Table of Content

30 April 2014, Volume 47 Issue 4

Previous Issue    Next Issue

Orginal Article

Research on Wind Power Operation and Accommodation Problems in China

PEI Zhe-yi, FAN Gao-feng

2014, 47(4):  1-4.  DOI: 10.11930/j.issn.1004-9649.2014.4.1.3

Asbtract ( )   PDF (789KB) ( )  

References | Related Articles | Metrics

With the rapid development of wind power in China, it is an urgency issue to solve the problems of wind power accommodating and curtailment . Based on the comparison with the European and American countries, this paper analyzes the wind power characteristics in China, including development speed, large-scale, high voltage integration, long-distance transmission, intermittent, and random characteristic, etc. It is pointed out that the causes of difficulty to accommodate large scale wind power are structural contradictions of power resources and inadequate capacity of interregional grid transmission . In order to improve the wind power accommodation level, the next road map is presented such as building inter-provincial grid, optimizing structures of power sources, constructing matched policy, etc.

Failure Analysis of T91/HR3C Dissimilar Steel Welded Joints in High-Temperature Reheater of USC Boilers

WANG Wei, WANG Xue, ZHONG Wan-li, HU Lei, HU Ping

2014, 47(4):  5-8.  DOI: 10.11930/j.issn.1004-9649.2014.4.5.3

Asbtract ( )   PDF (8766KB) ( )  

References | Related Articles | Metrics

Many dissimilar steel joints are used in the high-temperature section of boiler heating surface tubes of ultra-supercritical (USC) thermal power units and their welding quality and performance directly determines the operation security of the units. Macroscopic and microscopic examinations on the failure specimen of T91/HR3C dissimilar steel welded joints are conducted for the high-temperature reheater in a 3 033-t/h USC boiler. The results show that the failure part is located in the heat affected zone of T91 side with the cracks spreading along the circumferential direction of the tubes, starting from the CGHAZ and ending at the FGHAZ of the outer wall. The insufficient post-welding heat treatment, unstable microstructure in the HAZ and high hardness are the major causes leading to the cracking failure. Post-welding heat treatment(PWHT) is suggested to improve the ductility and reduce the residual stress for the welded joints. Furthermore, the delta ferrite of lower hardness white and bright is observed near the fusion line of T91 side. It is not directly related to the failure, but further study is required to evaluate its influence on the long-term performance of the welded joints.

Influences of Shot Blasting on Steam Oxidation Resistance of S30432 Boiler Tubes

ZHAO Hui-chuan, TANG Li-ying, JIA Jian-min, SUN Biao, WANG Cai-xia, CHEN Ji-gang

2014, 47(4):  9-13.  DOI: 10.11930/j.issn.1004-9649.2014.4.9.4

Asbtract ( )   PDF (4117KB) ( )  

References | Related Articles | Metrics

The 1 000-hour steam oxidation test was carried out on the domestic and imported, with and without shot blasting S30432 steel tube samples at temperatures of 670 ℃, 730 ℃, 760 ℃ and 790 ℃, respectively. The analysis in respect of macroscopical quality, oxidation weigh gain and metallographic performance was also conducted on the samples after the test. The test results show that shot blasting on the tube inner surface can significantly improve the steam oxidation resistance of the S30432 boiler tubes, and the oxidation rate can be decreased by about an order of magnitude. In the test condition of 1 000-hour steam oxidation, the critical temperature of rapid oxide skin growth ranges between 730 ℃ and 760 ℃ for Sample 1 and between 760 ℃ and 790 ℃ for Sample 3. The critical temperature of imported tube samples is 30 ℃ higher than that of the domestic tube samples, which indicates the better steam oxidation resistance.

Comparison between Ventilation Modes of Large Direct Air-Cooling System

LEI Ping-he

2014, 47(4):  14-21.  DOI: 10.11930/j.issn.1004-9649.2014.4.14.7

Asbtract ( )   PDF (8581KB) ( )  

References | Related Articles | Metrics

In this paper, a new hybrid ventilation system is introduced to improve the performance of the direct air-cooling systems. Two 1 000-MW direct air-cooling units are taken as the example to compare the hybrid ventilation cooling system with the mechanical and natural ventilation direct air-cooling systems with numerical simulation method. The back pressure variation obtained under typical summer wind speed conditions indicates that the hybrid ventilation direct air-cooling system has better operational economy in light winds and better security performance in strong winds than the mechanical and natural ventilation direct air-cooling systems. Therefore, it is very suitable for using in the areas of bad wind conditions.

Simulation Study on 1 000-MW Unit Speed Rise During Load Shedding

KAN Wei-min, HU Peng-fei, XIE Dan-mei, XIONG Yang-heng

2014, 47(4):  22-26.  DOI: 10.11930/j.issn.1004-9649.2014.4.22.4

Asbtract ( )   PDF (3100KB) ( )  

References | Related Articles | Metrics

Load shedding is the worst operation scenario for large turbo-generator sets, which will increase rotor speed rapidly and threaten the safety of units greatly. In this paper, the maximum speed rise of a 1 000-MW unit is simulated with Simulink, and quantitative analysis on the influence of reheat steam volume time constant and rotor time constant on the dynamic characteristics of the governing system is performed. Combined with the on-line test data, the fast cut back (FCB) condition is simulated with the speed rise estimated.

Analyzing and Troubleshooting the Steam-Flow Exciting Vibration Fault for 1 000-MW Unit

HE Guo-an, ZHAO Li-jun, REN Wei, ZHANG Xue-yan

2014, 47(4):  27-31.  DOI: 10.11930/j.issn.1004-9649.2014.4.27.4

Asbtract ( )   PDF (3072KB) ( )  

References | Related Articles | Metrics

The vibration characteristics and mechanisms are studied to address the issue of high-pressure rotor steam-flow exciting vibration which has been occurring frequently in the 1 000-MW steam turbines manufactured by DFSTW. Through the study, it is discovered that the steam excitation force mainly comes from the sealing force, tip clearance exciting force and static steam force. Therefore, corresponding measures such as changing the perspiring direction of inlet steam flows in the seal, improving the stability of bearings and optimizing the sequence of high-pressure valve opening on the spot are put forward for elimination or alleviation of the exciting vibration. At the same time, the actual engineering cases are provided for troubleshooting similar vibration faults.

Application of Flue Gas Deep Cooling System in 1 000-MW Ultra-Supercritical Units

DU He-chong, WU Ke-feng, SHEN Jian-dong, YUAN De-gang, LI Da-cai

2014, 47(4):  32-37.  DOI: 10.11930/j.issn.1004-9649.2014.4.32.5

Asbtract ( )   PDF (1969KB) ( )  

References | Related Articles | Metrics

In order to fully utilize the waste heat from flue gas to heat up the condensate to realize the low-temperature dust removal with high efficiency in the electrostatic precipitator(ESP) through reducing the fly ash specific resistivity at lower flue gas temperatures, to improve the boiler efficiency and to reduce the heat consumption and gross coal consumption for power generation units, a flue gas waste heat recovery device is designed and installed between the air pre-heater outlet and the ESP inlet in a 1 000-MW boiler. Practical operation shows that with the flue gas deep cooling device installed, the ESP dust removal efficiency is increased by 0.1% while the desulfurization water consumption is lowered substantially and the net coal consumption is significantly decreased.

Study on Oil-Saving Technology in Startup and Shutdown of 1 000-MW Units

ZHENG Wen-guang, SI Shun-yong, ZHU Liang-song, WU Gui-fu, CHEN Jian

2014, 47(4):  38-43.  DOI: 10.11930/j.issn.1004-9649.2014.4.38.5

Asbtract ( )   PDF (1173KB) ( )  

References | Related Articles | Metrics

In this paper, the high fuel oil consumption during the startup and shutdown processes of 1 000-MW ultra-supercritical units with single bypass system is analyzed in details. Several measures to lower the oil consumption are proposed, such as reducing the output of single oil gun and the number of oil guns, minimizing the heat losses of steam and water in the startup drainage system, optimizing the operation mode of unit bypass system, shortening the warm-up time and the time from synchronization to the minimum oil-free stable-combustion loading, increasing the boiler water temperature in the process of cold recycling cleaning and adjusting the coal level of the coal bunker in advance when the unit is shut down. Additionally, it is recommended that by heating up the starting boiler with neighboring boiler and implementing tiny-oil ignition system the oil consumption can be reduced even further during unit startup.

Operation Optimization for Condensate Polishing Mixed Bed of 900-MW Units

ZHANG Ting

2014, 47(4):  44-47.  DOI: 10.11930/j.issn.1004-9649.2014.4.44.3

Asbtract ( )   PDF (1417KB) ( )  

References | Related Articles | Metrics

Layered resin and residual failure resin appear in the spare mixed bed of the condensate polishing system for the 900-MW units of Shanghai Waigaoqiao No.2 Power Generation Co. Ltd., after seven-year operation. Studies on these phenomena are carried out, which demonstrates many problems in the system such as incomplete closing of valves, high water level before resin mixing, deflected spray nozzle and inadequate pressurization of filling water. Therefore, an optimization plan is made and implemented to address the above problems. On the premise of the qualified water quality through the mixed bed as well as the water and steam qualities of the thermal system, the throughput in the mixed bed cycle of the condensate polishing system is increased by 20%, while the acid and caustic consumption is reduced by 33% and the demineralized water used for resin regeneration per unit is reduced by 4 000 t annually, which shows significant economic and environmental benefits.

Optimization Tests on Main Steam Pressure for 600-MW Air-Cooling Heat Supply Units

WANG Jin-quan, LI Jun, LU Hong-kai

2014, 47(4):  48-51.  DOI: 10.11930/j.issn.1004-9649.2014.4.48.3

Asbtract ( )   PDF (827KB) ( )  

References | Related Articles | Metrics

The variation of steam extraction volume and exhaust pressure with main steam pressure is studied through the tests on the 600-MW air-cooling heat supply units and the quantitative measurement on the changes of the heat consumption rate under the conditions of different extraction volumes and exhaust pressures is conducted. The year-around efficient fixed and sliding pressure operation model is put forward and the original unit sliding pressure operation logic is modified. The operation results show that a decrease of net coal consumption of 1.1 g/(kW·h) can be obtained when the sliding pressure curve is at the loads of 450 MW and the heating steam extraction is 300 t/h.

Analysis and Processing on Shaft Displacement Migration in 330-MW Steam Turbines

WANG Wen-bing, ZI Juan, ZHAO Yan, HE Qiang, ZHAO Yan-tao

2014, 47(4):  52-55.  DOI: 10.11930/j.issn.1004-9649.2014.4.52.3

Asbtract ( )   PDF (1835KB) ( )  

References | Related Articles | Metrics

The steam turbine shaft displacement protection device can precisely reflect the working condition of thrust bearings. The gradual increasing axial displacement is observed frequently after the heating transformation was carried out in Turbine 3 of one power plant, and its variation is inconsistent with the temperature variation of thrust shoe. Through disassembling the thrust shoe and careful inspection, it is discovered that the thrust shoe is not in parallel with the thrust collar, which causes the increasing axial displacement during unit operation. Then the thrust tile repairing technology is modified and the thermal measurement points are adjusted. After such maintenance, the axial displacement is restored to the ex-factory value and the unit keeps running in a stable state.

The Retrofit of High-Temperature Corrosion Prevention and Operation Adjustment for 600-MW Supercritical Boiler

CHEN Min-sheng, LIAO Xiao-chun

2014, 47(4):  56-59.  DOI: 10.11930/j.issn.1004-9649.2014.4.56.3

Asbtract ( )   PDF (1921KB) ( )  

References | Related Articles | Metrics

The high-temperature corrosion was discovered in large area of the fire-side water-walls at the burner zones in one 600-MW supercritical boiler. In order to mitigate the possible risk to the water-wall operation, the retrofit of the boiler combustion system and the optimal design on the main burners with great impacts on both sidewalls are carried out. Meanwhile, three layers of close-to-wall air are installed along the front and back water-walls to reduce the concentration of de-oxidation atmosphere near the water-walls. Through the adjustment of the horizontal and vertical air distribution in the furnace, the negative effects of tube wall overheat in high-temperature heating areas, the increase of CO concentration in the rear pass and the uneven distribution of NO_x emission concentration caused by the installation of the three layers of close-to-wall air are effectively harnessed. After the retrofit, the factors causing high-temperature corrosion of boiler water walls are constrained, the average volume fraction of CO near the sidewalls is about 0.02%, and that of H₂S is less than 60×10^-6. Additionally, the boiler efficiency and the NO_x emission concentration are almost kept at the same level as those before the retrofit, which shows the good overall performance of the boiler.

Design and Operation of Supercritical Boiler Burning High Sodium and Chlorine Coals from Hami Area

WANG Yan-lin, GUO Qian-xin, ZHAI Wen-dong

2014, 47(4):  60-64.  DOI: 10.11930/j.issn.1004-9649.2014.4.60.4

Asbtract ( )   PDF (2667KB) ( )  

References | Related Articles | Metrics

The coals from Hami and Zhundong areas of Xinjiang containing high concentration of alkali and chloride ions, are prone to cause severe contamination, slagging and corrosion in supercritical boilers, which will affect the operation security of the equipment. According to the quality of designed coal for one 660-MW supercritical boiler under construction and based on the operation experience of 300-MW boilers and the mixed coal firing tests carried out on a 3-MW test bed for coal combustion, an optimization scheme for the design and operation is proposed to control the furnace outlet flue gas temperature by enlarging the furnace, and improve the contamination, slagging and corrosion on the heating surfaces by installing more soot blowers and carrying out mixed coal combustion and combustion adjustment etc. It is expected that with these measures, the 660-MW supercritical boiler being constructed can safely burn the Hami high alkali metal coal up to 60% of its overall coal fuels, and the annual fuel costs will be reduced by 30 million yuan, which means a great improvement for the economic efficiency of the power plant so as to bring the power transmission from the west to the east into full play.

Research of Modular Technology for Nuclear Power Projects Based on Reference Nuclear Power Plant

LU Qin-wu, ZHAO Shu-yu, LI Yi, HAN Xiao-ping, CHAI Wei-dong, ZHANG Shu-xia

2014, 47(4):  65-69.  DOI: 10.11930/j.issn.1004-9649.2014.4.65.4

Asbtract ( )   PDF (1236KB) ( )  

References | Related Articles | Metrics

As an important technology which can effectively shorten the construction period and reduce the cost of nuclear power projects, the modular technology has become one of the development trends for the third generation of nuclear power plants. Taking the present mainstay CPR1000 nuclear power reactor as reference plant and absorbing the advanced foreign modularization technologies, the overall concept design of main buildings of the nuclear island is completed with the independently-developed 3-D modular design system. On this basis, the detailed design for typical modules is carried out so as to verify the feasibility of the technology. Besides, an analysis on implementation of modular technology is performed from the aspects of procurement and construction so as to evaluate the feasibility of the research achievements for practical engineering projects.

Study on Voltage Stabilization of Tibet Nyingchi Power Grid Based on PSASP

FANG Ren-ting, TIAN Wei-ping

2014, 47(4):  70-74.  DOI: 10.11930/j.issn.1004-9649.2014.4.70.4

Asbtract ( )   PDF (1176KB) ( )  

References | Related Articles | Metrics

With the economic growth of Nyingchi, Tibet, the electric power grid has been quickly developing. As the result, the regional integral connection of has been achieved, its scales and the structure becomes bigger and more complex than before, in which the commerce and the civil power loads are main kind of power loads. In order to get the operation of Nyingchi power grid more security and stability. The new criterion method of small disturbance voltage stability in power system analysis software package(PSASP) is applied to calculate and analyze the voltage stabilization detailedly for Nyingchi power grid to recognize the weak buses and areas. Therefore, the voltage stability margin is carried out. Finally, some significant suggestions are offered for the system operation and dispatching, as well as the monitoring and control of the voltage stability.

Fault Diagnosis of Power Transformer Based on Vibration and Wavelet Neural Network

WANG Chun-ning, ZHU Yue-guang, MA Hong-zhong, ZHAO Hong-fei, CHEN Ji-ning

2014, 47(4):  75-79.  DOI: 10.11930/j.issn.1004-9649.2014.4.75.4

Asbtract ( )   PDF (997KB) ( )  

References | Related Articles | Metrics

A fault diagnostic method of power transformer based on vibration and wavelet neural network is presented, which gets the characteristics of the vibration in frequency domain from the vibration sampled from the tank of transformers to train for the wavelet neural network(WNN). With the output of the wavelet neural network, we can get the relationship between the faults and the frequency characteristics can be obtained. The experiment results show that the proposed method can be used for diagnosis of power transformer and output the type of the fault, and the wavelet neural has a good generalized performance.

Design and Implementation of Dispatcher and Operator Training Simulator Based on SG-OSS

JIANG Ye-feng, WEI Wen-hui, GAO Feng, ZHOU Ting, YUAN Qi-hai, XU Tian, ZHOU Shu-jin, FAN Qing, WANG Guo-ping

2014, 47(4):  80-85.  DOI: 10.11930/j.issn.1004-9649.2014.4.80.5

Asbtract ( )   PDF (2036KB) ( )  

References | Related Articles | Metrics

To meet training requirements of operators of electric power dispatching and control centers, this paper puts forward overall and systematic design of dispatcher and operator training simulator based on smart grid dispatching technical support system (SG-OSS), introduces software and hardware architecture, and describes support platform layer, simulation model layer, function layer and the application layer in detail. The research achievements have been applied to electric power dispatching and control center of Jiangsu province, and played the key role in the joint-act of anti-accident exercises on June in 2013. Application effects show that the training system can build all scenic, all processing, all dimensional and high fidelity training simulation platform for electric power dispatch, operator and substation operator, which can meet training, exercise and evaluation needs of electric power dispatching and control center.

On-line Detection Algorithm for Interharmonics Based on Spectrum Domain Filtering

CHI Yuan, TANG Wen-zuo, LIU Guo-ping, LIANG Wen-ju, ZHOU Nian-cheng

2014, 47(4):  86-91.  DOI: 10.11930/j.issn.1004-9649.2014.4.86.5

Asbtract ( )   PDF (879KB) ( )  

References | Related Articles | Metrics

Magnitude and phase on-line monitoring of harmonics and interharmonics are the foundation of power quality improvement while speed and precision of the algorithm are the keys of on-line monitoring techniques. This paper studies the spectrum leakage of harmonic and interharmonic and then proposes a rapid on-line detection algorithm based on spectrum domain filtering. The algorithm divides the original signals into three parts those are fundamental signals, harmonic signals and interharmonic signals, and then filters the harmonic signals in frequency domain so as to eliminate the spectrum interference to the interharmonic signals. Thus, only one time of FFT(Fast Fourie Transform) calculation is needed, which reduces calculation burden of the algorithm remarkably with a good precision and makes the algorithm easy to be implemented in on-line monitoring device. A comparative simulation of four different interharmonic detection algorithms was conducted in Matlab to verify the feasibility and superiority of the proposed algorithm.

Status Evaluation Method of Relay Protection Based on the Variable Weight Theory

PENG Zhi-feng, YANG Ming-yu

2014, 47(4):  92-96.  DOI: 10.11930/j.issn.1004-9649.2014.4.92.4

Asbtract ( )   PDF (864KB) ( )  

References | Related Articles | Metrics

Status maintenance for relay protection needs the basis of a scientific and reasonable status evaluation. According to the constructing principle of status evaluation index system, the main factors which affect the status of relay protection devices and secondary loop are extracted, and a status indicator model for status evaluation is constructed. By using analytic hierarchy process (AHP) and entropy value method to determine a combinational weight, an idea of variable weight was introduced to adjust the weight of each status indicator. In addition, through building a membership function in fuzzy normal distribution of status indicators, the status of relay protection devices and secondary loop in a certain space was evaluated. The result shows that the fuzzy comprehensive evaluation method based on variable weight can accurately evaluate the status of devices and secondary loop, and then find the unhealthy ones.

A Novel Type of High Gain DC-DC Converter

GUI Cun-bing

2014, 47(4):  97-101.  DOI: 10.11930/j.issn.1004-9649.2014.4.97.4

Asbtract ( )   PDF (2333KB) ( )  

References | Related Articles | Metrics

With the wide application of new energy of solar and fuel cells whose output voltage is low, researches on high power and high gain converter become one of the focuses of power electronics. To obtained the high gain and high reliability of the DC-DC converter, a novel type of no-isolated passive-clamped interleaving converter based on precharged capacitance unit is proposed, in which the inputs are in series and the outputs in parallel. To test the theory analysis, a 200 W experimental equipment is built. The experimental results indicate that this passive-clamped circuit can receive leakage inductance energy effectively, zero-voltage-switched and zero-current-switched are achieved, which has the similar effectiveness of active-clamped circuit, and the reliability of this device is improved. By using of this new converter, high gain is obtained in the context of suitable duty ratio, transformer turns-ratio is reduced and reverse recovery is restrained, the efficiency is improved, the power density is also improved, and the size of magnetic cores is reduced effectively. So, it is proved that this new converter is novel and practical.

Analysis on Operating Characteristics of the Multi-Send HVDC System in Xinjiang Power Grid

CHEN Shu-yong, PANG Bo, CHEN De-zhi, NIU Shuan-bao, WANG Ji-li, HUO Chao, SONG Yun-ting

2014, 47(4):  102-107.  DOI: 10.11930/j.issn.1004-9649.2014.4.102.5

Asbtract ( )   PDF (1846KB) ( )  

References | Related Articles | Metrics

This paper applies MIIF(Multi-Infeed Interaction Factor) and MOSCR(Multi-send Operating Short Circuit Ratio) and other index parameters to analyze the interaction between AC/DC and multiple DC systems of ±1 000 kV and ±800 kV in Xinjiang Power Grid. Analyzing data is the high load mode of Xinjiang Power Grid in the winter of 2015, on this basis, further simulation is implemented by using BPA simulation software to analyze the characteristics of multiple DC systems interactions and the emergency support with DC power, as well as the system stability with DC faults. Analysis results show that in the typical fault conditions such as single-pole block, the interaction between AC/DC and multiple DC systems is reasonable, but double-pole block and other serious conditions will make the system in a risk of angle and voltage instability. Power supply is one of the key factors to support power grid safety. Using emergency support with DC power can improve the stability of the sending system.

The Coordination Control for SSO Restrain in Multi-HVDC Transmission System

QI Yang

2014, 47(4):  108-112.  DOI: 10.11930/j.issn.1004-9649.2014.4.108.4

Asbtract ( )   PDF (2473KB) ( )  

References | Related Articles | Metrics

More attentions have been paid to subsynchronous oscillation(SSO) caused by HVDC transmission system in these years. Subsynchronous damping contraller (SSDC) is the main restrain scheme utilized widely. The coordination control of SSDC was investigated, in the background of the alternative-direct transmission power system of Guizhou province. Three conclusions were verified by both theoretical analysis and numerical simulations. Firstly, the SSDC and subsynchronous excitation damping controller(SEDC) are decoupled and can be set respectively in the SSO restrain. Secondly, the coordination control of SSDC in different converter stations are necessary. At the same time, the generator speed can be applied as the input signal for an effective restrain with the rapid development of communication technology.

Research of Phase Compensation Technology in Electronic Instrument Transformer

HUANG You-peng, ZHAO Shan, PAN Feng, XIAO Yong, SUN Wei-ming

2014, 47(4):  113-117.  DOI: 10.11930/j.issn.1004-9649.2014.4.113.4

Asbtract ( )   PDF (872KB) ( )  

References | Related Articles | Metrics

This paper introduces the analog phase compensation technology used in electronic instrument transformer , puts forward a method of digital phase compensation in electronic instrument transformer and carries out in the measurement system of 220 kV electronic instrument transformers. The resolution ratio of the phase compensation is 1 second and the maximum range of the phase compensation is 270 second, which can meet the phase adjustment of electronic instrument transformers. It also compares differences between analog and digital phase compensation technologies, analyzes their characteristics and applications.

Vehicle-Based Dry Ice Cleaning System for Live-Line Insulators in Substations of 220 kV

ZHENG Jun-jie, ZOU Jian-ming, JIANG Feng, YU Jian-hui, HAN Jun-jie, HE Xiao-xin, XU He-zhang

2014, 47(4):  118-122.  DOI: 10.11930/j.issn.1004-9649.2014.4.118.4

Asbtract ( )   PDF (1553KB) ( )  

References | Related Articles | Metrics

A set of vehicle-based dry ice cleaning system was designed, which includes a dry ice cleaning machine, cleaning terminals, mechanical arms, a hydrautic driven lifting platform, caterpillar chassis, and compressed air system, etc. This system cleans the insulating bushings and post insulators in substations with living environment by using dry ice as the insulating medium. The system can not only work fast and clean effectively, but also prevent insulators from flashover. The results of power-frequency voltage-withstand tests and leakage current tests indicate that the insulativity of the material used by the vehicle system meets the requirements of live-line cleaning works in 220 kV substations. In addition, its wireless communication will not be affected by and will not interfere with the equipment in substations. Therefore, the vehicle-based dry ice cleaning system mentioned above is safe and efficient for insulator surface cleaning.

Study on the On-line Monitoring and Fault Early-Warning Techniques for Medium Voltage Cable Terminals

WU Min-xiu

2014, 47(4):  123-127.  DOI: 10.11930/j.issn.1004-9649.2014.4.123.4

Asbtract ( )   PDF (5646KB) ( )  

References | Related Articles | Metrics

Based on the condition of wide distribution, poor working environment and inconvenient inspection of outdoor switchgear cubicles for loop network, an on-line monitoring and fault early-warning system is designed and developed for medium voltage cable terminals in order to assist the distribution network automation. The monitoring system architecture diagram is provided and the design method and function of various parts are described. To ensure the reliability of data acquisition, an anti-interference, high protection grade on-line intelligent monitoring device is developed with self testing capabilities, in which the optical fiber is used as communication medium to ensure the reliability of information transmission. In order to realize the intelligent analysis of fault early-warning techniques, a fault early-warning algorithm is designed based on the practical experiences.

Power Network Expansion Planning Integrated with Wind Farms Based on Discrete Probabilistic Load Flow

ZHANG Xin-song, GU Ju-ping, GUO Xiao-li

2014, 47(4):  128-133.  DOI: 10.11930/j.issn.1004-9649.2014.4.128.5

Asbtract ( )   PDF (1734KB) ( )  

References | Related Articles | Metrics

The discrete probabilistic formulation is utilized to describe the uncertain load flow resulted from uncertain nature of wind power generation and load. Monte Carlo simulation technique is adopted to simulate probabilistic distribution character of the integrated wind power, and normal distribution is utilized to describe the uncertainty of load. The uncertain wind power and load are converted into discrete representations with certain precision, and the probabilistic distributions of line flow are subsequently calculated based on the linear direct current power flow model. The minimized objective function of the planning model is the investment costs for the network expansion, and the chance constrained methodology is utilized to cope with the constraints on line load in the scenarios of normal and N-1 conditions. The basic Genetic Algorithm is employed to resolve the planning model. Finally, the simulation results on the modified Garver six-bus test system demonstrates the feasibility of the proposed methodology.

Transient Current Analysis Method of DFIG Voltage Dip Based on Crowbar Protection

WANG Yao-han, LIU Hui, LIU Ji-zhen, WU Lin-lin

2014, 47(4):  134-138.  DOI: 10.11930/j.issn.1004-9649.2014.4.134.4

Asbtract ( )   PDF (1473KB) ( )  

References | Related Articles | Metrics

A doubly fed induction generator (DFIG) may be switched off by its over current protection when a short circuit fault happens in the grid connected with it. Therefor, it is very important to analyze the influence of the short current on the low voltage ride-through (LVRT) of the DFIG quantitatively. The three phase symmetrical short-current linkage characteristics of DFIG have been analyzed. The transient current calculation method with voltage dip range has been given. Then the function of crowbar circuit for LVRT of a DFIG is taken into consideration, and a practical calculation method of transient current of the DFIG for three phase voltage dipping has been given. The comparation between calculation results and the test data taken from wind field prove the feasibility of transient response calculation method.

Study on Performance of Deactivated and Regenerated Catalysts for Coal-Fired Power Plant SCR Denitration

LIU Hong-hui, LIU Wei, HUANG Rui, YUAN Peng, XI Wen-chang, HUANG Xin-zhu, WANG Gang

2014, 47(4):  139-143.  DOI: 10.11930/j.issn.1004-9649.2014.4.139.4

Asbtract ( )   PDF (8558KB) ( )  

References | Related Articles | Metrics

The activity and SO₂/SO₃ conversion rate of catalyst units are tested for the fresh, deactivated and regenerated SCR catalysts used in a thermal power plant by means of XRF, ICP, SEM-EDX, BET, Mercury Porosimeter and XRD. The test results show that the activity of used catalysts greatly decreases (from 41.5 m/h to 29.5 m/h). The causes of deactivation are analyzed and the catalyst regeneration process is designed. Compared with the fresh SCR catalysts, the activity of regenerated catalysts can be recovered to 99% of that of the fresh ones (from 29.5 m/h up to 41.1 m/h), the SO₂/SO₃ conversion rate is well controlled, and the microstructure and properties are basically the same.

Research on Sound-Absorption Materials for Substation Noise Reduction

FAN Chao, NIE Jing-kai, XIAO Wei-min, CHEN Xin, HAN Yu, GENG Hui-jun

2014, 47(4):  144-147.  DOI: 10.11930/j.issn.1004-9649.2014.4.144.3

Asbtract ( )   PDF (2229KB) ( )  

References | Related Articles | Metrics

With the strictness of laws and regulations and the enhancement of residents’ environmental protection awareness, the problem of excessive substation noise has become the focus of substation complaint issues. This paper presents a study on the characteristics of substation noise and the property of the noise absorption materials. It is found that presently used sound-absorbing materials cannot meet the demand of the noise reduction and the service condition of substation. Therefore, microporous fiber composite acoustic board which is a new type of sound-absorbing material has been creatively developed. The board has two layers. The outer layer is the microporous acoustic board, while the inner layer is the aluminum fiber acoustic board .There are cavities behind the two layers,which can combine into a double-resonance structure to greatly broaden the absorption broadband of material and improve the low frequency absorption coefficient. In addition, the material of acoustic board is aluminum, which makes the structure have better properties of heat conduction, weather resistance, recoverability and economy. Applications of the microporous fiber composite acoustic board in a 110 kV indoor substation of one southern city have been conducted, the whole noise level of the substation has been reduced significantly. The microporous fiber composite acoustic board will be the ideal absorption material in substation noise control.

Numerical Simulation of New Oxygen-Enriched Waste Incineration Flue gas Purification Technology

HE Xue-hong, YAN Wei-ping, ZHAO Yong-ming

2014, 47(4):  148-152.  DOI: 10.11930/j.issn.1004-9649.2014.4.148.4

Asbtract ( )   PDF (1485KB) ( )  

References | Related Articles | Metrics

Derived from the combined technology of desulfurization and denitration for oxygen-enriched coal-fired flue gas based on CO₂ capture, a new flue gas purification process for waste incineration is proposed. The new technology can realize the simultaneous HCl, SO₂ and NO removing and recover the acid products in the flue gas compression and purification processes. With the Aspen Plus process simulation software, the numerical simulation of joint flue gas deacidification and purification process is carried out on a 350-t/d rotary kiln using pure oxygen melting incineration technology. The mass flow rate and component at critical nodes, the chemical reaction parameters and the HCl, SO₂ and NO removal efficiencies are obtained. The results show that the HCl and SO₂ removing efficiencies are about 100% and the denitration efficiency can reach 93%. At the same time, 306 kg of 40% dilute sulphuric acid and 51 kg of 15% diluted nitric acid can be recovered each hour. In addition, the sensitivity analysis on the influence of retention time on the efficiency of desulfurization and denitrification is also conducted.

Study on the Limestone Preparation System of CFB Boilers

ZENG Bing, WAN Cheng-jun, LIU Yi

2014, 47(4):  153-159.  DOI: 10.11930/j.issn.1004-9649.2014.4.153.6

Asbtract ( )   PDF (5130KB) ( )  

References | Related Articles | Metrics

The particle size distribution of limestone produced by limestone preparation system(LPS) directly influences the control of furnace desulphurization and the utilization ratio of limestone. The fine crushing and screening are the keys of the LPS to control the particle size. To effectively control the particle size and reduce the production costs, more and more plants with circulating fluidized bed (CFB) boilers choose to build their own LPS instead of purchasing limestone. In this paper, based on the engineering practice, the equipments for limestone crushing and separation are introduced. The focus is on the analysis of the technical and economic performance of three different LPSs, i.e. AUBEMA crusher + vibrating screen, column mill + PL type powder separator and the crusher fabricated by FAM. The study indicates that the LPS of column mill equipped with PL type powder separator has better economic performance, higher unit output, less moisture sensitivity and lower maintenance requirement. Therefore, it is a reasonable choice for the LPS of large scale CFB boilers.