Table of Content

20 February 2017, Volume 50 Issue 2

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Special Contribution

The 13th Five-Year Period: A Key Period of China’s Energy Low-Carbon Transition

DU Xiangwan

2017, 50(2):  1-4.  DOI: 10.11930/j.issn.1004-9649.2017.02.001.04

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On the basis of the 12th Five-Year Plan’s development, the four backgrounds of China’s energy development in the 13th Five-Year period are analyzed, that is, the development of China’s economy and energy is entering a new normal state; weaknesses have to be fixed to achieve the national goal of a comprehensive well-off society in 2020; the goals of low-carbon development at national level of 2020 must be met or exceeded; since the Paris agreement has started a new stage of the global green and low-carbon energy development, the direction of low-carbon transition should be well defined in the 13th Five-Year period. Therefore, the pathways of China’s energy low-carbon transition in the 13th Five-Year period are highlighted. The extensive development mode should be replaced by energy saving and efficiency enhancing mode. Coal consumption should be peaked within the 13th Five-Year period. Non-fossil fuels should be vigorously developed. Oil production should remain stable while it is expected to increase natural gas output. Intelligent energy internet should be developed. A low-carbon pathway should be followed as a new pattern of urbanization. Finally, four iconic targets of China’s energy low-carbon transition in the 13th Five-Year period are put forward.

Column of UHV Transmission

Research on Anti-Vibration Design System for UHV Large Crossing Transmission Line

QI Yi, RUI Xiaoming, ZHU Kuanjun, WANG Jingchao

2017, 50(2):  5-10.  DOI: 10.11930/j.issn.1004-9649.2017.02.005.06

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It is difficult for UHV large crossing conductors to resist aeolian vibration due to larger span and higher hanging point. At present, laboratory aeolian vibration simulation test is the only effective means to design anti-vibration schemes for UHV large crossing conductors. However, the test process is complicated, and real type conductors and hardwares must be used. An UHV large crossing anti-vibration design system is developed based on finite element method and energy balance principle. Modal analysis, spectrum analysis and transient analysis functions for bundled conductors aeolian vibration are provided, and the dynamic bending strain values at key points of bundled conductors are calculated. Optimized anti-vibration scheme can be recommended to aeolian vibration simulation test by comparison and analysis of several predesigned schemes. Simulation test period can be reduced and anti-vibration design efficiency can be improved with proposed method, which can better meet requirements of UHV power transmission project.

Simulation Research on UHV Equipment Condition Monitoring Data Communication

ZHANG Bowen, WANG Feng, HAN Shai, BI Jiangang

2017, 50(2):  11-16.  DOI: 10.11930/j.issn.1004-9649.2017.02.011.06

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In order to solve problems of data latency and high database server load of master station in UHV equipment condition monitoring system, a new data acquisition approach is proposed. Proposed approach extracts data directly from database server deployed in the substation instead of forwarding data from data center which deployed in control center. By using OPNET modeling method, two approaches are compared in terms of system load, CPU utilization and business processing time. Results show that proposed method is more efficient, and has less impact on the server.

Industrialized Installation Process and Its Implementation of 1 000 kV Outdoor GIS in Construction Site

LIU Jiannan, NI Xiangping, ZHANG Guoqiang, YAN Guozeng, BIAN Xiujie

2017, 50(2):  17-22.  DOI: 10.11930/j.issn.1004-9649.2017.02.017.06

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1 000 kV GIS equipment is very large, heavy and has large number of units. Its installation process typically lasts long and is easily influenced by external environment. In order to ensure installation quality and strict implementation of construction plan, State Grid AC Engineering Construction Corporation has developed a totally-enclosed self-assembly building for UHV GIS installation, which creates a completely closed factory installation environment in construction site and realizes industrialized installation of 1 000 kV outdoor GIS. The main structure of self-assembly building is introduced first. Then the industrialized installation process of 1 000 kV outdoor GIS in construction site is discussed based on the self-assembly building. The installation process has been successfully applied to Anhui-East project and Zhebei-Fuzhou project and achieved very good application results. The process has been selected to popularize in all subsequent UHV AC projects.

Terminal Planning of UHV Power Grid Based on Entropy Weight Theory

NIU Xinsheng, LI Xueliang, CHAI Yun, SHI Xiaohan, JIA Shanjie, LIU Xiaoming, MOU Hong, WANG Yuan, ZHANG Jie

2017, 50(2):  23-28.  DOI: 10.11930/j.issn.1004-9649.2017.02.023.06

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Based on the operational characteristics of UHV(ultra-high voltage) power grid, an index system is presented to evaluate the operation security, reliability and economy of the power grid, which include such indices as power flow distribution, bus voltage level, short circuit capacity, multi-infeed effective short circuit ratio, short circuit level, overload security margin and grid loss, and a matrix of basic indices is thus established to evaluate the performance of alternative schemes of UHV terminals. The matrix is improved based on the entropy weight and expert experience. By taking the approach degree between the indices of alternative schemes and that of the ideal optimal scheme as the objective function of UHV terminal planning, the optimal scheme is determined after comprehensive evaluation of the proposed alternative schemes, thus realizing the effective solution to the problems of terminal planning. Finally, the UHVDC terminal planning of Shandong grid is taken as a case study to demonstrate the effectiveness of the pro-posed method.

Research on Grid-Connection Modes of Sending Ends and Transmission Capability of UHV Transmission Lines

AI Lin, GUO Yanheng, XU Guoxin

2017, 50(2):  29-33.  DOI: 10.11930/j.issn.1004-9649.2017.02.029.05

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In order to improve the system stability and transmission capability of UHV transmission line, the paper proposes a method for choosing suitable grid-connection modes of sending ends in different UHV AC grid development stages. Firstly, the system stability is studied for different grid-connection modes of UHV sending stations. The impacts of electromagnetic looped network structure on stabilities of regional power system are analyzed. And then, the suitable grid-connection modes of sending ends are analyzed for different UHV grid development stages. The results show that suitable grid-connection modes of sending ends can improve the stability of the UHV system and the transmission capacity of transmission corridors. Finally, the feasibility and validity of the proposed method were verified through real power system.

General Interface Technology of Valve Control System in UHVDC Project

LU Yajun, SONG Shengli, XIAO Kun, LI Fengqi

2017, 50(2):  34-39.  DOI: 10.11930/j.issn.1004-9649.2017.02.034.06

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Converter valve is the core equipment of UHVDC transmission projects, and the valve control system and its interface play an important part in the reliability of UHVDC system. According to the valve control theory, a study is made in this paper on the general interface technology of valve control system in UHVDC project on the basis of a summary of the valve control system characteristics of existing UHVDC projects. The paper introduces the general interface technical scheme of valve control system in terms of overall principle, interface signals configuration and logical processing. The rationality is illustrated by real-time digital simulation test. The results are helpful for promoting the standardized design of valve control system in UHVDC projects and improving UHVDC operation reliability.

Study on Slope Tower in UHVDC Transmission Line in Mountainous Area

SONG Gang, CHEN Jiamiao, PAN Feng

2017, 50(2):  40-45.  DOI: 10.11930/j.issn.1004-9649.2017.02.040.06

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UHVDC Transmission lines are mainly across mountainous area with frequent lighting activities. Even with negative protection angle, lightning trip out rate is still high. A new type of tower, slope tower, which can reduce shielding failure rate is proposed. Its lighting protection performance is analyzed by using electrical geometry model. Combined CDEGS simulation software with empirical formula, its electromagnetic environment performance is also evaluated. The internal structure force, characteristic of economic feasibility, tower weight and amount of concrete of proposed design are also discussed. Results show that slope tower performs much better than usual T-type tower in lightning protection. Its electromagnetic environment level meets standard requirement. Tower’s inner force and construction cost is comparable with regular T-type tower. Slope tower is suitable for UHVDC transmission lines travelling through heavy lightning mountainous area.

Research on Induced Voltage and Current of UHV Circuits Produced by Parallel Lines

ZHAO Kangwei, ZHANG Chao, PENG Long, CAI Yufei, KE Qinghua, WEI Ran

2017, 50(2):  46-51.  DOI: 10.11930/j.issn.1004-9649.2017.02.046.06

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The induced voltage and current produced by parallel lines may influence the result of AC parameter test and threaten operator and instrument safety. It is necessary to research computational method of induced voltage and current of UHV circuits produced by parallel lines and the influence of various circuit parameters on calculation result. Taken Ximeng-Beijingdong UHV line as example, induced voltage and current of UHV circuits produced by parallel 500 kV lines are calculated and analyzed by EMTP-ATP simulation software. Calculation results show that parallel length, parallel distance, transposition method, transmission power, high voltage shunt reactor, series compensation capacitor all have influence on induced voltage and current.

Generation Technology

Analysis Method of Shafting Static Characteristics for Large Steam Turbine-Generators

LI Wangfan, JIANG Jun, SUN Qing, WANG Chao, WANG Kun

2017, 50(2):  52-56.  DOI: 10.11930/j.issn.1004-9649.2017.02.052.05

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The installation parameters of the shafting for large steam turbine-generators are directly related to the safe and stable operation of the unit. As a result, the installation catenarty curve should be designed reasonably to determine the bearing elevation and the static properties such as the loads, and be ensured during the installation. In this paper, the mathematical model based on the theory of three-moment equation and transfer matrix is established with the method to calculate the shafting’s catenarty curve and static characteristics and the computing program being proposed. Taking a shafting of a 1 000-MW level steam turbine-generator as an example, the catenarty curve and static characteristics of the shafting are calculated under the given boundary conditions and compared to the results of the finite element method. The comparison verifies the accuracy of the method, enabling it to provide technical support for the large shafting installation.

Impact of Thermal Contact Resistance on Heat Transfer Coefficient of Double H-Type Finned Tubes

GE Ming, ZHAO Lijie, SHU Shaoxin, ZHANG Shouyu, LV Junfu

2017, 50(2):  57-63.  DOI: 10.11930/j.issn.1004-9649.2017.02.057.07

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The actual heat transfer coefficients of two commonly-used double H-type finned tubes(ND steel and 316L stainless steel) are obtained through experimental study. A computational model of the overall heat transfer coefficient with the thermal contact resistance being incorporated into the fin efficiency is proposed, and the accuracy of the proposed model is validated through the experiments. The experiments show that the overall heat transfer coefficient of Sample ND is much bigger than that of Sample 316L under the condition of the same manufacturing technology and the same structural dimensions. From the difference between the experimental and the calculated data, the thermal contact resistance of each sample are obtained. By comparing the two samples, it is found that the thermal contact resistance of Sample ND is far less than that of Sample 316L. In addition, for the special double H-type fins, the thermal contact resistance decreases the coefficient of Sample 316L by 7 W/(m²·K) while its impact on Sample ND can be ignored. Meanwhile, the analysis of the computational model shows that when the unit thermal contact resistance is less than 0.001 m²·K·W^-1, its impact on the coefficient is too little to be counted, which proves the results of the experiments. The computational model can be used to predict the thermal contact resistance of finned tubes with special structures so as to determine the influence of the thermal contact resistance on the overall heat transfer coefficient. The study result can provide a reference on the selection of the materials and welding technologies for low-temperature economizer tube bundles in industrial applications.

Hydraulic Characteristics and Rectification Optimization of Circulating Water Pump Inlet Duct of Power Plant

WANG Weishu, CUI Qiang, MIAO Shichang, WU Xiaochuan, ZHANG Bin

2017, 50(2):  64-69.  DOI: 10.11930/j.issn.1004-9649.2017.02.064.06

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The advantages and disadvantages of circulating water pump inlet condition have a significant impact on circulating water pump efficiency and whether appear cavitation and vibration. In view of the vibration of the circulating water pump in a 300 MW power plant, the three-dimensional numerical simulation of the flow pattern of the circulating water inlet duct was carried out by using the RNG k-ε turbulence model. The whole flow field, the flow field in the region of the bell mouth and the velocity distribution around the pump body were studies. And the corresponding rectification optimization measures were presented. The results show that the slope gradient of the circulating water inlet duct is sharply, which leads to the uneven flow diffusion and large water surface flow velocity. There is a large vortex in the bottom of the slope and the intake sump. The bell mouth section exists water serious asymmetry phenomenon and appear obvious bias, so the pump inlet conditions are poor. Effective rectification and eliminating vortex measures can be taken to improve the flow pattern and even flow rate, and improve the inlet condition of the pump.

Case Study on Load Rejection Caused by Configuration Problems of Primary Frequency Regulation

SHENG Kai, CHEN Yanfeng, ZHOU Nianguang

2017, 50(2):  70-74.  DOI: 10.11930/j.issn.1004-9649.2017.02.070.05

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To analyze the load rejection accident happened in a 650-MW thermal generation unit, an accurate boiler-turbine model of the unit is built in the Digital Electronic Hydraulic (DEH, for short) system. By using the simulation function of DEH, the course of the accident is reproduced to find out the causes. The result indicates that the immediate cause of the load rejection during the control mode switchover lies in the irrational primary frequency regulation configuration, of which the superimposed effects make the valve position demand to be changed abnormally by a great margin. Furthermore, the influences of the related parameters on the load rejection are studied with real- time simulation. It is indicated that the DEH processing cycle, the turbine speed and the load condition are all related to the load rejection. At the end, the suggestions of normalizing the design and taking more simulative tests to verify the design rationality of primary frequency regulation are put forward.

Development and Engineering Application of Thermal Calculation System for Double-Reheat Ultra-Supercritical Boilers

SHI Shuyu, LI Zhi, ZHAO Chao, ZHANG Yong, YANG Tianliang

2017, 50(2):  75-81.  DOI: 10.11930/j.issn.1004-9649.2017.02.075.07

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The double-reheat technology for ultra supercritical boilers can improves the thermal efficiency of the unit, and has good environmental effects as well. At present, the introduced‘black box’ computational program, which has narrow and specific adaptability, is adopted in the domestic thermodynamic calculation of ultra supercritical boilers. In this paper, based on the multi-layer architecture of J2EE standard, the general model and the overall algorithm using unified steam and water flow circuit is proposed to calculate the thermal performance of the double-reheat ultra-supercritical boiler. And the thermal performance calculation system is developed to support different series of heating surfaces and flow sequential structure. At the same time, the effectiveness of the algorithm is verified through an application case of a 1 000-MW ultra-supercritical double-reheat boiler.

Numerical Simulation of the Effects of Refractory Belt Retrofit on the Combustion in the 300-MW Boilers

YAN Shunlin, SUN Zhiqiang, ZHU Guangming, DUAN Xuenong

2017, 50(2):  82-87.  DOI: 10.11930/j.issn.1004-9649.2017.02.082.06

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Regarding the problems of low reheat steam temperature, unstable combustion and low burnout degree due to the coal quality deterioration in the two 300-MW boilers of a power plant phase I project, the retrofit plan of laying some refractory belt on the water wall located at the lower part of the main combustion zone is proposed. The combustion conditions before and after the retrofit are simulated with the aid of the Fluent 6.3 software. In this way the effects of refractory belt arrangement on furnace temperature distribution, charcoal burnout degree and slagging performance are analyzed. Based on the analysis, a more desirable arrangement is designed. The study concludes that reasonable refractory belt arrangement is helpful to solve the current problems existing in the boilers.

Study on Tangential Boiler Temperature Field Using Closed-Loop Control

MA Ping, LIU Nannan, WANG Zhen, ZHAO Qian

2017, 50(2):  88-94.  DOI: 10.11930/j.issn.1004-9649.2017.02.088.07

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The boiler furnace temperature field is determined by coal combustion, working medium heat absorption, NO_x generation, as well as fouling and slagging, etc. It tends to be damaged by some uncertain factors, which will eventually affect the safe and stable operation of boilers. Therefore, the combustion adjustment experiment is performed at the load level of 300 MW, 270 MW and 240 MW respectively on Unit 2 of a power plant, and the real-time temperature data are collected by the acoustic temperature measurement system. Then, the processed data results are superimposed onto the original signals in the form of bias signals. By controlling the secondary air door opening size, the balance of temperature field and NO_x emission concentration are optimized in closed-loop control. The experiment results show that the temperature field balance has been improved and the NO_x emission concentration is also reduced effectively. Through this study the issue of lacking flexibility in manual adjustment based on operators’ experience is resolved. The intelligent level of the boiler control is also improved, which is very helpful for combustion optimization.

The Impact of Guide Vane on Nozzle Jet Rigidity

ZHANG Lidong, LI Weiwei, SHAO Tiancheng, YU Tingli, ZHOU Yang

2017, 50(2):  95-100.  DOI: 10.11930/j.issn.1004-9649.2017.02.095.06

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The rigidity of nozzle jets has great impacts on the aerodynamic field of the boiler furnace. It can be enhanced by installing collecting guide vanes at the nozzle inlet to make the air more concentrated. In this paper, the impacts of different guide vanes on the jet rigidity are analyzed with Fluent software. By adopting the k-ε model of turbulence, the velocity distributions of the nozzle outlet sections are studied under different operation conditions. Moreover, the effective range S, deflection angle β and velocity component v_z of different nozzles are compared between free jets and disturbed jets. The simulation results show that the collecting guide vanes can increase the jet central velocity, improve the jet anti-jamming capability and reduce the velocity such that the jet rigidity is enhanced. Through comprehensive assessment, it is concluded that the circular arc shaped guide vane has the best performance in rigidity improvement, while in order of performance the other shapes are the parabola curve, the cubic curve and the straight line shaped ones.

Optimization of Day-Ahead Gas Turbine Generation Scheduling with Gas Consumption Characteristics and Primary Energy Constraints in Consideration

LIU Lin, LUO Kaiming, ZHOU Ting, LIU Shengsong, LI Haifeng, LU Xiao

2017, 50(2):  101-106.  DOI: 10.11930/j.issn.1004-9649.2017.02.101.06

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Currently day-ahead gas turbine generation scheduling usually deviates a lot from the real generation curves, which brings much trouble to the operation and the peak load regulation of the power system. Thus, an optimization strategy for day-ahead gas turbine generation scheduling with the consideration of the gas consumption characteristics and the constraints of primary energy is proposed in this paper . The total gas supplied to the plant is fixed by the contract. The mathematical relationship between the output of a generator and its gas consumption can be acquired by linear approximation of the gas consumption characteristics. In terms of the day-ahead load forecasting, the generation curves are divided into three parts, i.e., the peak, medium , and low load periods. Then the gas consumed during the three periods can be obtained and summed up. The summed gas consumption is constrained by the total gas supplied. Therefore, an optimization model is built and solved with the bacterial colony chemotaxis algorithm to obtain the day-ahead generation scheduling. The results of two typical cases of summer peak and valley loads show that the mean squared errors between the calculated and the practical curves are less than 10 MW, which definitely meets the requirements of the real operation and proves the correctness and effectiveness of the proposed method.

Research on the Method of Steam-Water Reverse Power Control of Immerged Electrode Boiler for Nuclear Power Plants

WU Bingchen, WU Hangyu

2017, 50(2):  107-112.  DOI: 10.11930/j.issn.1004-9649.2017.02.107.06

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The electric boiler has long been adopted as the standby steam source for the auxiliary steam system in nuclear power plants. Recently the immersion-type electrode boiler has become the preferred design, while its power control mode is changed from positive direct voltage regulation control to steam-water parameter reverse indirect control. As the“immerged electrode + reverse indirect control” is firstly adopted in Haiyang Nuclear Power Plant, in this thesis the mechanical and electrical structure of the boiler is presented with the heating principle being analyzed. Then, the control mathematical model is established to study and propose the control method.

Discussion on the Application of FCS in Thermal Power Plants

ZHAO Xincheng, FU Junjun, LU Mingzhu

2017, 50(2):  113-116.  DOI: 10.11930/j.issn.1004-9649.2017.02.113.04

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The fieldbus control system(FCS) is able to realize the digital and internet-based field equipments and is regarded as the foundation for constructing digital power plants. Based on the application of FCS in two 1 000-MW ultra-supercritical thermal power generation units, this paper analyzes the technical advantages of intelligent devices to illustrate the importance of FCS in digital power plants. The structure, the devices, the key points of design, and the procurement and installation of FCS are presented as well. In addition, the problems in the commissioning process are summarized with the solutions being proposed, which can guide the newly-built power plants that use FCS.

Performance and Application of Heat Recovery System of Power Equipment

WU Xin, PAN Fumin, OU Dasheng, CHEN Ping, LUO Pingping

2017, 50(2):  117-123.  DOI: 10.11930/j.issn.1004-9649.2017.02.117.07

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In this paper, the program in Visual C++ is used to calculate the performance of the designed heat recovery steam generator (HRSG) to analyze its performance under variable conditions and derive the control strategies. Based on the HRSG, the performance of the designed and variable conditions of a chemically recuperated gas turbine(CRGT) are calculated. The results show that as the energy fed into the HRSG grows, the steam production grows and maintains a maximum value which is determined by the flasher pressure. When the steam production is set as the designed object, the optimal feed water volume is the designed value. The efficiency of CRGT is better than that of the prototype with less NO_x emission and reduced thermal pollution.

Thermal Insulation Performance Testing on New Composite Ceramic Insulation Materials

XU Shuai, ZHOU Zhangjian, ZHANG Xiaoge, HU Xueli, CHEN Lingzhi, GONG Mengqiang

2017, 50(2):  124-127.  DOI: 10.11930/j.issn.1004-9649.2017.02.124.04

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The insulation of thermal equipments and pipes is of great importance to reduce the energy consumption. In this paper, a new type of ceramic composite insulation material is applied in some of the equipment and piping of a 350-MW unit in Huaneng Dandong Power Plant 350 MW and corresponding testing is conducted regarding the surface temperature, surface heat losses and actual thickness, etc. In addition, the testing results are compared with the laboratory testing result data such as heat flux and material temperature change with respect to thickness variations. Then by virtue of the scanning electron microscopy images the impact of the material structure on the thermal insulation properties is analyzed. The experiment results show that the novel material has outstanding insulation performance due to its smaller pore size and longer heat conduction path with multilevel structure. With this novel thermal insulation material the outer surface temperature of the equipment(such as the burner) is lower than the limit specified in the national standard. The heat flow density value is only about 158 W/m², which is far below the maximum limit of 266 W/m² in the national standard. Compared with the aluminum silicate cotton insulation material, the material thickness can also be reduced by 65% for the same heat preservation effect.

Energy Conservation and Environmental Protection

Study on Synergistic Removal of Multi-Pollutants by WPTA

TAN Houzhang, XIONG Yingying, WANG Yibin, CAO Ruijie, YANG Zuwang, ZHENG Haiguo

2017, 50(2):  128-136.  DOI: 10.11930/j.issn.1004-9649.2017.02.128.07

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The technology of multi-pollutants synergistic removal in coal-fired power plants will become the research hotspots in the future. In this paper, a new device named wet phase transition agglomerator (WPTA) is designed and developed to achieve the goal of removing fine particles and multi-pollutants collaboratively from high temperature wet flue gas. Verified through lab-scale testing, pilot-scale testing and a full-scale onsite test under working conditions in a 660-MW lignite-fired power plant, this device has exhibited excellent performance in fine particle and multi-pollutant removal. The pilot-scale test indicates that after the flue gas flow passed through the WPTA, the volume fraction of particles changes from unimodal distribution into bimodal distribution. The peak value of the particle volume fraction is decreased substantially for the particle around 2μm while that of the particles over 10μm tends to increase. The full-scale test shows that the removal efficiency of PM_2.5 and PM_1.0 is improved by 5 and 15 percentage points respectively at full generation loading. The efficient removal of trace elements of Hg, Ba, Ga, As, Li, Mn, Sr and Ti is also achieved simultaneously, of which the removal efficiencies of Hg and As are improved by 4.18 and 2.82 times, respectively. The study result indicates that the new configuration of WPTA+WESP can meet the requirements for ultra-low emission standards on fine particulate matters and other pollutants for coal-fired power plants of China.

Ammonia Escape Testing and Ash Impact Analysis for an Inner Mongolia Power Plant

LI Yunchao, ZHAO Dazhou, LI Kai, ZHANG Haizhen, ZHENG Wenguang, HE Sheng

2017, 50(2):  135-138.  DOI: 10.11930/j.issn.1004-9649.2017.02.135.04

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The problem of ammonia escape has been existing prevalently in the selective catalytic reduction(SCR) system of coal-fired power plants. In order to better control the concentration of escaping ammonia, the study on field testing of ammonia concentration in flue gas is carried out by adopting the indophenol blue spectrophotometry. Taking the example of a 200-MW power plant in Inner Mongolia as the study case, the operation procedures and process of the indophenol blue spectrophotometry in the field testing are described in details. Then the comparison between the testing results and the online monitoring data is conducted with the impacts of the fly ash on the test results analyzed as well. The study results show that the concentrations of escaping ammonia can be obtained at different sampling points in the field test, which is helpful for ammonia spraying control. The presence of ash may enhance the absorbance of the samples substantially, which will cause higher testing result value. Therefore, for the sake of data accuracy, strict precautions should be taken to prevent ashes from polluting the samples in the sampling process.

New Energy

Benefit Analysis and Evaluation of Wind Power Integration Capability Based on Abandoned Wind Power Heating Mode

XU Yanping, WANG Yuefeng, TANG Lin, HE Xiaoyang, JIN Peng

2017, 50(2):  139-143.  DOI: 10.11930/j.issn.1004-9649.2017.02.139.05

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It is an effective way to solve wind power accommodation problem by using abandoned wind power for heating recently in “three north” regions during heating period. Firstly, the operation mode of electric heating for accommodating wind power is introduced. Then, based on time sequential simulation method, an estimation mode of wind power accommodation capability is build. With a certain provincial power grid as an example, the wind power accommodation capability under different operation mode of electric heating is assessed and analyzed. Finally, the related entities economic interests as well as the carbon emission reduction are quantitatively analyzed at existing abandoned wind heating mode and settlement pattern. Case studies presented here show that abandoned wind power heating does help to facilitate wind power integration and environmental benefits. However, due to limited wind power accommodation space,benefits of economic agents other than wind farms are not obvious.

Small Signal Stability Optimal Designing of Direct-Driven Permanent Magnet Wind Power System Based on Sensitivity Analysis Method

GUO Yongming, YOU Xiaoke, LIU Guanqi

2017, 50(2):  144-149.  DOI: 10.11930/j.issn.1004-9649.2017.02.144.06

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Based on an analysis of the working principle of wind power generation system, a mathematical model of the direct-driven permanent magnet wind power system with dual PWM converter is established in this paper. And then, the mathematical model is linearized at DC operating point to establish the small signal mathematical model. The eigenvalue sensitivity analysis method is used to intuitively sort out the key factors that affect the small signal stability of the system. From the point view of design, A parameter optimization scheme of grid-connected wind power generation system is proposed. The result shows that the stability of the power system is improved.

Power System

Research on Calculation Method for Step Voltage Limitation of DC Grounding Electrode Based on Surface High-Resistance Covering

YANG Jian, PAN Wenxia, SUN Honghang

2017, 50(2):  150-156.  DOI: 10.11930/j.issn.1004-9649.2017.02.150.07

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In order to guarantee the human safety near the DC grounding electrode, the requirement of step voltage limit must be satisfied in grounding design. Based on the horizontal double-ring DC grounding electrode, the computation method of step voltage limit is studied under the condition of covering the ground surface of grounding electrode with high-resistance layer, and a new computational formula is given. And then the grounding characteristics under different soil conditions is analyzed by using the boundary element method. The investigation results show that the surface high-resistance covering can greatly improve the tolerance limit of the step voltage for human body. The thickness of high-resistance layer is suggested to be 10~20 cm. In order to substantially improve the tolerance limit, the resistivity of high-resistance covering is better to be greater than 1 000 Ω·m. It is also shown that the surface high-resistance covering has little influences on the grounding resistance, ground potential rise, step voltage and distribution of leakage current, and its influence on the metallic facilities can also be neglected.

Analysis of Conduction Ground Surface Current at Vertical Grounding Electrode in Grounded System

XU Jialong, ZHU Liwei, WANG Xiaoyu, YAN Huajiang, YANG Fan, SHEN Xiaoming

2017, 50(2):  157-161.  DOI: 10.11930/j.issn.1004-9649.2017.02.157.05

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The vertical grounding electrode is an effective method to reduce grounding resistance. When grounding system drawings are missing or incorrect, it is important to detect vertical grounding electrode position accurately. According to ampere’s law, a method is proposed to locate vertical grounding electrode position by measuring conduction current of ground surface. Firstly, the conduction current distribution of vertical grounding grid and its connection branch is generated through the theoretical formula. Secondly, grounding grid model is constructed with and without vertical grounding electrode to simulate effect of vertical grounding electrodes on conduction current. Theoretical analysis and simulation model both indicate that vertical grounding electrode can be located effectively by measuring conduction current of ground surface. The detection method is simple, and can be used in further 3D imaging of grounded system structure.

Design and Development of PSS Parameters Calculation and Simulation Software

XU Junhua, LI Xiaocong, PEI Yunqing, XIE Weishan, LIAO Ersi

2017, 50(2):  162-168.  DOI: 10.11930/j.issn.1004-9649.2017.02.162.07

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Lack of simulation and verification functions in Power System Stabilizer (PSS) parameters calculation leads to uncertainty in PSS setting test. Based on mathematical model of power system, an integrated PSS parameter calculation software is developed. With MATLAB software package, the widely used models of PSS1A and PSS2A/2B are adopted to meet practical engineering need and relevant standards requirement. Using single-frequency and multi-frequency oscillation phase compensation, the software integrates functions of computation and simulation verification for PSS parameters with a well-designed human-machine interaction interface. Meanwhile, the digital simulation of a single machine-infinite bus power system is built in Simulink to simulate and verify the ability of PSS set to suppress low frequency oscillations. A testing case on certain plant in Guangxi indicates the simplicity, accuracy and convenience of developed software.

Study on the Two-Stage Frequency Security Emergency Control Strategy for Multi-Infeed HVDC Receiving Systems

LI Bijun, LI Zhaowei, WU Xuelian, LIU Fusuo, LI Wei

2017, 50(2):  169-174.  DOI: 10.11930/j.issn.1004-9649.2017.02.169.06

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The steady increasing of HVDC transmission capacity increases, to some extent, the risks of frequency security in multi-infeed HVDC receiving systems. Based on an analysis of the typical characteristics of dynamic frequency caused by contingencies, a two-stage frequency security emergency control strategy is presented in view of the goal of frequency security control. The control strategy of first stage is determined according to the requirement of the lowest frequency during dynamic process after contingency. The control strategy of second stage is determined according to the requirement of the steady state frequency. Considering the characteristics of frequency security control resource in multi-infeed HVDC receiving systems, the paper addresses the problems in establishing two-stage frequency security emergency control strategy, and the basic principle, procedures and key information for establishing the control strategy are presented. Based on a real power grid, the effect of two-stage frequency security emergency control strategy is simulated. It is shown by this study that two-stage frequency security emergency control strategy can be used to coordinate the control requirements of the lowest frequency and the steady state frequency after contingency.

The Relationship of Temperature Humidity Index and Meteorology Sensitive Power Load in Beijing

ZHAO Na, SHI Yuheng, LI Naijie, SHEN Jianhong

2017, 50(2):  175-180.  DOI: 10.11930/j.issn.1004-9649.2017.02.175.06

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In order to study the relationship between meteorological conditions and residential power load increase in Beijing, maximum instantaneous power load and temperature humidity change are analyzed based on statistical methods with daily historical data in summer from 2012 to 2013. Analysis result shows that influence of temperature humidity index on maximum instantaneous power load is higher than average temperature index and comfort index including wind factor. The maximum power load changes 386 MW with one unit change of temperature humidity index. A meteorological index reflecting maximum metrology sensitive load based on temperature humidity change is established to application classification.

Electricity Theft Identification Method Based on Curve Similarity

WU Di

2017, 50(2):  181-184.  DOI: 10.11930/j.issn.1004-9649.2017.02.181.04

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With rapid development of China’s power utilities, power theft becomes more and more prominent, which seriously affects stable development of power supply enterprise. According to the line-loss characteristic of electricity stealing, an electricity theft identification method is presented based on similarity between user load profile and irregular line loss curve. Two methods are proposed to compute similarity of two curves in both time and frequency domain. In time domain, similarity is measured by Euclidian distance, Cosine distance and Block distance. In frequency domain, power spectrums of two curves are calculated and compared using autocorrelation method, modified covariance method and Burg method. Application results show that proposed methods can narrow electricity theft detection range and identify target accurately.