Table of Content

18 October 2012, Volume 45 Issue 10

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Special Conlribulion

Comparison Study on Grid Codes for Connecting Wind Farm into Power System

DAI Hui-zhu, CHI Yong-ning

2012, 45(10):  1-6.  DOI: 10.11930/j.issn.1004-9649.2012.10.1.5

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The national standard GB/T 19963-2011 Technical Rules for Connecting Wind Farm to Power System was released in December 2011 and came into force from June 1, 2012. This paper focuses on interpreting the necessity of standard formulation and the detailed standard requirements, and conducting a detailed comparison study on the grid codes for connecting wind power to power system in other countries with many wind power installed capacities based on analysing the status of wind power development and the technical problems encountered. The formulation and implementation of the national wind power integration code will contribute a lot to upgrading the wind turbine technology and ensuring the secure and stable operation of the power system incorporating large-scale wind power.

Connotation of Wind Power Related Policies and Practices in Foreign Countries

JIANG Li-ping, WANG Qian-kun

2012, 45(10):  7-11.  DOI: 10.11930/j.issn.1004-9649.2012.10.7.4

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Major wind policies in a narrow sense, including general target, priority dispatching and purchase, feed-in tariff, cost sharing mechanism and technical standards, and major wind policies in a general sense, including construction of flexible generation plants, ancillary service, demand-side management and power grid construction are systematically analyzed. Emphasis is given to the main ideas and practices in maintaining incentives while strengthening industrial regulations for wind power. Finally some suggestions are put forward for the improvement of wind power policies in China.

Analysis and Revelation from Blackout Events in India

CHEN Jing-cheng, HUANG Han

2012, 45(10):  12-16.  DOI: 10.11930/j.issn.1004-9649.2012.10.12.4

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The“7.30” and“7.31” two serial blackout events in India show many issues in the managerial mechanism of power industry, potential operation risk prevention and power grid planning and construction. The current situation of Indias energy and power development is introduced and the direct reasons for these two blackout events are uncovered, that is, the system frequency in each region is too low and power oscillation happens later, which leads to system collapse. Considering the current situation of Indias power industry, the in-depth reasons and the lessons from the events are also dissected, which presents that the security and operation control system for large power grids with unified planning, unified dispatching and unified management is weak. Consequently, the revelation and recommendations for China focusing on power industry development are put forward.

Generalion Technology

Application of Scenario Analysis in the Research of Energy Economy

LOU Wei, LI Meng

2012, 45(10):  17-21.  DOI: 10.11930/j.issn.1004-9649.2012.10.17.4

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Scenario analysis method is widely used in the field of energy economy since its emergence. Based on the analysis of the relationship between scenario analysis and energy economy, and by taking the renewable energy planning with scenario analysis for example, the qualitative and quantitative scenario analysis method in energy economic field is studied. The result indicates that scenario analysis could provide support for developing high-quality energy planning and energy policy based on the analysis of the key future uncertainties and the depicting of many possible future scenarios.

Research of Economic Growth Based on Energy Constraint

LIANG Guang-hua

2012, 45(10):  22-26.  DOI: 10.11930/j.issn.1004-9649.2012.10.22.4

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Following the two-way causality between energy consumption and economic growth, and based on the Solow growth model and the optimal theory, the conditions for balanced economic growth are studied. In addition, a balanced economic growth model with exogenous knowledge is established, including representative vendors, non-renewable energy production departments, renewable energy production departments, the government and representative families. The conclusions show that the condition for balancing energy consumption and economic growth is the growth rate of energy quantity per effective work equaling zero. Finally policy-related suggestions are proposed from the angles of intensifying energy saving and emission reduction as well as resource taxation.

Trend of Recent Power Demand in Eastern China

GU Yu-gui, SI Zheng, SHAN Bao-guo, ZHAO Fan

2012, 45(10):  27-29.  DOI: 10.11930/j.issn.1004-9649.2012.10.27.2

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The trend of power demand from main industries in eastern areas of China is analyzed with the reasons for power demand variation in different provinces discussed. The results indicate that some industries are still in a leading position in the country while some accelerate the transfer. The future of east regional economic development and the trend of power demand are predicted. Finally, some suggestions for ensuring the economic development and power supply in eastern provinces are put forward.

Analysis on Load Characteristics of China Southern Power Grid in 11th Five Year Plan

TANG Bao, DONG Zheng

2012, 45(10):  30-35.  DOI: 10.11930/j.issn.1004-9649.2012.10.30.5

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Based on the load data of China Southern Power Grid （CSG） in 11th Five-Year Plan（2006-2010）, the yearly, monthly and daily load characteristics of CSG were analyzed and the load characteristics of five provinces of CSG were compared. The main factors affecting the load characteristics such as electric power consumption structure, demand-side management,energy saving and reduction of pollution policy were identified. In addition, It is proposed to investigate load characteristics of the typical industries and users. The above information will provide a reference for electric energy consumption planning, demand side managementand economic operation of power grid.

Study on Pipeline Characteristics and Selection of Primary and Secondary Air Fans for CFB Boilers

WANG Quan-hai, LU Xiao-feng, LU Jia-yi, ZHANG Wen-qing, XIN Sheng-wei, LIU Chang-xv, LI Lin

2012, 45(10):  36-41.  DOI: 10.11930/j.issn.1004-9649.2012.10.36.5

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Through analyzing the pipeline characteristics of the primary air and secondary air on circulating fluidized bed （CFB） along with several operating data from commercial CFB boilers, the selection principles of primary air fan and secondary air fan are studied. The results indicate that the maximum air flow and maximum pressure head of the primary air of a CFB boiler are not at the same operating point, forming a pipeline characteristic completely different from that of a pulverized coal boiler. The pipeline characteristic of the secondary air of a CFB boiler is similar to that of a pulverized coal boiler, but with the pressure drop produced by the particle concentration in the furnace added to the system resistance. When a primary air fan is selected for CFB boilers, the pipeline characteristic curve should be entirely included by the fan performance curve, and inlet guide vane adjustment or variable speed adjustment of lower energy consumption should be adopted. The selection principle of the secondary air fan for the CFB boiler is similar to that of the centrifugal fan with the pressure drop caused by bed materials beingestimated. For 300-MW CFB units, the pressure drop is usually between 5.5 kPa and 7.5 kPa.

Microstructure of Domestic TP310HCbN Steel After High-Temperature Creep-Rupture Test

GUO Yan, LIN Lin, HOU Shu-fang WANG Bo-han

2012, 45(10):  42-47.  DOI: 10.11930/j.issn.1004-9649.2012.10.42.5

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In order to investigate the strengthening mechanism and failure of domestic TP310HCbN steel, the microstructure of domestically-made TP310HCbN steel under different stress at high temperature by means of transmission electron microscopy(TEM) and scanning electron microscopy(SEM) is studied. The results show that the precipitates after the creep-rupture test are M23C6 carbides with face centered cubic (FCC) structure located both inside grains and at grain boundaries and NbCrN nitride particles with tetragonal structure dispersed within grains. After long time creep-rupture testing, σ phase precipitated. The hardness of the creep-rupture samples is enhanced due to the dispersed M23C6 and NbCrN particles. M23C6 carbides with lattice parameter of three times of the austenite matrix grow in a cube to cube orientation relationship with the matrix. The amount of M23C6 carbide particles increases with the testing time extended. For the domestic TP310HCbN steel, more attention should be paid to the distribution, size and amount of σ phase and M23C6 during service.

Analysis on Influence Factors and Economics of Quantity Control of Pulverizer Rejects in Milling System for Utility Boilers

WANG Chun-chang

2012, 45(10):  48-51.  DOI: 10.11930/j.issn.1004-9649.2012.10.48.3

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According to the characteristics of pulverizer rejects, the advantages and disadvantages of the reduction of pulverizer rejects are analyzed, particularly with the emphasis on the combustion efficiency of the pulverizer rejects returned to the furnace, the impact of the sulfur content of pulverizer rejects on high-temperature corrosion and the power consumption by the milling system and the desulfurization system. Through calculation, the impact of these factors on the reduction is studied, which concludes that pulverizer rejects are a kind of low quality fuel with low heat value, high sulfur content, poor grindability, bad inflammability and low combustion efficiency. When pulverizer rejects return to the furnace, not only the power consumption of the milling system and the desulfurization system will increase, but also the high-temperature corrosion in the furnace and the low-temperature corrosion in the air heater will deteriorate, which will result in negative comprehensive benefits. Therefore, reducing the quantity of pulverizer rejects needs more attention and carefulness. Quantitative studies on the economics of the utilization of pulverizer rejects should be enhanced to instruct power plants through the quantity control of pulverizer rejects in milling systems.

Analysis and Practice of Allowance -Reducing Technology for FGD Booster Fan of Thermal Power Plants

LIANG Shuang-yin, LI Ji-mao, HOU Yun-hao, GAO Xin-xi, JIA Li-sheng, ZHAO Yan-jun

2012, 45(10):  52-55.  DOI: 10.11930/j.issn.1004-9649.2012.10.52.3

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In view of the excessive allowance and low operating efficiency existing in FGD booster fans of thermal power plants, the transformation idea of reducing the allowance and raising the efficiency is put forward. Calculations and analyses for the FGD booster fan for a 200-MW unit are carried out, which indicates that the allowance of the fan is excessive and the operating efficiency is low. Therefore, a scheme for slowing down the speed and eliminating the allowance is promoted with the feasibility and economics being analyzed. After the transformation, operation indicates that the service power rate is reduced by 0.22%, which is very remarkable in energy-saving.

Application of Domestically-Made Profibus Control System in Thermal Power Plants

CUI Yi-qun, LI Yu, YAN Yu-ping, WANG Tao

2012, 45(10):  56-58.  DOI: 10.11930/j.issn.1004-9649.2012.10.56.2

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The independently-developed Profibus control system-FCS165 system successfully comes into service in the primary and auxiliary control systems of Huaneng Qinling Thermal Power Plant equipped with 600-MW supercritical units. The applicable range of this fieldbus technology in the primary and auxiliary control systems, and the development and application of the fieldbus device information (including the master state information, Profibus-PA equipment information, Profibus-DP equipment information) are introduced. The FCS165 system runs reliably, which not only meets the safe and economic requirements for the units, but also realizes remote diagnosis and management for field equipment with the diagnosis information and the state information from the Profibus.

Power Syslem

Study on the Transmission Line Inspection System Based on Quadrotor UAVs

WANG Zhen-hua, HUANG Xiao-ning, LIANG Kun, LI Shao-bin, YANG Zhong

2012, 45(10):  59-62.  DOI: 10.11930/j.issn.1004-9649.2012.10.59.3

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According to the requirements of the short-distance inspection of the transmission line, a quadrotor UAV is used to solve the problems of inefficiency, unsafe and technical threshold of routine inspection means. The images of the line defects and potential problems are located and collected with the aerial views of the cameras. Combined with the GPS of the transmission tower, an autonomous flight inspection is presented according to the default track points. A manual flight inspection is used to acquire the comprehensive images of the line's key components by observing the real-time images of towers transmitted by airborne equipments. The inspection system enhances the ability of the line state management and emergency solution. Also it can provide a full range of the line information support for the safety assessment, pre-disaster investigation, pre-warning of the accident, disaster repair, and even the state of maintenance and life cycle management.

Wind-induced Vibration Control for High-voltage Transmission System Using Viscoelastic-damper

ZHONG Wan-li, WU Yi, WANG Wei, CHEN Hang-hang

2012, 45(10):  63-67.  DOI: 10.11930/j.issn.1004-9649.2012.10.63.4

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For wind-induced vibration of power transmission tower-line system, the vibration control strategy and implementation method is studied based on energy consumption principle of viscoelastic-damper. Firstly, the layout scheme of damper on tower was proposed based on analyzing the principle and structure of viscoelastic-damper, and the structure of damper. Then, an finite element model of the coupling system including tower, insulate chain, phase line and ground line was built by using ANSYS. A wind-induced vibration transient response simulation was performed respectively for the tower system with and without dampers by using the time history samples of random fluctuating wind load obtained with harmonic synthesis method. Finally, the influence of viscoelastic-dampers on the displacement of the controlled nodes and the axial force of the controlled elements was compared. The results indicate that the viscoelastic-damper can suppress the wind-induced vibration and can reduce the node displacement by about 90%. Through comparison, the optimal installation scheme of viscoelastic-damper is obtained.

Active Power Conditioning Stralegy Based on Adaptive Inverse Control for Microgrids

CHEN Chao, LI Peng, ZHANG Shuang-le, TAO Qian, ZHU Jun-min

2012, 45(10):  68-72.  DOI: 10.11930/j.issn.1004-9649.2012.10.68.4

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Considering the performanceof microsources equipped with energy storage devices in an islanded-mode microgrid, an adaptive inverse control strategy applied to active power conditioning is developed. Regarding the P-f droop curve as a controlled object, the primary ideology of this method focuses on building an inverse function of the controlled object as a previa controller by using a digital filter with variable weight coefficients, with which a P-f slope coefficient can be obtained to modify the P-f droop curve. For a given microgrid in which unbalanced active power exists, this strategy can quickly find the best P-f slope coefficient along the negative gradient direction of the mean square error. Through the controlling process, the unbalanced active power among different microsources can be redistributed and the frequency of the microgrid can be preserved at the rated value. The validity and feasibility of this control strategy are verified by the simulation of a two-DG microgrid.

Calibration of SF₆ Gas Density Relays in Extremely Unusual Temperature Conditions

LI Zhi-gang, CAI Wei, DENG Chun, LI Fan

2012, 45(10):  73-76.  DOI: 10.11930/j.issn.1004-9649.2012.10.73.3

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SF₆ gas density relays are used to monitor gas density changes in SF₆ insulated equipment, whose performances have a direct influence on the safety and reliability of the equipment. Data from fields shows that the temperature compensation performances of SF₆ density relays will become worse in extremely unusual weather conditions, which will lead to greater errors. Therefore, it is necessary for SF₆ gas density relays to be calibrated in those weather conditions. A kind of calibration devices for SF₆ density relays in extremely unusual weather conditions and a set of calibration methods especially applied to North China areas with very low temperature were introduced. Test results suggest that a density relay with dual metal compensation is preferable than a standard cavity compensation relay in an extremely low temperature condition. By the performance calibrations, the action reliability and accuracy of a SF₆ density relay can be ensured, which can prevent some kinds of power grid accidents from happening.

New Energy

Control System of a Stand-Alone Microgrid Based on Multi-Grade Structure Theory

WU Zhi-feng, SHU Jie, ZHANG Xian-yong

2012, 45(10):  77-81.  DOI: 10.11930/j.issn.1004-9649.2012.10.77.4

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Based on the analysis of microgrid developments, a stand-alone microgrid that can be applied to island, desert, remote mountain areas was built according to the theory of multi-grade structure. The topology and characteristics of this kind of microgrids were illustrated. A MW-grade and stand-alone microgrid with wind/solar/diesel/battery supplies was built for a given island. Key technologies in scheduling control strategies, such as multi-grade control methods, energy dispatching processes and multi-goal coordinated controls, were expounded. The overall structure and functions of the control system for the microgrid were validated by implementing the integration of SCADA and dispatching.

Application of Intelligent Security and Stability Control System to Power Grid with Large Scale Wind Power

WANG Chun-hua, GUO Lei, WANG Jian-xun, GAO Pei-sheng

2012, 45(10):  82-85.  DOI: 10.11930/j.issn.1004-9649.2012.10.82.3

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Increasing power transmission pressures are brought on Songbai power grid of Jilin province by concentrated accession of wind power and thermal power. And serious stability problems will be caused by the 500 kV multiple-circuit transmission lines at concurrent fault. An intelligent security and stability control system was built for Songbai power grid in order to solve those problems, which consists of stability control devices in eight stations (power plants). The system is designed by using layering and zoning strategy and can automatically identify the power grid information and fault types and rapidly cut off the wind power plants and thermal power plants in turn to protect the stability of power system according to the preset strategy. The configuration, control strategy, design and simulation analysis of the regional security and stability control system for Songbai power grid are presented in this paper. Results show that the security and stability control system can guarantee security and stable operation of power grid and improve the power supply ability of Songbai power grid.

Study on Analysis Model and Method of Wind Power Adequacy Capacity Cost

XIE Guohui, LI Qionghui, WANG Qingran

2012, 45(10):  86-89.  DOI: 10.11930/j.issn.1004-9649.2012.10.86.3

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Large-scale wind power integration will sharply increase the power system adequacy capacity cost due to the low capacity credit of wind power, which needs to be considered in power planning and operation. An analytical model and method of wind power adequacy capacity cost is proposed on the basis of an in-depth analysis of the impact mechanism of wind power integration on power system adequacy capacity. A wind power capacity credit calculation model is established based on the Effective Load Carrying Capability Algorithm and an adequacy capacity cost calculation model was established based on capacity credit. The case study shows that the wind power capacity credit decreases and the adequacy capacity cost increases with increase of the wind power capacity. The adequacy capacity cost reaches as high as 0.06 yuan/kWh when the wind power capacity makes up 10% in the power system.

Electric Power Economy

Cost Analysis on the Project of 1 000-MW Class Coal-Fired Generating Units

CHEN Jian-huan

2012, 45(10):  90-94.  DOI: 10.11930/j.issn.1004-9649.2012.10.90.4

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The cost of coal-fired generating projects is one of the vital bases for investment decisions. Meanwhile, it is also a decisive reference for the management departments to evaluate the feasibility of project during the approval process. By taking advantage of the data from several 1 000-MW class coal-fired generating projects(some are still under construction while some are already put into operation) the index calculation and analytical induction are performed. The cost of several 1 000-MW class ultra-supercritical units in static investment period is studied with analogy. The impacts of construction properties, technical plans and site conditions on engineering cost are analyzed considering the variances of each single item cost.

BP Neural Network Based Cost Prediction Model for Transmission Projects

LING Yun-peng, YAN Peng-fei, HAN Chang-zhan, YANG Chen-guang

2012, 45(10):  95-99.  DOI: 10.11930/j.issn.1004-9649.2012.10.95.4

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A BP neural network based method for predicting the cost of transmission projects is proposed to quickly and accurately compare the costs and assess the reasonableness of different plans with limited information during the early stage of the decision-making process. The factors influencing the project cost are also analyzed. Furthermore, by putting these factors into BP neural network as input variables and the project cost as an output variable, a BP neural network model of three-tier structure is constructed using actual project data for data training and prediction model verification . The example using this method shows it can forecast the project cost quickly and accurately, which is suitable for comparison of project cost and assessing the reasonableness of different plans.