61588 in smart substation is studied. The implementation scheme of time synchronization mode in the process level of smart substation is proposed.

Smart Grid

Overview and Reflection of European Smart End-use Development

HUO Mo-lin, SHAN Bao-guo

2012, 45(11):  91-95.  DOI: 10.11930/j.issn.1004-9649.2012.11.91.4

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European countries are at the forefront of world smart meter deployment and have conducted a large number of R&D and demonstrations in terms of smart demand response, electric vehicles and the access of distributed generation. Two-way interaction between power grid and customers are realized through smart end-use. The European experiences in smart end-use development were studied and it is concluded that R&D, demonstration and promotion of smart end-use needs to be pushed by legislations and policies; scientific assessment of demonstrations can increase the resource allocation efficiency in the deployment; deployment planning should be made based on the cost-benefit analysis and minimum functional requirements and technical standards be made according to national conditions; new business models need to be explored.

An Optimization Approach for the Layout and Location of Electric Vehicle Charging Stations

GE Shao-yun, FENG Liang, LIU Hong, WANG Long

2012, 45(11):  96-101.  DOI: 10.11930/j.issn.1004-9649.2012.11.96.5

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With consideration of the interests of both charging station operators and users, an optimization model for electric vehicle charging station planning which is based on the minimum cost of the whole society is presented. An optimization method for locating and sizing of charging stations is proposed with the consideration of the road network, the traffic flow and the users′ loss on the way to the charging station. The traffic flow of each intersection node is used to represent the road network traffic. The weights are used to reflect the impact of traffic density on the charging station service area. The users′ minimum loss on the way to the charging station is chosen as the objective function for locating the charging station. And the weighted Voronoi diagram is used to partition the service areas of charging stations. Finally, the optimal scheme of charging stations is selected to minimize the cost of the whole society. The example proves that the methods and models proposed in this paper are feasible and reasonable for the charging station optimization planning in the city area.