Electric Power

A novel fault location method based on the approximate entropy for small current grounding system

WANG Xiao-wei, ZHANG Tao, TIAN Shu, ZHANG Yu-jun, LI Tao, CHENG Zhi-lei

2012, 45(3): 1-6. DOI: 10.11930/j.issn.1004-9649.2012.3.1.5

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A new fault location method based on approximate entropy for the transient zero-mode power was proposed. In this method, the approximate entropy value of every detection point for transient zero-mode power was calculated first. The scale factor value of approximate entropy for each section was then calculated and compared to the threshold which preset in control main station. If the scale factor value is greater than the threshold, the section is determined as healthy, otherwise faulty. A large number of ATP simulation shows that fault in both ungrounded system and grounded system with arc suppression coil can be located effectively with random initial phase and transition resistance. The method has good performance even with grounding impedance as high as 5 000 ohms. According to the ratio curve of scale factor versus margin settings, the optimal working range for each initial phase was also defined.

Protection of AC filter connection in HVDC

SONG Hong-tao, HU Xiao-jing, WANG Hong-qing, ZHANG Guang-pu, WANG Hai-liang, ZHU Yan-na

2012, 45(3): 7-10. DOI: 10.11930/j.issn.1004-9649.2012.3.7.3

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A HVDC system has some characteristics which should be considered in AC filter connection protection, such as harmonic, island operation, breaking capability of circuit breaker and TA saturation. An AC filter connection protection scheme was proposed with the consideration of these characteristics. The scheme includes differential protections taking accounts of TA saturation and over voltage protections involving the factors of harmonic, AC over voltage, circuit breaker capacity and island operation. The proposed scheme has been successfully applied to a number of domestic projects of HV and EHV DC. Operation performences show that the proposed protection scheme can provide a good protection for AC filter connection.

Study on the HVDC AC filer synchronous switching and protection improvement

CHANG Yong, CHEN Qiu-an, ZHANG Ping, YAO Hong-chuan

2012, 45(3): 11-13. DOI: 10.11930/j.issn.1004-9649.2012.3.11.2

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Capacitive compensation is widely used in power systems at different voltage levels. Gaoling back to back converter station is a key project of State Grid, which connects the Northeast and North China power grids. Mal-operations of the AC filter differential protection occurred after the station was commissioned in 2008. In order to keep the security of the AC filter and capacitor banks, unfavorable transient problems associated with capacitor switching and potential nearby faults were inspected thoroughly. The configuration of the AC filter in GaoLing station was introduced. Based on a fault record, the causes of one of the mal-operation were analyzed. The optimal filter switching time was studied. Based on the analysis, parameters for the point on wave switching equipment were calculated. Improvements was made in the AC filter differential protection.

Design and full-scale test for steel tubular tower of UHV and EHV quadruple-circuit transmission line on the same tower

LI Qing-hua, YANG Jing-bo, HAN Jun-ke, DONG Jian-yao

2012, 45(3): 14-17. DOI: 10.11930/j.issn.1004-9649.2012.3.14.3

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The SSZT2 tower,on which 1 000 kV AC double-circuit and 500 kV AC double-circuit are arranged,is the highest steel tubular tower with the biggest load and largest transmission capacity within conventional lines all over the world. The tube is made from Q420 high-strength steel and connected by plug-in boards and forging flanges. The strength classification technical is applied in forging flanges for the first time. The design of multi-circuit steel tubular tower for UHV and EHV is improved through different aspects of studies including tower structure, wind vibration coefficient, Eiffel effect and bending moment. The success of full-scale test verified the reliability in design and manufacture of multi-circuit steel tubular tower for UHV and EHV which can be used in future projects.

Electromagnetic environment monitoring of typical transmission substation and transmission in Foshan area

LIU Yi-jun, WANG Yan, REN Ya-ying, NI Yuan

2012, 45(3): 18-22. DOI: 10.11930/j.issn.1004-9649.2012.3.18.4

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By field measurement and simulation of electromagnetic field of 110~500 kV typical transmission lines and substations in Foshan area, the electromagnetic environment impact and distribution levels around different transmission lines and substations are given. The results show that all environment parameters meet related standard requirement. The characteristics of electromagnetic field around transmission device such as 500 kV transmission line and 220 kV urban distribution station are analyzed in detail. Suggestions for planning and design of future transmission network with respect to electromagnetic field environment problem are proposed.

Construction technology and application effects of a novel anti-icing coating for insulator

PENG Xiang-yang, XU Zhi-hai, MAO Xian-yin, JIA Zhi-dong

2012, 45(3): 23-27. DOI: 10.11930/j.issn.1004-9649.2012.3.23.4

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Transmission lines ice flash may occur continously in large scale under particular climate conditions, which is serious threat to power grid security. In year 2010 to 2011, large scale ice flash accident happened again in Southern Power Grid after ice disaster in 2008. An active anti-icing coating for overhead transmission line insulator was proposed. The coating painting methods on insulator surface were also developed. The testing results in climate chamber verifies the significant anti-icing effect of proposed coating material. The coating can delay and reduce the formulation of ice on insulator, which in turn reduce transmission line ice flash accident rate. Observation and montioring data on field device shows that proposed anti-icing coating has practical effect. However, field construction technology and environmental condition of overhead transmission lines have big impact on the effect of anti-icing coating. Further study on coating application is needed in order to achieve practical goals.

The impact of load shedding characteristic on transient stability analysis

LI Hai-feng, ZHENG Jing-yuan, XU Yong-hai

2012, 45(3): 28-32. DOI: 10.11930/j.issn.1004-9649.2012.3.28.4

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Load model has great impact on power system simulation results. With the increasing number of voltage sensitive loads in the grid, the impact of load shedding due to short time low voltage on the simulation results cannot be ignored. The analysis of field measurement data indicates that load shedding happens during system low voltage. The simulation results of a ten-machine thirty-nine node system shows the importance of load shedding characteristic during transient stability analysis. Based on the analysis of field data and traditional load model, a new load model with load shedding factor was proposed. The proposed model has the ability to describe load shedding characteristic under low voltage and provides guidance for power system dynamic analysis.

Economic benefits and voltage stability of distributed generation integrated into distribution network

LI Hong-ze, WANG Bao, GUO Sen

2012, 45(3): 33-37. DOI: 10.11930/j.issn.1004-9649.2012.3.33.4

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With the connection of main network and distribution network through regression analysis, an analytic model on economic benefits and voltage stablity of DG integrated into distribution network is established based on spot price theory. A testing system is established by intergrating 4 DGs into the distribution network connceted to Bus 8 in IEEE 30-bus system.A quantitive analysis of economic benefits and voltage stablity before and after DG's integration is performed for 6 typical days. Results demonstrate that after reasonable integration of DG, several different goals can be achieved. Payment prices of end-users are reduced and possible transmission congestion is eliminated effectively. Loss rates of distribution network and main network are decreased significantly, thus improving power transmission efficiency. Total power purchase costs of distribution network and main network are also reduced, thus elevating market operation efficiency. DG owners can obtain relatively high profits by full power generation due to comparatively lower costs during load peak. Distribution network voltage stability is also enhanced. With the development of DG technique, DG will become an effecitve supplement to traditional grid with its possessing cost and location advantages.

Research on microgrid power quality and control measures

LIU Jin-xin, LI Peng, CUI Hong-fen, XI Peng

2012, 45(3): 38-42. DOI: 10.11930/j.issn.1004-9649.2012.3.38.4

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The microgrid technologies have many outstanding advantages. However, the inherent characteristics of distributed generators （DGs）, the special network topology and the operation performances of microgrids bring unfavorable impacts on microgrid power quality. The structure and performances of microgrids were discussed. Based on the discussion, the microgrid power quality was analyzed and compared with traditional distribution grids. By replacing lowpass filter with mathematical morphological filter in detection unit, shunt active power filter （SAPF） model was improved. The selection of filter structure elements was also well analyzed. Simulation study was done with Matlab/Simulink software. The simulation results prove that the improved SAPF model can meet the real-time requirements of microgrids for power quality regulating devices.

Comparison analysis and improvement scheme on two soft measurement methods for calorific value

WANG Qi, LIU Ji-zhen, LIU Xin-ping, TIAN Liang

2012, 45(3): 43-46. DOI: 10.11930/j.issn.1004-9649.2012.3.43.3

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Calculating the calorific value signal on line is the supporting for the optimization of boiler control and combustion. Based on the energy balance and chemical mass balance, the soft measurement of calorific value was researched, and was implemented in a 600 MW thermal power unit. The calculation results show that the energy balance method has higher static precision and worse dynamic characteristics, and the chemical mass balance method has better dynamic characteristics and lower static precision. So an improvement of information fusion technology was proposed. A new calorific value signal with the low frequency of energy balance signal and the high frequency of the chemical mass balance signal was constructed, which can meet the requirement of static precision and dynamic response speed.

Design and realization of the multi-model function in stimulation mode simulation system

CAO Gao-cheng, DONG Ze, SONG Yun-yan, ZHANG Yue

2012, 45(3): 47-50. DOI: 10.11930/j.issn.1004-9649.2012.3.47.3

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The multi-model function was widely used to increase the utilization rate of simulation training system （STS）. Based on the function the efficiency of STS in thermal power plant will be greatly improved, so it has become the essential function in thermal power unit training systems. The multi-model simulation system of domestic power plants was introduced. The structures of simulation systems in stimulation mode and traditional mode were analyzed, as well as the similarities and differences of multi-model functions between them. Relying on the stimulation mode simulation support system, which was based on virtual DCS, and was independently researched and developed, the real-time database was constructed. The database was used for the design of some sub-functions such as multi-model data management, simulation task scheduling and model control in the Windows platform. Finally an example of a triple model simulation system was realized.

Application of turbine-driven induced draft fan in 1 000 MW ultra-supercritical unit

FU Long-long, LEI Zhao-tuan, GAO Jing-hui, LI Xue-zhong, YAO You-jiang

2012, 45(3): 51-53. DOI: 10.11930/j.issn.1004-9649.2012.3.51.2

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For energy-saving and emission-reducing, enhancing the efficiency of energy utilization, the technological innovation for induced draft fan with the maximum power in 1 036 MW ultra supercritical unit of Huaneng Haimen Power Plant was implemented. Changing general motor-driven induced draft fan to turbine-driven mode for the first time, merger setting the induced draft fan and the FGD booster fan, not setting FGD booster fan alone, the power plant using electricity rate was obviously reduced. And 6 kV power of the auxiliary power system was reduced. The induced draft fan can realize variable speed adjustment, and the loss of throttling was reduced, the energy-saving effect was remarkable. The operation of the induced draft fan driven by turbine was stable, the function of furnace pressure adjustment was good, and which can satisfy the index request of induced draft fan performance under full load condition.

The new combination of fast-cooling down technology in 1 000 MW units

CHEN Fan-fu, FENG Ting-you

2012, 45(3): 54-57. DOI: 10.11930/j.issn.1004-9649.2012.3.54.3

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The new technology of combined fast-cooling down, the real fast-cooling down process and economic performance valuation of the 1 036 MW ultra-supercritical unit in Huaneng Haimen Power Plant were introduced. Through the actual analysis on the depth sliding parameter shutdown technology and the scheme of multi-means combination for turbine fast-cooling down, the fast and safe cooling down of turbine in each stage were achieved, the cooling time of the turbine was greatly reduced, the maintenance time duration was saved, the availability of unit was improved, and its economic and social benefits were significant. The operation idea and recommended rapid cooling down curve for turbine in million-kilowatt unit were summarized and given. The optimization method, procedure and attentions were given, which can provide a reference and application for the depth fast-cooling down in million-kilowatt unit.

Property evaluation for heat resistance of condensate polishing treatment with anion resin and filtering element in air-cooling units

LIU Wei-wei

2012, 45(3): 58-61. DOI: 10.11930/j.issn.1004-9649.2012.3.58.3

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During high temperature period in summer, the temperature of condensate water in direct air-cooling unit may be over the inherit range of ion exchange resin, which are strong base anion exchange resin and filter element. The systemic study of heat resistance on condensate polishing treatment with anion exchange resin and filter element of powder resin filter at high temperature in the air-cooling unit was implemented. Six representative kinds of anion exchange resin were selected to implement the static experiments at 95℃. Three selected anion exchange resins, which meet the standard of electric power industry DL/T953-2005, were implemented dynamic experiments for heat-resistant at 70 ℃, 75 ℃ and 80 ℃.Through testing the change of the rate of decline in anion exchange resin alkali groups and the extraction of the three anion exchange resins in the high temperature cycle, the thermal stability performance of anion exchange resin was inspected. The anion exchange resin with finer heat-resistant performance applied in power plant for determining the effect of silicon removal was selected. The organic extraction of winding filter element of powder resin filter at high temperature was tested. The result shows：（1） the exchange capacity of strong base groups of anion exchange resins is inversely proportional to run time and operation temperature at 70 ℃, 75 ℃ and 80 ℃.The longer the operation time, the higher the operation temperature, the faster the exchange capacity of strong base groups decreased. Comparing the three selected kinds of anion resin, the heat-resistant performance of big hole of Ⅰtype styrene of anion exchange resin of Germany is better; （2） the heat resistance of polypropylene winding from different manufacturers varies greatly. The heat resistance of the two selected kinds of winding filter element in air-cooling unit can meet the technical requirements, but the operation temperature should not be more than 80 ℃.

Experimental study on the characteristics of NO_x emissions from 600 MW supercritical bituminous coal fired boiler with swirl burner

YUE Jun-feng, QIN Peng, ZOU Lei, LIANG Shao-hua, ZHANG En-xian, HUANG Lei

2012, 45(3): 62-67. DOI: 10.11930/j.issn.1004-9649.2012.3.62.5

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NO_x emissions from a 600 MW supercritical boiler with swirl burner were investigated by performing a serial of tests such as changing O₂ concentration, air-distribution of different level burners, secondary air ratio, secondary and tertiary air swirl strength, air-distribution of the burners in same level and boiler load. The test results show that for the bituminous coal fired boiler with swirl burner, the O₂ concentration, over fire air （OFA） ratio, boiler load and air-distribution mode of the burners in same level are the main factors affecting NO_x emissions. In order to reduce NO_x emissions and keep higher boiler efficiency, the following principles about combustion adjustment should be obeyed: （1） the O₂ concentration should be kept in the premise of ensuring safe operation of boiler as lower as possible;（2） large proportion of OFA should be adopted; （3） boiler load should not be too low; （4） two-peak air distribution mode should be taken among the same level burners.

An optimized CVR model for short-term wind speed forecasting

LI Yuan-cheng, YANG Rui-xian

2012, 45(3): 68-71. DOI: 10.11930/j.issn.1004-9649.2012.3.68.3

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It is difficult to merge wind power into a grid, owing to wind power’s uncertainty and prediction inaccuracy. Wind speed is an important factor affecting wind power, so the accuracy of wind speed prediction has a major impact on the wind power prediction. An optimized prediction model based on core vector regression（CVR） is proposed in short-term wind speed forecasting. The wind speed data from a wind farm are collected hourly as the inputs. The particle swarm optimization （PSO） method is used to optimize the CVR model parameters. Experimental results show that the method has higher prediction accuracy than the CVR and support vector regression （SVR） method.

Review of advanced energy research projects in U.S.A.

ZHU Xin-jia

2012, 45(3): 72-75. DOI: 10.11930/j.issn.1004-9649.2012.3.72.3

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About 121 advanced energy research projects are introduced in ARPA-E’s Fiscal Year 2010 Annual Report. All these projects, which cover many areas in energy industry with a total of $365.4 million, are for accelerating the development of transformational energy technologies. These ARPA-E funded projects are full of risk in investment but will benefit the U.S. greatly if some of them would be successful. They will keep the U.S. in technological lead in the world. The backgrounds, selection criterions, risk control and administration of the projects were described. Some reference meanings for China’s science and technology administration in energy industry were pointed out.

Indicators system of strategic environmental assessment for urban green electricity power

CHENG Chao, ZHOU Yu-hui, YUE Kai-wei, YANG Jian, HE Zhan-yong, LIANG Na

2012, 45(3): 76-80. DOI: 10.11930/j.issn.1004-9649.2012.3.76.4

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There is no systematic evaluation system for urban green electricity power at present, in order to promote the orderly and rapid development of the urban green electricity power, the indicators system was researched. The DPSIR framework model of strategic environmental assessment for the evaluation of urban green electricity power was constructed for the first time. The content and relations between related factors of DPSIR framework model were introduced. A fuzzy complementary judgment matrix was established and was transformed into a fuzzy consistent judgment matrix. Based on the application of fuzzy analytic hierarchy process（FAHP） method for determining the weight of each factor, the more comprehensive and operable indicators evaluation system of urban green electricity power was constructed. By using the evaluation system to analyze a city's green electricity indicators system, the results are: the share of renewable energy is the most important for the urban green electricity indicators system, the development of the renewable energy industry is the second and the deliverability of green electricity market is the third.

Energy and electricity consumption level in 2020 based on the CO₂ reduction target

WU An-ping, HE Yan, LIU Yue, CHEN Lei

2012, 45(3): 81-84. DOI: 10.11930/j.issn.1004-9649.2012.3.81.3

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According to the government’s commitment on CO₂ reduction to the international community, an energy demand formula which can reflects the variation influence of CO₂ emission per GDP was proposed. By quantitatively research of the effect of correlative factors on the energy demand, the total energy consumption of different situations in 2020 was gained. According to the inherent relations between supplier’s total energy consumption and electricity consumption level, the community’s total electricity consumption was calculated. The total energy consumption of China in 2020 should be controlled within 5.1 billion tons of standard coal. The electricity consumption of entire community is around 7 500 billion kW·h. The results can provide a reference for related departments to make appropriate control target of total energy consumption.

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