Table of Content

20 December 2017, Volume 50 Issue 12

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Electricity and Economy

The Application of Electricity Elasticity Coefficient During Economic Transition Period

SHAN Baoguo, LI Jiangtao, TAN Xiandong, SHAN Baoping

2017, 50(12):  1-4.  DOI: 10.11930/j.issn.1004-9649.201709001

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Based on an analysis of the variation of China’s electricity elasticity coefficient since 1978, this paper elaborates the reasons for the large variation of China’s electricity elasticity coefficient in the short term, and finds out the long-term pattern of the variation. Through comparison with the developed countries’ experience in electricity elasticity coefficient variation, a method is proposed for the application of electricity elasticity coefficient during economic transition period, and a check is made on the power demand forecasting for the 13th, 14th and 15th Five-Year Periods (2016–2020, 2021–2025 and 2026–2030, respectively).

Study on the Difference Between China^,s Total Electricity Consumption and Economic Growth Under the New Normal

TAN Xiandong, SHAN Baoguo, WU Shanshan, SHAN Baoping

2017, 50(12):  5-9.  DOI: 10.11930/j.issn.1004-9649.201708230

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Since China^,s economy entered a new normal, the growth rate of total electricity consumption has been lower than that of GDP, and in some years, their difference is large. A model is established in this paper for calculating the difference between the electricity consumption and GDP growth rate, which is mainly composed of structure effect, intensity effect and residential effect. The model can comprehensively and scientifically measure the specific compositions of the gap between the total electricity consumption and GDP growth rate and analyze the main reasons for their gap. It is found through the model calculation that the total electricity consumption growth rate from the year 2012 to 2016 is lower than that of GDP by 2.3, 0.2, 3.2, 5.9 and 1.8 percentage points, respectively, of which the intensity effect makes the total electricity consumption growth rate lower than that of GDP by 2.7, 0.4, 1.9, 4.9 and 1.5 percentage points respectively, while the structure effect makes the electricity consumption growth rate 0.1 higher, 0.1 higher, 0.6 lower, 0.8 lower and 0.8 lower than the GDP growth rate in percentage points, respectively, and the residential effect makes the electricity consumption growth rate 0.3 higher, 0.1 higher, 0.7 lower, 0.2 lower, 0.5 higher than the GDP growth rate in percentage points, respectively. The calculation results show that the intensity effect is the key reason for the total electricity consumption growth rate being lower than that of GDP.

Analysis on the Electric Power Demand of Jiangsu Province Under China’s New Normal

SHI Jing, ZHOU Qi, TAN Jian, ZHU Lei

2017, 50(12):  10-15.  DOI: 10.11930/j.issn.1004-9649.201708233

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Under China^,s new normal, the driving factors for Jiangsu Province^,s economic growth have shifted from the secondary industry to the tertiary industry and consumption. Jiangsu Province’s power demand has also undergone significant changes. In order to accurately predict the new trend of electricity demand of Jiangsu Province, this paper analyzes the power consumption characteristics of Jiangsu Province since the 12th Five-Year Plan period (2011–2015), which is mainly manifested in the declining trend of power elasticity coefficient and the significant difference in power consumption growth among three typical regions in southern, middle and northern Jiangsu Province. The electricity consumption of the southern and middle regions shows a high growth rate, while the northern region has a low growth rate. A forecasting is made on the electricity demand of Jiangsu Province under China^,s new normal. It is predicted that the total electricity consumption growth rate of Jiangsu Province will be about 5.1% during the 13th Five-Year Plan period (2016–2020), and the southern, middle and northern regions will have an electricity consumption growth rate of 5.7%, 6.2% and 2.9%, respectively.

Research on the Evolution Trend of Electricity and Economy Relations in Henan Province

BAI Hongkun, LIU Junhui, YIN Shuo, WANG Jiangbo, DENG Fangzhao, YANG Meng, ZHAO Wenjie

2017, 50(12):  16-21.  DOI: 10.11930/j.issn.1004-9649.201708308

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This paper makes a comprehensive analysis on the relationship between electricity and economy in Henan Province from 2010 to 2016, and studies the variation characteristics of electricity structure and economic structure, the variation law of electricity intensity, with focus on the relationship between the development of high energy-consuming industries and electric economy. The key factors that influence the power consumption and GDP growth are identified. The research findings are helpful to find the positive changes brought by the economic structure adjustment, and also have a guiding significance for understanding about the periodic phenomenon of the large growth difference between electricity consumption and GDP.

Correlation Analysis on Economic Indicators and Electric Power Demand of Liaoning Province

DENG Xinyang, JIANG Lei, LI Yongrui, YU Haiyang

2017, 50(12):  22-26.  DOI: 10.11930/j.issn.1004-9649.201708230

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Electric power plays an increasingly important role in economic development. It is important for accurate power demand prediction to understand the interaction between electric power demand and economic growth. Based on the economic development and electric power demand of Liaoning Province during 2005-2016, this paper analyzes the influence of economic structure adjustment on electric power demand. The data of main economic indicators of Liaoning Province are selected for a correlation analysis of electric power demand. Such strong correlation indicators as public financial expenditure budget, gross domestic product (GDP) and total freight volume are used to establish a forecasting model of total electricity consumption by using the ridge regression analysis method, and the electric power demand of Liaoning Province during the 13th Five-Year Plan period (2016-2020) is predicted, which can provide the basis for the decision-making of government departments and the power supply companies.

Analysis and Prospect of Electricity Demand in Ningxia under China’s New Normal

TIAN Xing, YU Lei, DONG Xiaojing, QI Caijuan

2017, 50(12):  27-32.  DOI: 10.11930/j.issn.1004-9649.201708235

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Based on an analysis of the economic development characteristics and power demand changes in recent years in Ningxia, the influence of China’s new economic normal on the power demand is studied from two dimensions of macro and micro mechanism. The dynamic grey Verhulst model that suits S-type growth is used to forecast the future electricity demand of Ningxia, which can provide a reference for Ningxia’s electric power planning and power industry layout.

300 Mvar Large Synchronous Condenser

Internal Fault Analysis and Optimization Design of Main Protection Scheme for Shanghai Electric Phase Modifier

GUI Lin, ZHAO Binchao, WANG Guang, WANG Xiangheng, WANG Weijian

2017, 50(12):  33-37.  DOI: 10.11930/j.issn.1004-9649.201711222

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Due to the possible stator winding inter-turn short circuit in large phase modifiers, there will be seriously potential risk for the safe operation of the phase modifier without inter-turn short circuit protection. Internal fault analysis and main protection configuration scheme optimization design of a 300 Mvar phase modifier manufactured by Shanghai Electric are carried out with the multi-loop method. The analysis showed that different main protection configuration schemes should be chosen for different outgoing modes of the phase modifier neutral point. Compared with the neutral point outgoing mode and main protection scheme based on the traditional electromagnetic current transformer, the split-phase transverse differential protection based on FOCT will completely change the current status of large turbo-generator without stator winding inter-turn short circuit protection and has little influence on generator design and manufacture, thus providing the high quality guarantee for the safe operation of the generator.

Reliability Research on Idle Speed Synchronization of Large Condenser

ZENG Xianfeng, HOU Wei, CHEN Jun

2017, 50(12):  38-43.  DOI: 10.11930/j.issn.1004-9649.201711231

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The output side of the static frequency converter (SFC) which is not equipped with step-up transformer can reduce the overall cost of installing the condenser, but then the conditions of grid connection will become harsh when the rotor speed is no longer controllable. In order to improve the grid-connected reliability of synchronization, firstly the relationship is established between the inrush current, frequency difference and angular difference, secondly the existence probability of synchronous point are researched on, then some suggestions that select a small lag angle in the positive frequency difference, a small advanced angle in the negative frequency difference and so on are put forward to improve the reliability of synchronization. Based on the example, the existence probabilities and permissible frequency differences are studied that verify the proposed methods can effectively improve the reliability of synchronization.

Research on Control Strategy of Large Synchronous Condensers

SHI Xiangjian, MU Wei, HAN Jiao, FANG Bing, GAO Sen, WU Long, LIU Weiqun

2017, 50(12):  44-50.  DOI: 10.11930/j.issn.1004-9649.201707153

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With the development of high voltage direct current transmission, the problem of reactive power compensation has become increasingly prominent. The large synchronous condensers are ideal for reactive power compensation because of fast reactive response and fault crossing ability. Firstly, project background of synchronous condenser is introduced. Secondly, control strategies including static frequency converter(SFC) starting method, coordinated control strategies of reactive power-voltage and power system voltage regulator (PSVR) control method in excitation system are described. Finally, experiments are designed and performed to validate proposed control strategy. The results show that proposed control strategy can be used to meet starting and operation requirements of synchronous condenser.

Contents and Key Technical Problems in Start-Up and Commissioning of Large-Scale Synchronous Condenser in UHVDC Project

TAO Qian, WANG Qing, RUAN Ling, CAI Wanli, CUI Yibo, LING Zaixun

2017, 50(12):  51-56.  DOI: 10.11930/j.issn.1004-9649.201610046

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300 Mvar large-scale synchronous condenser used as dynamic reactive power support in UHVDC project is the first application in DC convertor station. The requirements include good dynamic characteristics, high reliability and easy maintenance. There are no previous experience in design, manufacture, operation and maintenance for synchronous condenser at this capacity, both in China and aboard. The characteristics of large-scale synchronous condenser set are introduced first. Main contents and requirement for condenser starting and operation are also summarized. Key techniques are discussed including emergency power supply switchover, excitation system switchover, coasting synchronization, reactive power regulation and reactive load rejecting test. The discussion gives important reference for smooth operation of future large-scale synchronous condenser set in UHVDC projects.

Study on the Performance Feature and Key Engineering Application of New Large Capacity Condenser

RUAN Ling, WANG Qing, LING Zaixun, YANG Pengcheng, CUI Yibo, CAI Wanli, TAO Qian

2017, 50(12):  57-61.  DOI: 10.11930/j.issn.1004-9649.201610028

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With mass application of UHVDC transmission project and rapid development of new energy, using new large capacity condenser to provide dynamic reactive power support and improve power system operation stability has brought lots of attention in power industry both in China and abroad. Various topics related to new large capacity condenser are discussed in detail including application advantage, key index requirement, system configuration, quality control and performance test. The discussion provides theoretical foundation for equipment performance optimization and new large capacity condenser supporting project evaluation.

Generation Technology

Online Monitoring and Optimization of Valve Discharge Characteristics for a Reheat Turbine

SHENG Kai, ZHOU Nianguang, SONG Junying, LEI Bin, PENG Shuangjian, XUN Xin

2017, 50(12):  62-67.  DOI: 10.11930/j.issn.1004-9649.201608009

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The reasonable configuration of the discharge characteristic function of turbine governing valves is essential to linear power control for thermal power units. Then the discharge characteristic function of turbine governing valves shall be re-optimized when there exists any undesired nonlinearity of the discharge characteristics which may degrade the control performance. Currently, the optimization of the discharge characteristic function depends on the valve discharge characteristic experiment. In this paper, based on the test study of a 362.5 MW unit, a method of online valve discharge characteristics monitoring and optimization is proposed, which can observe the valve discharge characteristics and optimize the discharge characteristics function by using the historical DCS data. Furthermore, by virtue of this method the valve discharge characteristics function can be rectified in advance according to the changes of the valve discharge characteristics to avoid the performance degradation of primary frequency regulation and the power oscillations caused by the nonlinearity of the valve discharge characteristics.

A Method of Online Monitoring on Characteristics of Primary Frequency Regulation in Thermal Power Units

TAN Bo, CHEN Zhigang, GU Tao, ZHAO Zhidan, YU Jing, CAO Chen

2017, 50(12):  68-74.  DOI: 10.11930/j.issn.1004-9649.201608079

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Aiming at the security risks of power grid frequency oscillations caused by the external transmission line faults from the eastern developed area, the architecture of automatic generation control between power grid and power plant is analyzed, and a method of online monitoring of the characteristics of primary frequency regulation(PFR) in thermal power units is proposed. Based on the hybrid energy management system, the schematic diagram of PFR online monitoring is designed. According to the engineering practice, the effect of PFR is measured in terms of different evaluation indexes. Considering the performance of ultra-supercritical units and the technology of time division, the control strategy of PFR online monitoring is established. The test results demonstrate satisfactory performance of the proposed online monitoring system. In addition, improvement is made by replacing the original post-faults analysis with pre-faults supervision, and the parameters of PFR can meet all the requirements of dispatching procedures.

Design and Operation of a 300 MW Ultra-Low Emission CFB Boiler Burning Low Calorific Coal

TONG Boheng, LIU Chengliang, SU Hu, LIU Qing, YANG Hairui, JIANG Wenbin

2017, 50(12):  75-80.  DOI: 10.11930/j.issn.1004-9649.201612119

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The paper introduces the design and operation of Shanxi Guofeng 300 MW ultra-low emission subcritical units burning low calorific coal. The principles and the application of the pollution controlling technologies are discussed. In this project, in-furnace desulfurizationand semi-dry flue gas desulfurization are used to control SO₂, the low-nitrogen combustion technology based on the state specification theory and SNCR to control NO_x, and bag filters to control powder . The results show that the boiler runs steadily and efficiently. The thermal efficiency at full load is 90.61%. The SO₂, NO_x and dust emission concentration at full load are 18.75 mg/m³, 40.30 mg/m³ and 4.9 mg/m³, respectively, all of which meet the ultra-low emission standards. The results indicate that the low-NO_x combustion combined with ultra-low emission technologies is applicable.

Experimental Study on and Application of Steam Turbine’s Variable Pressure Thermal Economic Characteristics

WAN Zhonghai, YAN Tao, LU Jin, CAI Wen, CHEN Wen

2017, 50(12):  81-86.  DOI: 10.11930/j.issn.1004-9649.201702112

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Compared with the theoretical calculation and the conventional test method, the global dynamic variable pressure test method is more suitable for accurately and completely describing the variable pressure thermal economic characteristics of steam turbines in terms of the accuracy of the analysis results, the convenience of implementation and the degree of close correlation with the flow characteristics of the control valve. The application of several units shows that the variable pressure thermal economic characteristics of steam turbines obtained by using this method can reflect the continuous change trend of the heat rate of the unit with the different initial pressure of the feasible valve range under the certain electric power which not only enables to clearly exhibit the inherent law of the variable pressure operation for different types of steam turbines; but is also helpful for the quantification of the influence of the regulating valve throttling frequency modulation and the regulating valve overlap degree on the heat rate of the unit. This method is greatly applicable in the electric power production process. The study can provide the technical reference for the technical and economic comparisons of the wide load peaking operation mode of the coal motor unit, the comprehensive optimization of the steam turbine and its control strategy.

Online Calculation of Steam Turbine Valve Discharge Characteristics by Dynamic Data Mining Approaches

WEN Le, YANG Xinmin, XUE Zhiheng, GAO Lin, ZHAO Jinxu

2017, 50(12):  87-92.  DOI: 10.11930/j.issn.1004-9649.201608015

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For the purpose of conducting real-time analysis and online monitoring on the valve discharge characteristics of the steam turbine, one dynamic data mining model is built up for the valve discharge characteristics calculation. A 350 MW turbine set is used to validate the dynamic data mining model. The results show that the dynamic data mining model can extract and update calculation samples. Moreover, the mathematical model established by moving least square method can simulate the mapping relationship between the input and output parameters well. The average relative error is less than 1.5% between the mathematical model and the results of the steam turbine performance testing, which verifies that this dynamic data mining model is an effective approach for valve discharge characteristics online calculation.

Research on and Application of Optimal Distribution of Thermal Power Load in the Captive Thermal Power Plant of the Petrochemical Enterprise

WU Tao, HU Honghua, HUANG Tinghui, HE Xin, WANG Jianping, CHEN Jing, MA Yufeng, WANG Bin

2017, 50(12):  93-97.  DOI: 10.11930/j.issn.1004-9649.201705069

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According to the characteristics of the captive power plant of the petrochemical enterprise, the load optimal distribution model based on heat balance (Model One) and the one based on fuel and electricity prices (Model Two) are established and implemented online simultaneously on the basis of the production process monitoring and the optimization system of the plant. Through the analysis of the operation data before and after the optimization, it is shown that the coal consumption can be saved at least 4.5 g/(kW·h) with Model One, and the profit can be increased by 6 492.16 yuan/h with Model Two. The two models can be generally applied to the captive power plants the petrochemical enterprises.

Factors Affecting Power Plant Boiler Water Quality Test Results

ZHAO Qing, CHEN Caixia, WANG Yining

2017, 50(12):  98-100.  DOI: 10.11930/j.issn.1004-9649.201702085

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As a specific type of equipment, the boiler’s operation conditions are closely related to the safety of the public’s life and property. Its water quality is greatly important to the the safe operation of the boiler as well as energy-saving and emission reduction. Based on the operation experiences, factors affecting the results of the boiler water quality detection including the detection standard selection, the field sampling, the field detection and the lab analysis process are analyzed. The purpose of the analysis is to improve the accuracy of the water quality test results to better guide the boiler’s safe and economic operation.

Analysis and Study on the Difficulties in Fieldbus Commissioning in a Thermal Power Plant

CUI Chaochao, ZHANG Ying, SHEN Dongsheng, CUI Yiqun

2017, 50(12):  101-105.  DOI: 10.11930/j.issn.1004-9649.201606047

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Through the implementation and application of fieldbus in huaneng luntai power plant, this article fully analyzes the difficulties in the fieldbus commissioning process from the aspects of management and technology under the current technology conditions. Specifically this article systematically puts forward the principle of the organization division of labor and the overall commissioning process in terms of management, while summarizes the difficulties encountered in the commissioning process from technical viewpoints. The study results will provide a systematic solution to the similar types of engineering applications under the circumstances of incomplete engineering commissioning standard.

Power System

Parameter Tuning of New PSS-NB Model and Its Engineering Application

WU Kuayu, SHEN Yijun, HAN Bing, LU Cencen, WU Long, LU Haiqing

2017, 50(12):  106-111.  DOI: 10.11930/j.issn.1004-9649.201608125

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A new type of PSS-NB power system stabilizer model is proposed. Based on design concept, operating principle and advantage of low frequency oscillation suppression capability, supporting parameter tuning test content and parameter tuning calculation method of PSS model are described in detail. Taking PSS-NB commissioning test of a 330 MW unit as an example, parameter tuning calculation method is presented and low frequency oscillation suppression effect is verified with comparison of traditional PSS2B during engineering application process. It is proved that proposed new PSS-NB can not only meet full-band phase compensation requirements, but also provide better suppression effect on medium and low frequency band.

Quality Control of Materials and Components for 1 000 kV Transformers and Reactors

GUO Rui, WANG Xiaoning, ZHANG Hejun, CHENG Huanchao, ZHANG Shuqi, LI Jinzhong, LIU Xueli, TANG Hao, QIU Yuzhou, WU Chao, YU Xinru

2017, 50(12):  112-117.  DOI: 10.11930/j.issn.1004-9649.201608044

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In order to control the quality of main materials and components which are used for 1 000 kV transformers and reactors, this paper describes the applications of these materials and components such as electromagnetic wire, silicon steel sheet, insulation material and high-voltage bushing and summarizes the typical quality problems that occur during inspection and manufacturing. The pertinent quality control method and technical requirements are proposed, which will effectively avoid the use of materials and components that have quality problems, thus enhancing the quality stability of transformer and reactor.

Analysis on the Relevance of Core Magnetostriction and Oil Tank External Characteristics of Power Transformers

NIE Jingkai, LU Lin, LI Rui, JIN Wende, KONG Xiaofeng, PAN Weiwei, ZHAO Shen

2017, 50(12):  118-124.  DOI: 10.11930/j.issn.1004-9649.201611175

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The paper mainly focuses on the study of the vibration principle and noise spectrum characteristics of transformer bodies, and on the establishment of the relevance of magnetostriction, vibration transmitting path, tank vibration and the external noise characteristics of oil tanks. An introduction is made on the mismatching problems between the existing equipment standards and noise emission standards. The vibration accelerations of cores are measured in two directions to determine the frequency characteristics of vibration. The sound pressure level characteristics, frequency spectrum characteristics, vibration characteristics and their concentration of power transformers are discussed based on a comprehensive analysis of numerous measured noise data of substations. The correlation between the magnetostriction frequency and the external noise characteristics of oil tank is established, and it is proved that the noise frequencies are mostly 100 Hz or its integer times. The vibration frequency of transformer core caused by magnetostriction is two times the frequency of power frequency exciting current, which is equal to 100 Hz. The external noise of oil tank is characterized by that both the fundamental frequency of 100 Hz and the higher harmonic frequency of its integer times such as 200 Hz, 300 Hz and 400 Hz have remarkable peak values. It will be the focus in the future to develop the technology for noise reduction of the transformer bodies.

Research on the Impact of 30 mA Leakage Current on the Atmospheric Corrosion of Transmission Lines

LUO Guoming, MAO Xiaopo, ZHANG Yu, LU Jinpei, ZHOU Junyu, CAO Xiangwei, ZONG Yun

2017, 50(12):  125-129.  DOI: 10.11930/j.issn.1004-9649.201608023

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In order to study the corrosion behavior of transmission line under 30 mA leakage current, in this paper, the corrosion weightlessness of metallic materials under different SO₂ concentrations and different leakage currents is analyzed. When SO₂ concentration is relatively low, the effect of leakage current on corrosive weightlessness is not obvious; when SO₂ concentration is relatively high, leakage current will expedite the corrosion of metallic material and more metastable γ-FeOOH will accumulate on the surface. When γ-FeOOH accumulates to a certain extent, parts of it will convert to relatively stable α-FeOOH and Fe₃O₄ and the corrosion is mitigated by the stable products, which improves the corrosion resistance of samples.

Study on Influence of Coupling Transformer Charging Inrush Current to Hami-Zhengzhou UHV DC Project

ZHENG Bin, YANG Peng, TENG Wentao, BAN Liangeng, XIANG Zutao, WU Yani, ZHANG Yuanyuan, LUO Lishi, PAN Yifei

2017, 50(12):  130-135.  DOI: 10.11930/j.issn.1004-9649.201608065

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Inrush current during charging of coupling transformer in UHV DC converter station results in converter AC bus voltage distortion and harmonics in DC system. The harmonics are dominated by second and third order harmonic. Harmonic leads to DC voltage, current and power fluctuations and especially system overvoltage, which may result in DC power system harmonic protection alarm and even action in severe cases. It affects safe and stable operation of UHV DC project. Based on practical system condition, charging inrush current and voltage harmonic characteristics of two expansion groups of 750/500 kV coupling transformers in Tianshan converter station are studied. The influence on harmonic protection of Hami-Zhengzhou ±800 kV UHV DC project is investigated and suggestions on safety measures for coupling transformers energizing are proposed. The results provide effective countermeasures to ensure safe operation of Hami-Zhengzhou UHV DC project. These results also offer useful reference and guidance for other similar projects.

Analysis and Prospect on the Application of Artificial Intelligence Technologies in Smart Grid

LI Bo, GAO Zhiyuan

2017, 50(12):  136-140.  DOI: 10.11930/j.issn.1004-9649.201711221

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The progresses and breakthroughs of artificial intelligence technologies are of great significance to improvement of intelligence level of smart grid. starting from connotations of smart grid, combined with characteristics and applicable scopes of all kinds of artificial intelligence technologies, the intelligence needs of smart grid are combed. Possible application scenes are designed, a SWOT analysis on some key artificial intelligence technologies is carried out and possible difficulties are estimated. It is pointed out that, many artificial intelligence technologies have important reference values in the smart grid applications, including planning, prediction, auxiliary decision-making, intelligent control, video surveillance and inspection fault diagnosis. neural networks, expert systems, data mining and other technologies all have their own advantages, disadvantages and applicable scopes. we should pay enough attention to scientific choice of all kinds of technologies, and prepare for possible challenges such as reliability, interpretability, accumulation of data samples, revision and maintenance of knowledge base, infrastructure preparation and confidentiality.

Application of Multi-Rotor UAV Patrol System in UHV Power Grid Construction

LIN Yulong, LI Bing, WANG Deyu, GAO Ju, CHEN Yongting

2017, 50(12):  141-147.  DOI: 10.11930/j.issn.1004-9649.201701129

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In view of the present situation of ultra-high voltage(UHV) power grid construction in northern Hebei, the multi-rotor UAV patrol inspection is proposed as a new technique for construction management. Based on the characteristics of multi-rotor UAV’s structure and flight control system, a model is constructed to make a systematical analysis. In light of the actual characteristics of power grid construction, the UAV patrol and evaluation program, including checklist method and special program fault tree analysis method, is established to conduct qualitative and quantitative analysis of the construction sites. Finally, according to the actual application results, the effectiveness of UAV patrol is evaluated in terms of inspection time and cost saving, safety risk mitigation, compensation reduction, and environmental protection improvement. It is proved that UAV patrol used in grid construction can broaden the scope of construction management, reduce on-site construction control loopholes, lower on-site management risks, and improve working efficiency.

Research on Intelligent Detection System of SF₆ Biotoxicity

WANG Haifei, YUAN Xiaofang, QI Jiong, ZHAO Yue, SU Zhenxi

2017, 50(12):  148-152.  DOI: 10.11930/j.issn.1004-9649.201611016

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Some toxic substances may remain during the new SF₆ production, biotoxicity is an important indicator of the total analysis of SF₆ gas. The traditional detection method costs a long time and needs a technical person on guard. In order to meet needs of the rapid development of electric power construction, and enhance the detection efficiency of SF₆ gas, a set of SF₆ toxicity intelligent detection system was developed, in which many advanced technologies were applied, such as the multi-channel flow control and protection, rapid gas balance and remote video monitoring. The function and effect of each main module in the system are introduced in this paper, the experimental results show that the expected design goal was realized, which can effectively improve the working efficiency of the test work, protect the test environment and ensure the quality of the equipment. Besides, it do not need a special person to watch and have the value of popularization and application.

New Energy

Spectrum Analysis of Nonstationary Vibration Signal for Wind Turbine Gear Box

DING Xian, LIU Yibing, TENG Wei

2017, 50(12):  153-158.  DOI: 10.11930/j.issn.1004-9649.201702009

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Gearbox is an important component of wind turbine, which directly determines wind farm revenue. It is of great significance to gearbox operational status evaluation by analyzing vibration signals. The structure and failure characteristics of wind turbine gearbox are discussed first. According to characteristics of one type of wind turbine gearbox, schemes for vibration data acquisition are established and high-speed shaft vibration signals from two wind turbine gearboxes are collected. Comparative analysis is performed by using Hilbert energy spectrum and short-time Fourier spectrum rearrangement methods to extract fault characteristic frequency from high-speed shaft measuring point vibration signal on two wind turbine gearboxes. Analysis results indicate that one gearbox has high-speed shaft damage which is verified by field test. The result confirms validity and practicability of combination of Hilbert energy spectrum and short-time Fourier spectrum rearrangement methods in extraction of wind turbine gearbox fault characteristic frequency.

The Ultra-Short-Term Forecast of Photovoltaic Power Output Based on Grey Relational Analysis and Empirical Mode Decomposition

SUO Chunmei, SUN Jian, ZHANG Zongfeng, WANG Xianzong

2017, 50(12):  159-164.  DOI: 10.11930/j.issn.1004-9649.201707137

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PV power output is affected by solar irradiance, temperature and instantaneous cloud, and its generation presents obvious non-stationary features, which increases the difficulty of prediction. To reduce the influence of output volatility on the prediction effectiveness and satisfy the accuracy requirement of ultra-short-term prediction, this paper proposes a two-stage method to build input samples. Firstly, the grey correlation principle is applied to build similar sample collection. Then, the empirical mode decomposition method is used to decompose the output sequence of similar days. After getting the relatively stable function and the remaining component, the support vector machine, a data mining tool, is used to do rolling prediction for every component. Finally, all the prediction results are added to get the prediction of next moment. A case study proves that the root-mean-square error of the combined model shows a high precision of 1.93, which can provide more decision-making support for PV power scheduling.

New Microgrid Fault Analysis Method Based on Inverter-Type DG Characteristic

JI Liang, ZHANG Haitao, REN Jianming, YANG Xingwu, TAO Xiaojie

2017, 50(12):  165-172.  DOI: 10.11930/j.issn.1004-9649.201707136

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Inverter-type distributed generation output is different from traditional generation during system fault. This results in challenges on fault characteristic analysis and protection schemes of microgrid. The output of inverter-type DG depends on not only microgrid conditions but also control modes. Firstly, new equivalent fault analysis model of microgrid is developed with consideration of PQ control and V/F control constraints. Secondly, Based on equivalent model, DG fault voltage and current under both symmetrical and asymmetrical conditions are determined. Finally, the well-developed power grid simulation software DIgSILENT is used to build microgrid simulation model of inverter-type DG with both PQ control and V/F control functions. The simulation results are compared with results calculated by traditional fault analysis. The comparison results verify the effectiveness and accuracy of proposed fault analysis method.

Energy Conservation and Environmental Protection

The Application and Performance Evalution of Bundle Precipitator in Series Absorpti Tower of Desnifurization System

YOU Liangzhou, DU Zhen, JIANG Jianping, ZHU Yue

2017, 50(12):  173-177.  DOI: 10.11930/j.issn.1004-9649.201608057

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To achieve the target of ultra-low emissions, the original defogger was replaced with a tube bundle precipitator in the 670 MW coal-fired units. In this paper, by tuning the electric fabric filter bypass opening and desulfurization spray level system operating mode, the overall coordination cleaning efficiency of desulfurization system was tested under various working conditions. According to the test results, the tube bundle type dust collector exhibits higher efficiency under high-load conditions. However, under low load conditions, the efficiency drops down drastically and the slurry droplet concentration goes up. Especially, the spray layer operation mode has great impacts on the dust washing effect.

Research of PM Removal Mechanism and Emission Characteristics for WESP in a Coal-Fired Power Plant

LIU Hanxiao, YAO Yuping, LI Jianguo, CHEN Zhaomei, FANG Xiaowei

2017, 50(12):  178-184.  DOI: 10.11930/j.issn.1004-9649.201706180

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In this paper, the WESP fine particle strengthening removal mechanism is analyzed for the first time from the aspects of strengthened charging and promoted fine particle coalescence. Then through further investigation and on-site measurement, the PM emission characteristics of WESP are studied comprehensively. The inlet and outlet particle size distribution, total dust concentration, PM₁₀/PM_2.5 concentration and SO₃ concentration of WESP were measured by virtue of ELPI, filter cartridge, ELPI/PM-10 or DGI and condensation method, respectively. Based on the statistical analysis of the research and measured data, it is shown that PM₁₀ is divided into 12 levels ranged from 0.03 μm to 10 μm by using ELPI and dust particles in each level are removed significantly using WESP with the removal efficiency of both number concentration and mass concentration exceeding 40%, and the maximum even reaching more than 90%. The outlet dust concentration of WESP is between 0.43 mg/m³ and 12.5 mg/m³, most of which is lower than 5 mg/m³. Moreover, dust removal efficiency is above 70%, with the maximum over 90%. The outlet PM_2.5 concentrations of WESP are limited in the range between 0.35 mg/m³ and 1.59 mg/m³ while most of them are lower than 1 mg/m³ and PM_2.5 removal efficiency is above 60%, with the maximum more than 90%. The outlet SO₃ concentration of WESP is within the range between 0.10 mg/m³ and 3.21 mg/m³. SO₃ removal efficiency is achieved above 60% with the maximum more than 90%. The outlet CEMS data for three months of continuous operation of WESP of a 350 MW unit was studied and the result showed that hourly concentration control rate reached 100%. Therefore long term stable operation of the system is realized.