Table of Content

16 May 2016, Volume 49 Issue 5

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Security Column

Analysis of the Breakage Mechanism of Iced-Wire for a 220 kV Transmission Tower-Line System Considering the Microtopography

ZHANG Yujiao, KONG Tao, SU Pan, DONG Xiaohu, LEI Chenghua

2016, 49(5):  1-7.  DOI: 10.11930/j.issn.1004-9649.2016.05.001.07

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In order to analyze the effect of the microtopography on the imbalance tension of iced transmission lines and the amplifying effect when the iced wires are breaking, a finite model is developed for a four-tower-three-level tower-line system for the accident area. The model is applied to determine the critical thickness of the icing under different working conditions and the corresponding shocking responses when ice covered wires are breaking. Data is collected and cross-compared for different icing conditions and microtopographies. The results show that the heavy ice formulation in the microtopography and the large height difference between towers increase the imbalance tension. Further, the dynamic response effect caused by the breakage of the iced wires in the microtopography is significantly higher than in a non-microtopography area. Finally, the heavy formation of ice in the microtopography and the large height difference between towers increase the shocking effect of wire breakage.

Corrosion Analysis and Protection Technology for Overhead Transmission Conductors

ZHU Zhixiang, CHEN Baoan, ZHANG Qiang, HAN Yu, YANG Changlong, WANG Hongmei, ZHANG Yuyan

2016, 49(5):  8-13.  DOI: 10.11930/j.issn.1004-9649.2016.05.008.06

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In order to study the corrosion behavior and protection technology of overhead transmission lines, the corrosion mechanism, causes and mode of overhead conductors are introduced. The main corrosion protection technologies and their performance characteristics, as well as the development and application of the new corrosion protection materials are summarized. According to the requirement of power grid development and construction in China, the development direction of anti-corrosion technology for overhead conductor is proposed, and the processing techniques and application prospect of novel high-performance anti-corrosive oil products is discussed.

Power Supply Reliability Grey Correlation Analysis Based on Fault Tree Method

SUN Yixin, , QIN Chao, ZHANG Wei, YAN Qingyou, TAN Zhongfu

2016, 49(5):  14-19.  DOI: 10.11930/j.issn.1004-9649.2016.05.014.06

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New electricity reform program focuses on strengthening government supervision, improving electric power operation safety, efficiency and reliability. In order to improve power supply reliability, reasons that cause residents and industrial user’s blackout need comprehensive analysis. Recent research on power supply reliability of distribution network emphasizes more on network evaluation algorithm. The paper analyzes power supply reliability and its influence factors firstly, builds blackout reasons fault tree logic diagram using fault tree analysis, and obtains maximum influence factor of the bottom event according to set pair analysis. Then, based on maximum influence factors, six evaluation indexes affecting power supply reliability are chosen. Grey correlation degrees among evaluation index and power supply reliability are obtained by grey incidence analysis method. Finally, power supply reliability influence factors ranking is obtained through case study. The results provide technical support to quality improvement of power supply and power grid enterprise service.

Analysis of the Excitation-Loss Fault of a Large Generator

CHEN Shougen, HAO Wei, WANG Kai

2016, 49(5):  20-23.  DOI: 10.11930/j.issn.1004-9649.2016.05.020.04

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The auxiliary exciter fault of a mega-kilowatt turbo-generator unit caused the loss of excitation, resulting in a set of out of step protection tripping of the 500 kV circuit breaker. Based on the data of the fault oscillograph, the trajectory of the terminal admittance and impedance is calculated. The basic causes for the expansion of the accident is analyzed, and some improvement measures are proposed to prevent similar incidents from happening again.

A D5000 System-Based Black Start Parallel Recovery Strategy

LIU Xiangyu,HU Wenping,LIANG Bin,LI Xiaoming,WANG Xiaowei

2016, 49(5):  24-29.  DOI: 10.11930/j.issn.1004-9649.2016.05.024.06

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The generator parallel recovery strategy is studied in the paper based on the related problems of unattended substations. Firstly, in view of the existing operation condition of power grid, a line startup time model is established for unattended substations to obtain the line startup time cost expectations. Then, a time-depended function is established for the generator active power output and the leading phase capability. After that the concept power center is defined in the paper, based on which the distance cost of generator startup is calculated. With consideration of a variety of constraints of the generator unit startup, the Dijkstra algorithm is used to calculate the optimal generator unit startup sequences of time and distance cost, and determine the generator unit startup sequence through parallel calibration. At last, the proposed method is validated on the IEEE 39-bus power system, and the result shows that it can obviously improve the efficiency of generators restoration.

Study on the Security and Stability of Jiangsu Power Grid Based on Multi-infeed DC Assessing Index

HUANG Junhui, WANG Haiqian, WANG Weiyuan, XIE Zhenjian, ZHANG Wenjia, SUN Wentao

2016, 49(5):  30-34.  DOI: 10.11930/j.issn.1004-9649.2016.05.030.05

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Multi-infeed HVDC has significant negative impact on the security and stability of Jiangsu power grid. In this paper, an appraisal method is proposed for assessing the impact of multi-infeed DC integration on the security and stability of power grid based on the Multi-Infeed Effective Short Circuit Ratio(MIESCR), Multi-Infeed Interaction Factor(MIIF) and Commutation Failure Immunity Index(CFII), and it has been used for simulating the security and stability of Jiangsu power grid integrated with multi-infeed DC system. The simulation result shows that Jiangsu power grid has a strong AC system, which is high in security and stability and can satisfy the requirement for safe operation. The Jinping-Suzhou UHVDC system is located in the center of receiving end with huge capacity, which is vulnerable in commutation failure. In order to solve this problem, the dynamic reactive power compensation can be used in the power grid near the Jinping-Suzhou UHVDC system.

Analysis on the Abnormal Heating of the Link Fittings for Double-Bundled Conductors

LI Yanglin, ZHOU Longwu, ZHANG Yu, ZOU Jianzhang, RAO Binbin, KUANG Yanjun

2016, 49(5):  35-38.  DOI: 10.11930/j.issn.1004-9649.2016.05.035.04

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The abnormal heating of strain clamp is one of the most common defects of the overhead transmission lines. The abnormal heating of the link fittings is, however, very rare because the link fittings generally carry mechanical load instead of current. In this paper, an in-depth analysis is made on one abnormal heating defect of the link fittings for double-bundled conductor, and the result indicates that the main causes for the abnormal heating of the link fittings are the poor contact of the strain clamp. Further modeling and simulation analysis shows that the heating power of the strain clamp of a sub-conductor rises with the increase of the corresponding contact resistance. When the contact resistance increases to a certain extent, the heating of the clamp will gradually transfer to the link fittings because of the shunting effect of the sub-conductor, and the value of the contact resistance at the turning point is closely related to the resistance value of the link fittings. This research can provide a valuable reference for infrared detection of the abnormal heating of the strain clamps or link fittings for overhead transmission lines.

Diagnosing of Winding Looseness of a Transformer Based on no-Load Switching-on Vibration Signals

WANG Taoyun, MA Hongzhong, JIANG Ning, LI Kai, XU Honghua, WAN Da, CUI Yangliu

2016, 49(5):  39-43.  DOI: 10.11930/j.issn.1004-9649.2016.05.039.05

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The wavelet packet method is used to analyze the vibration signals as a measure of mechanical vibration properties when a transformer is switched-on under no-load state. In the experiment, two transformer statuses-the normal and the winding looseness statuses-are simulated, and the vibration signals under the no-load condition are collected for each status. The energy percentage distribution is determined based on the wavelet package-energy spectrum analysis and used as the characteristic parameter for the comparison and analysis of two conditional vibration signals. The experiment results show that there is a significant difference in vibration signals’ energy distribution characteristics between the normal and the fault conditions. The method presented in this paper can effectively extract switching-on vibration signal characteristics under different states. As such, the wavelet package-energy spectrum analysis can be effectively applied in diagnosing transformer winding looseness based on the vibration signals of switching-on under no loads.

Reliability Evaluation of the Bulk Power System with Consideration of the Lightning Weather

ZHANG Fuchun, ZHANG Fuchao, HUANG Jiadong

2016, 49(5):  44-48.  DOI: 10.11930/j.issn.1004-9649.2016.05.044.05

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Lightning weather will lead to increased transmission line failure rate, which significantly affects the reliability evaluation of bulk power system. Recognizing transmission lines under different lightning levels have different failure rates, different lighting regions are divided according to the lightning flash density, and a transmission line failure rate model is established for the lightning region. A reliability evaluation method of bulk power system considering lightning weather based on Monte Carlo simulation is proposed. The method makes use of the Monte Carlo sampling of lightning weather and transmission lines to determine the lightning weather conditions and transmission line status and to generate a deterministic system status, and then conducts reliability evaluation of the bulk power system. Finally, the flowchart for the bulk power system reliability evaluation with considerations of lightning weather is provided. Case studies are presented to illustrate the impact of lightning weather conditions on the power system adequacy.

Characteristics Analysis on SPD Grounding Current for Overhead Distribution Line Based on Artificial-Triggered Lightning

CAO Xuefen, CHEN Shaodong, YAN Xu, ZHANG Yong, XIE Zhiyong

2016, 49(5):  49-52.  DOI: 10.11930/j.issn.1004-9649.2016.05.049.04

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The waveform characteristics of grounding current of SPD for overhead distribution lines is investigated based on an artificial-triggered lightning. It is found that when lightning occurs at close range, the SPD grounding wire current resulted from overhead coupling over voltage reaches peak value of 961.0 A, average rise time of 10% to 90% of 17.5 μs, and average half peak width of 68.1 μs. The testing results are much different from standard laboratory test. In addition, SPD is not easily damaged by induced electromagnetic pulse due to lightning over-voltage shock. Correlation analysis finds that parameters of SPD grounding wire current are closely related to the steepness of 10% to 90% rise time of artificial-triggered lightning current. SPD grounding line current peak, half peak width, amount of charge neutralized, as well as energy of per unit resistance have good linear correlation with the steepness of 10% to 90% rise time of artificial-triggered lightning current. The linear correlation coefficients are 0.83, 0.83, 0.90 and 0.94.

E-mail: wzhy1991@yeah.net

WANG Zhongyue, LIN Jikeng, HU Shijun, LIU Hui, YE Jianhua, WEI Wenhui, LIN Changnian, SUN Yihao

2016, 49(5):  53-58.  DOI: 10.11930/j.issn.1004-9649.2016.05.053.06

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To solve the problem of flashover risk forecasting of contaminated insulator in high power grid, this paper presents a new method of salt deposit density forecast and flashover probability calculation based on air quality index and weather conditions from micro meteorological stations. Firstly, salt density and meteorological data on section center are acquired from air quality index and information from micrometeorological station. Then a salt density forecasting model is established based on salt density and meteorological data on section center with support vector machine(SVM). According to meteorological information of other insulators, salt density is obtained through proposed forecasting model. Finally, combined with probability model of contaminated insulator under certain voltage, flashover probabilities of transmission lines are calculated. The historical data of 220 kV transmission lines in Anhui power grid verify the correctness and efficiency of proposed method.

Analysis and Countermeasures on a Malfunction of Zero-Sequence Directional Protection Due to Mutual Inductance

CHEN Shuiyao, , HUANG Shaofeng, YANG Songwei

2016, 49(5):  59-62.  DOI: 10.11930/j.issn.1004-9649.2016.05.059.04

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A high frequency zero-sequence directional protection of a 220 kV line took false action with obvious distortion on voltage waveform. Through harmonic analysis of voltage waveform, it is found that CVT transient characteristics lasted shortly around 5~10 ms, while zero-sequence directional protection acted 20 ms later. The possibility of malfunction caused by transient characteristics of CVT is excluded. Based on zero-sequence voltage, current and sequence on both sides of protection, the induced voltage is calculated. It is inferred that mutual inductance is the cause of malfunction of zero-sequence directional protection. A new zero-sequence directional protection scheme with negative sequence current opening identification is proposed.

Fault Diagnosis of the SCR System in a Power Plant

CHEN Chongming, HOU Haiping, ZOU Siyi, SONG Guosheng

2016, 49(5):  63-66.  DOI: 10.11930/j.issn.1004-9649.2016.05.063.04

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Taking the SCR(selective catalytic reduction) system in a 330-MW power plant as an example, the concentration and flow distribution measurement and catalyst detection are carried out to solve the problems occurred during the operation, such as the high ammonia escape rate, the large pressure difference of the air preheater and the high NOx concentration deviation between the SCR outlet and the stack inlet. The results show that the uneven flow distribution is the major cause for catalyst corrosion, and the decreased activity of the catalyst and the unreasonable ammonia injection contribute to the fault of the SCR system. Through optimal adjustment of the ammonia injection, the distribution of SCR outlet NOx concentration is improved and the ammonia escape is reduced. Meanwhile, suggestions for the SCR system upgrading are proposed based on the diagnosis analysis.

The Time Dependent Failure Assessment Diagram and Defect Assessment of in-Service P92 Steam Pipe Containing Defects

LIU Yi, ZHANG Guodong, ZHAO Yanfen, LI Jian, ZHOU Changyu

2016, 49(5):  67-71.  DOI: 10.11930/j.issn.1004-9649.2016.05.067.05

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Based on the high-temperature short-time mechanics test at 610 ℃ and the creep tensile test conducted on the 30 000-h P92 welded joint, the isochronous stress-strain curve and the steady-state creep rate formula are obtained. Then, the time dependent failure assessment diagram(TDFAD) is drawn. By adopting the TDFAD, the critical crack sizes of P92 steam pipe under different stresses are analyzed. The results show that the critical crack size is affected by the time significantly when the crack sizes are large and the stresses are low. The critical crack size determined by the currency failure assessment curve(R6 option 1) and TDFAC has no significant difference under high stresses. Using TDFAD for the defect assessment of the equipment serving long under high-temperature conditions can obtain safer and more conservative assessment results.

Finite Element Analysis on Deformation and Cracking of the Cooling Tubes of a

DENG Linghui, KANG Yujun, WANG Junmin, CHENG Yongming, WANG Bining

2016, 49(5):  72-75.  DOI: 10.11930/j.issn.1004-9649.2016.05.072.04

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By establishing the three-dimension finite element model of the reheat steam cooling tube of a supercritical boiler, and taking its working temperature and constraints as the boundary conditions, the deformation of the cooling tube is analyzed. The analysis results show that some water subsides at the bottom of the tube due to the poor water atomization, causing a large temperature disparity between the top and bottom of the tube, which leads to a great axial tensile stress at the bottom of the pipe and a high axial compressive stress at the top. The alternating stress caused by the spray of the cooling water in the pipe is the main reason of the tube fatigue. The finite element computation results are closely identical with the actual deformation, with an error of about 8.3%.

Genration Technology

Post-Design Variation Selection and Verification for the Turbine Bypass Valve in a 1 000-MW Nuclear Power Plant

JI Runjing, HUANG Zhixing, SHI Shuyu

2016, 49(5):  76-81.  DOI: 10.11930/j.issn.1004-9649.2016.05.076.06

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To make post-design variation selection and verification for the turbine bypass valve in a 1 000-MW nuclear power plant, the working flow is established according to the trim types for selection. The flow consists of two stages, designing verification and full-scale model test. Several methods including CFD, FEM, model test, water flow test, non-load test and actual steam flow test are used to conduct comparison on Cv characteristic and controllability among the trim types, and eventually, the ideal type is obtained. The test and verification flow and methods proposed in this paper can provide reference for other nuclear projects. Meanwhile, the characteristics and existing problems of different valve types reflected by the test and calculation results also can make important reference for the selection of the turbine bypass valve.

Analysis of Two-Stage Valve Shutdown Scheme in Essential Service Water System of a Nuclear Power Plant

MAO Yujia, YANG Ruobing, LI Jing

2016, 49(5):  82-86.  DOI: 10.11930/j.issn.1004-9649.2016.05.082.05

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The essential service water system of a nuclear power plant is the DC water heat transport system from the auxiliaries cooling water system to the sea, whose long-term safe and stable operation must be ensured. The pump-stop water hammer of the essential service water system of a nuclear power plant is simulated with transient calculation function of PIPENET software for system design and optimization. The issues of liquid column separation, outlet pressure and pump backflow are analyzed for the check valve downstream from the pump through the simulation. An optimized scheme of shutdown durations of 4 s and 7 s for the quick and the slow stages respectively is obtained through the scheme comparison. The simulation results show that the scheme can not only significantly reduce the reverse rotation of pump, but also ensure the water hammer pressure lower than the designed value.

Optimization of Turbine Flow Characteristics Based on Modeling with Sectional Linearization of Dead-Zone Projection

YANG Yanbo, HU Tingting

2016, 49(5):  87-90.  DOI: 10.11930/j.issn.1004-9649.2016.05.087.04

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Aiming at the problems of load jump, valve jitter, poor load and primary frequency control qualities caused by the large function deviation between the real flow characteristics of the high-pressure governing valve and the theoretical setting values in DEH during the operation process, the linear model of governing valve opening-flow commands is established in sections based on dead-zone projection, and combing with the discretization formula of inlet-steam-quantity and valve switching, the characteristic functions are obtained in both single and sequence valve controls. At the end, the feasibility of the proposed method is verified by applying it on a 200-MW thermal power unit.

Impact of Air Leakage from Furnace Bottom on Flame Style and Exhaust Flue Gas Temperature

ZHAO Zhenning, LI Yuanyuan, ZHANG Qingfeng, ZHAO Zhenzhou

2016, 49(5):  91-96.  DOI: 10.11930/j.issn.1004-9649.2016.05.091.06

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To uncover the reasons for the substantial exhaust flue gas temperature rise without much flue gas temperature change at the air heater inlet when cold air leaks from the furnace bottom, the computational fluid dynamics simulation is conducted to study the variation patterns of the flame style with Fluent software. The results show that the bottom air leakage has very few impacts on the flame style in the area above the combustor zone and the flame center. However, if the bottom air leakage reaches as much as 10% of the total air volume, the flame temperature at the furnace outlet will increase by 15.7 ℃. Based on the heat balance principle of the air heater, two relational expressions are derived presenting the exhaust flue gas temperature rise due to the air reduction in the air heater caused by bottom air leakage, which explains why the exhaust flue gas temperature rises significantly while the flue gas temperature remains almost the same at the air heater inlet in the event of furnace bottom air leakage. The study results can provide reference for relevant work in this field.

Analysis and Optimization on Even Chamber Pressure Distribution for 300-MW CFBB Dual Air Inlets

MENG Fanming, XIN Xiaoying, XUE Zhipeng, CHEN Jian

2016, 49(5):  97-101.  DOI: 10.11930/j.issn.1004-9649.2016.05.097.05

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Through the cold dynamic field test on a 300-MW circulating fluidized bed boiler(CFBB), it is discovered that the fluidization around the left and the right manhole doors is extremely poor. When the primary air volume reaches as much as about 280 m3/h, the both sides might reach the critical fluidization state, which is very different from the designed values and affects the safe operation of the boilers with this kind of primary air inlets. Based on the adjustment on the hood holes and the pressure distribution and by virtue of the fluidization uniformity test to determine the high and the low pressure areas, the modification area is fixed. With the help of the theoretical analysis, the resistances of the hoods in the middle of the air chamber are increased by technical means without any changes in the primary air inlets. Therefore, the even air distribution is gradually realized on both sides and in the middle of the air chamber, thus solving the problems such as inadequate fluidization and coking at both sides of the air chamber and improving the boiler efficiency.

Study on Electronic Belt Scale Online Remote Automatic Testing and Diagnosis System

YANG Minghua, YU Songqing, CHEN Huiyun, HUANG Zhenwei, XU Feng

2016, 49(5):  102-105.  DOI: 10.11930/j.issn.1004-9649.2016.05.102.04

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Presently, the electronic belt scale testing is classified as material and simulation testing. However, these two methods can neither eliminate the errors caused by the belt tension changes nor conduct online testing. This paper introduces the structure, principle and functionalities of the electronic belt scale online remote automatic testing and diagnosis system. The system is based on double-weight superposition method, which adopts two testing points for the simulated linear fit of the belt scale, and simultaneously reduces the errors since the ratio of double weights to total load may reach as much as 50%. The overlaid weights which lay directly on the scale offset the effects brought about by the belt tension changes. The test data can be transmitted in real time during material conveying and the belt scale can also be checked both remotely and automatically, which significantly reduces the scale checking and maintenance workload.

Study on Comprehensive Evaluation Method for Elemental Carbon, Hydrogen and Nitrogen Detection of Coal

ZHANG Hongliang, LIANG Hanxian, LI Yuchun, SU Wei, LI Wei, CHEN Gang, LIN Musong

2016, 49(5):  106-110.  DOI: 10.11930/j.issn.1004-9649.2016.05.106.05

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In view of the wide application of fast fuel element analysis method(non national standard method) in the power industry, by taking advantage of the robust statistics method, the carbon, hydrogen, nitrogen and other characteristic indices tested with the high-temperature combustion infrared thermal conductivity method areacquired for 22 provincial electricity coal testing centers The |z| value for the discrimination of test result outliers are also calculated. The standard comparison method is applied to determine the qualification of the outliers and assess scientifically and objectively the laboratory capabilities of evaluating to detect carbon, hydrogen and nitrogen. Meanwhile, the cause analysis on the suspicious and outlier values of each index is conducted. Finally, the improvement measures on fuel laboratory detection quality control are put forward to ensure the accuracy of C, H and N detection of coal by high-temperature combustion infrared thermal conductivity method.

Smart Grid

A Power Supply Device Based on Wireless Power Transfer for the Online Monitoring Equipment of Power Lines

ZHOU Hong, JIANG Yan

2016, 49(5):  111-115.  DOI: 10.11930/j.issn.1004-9649.2016.05.111.05

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Reliable power supply for the online monitoring equipment of power transmission lines is one of the most urgent problems needing to be solved. For this purpose, a magnetic resonance coupling-based wireless power supply device is designed，which is convenient for maintenance and free of weather influence. On the basis of analyzing the output power of the wireless power supply device, the maximum power point tracking control system is used to ensure a stable power output. The device has been tested by the dedicated state-own inspection agency in power frequency withstand voltage, power output and tuning control, which shows that the device can work normally after power frequency withstand voltage testing and can provide stable outputs throughout the range of simulated power line current varying from 200-1 000 A, and the output power can increase by more than two times after adding frequency tuning control. The testing result proves that the device can provide a stable power supply in a transfer distance of 1.1 m.

Design of Intelligent Monitoring Device for Box-Type Substations

HUANG Xinbo, WU Mengkui, ZHU Yongcan, ZHU Haitao, WANG Jun’an

2016, 49(5):  116-122.  DOI: 10.11930/j.issn.1004-9649.2016.05.116.07

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According to the problem of low intelligence and poor inter-device operability of the traditional box-type substation’s control system, a design scheme of intelligent monitoring device is proposed for box-type substations according to the functional requirements of the box-type substations. The hardware platform is designed based on the processors S3C2440A and STM32F4. The information interaction is realized via LAN communication. The function is analyzed and the information model is established according to the IEC 61850 standard protocol. The experimental results show that the precision of voltage, current and active power of the device can reach level 0.3, and the reactive power can reach level 1. The operation of the box-type substation can be supervised in real-time, and such functions can be realized as the communication inter-operation between devices, the automatic control, fault alarming and auto-reclosing.

A Design of IPv6 Based Multi-Access Smart Grid Gateway

XIANG Min, HUANG Shenggang, TIAN Li, HUANG Haolin, HE Jinxing, TANG Liang, ZHU Dapeng

2016, 49(5):  123-128.  DOI: 10.11930/j.issn.1004-9649.2016.05.123.07

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To address the issues of poor connectivity with local communication systems and a lack of IPv6 technology based local communication applications in the smart grid gateway, an IPv6 based multi-access smart grid gateway is designed. The new gateway design is based on STM32F07 high speed processor and uC/OS-II embedded operating system, utilizing a self-developed IPv6 protocol stack. It enables a variety of IPv6 compatible local communication modes (Power Line Carrier, 433 MHz, 470 MHz, 780 MHz, 2.4 GHz) and many functions such as Ethernet and GPRS remote output, data storage, and dynamic parameter configuration. Test results show that the gateway design is feasible in enabling IPv6 based access to a variety of local communication modes and capable of adapting to various grid communication environments.

Graphical Generation Method and its Implementation of Virtual Terminals in SCD of Smart Substation

YIN Sun, YANG Depei, ZHENG Yongkang, TONG Xiaoyang, CAI Ganglin, ZHUANG Xiantao, TIAN Lizhi,PAN Feng, CHEN Luofeng, HU Defeng

2016, 49(5):  129-135.  DOI: 10.11930/j.issn.1004-9649.2016.05.129.07

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In order to assist speedy design of virtual terminals in SCD, a graphical generation method and system for virtual terminals in intelligent substation are studied. Some key technologies are described, including manual rapid association, template-based search for output terminals and copy virtual connections to similar objective devices. The virtual input terminals are displayed graphically with multiple partitions and columns, as well as output terminals and their sending sources. With dragging and dropping technology, the output virtual terminal is designated to corresponding input virtual terminal. For an input terminals, with the virtual connections from SCD templates, the similar candidate terminals can be found by matching virtual terminals description and keywords to generate virtual connections for objective device. The graphic generation system has been implemented by Qt C++. It has been applied to actual substation design and improved design efficiency and accuracy.

Development and Application of Testing Tool for Virtual Circuits in Smart Substation

TANG Fan, DONG Mo, LIU Shourui , QIAO Hui

2016, 49(5):  136-140.  DOI: 10.11930/j.issn.1004-9649.2016.05.136.05

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At present, no circuit examination is required in acceptance of smart substation, which results in low efficiency in acceptance. In this paper, a testing tool of virtual circuit is developed in VB environment based on the uniqueness of the publisher in the process of GOOSE/SV packets handshaking. The operational errors of substation configuration description (SCD) could be checked out by comparing virtual circuits in SCD and virtual terminal table. Therefore, a scheme of dual acceptance is proposed for smart substation. By testing the virtual circuit before debugging, the defects can be reduced and the efficiency of acceptance can be improved. The proposed scheme was applied in the acceptance of Wujiazhuang 220 kV smart substation and was proved effective.

New Energy

Optimized Energy Storage Capacity Allocation Based on Prediction Error Compensation Degree and Economic Benefits of Wind Power

HU Yawei, LI Jiang, HU Liqiang, CHAO Qin, HU Xukun, YANG Yang, LIU Qinggui

2016, 49(5):  141-148.  DOI: 10.11930/j.issn.1004-9649.2016.05.141.08

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The energy storage system can, through real time charging and discharging, compensate the error between predicted day-ahead output and actual output of wind power to indirectly improve the wind power prediction accuracy and utilization efficiency. Due to the constrains of energy storage cost, it is imperative to study the method for selecting the optimal energy storage capacity. Based on the contrast analysis of abandoned wind reduction, thermal power reserve capacity reduction, environment-friendly benefits, energy storage investment and operation & maintenance cost, different error compensation degrees are determined according to the probability distribution of wind power prediction errors, and subsequently the corresponding energy storage capacity, the economic benefits and the years for recovering the energy storage costs are in turn obtained. The energy storage capacity allocation and the year for recovering costs under the optimal compensation level are determined according to the relationship among compensation degree, energy storage capacity and the year for recovering costs. A case study is conducted by simulation for a wind farm of 148.5 MW in Xinjiang, and it is concluded that by limiting the day-ahead prediction error of wind power to ±25%, the optimal compensation degree is 91.5%, the optimal energy storage capacity is 12.28 MW, and it needs about 7.58 years to recover the costs.

Research on Evaluation Indicators for a Comprehensive Assessment of Operating Status of Lithium Battery Energy Storage

CHEN Hao, DIAO Jia, BAI Kai, GAO Fei, MA Buyun, LI Na

2016, 49(5):  149-156.  DOI: 10.11930/j.issn.1004-9649.2016.05.149.08

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With the continuous improvement of lithium battery energy storage technology and increased number of lithium battery energy storage stations in operation at home and abroad, the operating status of lithium battery energy storage has attracted increased attention. Based on the operational data and theoretical analysis, this paper studies a number of evaluation indicators for measuring the operating status of lithium energy storage, including the range of battery voltage, the coefficient of standard deviation of battery voltage, the range of battery temperature, the range of SOE, the degree of correlation between power and SOE, the charge-discharge efficiency. The paper provides a comprehensive assessment of the evaluation indicator system based on the internal relationship among the indicators. The results show that these indicators can be used to assess the operating status of lithium battery energy storage effectively, and applied to identify battery fault and guide the arrangement of battery inspection and maintenance.

Short-term Photovoltaic Power Prediction Based on Typical Climate Types and Stochastic Prediction Error

CHEN Yaoqi

2016, 49(5):  157-162.  DOI: 10.11930/j.issn.1004-9649.2016.05.157.06

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Photovoltaic(PV) power output is directly related to the climate types and the prediction accuracy of PV power decreases for cloudy and rainy weathers. Based on the categories of typical climate types, a PV power forecast model is proposed with consideration of the predictive relative tolerance and the relative affective factor(RAF). At first, the historical climate data are categorized according to the definition of typical climate types and the RAF is put forward; Then the probabilistic model of predictive relative tolerance is established by using the t Location-Scale distribution and the Latin hypercube technique is used for sampling of the predictive relative tolerances; Finally, the predictive relative tolerance and the predicted value are superimposed to obtain the final prediction results. A case study has proved the feasibility and effectiveness of the model.

Power System

Risk-Constrained Day-Ahead Scheduling Optimization Model of Hydro-Wind Power Generation

ZHANG Wei, LI Dan, ZHANG Xiangyu, LI Jiayu, TAN Zhongfu

2016, 49(5):  163-170.  DOI: 10.11930/j.issn.1004-9649.2016.05.163.08

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In order to overcome the influence of wind power on power system operation, peak shaving is introduced. The wind power output and cascaded hydroelectric unit model are modeled at first. Based on hydro-wind coordination constraints, a day-ahead scheduling optimization model is built with consideration of risk constraint. A heuristic algorithm is applied to linearize proposed model. At last, a simulation system is built with three wind farms and seven hydroelectric power stations in two basins. The simulation results show that proposed hydro-wind coordination strategy can be used to increase wind power generation and reduce operation risks. Both internal and external uncertain factors need to be integrated into the joint scheduling optimization of hydro-wind power generation, which is essential for obtaining optimization solution considering both system operation benefits and risks.

Experimental Study on Shape Coefficient of Bundle Conductors

MIN Xuan, NIU Huawei, WEN Zhike, FU Jing, ZENG Yunfei

2016, 49(5):  171-177.  DOI: 10.11930/j.issn.1004-9649.2016.05.171.07

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In order to study the effects of bundle conductor’s aerodynamic interference on shape coefficient, different types conductors are chosen for model wind tunnel test of real conductor section to analyze the factors that affect the shape coefficient, including conductor cross-section, wind speed, wind attack angle, bundle number and flow field. The test result shows that the shape coefficient of double bundle conductors increases with the wind attack angle before deflection critical position. When the wind attack angle reaches the critical position, the increase of wind attack angle has no effect on the shape coefficient of double bundle conductors. The shape coefficient of 4-, 6-, and 8-bundle conductors increases first and then decreases with changing of wind attack angle, with the peak reaching at a certain angle. The bundle conductors shape coefficient under the condition of 10% turbulence intensity is larger than that in the uniform flow field by 10%~15%. In the scenario of 30 m/s wind speed under turbulence, the shape coefficient of 4-, 6-, and 8-bundle conductor JL/G1A-630/45 are respectively reduced by 27.60%, 24.38% and 22.51% compared to the value specified by design code.

Structural Design and Bearing Capacity Analysis of a Lattice FRP Transmission Pole

YANG Fengli, XING Haijun, LI Zheng, YANG Yuanchun

2016, 49(5):  178-184.  DOI: 10.11930/j.issn.1004-9649.2016.04.178.07

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According to the meteorological conditions in littoral typhoon areas, the designed load of a lattice FRP transmission pole is calculated under high wind condition, and the structural arrangement pattern and member sizes of the FRP transmission pole are determined. With consideration of the large deformation and aging effects of the FRP transmission poles in their service period, the general finite element analysis software(ANSYS) is used to make a structural analysis of the lattice FRP transmission pole. Comparing with the conventional reinforced concrete transmission pole, the weight of the FRP transmission pole can be reduced over 60%. In order to check the bearing capacity of the lattice FRP transmission pole, prototype tests are conducted respectively under 100% designed load and overloading condition with 90 degree high wind load. The displacements of the pole body along height direction and the strains at typical member sections are obtained and compared with the calculated displacements at the pole top as well as the stresses of main members by FEA method. It is indicated that when the testing load is less than 250% of the designed wind load, all the members are in linear elastic state with the maximum stress of the main members being 159.8 MPa, much lower than the yield stress of 300 MPa for FRP; the displacements at the pole top as well as the stresses of the main members calculated by FEA model are basically consistent with the testing values; when the testing load is over 260% of the designed wind load, shear failure occurs on the hole wall at the bottom of the lattice FRP transmission pole.