bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-Term Multi-Objective Optimization Dispatch and its Evaluation in Wind Integrated Power Systems
Authors: Wang Ke , You Da Hai , Pan Kai
Published: August 2013

With energy saving and emission reduction paid more and more attention in electric power industry, long-term optimization dispatch in wind-integrated power system must take into consideration many inconsistent factors. In this paper on the basis of comprehensive consideration of coal consumption, emissions, openness and impartiality, a long-term multi-objective fuzzy optimization dispatch model is established. The model can optimize jointly generation maintenance scheduling, unit commitment and power output. After piecewise linearization of the objectives and the constraints, the optimization model is converted to a mixed integer linear programming (MILP) problem. An efficient optimization software CPLEX is employed to solve the problem. In order to analyze and compare different generation scheduling, a series of indices and fuzzy comprehensive evaluation method are utilized to evaluate the optimal results obtained. The proposed model is tested in IEEE 118-bus system incorporating three wind farms. The results show that the optimization model and the evaluation system built are effective and feasible.
A New Method of Fault Phase Identification for High Voltage Transmission Lines Based on the Fault Component of Phase Voltage
Authors: Chen Yang , Hu Yan , Tai Neng Ling
Published: August 2013

Since the existing fault phase identification methods can not identify all fault types quickly and accurately for high voltage transmission lines, this article proposed a new method of fault phase identification based on the fault component of phase voltage difference and the kalman filter algorithm. The method defined the fault components ratio of one phase voltage to the difference of the other two phase voltages as a fault phase identification factor. By analyzing the characteristics of fault phase identification factors in each fault type, the fault phase can be identified. Simulation results show that using the kalman filter algorithm to extract fundamental component is faster and more accurate. Meanwhile, the method can identify fault phases within half a cycle and is scarcely influenced by fault resistances, fault locations and fault initial phase angles. It also has a high sensitivity when the fault is on the side of strong source.
Research on a New Digital Algorithm to Improve the Monitoring Accuracy of the Dielectric Loss Factor
Authors: Zhao Tong , Xia Tian Xiang , Yu Qing , Zhang Li , Zou Liang
Published: August 2013

Based on Hilbert transform and complex trigonometric operation, this paper presents a new digital algorithm to improve the monitoring accuracy of the dielectric loss factor, and the theoretical basis of the algorithm is also deduced. Simulation results show that, the new algorithm renders good application performance when there exists power frequency fluctuation or the sampled data length is not exactly an integer fold of a power cycle, which demonstrates the algorithm can effectively solve the issues incurred from asynchronous sampling.
Investigation on Heat Transfer Performance of External Heat Exchanger for Circulating Fluidized Bed Boiler
Authors: Zhang Da Long , Yang Ding Hua , Yang Gen Sheng , Li Zhong , Lv Jun Fu
Published: August 2013

A heat transfer model of external heat exchanger (EHE) in large-scale circulating fluidized bed (CFB) boiler was suggested based on experiment data and theoretical analysis. And the model parameters were also provided. With this model, the heat transfer performance of the EHE in an actual operating 300MW CFB boiler was predicted. The comparison between the model predictive results and the actual results showed that the relative error is less than 7%. This indicated that the model established in this paper is reliable and can provide a significant reference in EHE of large-scale CFB boiler design.
Experimental Study on Gas Atmosphere near Side Walls of Swirl Opposed Supercritical Boiler
Authors: Yang Xing Sen , Zhou Xin Gang
Published: August 2013

High temperature corrosion of metal material was found on the side water-walls of a swirl-opposed firing supercritical boiler. The gas atmosphere near the side wall has great relationship with the high temperature corrosion. Test holes were installed on the side walls to form an experimental system. The gas compositions near the side walls were analyzed under different combustion conditions. High CO concentration is detected near the side walls. The effects of the operation states of burners on the CO concentration near side walls were tested. High over-fire air quantity results in strong reducing atmosphere of the test area. The adjusting method to control the atmosphere is suggested.
Square of Voltage Out-Loop Based Feedback Linearization Control of Voltage Source Converter (VSC) in SMES
Authors: Dai Xiao Kang , Zhang Bu Han , Chen Yi
Published: August 2013

To improve the response characteristic of the VSC in SMES (Superconducting Magnetic Energy Storage) with wide load disturbance, a new square of voltage out-loop based feedback linearization control strategy is proposed for the control of VSC. The input variable was controlled by a combining of square of voltage out-loop based direct voltage control and current inner-loop control to achieve fast stabilization of DC bus voltage and accurate tracking of power of PCC. Stability and dynamic response characteristics of the system were verified by simulation results. It is shown that the proposed strategy can improve the DC bus voltage transient response with load step change, with simplified control variable expression and reduced calculating burden.
MotoTron-Based Rapid Prototyping Development Platform
Authors: Zhou Xia Wei , Zhu Chang Ji , Qu Da Wei , Wang Lian Xu
Published: August 2013

The ECU development is an extremely complex process. It includes multiple steps and tasks: modular-oriented modeling, auto code generation, ECU flash, calibration and so on. The configuration and function of MotoTron-based rapid prototyping development platform are introduced. The control function finally meets the basic requirements of engine control.
Design of Heating Control System for UEGO Sensor
Authors: Lu Ji Fei , Zhu Chang Ji , Qu Da Wei , Lu Xiao
Published: August 2013

Universal Exhaust Gas Oxygen (UEGO) Sensor is one of the most important sensors for the close-loop air-fuel-ratio control system of automobile engine. Due to its special structure, controller is used to control sensors temperature so that UEGO sensor can work normally. Aiming at nonlinear characteristic of the temperature control module, a subsection heating control method and a PID algorithm is studied. UEGO heating controller is implemented by means of Motohawk real time simulation system. Experimental results show that under the condition of different temperature, the UEGO is also able to maintain the best working temperature.
A Non-Isolated Buck-Boost Grid-Connected Inverter with no Shoot-Through Problem
Authors: Yao Zhi Lei , Kan Jia Rong , Hu Guo Wen
Published: August 2013

The grid-connected inverters required for distributed generation systems should have high reliability. However, a shoot-through problem, which is a major killer of the reliability of the inverters, exists in the conventional bridge-type voltage-source inverters. In order to solve the aforementioned problem, a non-isolated buck-boost grid-connected inverter with no shoot-through problem is proposed. The hysteresis current control is used. The output voltage of the proposed grid-connected inverter can be larger or lower than the input voltage. The operating principle is illustrated. Simulation verifies the theoretical analysis.
A Proposed Communication System for Field Area Networks of Smart Grid
Authors: Sun Zhong Wei , Jia Tao
Published: August 2013

A robust communication infrastructure, which consists of different network components, such as Home Area Networks (HANs), Feighborhood Area Networks (FANs) and Wide Area Networks (WANs), is the touchstone of a smart grid. However, the existing communications network is insufficient due to the factor that it does not cover the distribution side where the major changes are expected to occur. Field area networks form the communication facility for the electricity distribution systems and act as a bridge between customer premises and substations with collectors, access points and data concentrators. This paper focuses on design aspect of communication system for FANs of smart grid. The communication infrastructure using Ethernet Passive Optical Networks (EPONs) is discussed. And based on the power system applications operating in the distribution domain, communication systems for field based application are presented.
Comprehensive Fuzzy Evaluation for Transmission Network Planning Scheme Based on Gray Correlation Analysis
Authors: Liu Lian Guang , Zhao Wan Li , Chen Yan Wei
Published: August 2013

The comprehensive fuzzy evaluation method for transmission network planning scheme has the drawback that relying more on the subjectivity. To solve this problem, gray theory is introduced into comprehensive fuzzy evaluation method. Gray correlation analysis method is used to calculate gray correlation coefficient as the membership of evaluation index to get fuzzy evaluation matrix. Then, the fuzzy weight vector is determined by the subjective and objective empowerment by integrating AHP and entropy method. Comprehensive fuzzy evaluation vector is obtained by using composite operator to synthesis evaluation matrix and fuzzy weight vector. The obtained result is used to evaluate transmission network planning scheme. Therefore, the problem that judger definate membership function based on subjective view is solved by combining the two methods. Calculation results show that the proposed method has a certain practical value.
Thermal Bridges in Insulation Systems
Authors: Petranek Vít , Šubrt Roman , Plachy Jan , Nevřivová Lenka , Petricek Tomas , Kalousek Lubor , Caha Zdenek
Published: August 2013

The article points out and describes in detail the basic thermal bridges in contact thermal insulation systems and in ventilated facades. Thermal bridges are illustrated by means of thermal images of spot thermal bridges and the calculation of spot heat transfer coefficients.
Quantitative Study on Model and Basic Concepts of Thermodynamic System
Authors: Wang Zhi Guo , Chen Jian , Yin Chai Ling
Published: August 2013

Dynamic changing process is caused by heat and mass transfer between thermodynamic system and outside, which is not entirely judged in Traditional thermodynamics. Drawing on Modern Thermodynamic and Shell Theory, a new thermodynamic system has been conducted, which consists of inner system, border (shell) and outside. Shell is formed by shell wall and shell gates, and shell wall is insulated. On the basis of above, the opening degree and exchange rate, and the relationship between them are proposed. In the new system, the message as a physical quantity is equivalent to material and energy. The exchanging physical quantities include information, material and energy between thermodynamic system and outside. As the material flow exchange process, stability criterion (border opening degree) is derived. Traditional thermodynamics is perfected and supplemented by the research findings, which offered theory basis for thermodynamic system exact analysis.
Distribution Characteristics of Exergy Dissipation of a Large-Scale Coal-Fired Power Generation Units
Authors: Deng Jian Ling , Yang Zhi Ping , Fu Peng , Liu Ji Zhen
Published: August 2013

The distributions of exergy dissipation in a 1000MW coal-fired power plant under different operation conditions were analyzed. Mass and energy balance models of different components were constructed to determine the thermodynamic properties of each stream. A variant of exergy analysis, the proposed equivalent specific fuel consumption (ESFC) analysis, were conducted to determine the additional specific fuel consumptions (ASFC) of individual component and, therefore, to obtain the characteristic of its temporal and spatial distribution. The off-design modeling of main components was established. The methodology and results of analysis in this paper can be taken as valuable guidance for the optimal design and operation of thermal power plants and for the improvement and retrofits for more cost-effective and environmental-friendly power plants.
Experimental Analysis on Non-Dimensional Parameters of Closed-Loop Pulsating Heat Pipes
Authors: Wang Xun , Zhang Xiao Wen , Yang Cheng Si
Published: August 2013

Based on experimental studies, this paper discusses the variation tendencies of three non-dimensional parameters including Ja, Bo and Pr which consist of various operational parameters and characteristic parameters, and then analyses their effects on heat transfer performance of closed-loop pulsating heat pipes (PHPs) at startup stage and steady operation stage. Results indicate that at startup stage, the values of Ja and Bo increase over time as a whole, while the values of Pr decrease; at steady operation stage, the values of three parameters all fluctuate within a narrow range. The results also show that heat transfer is due mainly to the exchange of latent heat under the experimental conditions.
Simulation of Main Steam Temperature Control System Based on Fuzzy PID and Improved Smith Predictor
Authors: Liu Chang Liang , Zhang Yong Bo
Published: August 2013

The main steam temperature process has the characteristics of large inertia, large time delay and time-variation , to solve this problem, the fuzzy PID cascade control system with Smith predictor is presented .The improved Smith predictor with the effect of filtering was used in the main loop of the cascade control system, and fuzzy PID compound controller was used as the main controller based on the advantage of fuzzy control and PID. Through establishing the mathematical model and simulating the main steam temperature control system, either the parameter changed or invariable, the results show that the method can improve the control qualities and enhance the robustness and stability of the control system.
Study on the Optimal Running Temperature of Circulating Fluidized Bed Boiler Burning Fujian Anthracite
Authors: He Hong Zhou , Zhuang Huang Huang
Published: August 2013

There is a contradiction in selecting the running temperature for CFB boilers burning Fujian anthracite, in order to simultaneously satisfy the requirement of efficient combustion and high desulfurization efficiency. Based on numerical simulation and industrial experiments, the effect of the running temperature on the carbon content in fly ash and the desulfurization efficiency were analyzed for two types of CFB boilers with different capacities. It is found that, with the rise of running temperature, both decrease quasi-linearly. For the 75 t/h CFB boiler, when the running temperature is lower than 950 °C, the carbon content in fly ash is very high, causing a low burnout efficiency; maintaining the running temperature at 1000 °C is favorable for the fine char to be burned out, however, continuous raise becomes almost useless. For 440 t/h CFB boiler, a higher burnout rate of the fine char particles can be obtained when the running temperature is kept at about 950 °C, and further increase brings no evident benefit either. For the 75 t/h and 440 t/h CFB boilers burning Fujian anthracite, considering both the boiler efficiency and the combustion desulfurization efficiency, the optimal running temperature should be respectively about 980 °C and 950 °C.
The Calculation of Heat Transfer of Surface Type Heat Exchanger
Authors: Wang Ya Rong , Wang Pei Rong
Published: August 2013

Heat exchanger is an equipment for general purpose. It is very popular in the industry of energy and power, refrigetion,chemical and oil. And it is also very important for company, energy and application. Its efficiency of transferring heat and its safety of operation are very important for our society, especially in these days energy becomes more and more valuable. In this paper ，we used practical examples to describe the calculation of heat transfer of surface type heat exchanger .
The Design Optimization Method of Steam Turbine Cold End in Coal-Fired Power Plant
Authors: Wang Yun Min , Ma Hai Long , Zhang Xi Fu
Published: August 2013

The design optimization of steam turbine cold end is an important measure to ensuring safety and economic operation of the unit. Based on the universal calculation method of steam turbine output correction, considering investment cost, operation cost, cooling water expenditure and hot pollution cost, the design optimization of steam turbine cold end was carried out. An example of the domestic 300MW unit was presented to show the validity of this method. The design optimization results can be used as a foundation for the equipment selection and inviting bid documents compilation of steam turbine cold end in coal-fired power plant.
Visualization Experiment on the Steady Operating Process of the close Loop Pulsating Heat Pipe
Authors: Wang Xun , Li Yun Zhao , Yang Cheng Si , Zhang Xiao Wen
Published: August 2013

A visualization experimental investigation for the pulsating heat pipe (PHP) was carried out to obtain the flow characteristics in the PHP steady operating process with controlling the input heat flux and condensing temperature. The experimental results show that the flow patterns are mainly slug flow with the intermittent pulsation at low heating power, churn flow, and annular flow with steady unidirectional circulation at high heating power. The flow direction switch phenomenon was also observed and analyzed. When the PHP heating section is occupied by vapor slugs for a long time, the backflow phenomenon provides liquid to the bottom of the heating section and reforms a new liquid slug.
Study on the Load of Crankshaft of Hybrid Ship Main Diesel Engine
Authors: Ren Hong Ying , Sun Pei Ting , Wang Di
Published: August 2013

In order to study the load pattern of crankshaft of hybrid ship main diesel engine, in this thesis, MAN B&W 5S60MC diesel engine model has been established using ADAMS software. The load pattern of crankshaft of diesel engine at variable load, and variable speed conditions due to the changes of assisted driving force have been calculated by the virtual prototype. The result shows that the influence of crankshaft load pattern is tiny when the diesel engine load is variable, but the influence of crankshaft load pattern is large when the diesel engine speed is variable. The research of hybrid ship sailing model study provides theoretical basis. The study provides theoretical foundation to the control model research of hybrid ship main diesel engine. It is helpful to improve the application process of hybrid ship.
Fault Diagnosis Based on Rough Set and BP Neural Network (RS-BP) for Gas Turbine Engine
Authors: Zhao Ning Bo , Li Shu Ying , Yi Shuang , Cao Yun Peng , Wang Zhi Tao
Published: August 2013

This paper presents a new fusion diagnosis based on rough set and BP neural network for the fault diagnosis of gas turbine. The frame is designed to fusion fault diagnosis, which is composed by three parts: the rough set data pre-processor, rough set diagnosis model and BP neural network diagnosis model. Aiming at the difficulty in getting adequate fault samples in fault diagnosis, rough set theory is first used to process the original data, establish the decision table and generate rules, which can eliminate the redundant information and build the rough set diagnosis model. After that, according to the optimal decision attribute pre-treated by rough set, BP neural network is designed for fault diagnosis, which can reduce the scale of neural network, improve the identification rate, and improve the efficiency of the whole fusion diagnosis system. Finally, an example of gas turbine generator sets fuel system is taken as a case study to demonstrate the feasibility and validity of the proposed method in this paper.
Numerical Study on the Flow Characteristics of Low Head Small Hydraulic Turbine
Authors: Byeon Sun Seok , Boo Jin Hyo , Park Chong Yun , Kim Sung Soo , Kim Youn Jea
Published: August 2013

A small hydraulic turbine more still remains to improve the mechanical performance because it does not come fully similarity as compared with the large-scale hydraulic turbine. Many studies on the small hydraulic turbine focused on the increase of performance. In this study, the characteristics of axial propeller turbine which is appropriate equipment for low head conditions and high flow rates were numerically investigated using the commercial code, ANSYS CFX. A parametric study was carried out with two different geometrical parameters, such as blade number and tip clearance between casing and blade. Results showed that the hydraulic loss was increased and the efficiency of small hydraulic turbine was decreased because of increasing tip clearances, which lead to the increase of absolute velocity at the exit of the runner blade.
Thermodynamic Analysis of a R32/CO2 Cascade Refrigeration Cycle
Authors: Xiao Jian , Liu Ying Fu
Published: August 2013

A R32/CO2 cascade refrigeration cycle was analyzed thermodynamically, the results show that: Under given working conditions, there exists the best condensing temperature of the low-temperature circuit to make the maximum COP of the cycle. The lower evaporating temperature is, the lower the best condensing temperature of the low-temperature circuit is. Under the same evaporating temperature, COP increases and mH/mL decreases along with condensing temperature decreasing, under the same condensing temperature, COP decreases and mH/mL increases along with condensing temperature decreasing. To reduce the temperature difference in the cascade-condenser can increase COP and decrease mH/mL.
Simulation and Optimization on Outlet Velocity of Industrial Plant Air Supply Cylinder
Authors: Kou Guang Xiao , Wang Hang Qing , Feng Bo , Hu Liang Liang
Published: August 2013

By using numerical simulation method,the three-dimensional flow field of air supply cylinder using for displacement ventilation in industrial plant is analyzed. The internal structure, effective wind sent area and the shape of wind outlet small hole which affected the air outlet wind speed of air supply cylinder are researched. While compared with the simulated and measured result of the outlet velocity of the wind outlet small hole, the best feature parameters of wind speed in air supply cylinder has been gained. The result shows that: by changing the internal structure and decreasing the effective air supply area of the air supply cylinder, the wind speed from the air-outlet on the small hole can be more reasonably distributed; although by increasing the effective air supply area and changing the shape of outlet hole on air supply cylinder will make the air outlet be more effectively distributed, its value is unreasonable.
Analysis of Influencing Factors of Pressure Pre-Cooling Rate for Fruits and Vegetables
Authors: Wang Qiang , Wang Fan , Wang Qi , Liu Feng Zhen
Published: August 2013

Cooling rate is an important evaluation index of pressure pre-cooling effect for fruits and vegetables. Experimental device of pressure pre-cooling for fruits and vegetables has been established. Pre-cooling process of golden pears has been tested. The key parameters which affected pressure pre-cooling 7/8 cooling time of golden pears such as different air flow rates, different shapes and sizes of vent hole and arrange form have been analyzed. The results show that it is better that cooling air flow rate is between 1.5 m/s and 2 m/s. Ellipse vent hole shape is the best vent hole style and key-groove vent hole is the worst. The cooling rate of stagger array form is faster than the parallel array form.
Dynamic Simulation and Analysis of the Process of Cold-Storage Plate Release Cool in Refrigerator Vehicle
Authors: Li Xiao Yan , Du Shi Qiang , Li Yue Ming
Published: August 2013

This paper presents a mathematical model for simulating the heat transfer process in a cold-storage plate that can be used in the refrigerator vehicle. The numerical method studied was an enthalpy method. Variation rule between process of release cool and influenced factors were obtained. The effect of solar radiation time was investigated in discharging process. Both increasing the number of cold-storage plate and improving sealed performance of door and compartment can extend release cool time. The results show that according to the different breath heat of goods, reasonable arrangement of number of cold-storage plate can meet cold demand in the transport; solar radiation also has influence to the process of cold-storage plate release cool, with considering cold load caused by solar radiation, release cool time is shortened by 13%.
Investigation and Analysis of the Heating Present Situation in Shenyang
Authors: Wang Hong Wei , Song Hua , Feng Guo Hui , Wang Bao Ling
Published: August 2013

Large-scale detailed survey and summarized on the heating present Situation of Shenyang City. Analyze and discuss the existence of the problems. Shenyang heating is still mainly coal-fired boilers in winter. The heating planning and district heat-supply detail planning should be made on the basis of city heating present situation. Adjust the unreasonable heat source and the energy structure, rearrange the unreasonable urban heating supply network, and plan the urban heating scientifically and reasonably. Control the emissions of coal-fired boilers indicators, strengthen the optimization of the efficiency of coal-fired boilers, to achieve the national energy saving and emission-reduction standards, and to promote the sustainable development of city heating.
An Empirical Correlation for Steam Condensing and Flowing Downward in a 50mm Diameter Inclined Tube
Authors: Yang Jian Guo , Ju Xiao Li , Ye Sheng
Published: August 2013

The heat transfer characteristic of steam condensation in a 50mm diameter and 30° inclined tube was experimentally investigated. Based on the experiment and Akhavan-Behabadi correlation, a new correlation has been developed. It is shown that the heat transfer coefficients for the inclined tube are approximately 1.06-2.98 times higher than those for the horizontal tube. The heat transfer coefficients predicted by Shah correlation, Würfel correlation and Akhavan-Behabadi correlation deviate greatly, though Akhavan-Behabadi correlation is better. But by the developed correlation, more accurate heat transfer coefficients are predicted than Shah correlation, Würfel correlation and Akhavan-Behabadi correlation, and the deviation is less than 15%. The developed empirical correlation is a better one to predict heat transfer coefficients for steam condensation in larger diameter inclined tubes.
Methods of Failure Analysis of 35-110 kV Overhead Transmission Lines
Authors: Khalyasmaa Alexandra I. , Dmitriev Stepan A. , Kokin Sergey E.
Published: August 2013

This paper addresses the problem of failure analysis of 35-110 kV overhead transmission lines using the main methods: correlation analysis, regression analysis and expert judgment method. There are weaknesses identified of these analysis methods for power network district of the city for 35-110 kV overhead transmission lines.
Study on Relationship between Power Grid GIC (Geomagnetically Induced Currents) and Interplanetary Disturbances
Authors: Du Guan Nan , Liu Lian Guang , Wang Kai Rang
Published: August 2013

Geomagnetically induced currents (GIC) are very harmful to the power system and caused by the changes of geomagnetic field. The changing magnetic fields originate from the interplanetary space. Therefore, recognizing the relationship between GIC and interplanetary disturbances is significant for the prediction of GIC. In this paper, we collected 35 GIC events during 1999-2005 and the corresponding interplanetary data observed by ACE satellite to analyze the correlations of various interplanetary parameters with GIC. The results show that there is positive correlation between GIC amplitudes and interplanetary parameters. As a single factor, solar wind dynamic pressure (Pk) correlates best with GIC, while interplanetary electric field (Ey) and interplanetary magnetic field (|B|) also correlate well with GIC. In addition, we investigated the relationships between interplanetary parameters and GIC amplitudes for different intensities (GIC>10A, GIC>20A). Comprehensive analysis shows that Pk and Ey are the most closely parameters related to GIC.
An Experiment Investigation of Heat Transfer Enhancement by Pulsating Laminar Flow in Rectangular Grooved Channels
Authors: Li Yan , Jin Dong Xu , Jing Yan Qin , Yang Bing Chang
Published: August 2013

In this paper, the heat transfer enhancement by pulsating laminar flow in rectangular grooved channels was experimentally investigated. Effects of Reynolds number Re, pulsation frequency, groove depth and groove length on the heat transfer enhancement were studied. Experimental results show that Nusselt number increases with Re increases both in steady and pulsating flow cases. Pulsating flow can efficiently enhance heat transfer in the grooved channels and the heat transfer enhancement factor increases with the increase of Re. There exists an optimal pulsation frequency, corresponding to the maximum heat transfer enhancement factor, which is almost the same for different Re, groove depth and groove length.
Research on the Reliability Evaluation Method for DC Grid
Authors: Dai Hong Yang , Li Ya Lou , Hao Jian Hong , Li Mu Yi
Published: August 2013

The reliability indexes and evaluation methods of AC transmission system and high voltage direct current (HVDC) transmission system were introduced. According to the characteristics of the DC grid, whether the above methods could be applied to DC grid reliability evaluation was analyzed, and the reasons and applications were also presented. The results show that state enumeration method, Monte Carlo method, and hybrid method can be applied to the large scale DC grid reliability assessment, based on either the grid frame structure or the power flow calculation; and the FD (frequency and duration)-FTA (fault tree analysis) method and FD-model combination method are more suitable for simple DC grid reliability assessment based on grid frame structure.
A New Method to Solve Static Voltage Collapse Point with Hybrid Power Network Equations
Authors: Yi Tao , Li Jian Peng , Zhang Song , Zhang Ying Bin
Published: August 2013

Electric power network components can be simulated with equivalent circuit and establish the hybrid node voltage and branch current electricity network analysis model based on it. We form the equations reflected the voltage collapse conditions, and establish the extended power flow equations with the hybrid equations, the static voltage collapse point can be calculated by solving them. The advantage of this method is that the power flow calculation can be convergence smoothly near the collapse point because of the extended power flow equations when the Jacobian matrix tends to be singular. The convergence can be achievable just because the joining of the equation reflecting the voltage collapse conditions has changed the structure of the Jacobian matrix. The simulation results show that this method is very effective.
An Active Equalizer for Serially Connected Lithium-Ion Battery Cells
Authors: Liu Hong Rui , Xia Chao Ying
Published: August 2013

This paper proposes an equalizer for serially connected Lithium-ion battery cells. The battery cell with the lowest state of charge (SOC) is charged by the equalizer during the process of charging and discharging, and the balancing current is constant and controllable. Three unbalanced lithium-ion battery cells in series are selected as the experimental object by this paper. The discharging current under a certain UDDS and 20A charging current are used to complete respectively one time balancing experiment of discharging and charging to the three lithium-ion battery cells. The validity of the balancing strategy is confirmed in this paper according to the experimental results.
Coordinative Optimal Design for PSS and Auxiliary Damping Controller on SVC under Multi-Operating Conditions
Authors: Miao Xiao Gang , Zhang Bu Han , Li Zhong Cheng , Wu Jun Li , Mao Cheng Xiong , Li Xiao Ping , Sun Jian Bo , Li Miao , Li Da Hu
Published: August 2013

Based on power system stabilizer (PSS) and the damping controller of flexible AC transmission system (FACTS),a problem of optimal design is researched by the example of static var compensator (SVC). Minimum damp ratio of system electromechanical oscillation modes eigenvalue in the weak damping operation condition is selected as the object function. Parameters of damping controllers are optimized by the algorithm which is combined by genetic algorithm (GA) and back propagation (BP) neural network based on adaboost (Ada-BP). Simulation shows the optimized damping controllers can restrain the low frequency oscillation in multi-operating conditions of system. The algorithm provides an effective solution for optimization calculations which calls the complicated calculations.
Fast Analysis of Power System Stability by Artificial Neural Network
Authors: Li Chao Chun , Huang Pei Hwa
Published: August 2013

Power system small signal stability concerns the ability of the power system to maintain stability subject to small disturbances. The analysis of small signal stability often has to deal with high-order system matrix due to the large number of generating units so that it is not easy to calculate and analyze the original system matrix and the whole set of eigenvalues. In this paper a new approach is proposed to take advantage of the specific feature of the parallel structure of artificial neural network for calculating the most critical eigenvalue or all eigenvalues of the unstable oscillation mode. The developed algorithm is tested on a sample power system to validate the feasibility of the proposed method for the calculation of the critical eigenvalue.
ILC-Based Internal Model Control of Superheater Steam Temperature
Authors: Lu Wei , Wang Ming Chun
Published: August 2013

This paper proposes a novel Internal Model Control (IMC) method for the control of superheater steam temperature. The IMC is known for good robustness including handling of systems with time delays. While Iterative Learning Control (ILC) is a strategy for dealing with periodic disturbances. By using a combination of IMC and ILC, their individual advantages are used to increase the robustness against modeling uncertainties and handling time as well as decreasing the influence of the periodic disturbances affecting the superheater steam. Some simulation examples are shown to illustrate performance improvements that can be achieved by the new method over the conventional IMC and PID methods. Key Words: Superheater Steam Temperature; Internal Model Control; Iterative Learning Control
Impacts of Distributed Generators on Voltage Sag Analysis
Authors: Boonnamol Jenjira , Tayjasanant Thavatchai
Published: August 2013

This paper presents impacts of distributed generators (DGs) such as synchronous-based DG and inverter-based DG on voltage sag analysis in distribution systems. Voltage sag analysis is assessed through area of vulnerability (AOV), number of sags frequency (NSF) and voltage sag index (SARFI). Single line-to-ground and three-phase faults are investigated. Size and location of DG are carried out by using Particle Swarm Optimization algorithm (PSO) in order to minimize losses and number of sag frequency. Roy Billinton Test System (RBTS) Bus 2 is used for simulation cases. Results show that the distribution system with DG installed improves voltage sag performance compared with the system without DG installed.
Analysis and Solution of Fouling on Flow Path for Supercritical Steam Turbine
Authors: Jiang Wei Li , Xu Jian Qun , Yang Tao , Shi Yong Feng
Published: August 2013

Insufficient output and rising pressure after governing stage of a 630 MW supercritical unit occurred only 18 month after the first outage. Though analysis based on measured parameters, fouling existed in governing stage and the first stage group. By virtue of linearization of formula and decoupling the impacts to thermal characteristic parameters, the quantified deposition degree was obtained. The fouling reason was determined by scale sample analysis, and the solution was proposed by quantitative calculation. The problem was successfully solved with boiler pickling, turbine cascade jet-beading and pulsing minimum oxygen to inhibit flow accelerated corrosion. A steam quality detection method was also proposed as the installation of measurement point after governing stage of supercritical unit. These treatments provided building and operation experience for 1000MW ultra-supercritical turbine and the same type of equipments.
Power System Stability Study with Empirical Mode Decomposition
Authors: Lu Chia Liang , Huang Pei Hwa
Published: August 2013

Low frequency oscillations (LFO) reflect the damping and the stability of a power system and is essentially non-stationary. The LFO is a composite response of various oscillation modes and of which the frequency may be changing with time; thus, direct analysis of such time-domain responses is difficult. The main purpose of this paper is to apply the method of empirical mode decomposition (EMD) to the study of power system stability. First the method of EMD is to expand the time-domain responses under study into multiple intrinsic mode functions (IMFs). Then the 2D time-frequency information inherent in the response under study is obtained using the wavelet transform. The 2D time-frequency graph is further expanded into a 3D time-frequency-energy graph. Information from the 3D time-frequency graph is analyzed to determine those generators that have higher extent of oscillation involvement during the occurrence of LFO in the power system. The results from comparative analysis show that, at specific frequencies from LFOs, higher extent of oscillation involvement will reveal a greater factor of involvement in the frequency domain behavior.
State Estimation of Equivalent Current Measurement Transformation Based on Generalized Tellegen's Theorem
Authors: Lin Gui Hua , Zhang Yan Jun , Wang Tao , Wang Yu Ying
Published: August 2013

One of the most important ways to enhance the speed of state estimation is to establish the constant matrix Jacobian. This essay puts forward the state estimation method of the equivalent current transformation based on the Generalized Tellegen’s Theorem. This estimation method establishes the constant Jacobian matrix without neglecting the secondary factor making use of the Generalized Tellegen’s Theorem, solves the numerical stability problem caused by the establishment of the constant Jacobian matrix in the current state estimation, and has the advantages of a relatively rapid computing rate and an unparalleled astringency. The method put forward in this essay has been verified through IEEE-30 Node System, and the efficiency of it has been fully proved by the example results.
Tin in the Comprehensive Utilization of Mineral Processing Engineering and its Research Progress
Authors: Wang Ju , Dai Hui Xin , Luo Lan
Published: August 2013

Tin is a metal of commercial value, in the sorting of mineral processing engineering have many different ways. This article simply introduces the tin in the mineral processing and comprehensive utilization, and it proposed the related research progress, comprehensive utilization of tin and better service to humans.
Experimental Study on Concentrating Scandium by Leaching from Associated Scandium Ore
Authors: Zhang Gui Fang , Yan Peng , Yang Qing Rong
Published: August 2013

Based on the benefication of the complex silicate ore containing scandium, the research about aid-leaching agent used in the leaching of the scandium concentrate was been conducted. And the suitable leaching agent and aid-leaching agent which the useful ions entered into leaching liquid and the harmful ions were kept in leaching residue were been found according to the experiment results. For the scandium of sample existed various complex silicate ore as isomorphism form, the research has adopted hydrochloric acid with aid-leaching agent to dissociate the silicate ore and make scandium entering into solution. The research results has shown that the scandium leaching rate could reach 92.06% under the optimal conditions which the hydrochloric acid concentration is 22.8%, the dosage of aid leaching agent is 6%, liquid solid ratio is 4:1, particle size of leaching material totally is less than 0.15mm and leaching time is 8h.
Research of the Low Grade Fluorite Flotation Orthogonal Test
Authors: Yang Jun Long , Liu Quan Jun , Guo Yan Hua , Xiao Hong , Jiang Mei Guang
Published: August 2013

The run-of-mine ore samples which have been used in the study were taken from a fluorite ore. The grade of fluorite was 28.65%. From the condition test, the optimal grinding fineness was-0.074mm accounted for 79.5%. The final optimal reagent system was A1B3C3D3E3 with comprehensive consideration. That is, sodium carbonate was 2000 g/t, sodium silicate was 1000 g/t, aluminum sulfate was 200 g/t, sodium hexametaphosphate usage was 1000 g/t, oleic acid dosage for 2000 g/t. Through the closed-circuit test of flotation, the final index was the fluorite grade of the concentrate was 97.69% and the recovery was 48.07%.
Study on Coal Separability for Wangcun Inclined Shaft in Chenghe
Authors: Yang Xi Yuan , Du Mei Li , Zhang Jin Ren , Yang Jian Li
Published: August 2013

On the basis of the coal quality characteristics, the screening and drifting tests have been carried out to investigate the separability of the coals in the inclined shaft coal samples of Chenghe Wangcun coal mine. The results showed that the mine raw coal seams are medium ash, high sulfur and medium volatile coals. The screening test results showed that the water content and sulfur content of coals samples in each grade after sieving essentially remained the row coal characteristic. Heating value increased with the decrease of particle size, but ash content decreased with the particle size. The float-and-sink tests showed that when the given clean coal ash content was 10%13% and 15% respectively, the coal samples were in the extremely difficult degree, medium separability degree and medium separability degree respectively.
The Application Status of Triboelectric Separation and its Progress
Authors: Wang Ju , Dai Hui Xin , Luo Lan
Published: August 2013

This paper discusses the friction charged in the mineral processing of the progress made, according to the ideas put forward by the previous experience and basic theoretical research, the detailed introduction triboelectric and elaborates further study. riboelectric selection has certain limitations, but under certain conditions applied in mineral processing are quite broad prospects.
A Grey Model for Predicting Water and Oil Production Rate
Authors: Song Kao Ping , Tao Jian Wen , Zhang Ji Cheng
Published: August 2013

Grey system theory is a kind of method and system that contains something known and unknown. A completely definitive number is called a white number, while for one that does not have a definite value but a general range is called a grey number, whose greatest attribute is forecasting single data series. The grey theory was applied to predict the development index of X-L oilfield, including oil production, water production and water cut. The result is of very good accuracy.
Application of New Hardware and Software Technology in the Oil and Gas Seismic Exploration and Development
Authors: Hao Jian Ming , Zhao Wei , Zhang Jian Guo , Jiang Zai Xing
Published: August 2013

Seismic exploration of petroleum is a kind of high technology which integrated hardware and software. The improvement of software engineering has produced an active influence on seismic exploration. The recent advance mainly expressed on acquisition, processing and interpretation of high frequency three dimensional seismic data. Application of new algorithm and super integrate large-scale software can improve the accuracy and efficiency of the petroleum discovery. Development seismic is new frontier of seismic application. Its a new branch of learning which makes full description and dynamic detection during petroleum exploration. It need use manners of oil and gas reservoir observation and information processing technique, combining with the data of drilling, geology and reservoir engineering etc. This can also take related hardware and software technological advances and development.
Simulation of Hydraulical Fracture Height by Creating Artificial Barrier
Authors: Li Chuan Min , Hu Yong Quan
Published: August 2013

It is quite difficult for reservoir exploitation with worse barrier zone, especially in thin pay-zone, limiting hydraulic fracture height propagation. This paper described the theory of controlling the fracture height by creating artificial barrier, and net pressure distribution in the crack was determined by assuming the artificial barrier is with stress gradient. Then, stress intensity factors in the crack tip were gotten on the basis of fracture mechanics theory, and fracture propagation model was established in accordance with fracture criteria of tensile open crack. The established model also described the action of treatment pressure on the fracture height and influence of artificial barrier on the fracture height propagation. By contrasting the results, it is feasible for artificial barrier to limit the fracture height propagation, and this model also can be used in hydraulic fracturing design in the oilfield.
Late Cenozoic Faults and Shallow Oil Accumulation in the Nanpu Sag
Authors: Zhou Tian Wei , Cui Ze Hong , Ming Hai Hui , Xu Hai Long , Xin Yu Xia
Published: August 2013

The Nanpu Sag, located in the north part of Huanghua Depression of Bohai Bay Basin, is a Cenozoic petroliferous extensional sag, the shallow oil reservoirs have great exploration potential. Former exploration suggested that there is complex relationship between Late cenozoic faults and hydrocarbon accumulation, but there is no detailed discussion. Based on the structural interpretation of 3D seismic data, the Late Cenozoic fault characters including typical fault configuration in profile and fault arrays in plane are analyzed, furthermore, the formation mechanism of the faults is discussed. It is concluded that late Cenozoic faults were formed by extension other than strike-slip movement, which was controlled by the mechanism of pure shear in the lower crust during the period. In addition, the relationship between Late Cenozoic faults and shallow hydrocarbon accumulation is discussed, it indicates that the faults controlled the formation of shallow closures and constituted the effective hydrocarbon pathways connecting deep source rock and shallow traps.
The Effects of Qijia Oilfield Water Sensitivity to Formation Scaling of Injected Water
Authors: Cheng Shao Wei , Cao Guang Sheng , Liu Zhi Mei , Yang Wen Wu
Published: August 2013

The Qijia oilfield is a low permeability reservoir, and it is difficult to inject water. For improving the water injection capability of Qijia oilfield, the experiments of water sensitivity and scaling evaluation are developed, and so on. But these experiments are the evaluation about single element. The actual situation of reservoir is not reflected accurately by this way. For determining the main element of water injection difficulty in Qijia oilfield, the experiment of core scaling after water sensitivity is carried on. It is known that the damage ratio to the permeability of core scaling after water sensitivity is more than the simplex scaling through comparing this experiment to the simplex scaling experiment. The reason is that the sloughed clay granule is existed in core after water sensitivity, and the new crystal nucleus is provided for scaling crystal. At the same, the inside wall of core porous channel is becoming coarse, the contact area is increased with the fluid, and it is instrumental for the adhesion and deposition of scale.