The junction temperature simulation assessment model of IGBT module in three-phase inverters

Insulated gate bipolar transistor (IGBT) power module operating performance and reliability and its design of heat dissipation system in inverter are directly related to its operation junction temperature. Investigation of temperature of power device junc     

A Method for Online Measurement of Dielectric Loss of HV Capacitive Equipment Insulation

It is still a major problem for research on online monitor dielectric dissipation factor of high voltage equipment insulation. In the field, new methods are paid attention by researchers especially. At present, there are no methods achieving the satisfactory measurement results. Based on the voltage and current at their respective zero crossed points, this paper proposes the integral measurement method which can be used to measure the dielectric dissipation factor of high voltage capacitive apparatus. The formula for dielectric dissipation factor angle computation is deduced by theoretical analysis and the computation results are achieved by digital simulation. Meanwhile, this paper explains the effect to measurements by system frequency, content of harmonic and zero-drift and draws the relevant error curves. It also proposes the measures to reduce the integral measurement method presented in this paper,which can convert measurement of small signal into that of big signal and accurately measure dielectric loss of capacitive apparatus. It also possesses great anti jamming ability under strong electromagnetic interference environment. The online measurement system can detect the dielectric dissipation factor of high voltage equipment by the integral measurement method.     

Study on the Sand Duct Pressure and Energy Dissipation for Tongkou Hydro Power Station

Tongkou power station is an all-round hydro project,where the mixed exploitation mode is adopted with mainly for power generation.Integrated with the model test result,the duct discharge capacity and flow coefficient in various discharge hole are discussed,the influence of duct shape on inlet pressure,energy dissipation and tail water is analyzed,the improvement measures on conveyer way pressure and energy dissipation are put forward too.The achievements of this study have been adopted by the designers.     

基于LabVIEW的潜油电泵数据采集系统

应用LabVIEW虚拟仪器现场可编程门阵列(FPGA)对潜油电泵的电压、电流参量进行实时数据采集,通过上位机对采样数据进行分析处理,得到潜油电泵的视在功率、有功功率、无功功率和功率因数,并与电能质量检测仪检测数据进行对照。系统硬件采用NI sbRIO-9606和NI9683夹层板配合使用,突破了传统的依靠DAQ助手的硬件采集,基于现场可编程门阵列(FPGA)的数据采集系统,由软件构成采集功能芯片,可控性强,准确性高,应用性好。实验表明,该系统在误差允许范围内能够对数据进行准确采集。     

Real-Time Tracing of 200 MW Power Plant Generators By A 3~+ Network

The communication of the application program among work tations of 3+ network is realized by the shared file on harddisk of the network server,which does not support the application program' s real-time communication among the network workstations nor supplies software or hardware needed for information refreshing, nor fits for field multibatch continuous real-time transmission and processing of working condition information, by using the NETBIOS function call method, the real-time communication among network workstations is realized and a power plant working information background real-time communication and data processing system is developed which effectively traces working condition from tow 200 MW power plant generators, altogether 321 points from a cycling detecting system and 78 binary points for broadcasting the information to other workstations,and realizes a complx display of 14 working condition graphs and a real-time data simulation graph.     

采用智能通风的科技手段实现仓房节能排热低温储粮

通过利用智能通风控制系统对仓房进行夏季排热与常规夏季排热的对比,发现达到同样的排热效果的情况下,智能通风排热更加经济、便捷;同时也通过不同仓型之间的对比找出了各种仓型的排热特点。     

Distributed Power Flow Method Based on Ward Equivalent

With interconnecting and developing of power system, the problem of power flow computation on dispersed data resource need to be solved. A new distributed computation method of power flow based on Ward equivalent is presented. According to master-slaver splitting principle, multi-area interconnected power system is divided into master-slaver areas. Boundary buses in different areas are defined as different bus-types. Neighborhood areas are equivalent by Ward equivalent principle, and the equivalent injection power and equivalent impedance are worked out. Power flows from master area to slaver areas are solved by Newton method, and the equivalent injection power and equivalent impedance on the boundary are modified by their solutions. The process above repeats until to convergence. The proposed distributed power flow method takes full advantage of the information of power, voltage, network configuration in neighborhood areas, so it is better on convergence and quality of solution. The proposed algorithm is testified by IEEE 14-bus system and a practical 181-bus system.     

Heat dissipation optimization of DC-DC and IPU for hybrid electric vehicle

Due to the bad heat dissipation of the existing heat dissipation structure of DC-DC and IPU for hybrid electric vehicle(HEV), the temperature of DC-DC and IPU will rise during the running process, which in turn decreases the stability and reliability of the hybrid electric system. Aiming at this problem, a three-dimensional, transient heat dissipation model is built for DC-DC and IPU heat dissipation structure based on the mass, momentum and energy conservation equations. By using computational fluid dynamics (CFD) software, flow field and temperature field of DC-DC and IPU heat dissipation structure are numerically simulated. Based on the simulation, and combined with heat transfer theory, an improvement scheme of heat dissipation structure is proposed. The simulation results and experiment results of thermal performance and temperature rise show that the improvement scheme can improve the thermal performance, and decrease the temperature rise of DC-DC and IPU effectively, thus satisfy the application requirements in HEV.     

农地征收中的产权弱化问题分析

基于产权理论角度分析中国农地征收中存在的产权弱化问题。经过分析发现,农地产权的弱化导致农地征收的租值消散问题、农地征收定价困难问题与农地产权保护薄弱问题,这些问题都是造成农地征收补偿矛盾的重要原因。因此,中国农地征收可以从建立农地使用权交易市场、建立第三方评估制度、转变政府职能、加强农地产权保护等方面进行农地征收的制度完善,以强化农地产权,解决征地补偿中出现的诸多矛盾和问题。     

Study on constant current control of inductive power transfer with parameter identification

Aiminy at magnetic exciting current (resonant current) control, a constant current control method based on dynamic parameter identification is put forward. With energy conversion analysis, the energy storage, supply and dissipation functions of the system resonant network are constructed. The reflecting impedance identification functions are obtained by constructing the energy equilibrium relations in a period and among several periods. Furthermore, a constant current control strategy by regulating the system input voltage with Buck converter is presented. Combining the relations among system input voltage, the envelope of resonant current and the input of Buck converter, the constant current control law is proposed. The control law is verified with experiments. For the proposed method, in parameter identification, only the data of zero crossing point of resonant voltage and current are required, which reduces the complexity and costs of sampling system. Also, the constant current control law does not need complex computation and is easy to implement.     

Kolmogorov entropy analysis of surrounding rock system in the processing of unloading for deep buried tunnels

Rock is a kind of physical nonlinear complicated medium, under deep buried condition the surrounding rock system deformation shows geometrical nonlinear characteristic, and the interaction between the two nonlinear mechanism makes the unloading of surrounding rock system evolving complexly. Based on the Lagrangian method and large deformation caculation method, both the double nonlinearity and nonlinear dynamics character of deep buried tunnel surrounding rock system under unloading are studied. The numerical model results show that the Kolmogorov entropy has been extracted from the evolution data in the unloading process of surrounding rock system. The analysis indicates that the typical chaos character has been demonstrated in the process of unloading for deep buried tunnel surrounding system and the rock mass energy dissipation is analyzed at the stage of unloading.     

A power distributed computing system model based on services-oriented architecture

Process communication based power distributed computing model satisfies the demand on real time monitoring and analysis for the economical operation of power grid based on power distributed computation methods, but there are some problems on complexity in common basic functions development and lack of system extendibility. An extendable services-oriented power distributed computation system model is designed and implemented. Software design patterns are applied to design low coupling and extendable system framework. Windows Communication Foundation (WCF) technology is used to implement the services-oriented distributed data communication functions. Windows Workflow Foundation (WWF) technology is used to design the business logic of power distributed computation visually. Data integration functions are implemented by combining the ADO.NET technology. The services-oriented system architecture enhances the integration ability and extendibility. The use of WCF and WWF technology reduces the complexity of the system development.     

Intelligent Extracting Method for Feature Mode of Electric Days Load

Generally there have a number of bad data in the electric load data and it affects the precision of load forecasting,so it is necessary for extracting the feature mode of days load data,then cleaning the load data before it is used to forecasting electric load or performing power system analysis.Inspired by soft clustering thought,a intelligent feature mode of days load data extracting method is proposed based on the mutual offset of fuzzy c-means clustering arithmetic and Kohonen self organization feature map neural network.With the merits of not only high extracting precision and convergent speed but also dynamic calculation capability,the method proposed can supply load forecasting or system analysis procedure with due data.Test results using actual data of Chengqu power supply bureau in Chongqing demonstrate the effectivity and feasibility of the method.     

STUDY ON SELF -SCANNING CIRCUIT OF LOW POWER DISSIPATION MOS IMAGE SENSOR

The paper studies a self- scanned circuit used in MOS image sensor with the demand of developing of high -order.low power disspation MOS image sensor and puts forward a kind of self -scanned circuit .which uses a three tramister dynamic nocomparing circuit whith a changing capacitor bootstrap circuit as MOS image sensor. The circuit adopted a silicon gote P -MOS technique, which is a high -speed low-dissipation dynamic no-coparing circuit. It is a practical unit circuit in the high -order array and solves the problem that the power dissipation of array rises with the increase of the array bite.     

Model for Coupled Electro-Mechanical Behavior of Ferroelectric Crystal

Ferroelectrics are important materials applied in smart structure and system. A model is developed to simulate the electro-mechanical behavior of ferroelectric crystal. An analogy is drawn between the slip system of dislocation in metals and domain wall movement in ferroelectrics. It's assumed that switching is resisted by the dissipation motion of domain walls. Simulation results show typical nonlinear electro-mechanical behavior of ferroelectric crystal.     

Cellular automata spatial temporal data model and forecasting approach

The standard cellular automata(CA) model is expanded to meet requests of space time dynamic simulation and forecast under the platform of geographic information system(GIS). Taking power load forecasting of the electric power industry as the specific application, the relations between dynamic model of the land use and power load space are established. The data and attribute data interactive discrete in spatial temporal data management have been solved. The CA theory is practically used to simulate the process of urban land use dynamic development, to forecast future land use types of each small area, to establish spatial load forecasting model. It breaks through the localization of all kinds of forecasting methods of traditional space time separation power prediction. The effectiveness of the prediction method is verified by example.     

Control Method of Voltage-reactive Power of Substation Based on the Real Time Adjusting Voltage Calculation

The main means of the voltage-reactive power control of substation are adjusting the taps of load-tap-changing transformer or the reasonable capacity of parallel compensating capacitors according to the operation condition of substation.The "nine-area control strategy" is widely used to adjust voltage in the stated range and reduce the transmission capability of reactive power for power system at present.By analyzing the existent shortages of nine-area control mode for voltage-reactive power,an adjusting voltage calculation method is put forward,input data of which are the real time data of current,voltage and power of the substation.Then operation decision of voltage-reactive power control method of substation is made.By the simulating analysis,predigesting method of upper system is built,based on which an applied real time calculating model and calculating steps is given.     

Operation Optimization of Ball Type Pulverizer Based on System Identification

The ball type pulverizer system is widely used in power plant in China because of its better coal adaptability, easy maintenanceand high reliability. However, its primary disadvantageis high power consumption. Itis not only the big consumer of power plant ,but also thebig latenteconomizer. Some existentresearches mostly focus on pulverizer, not on the ball type pulverizer system. An operation optimization method is presented in the disquisitionbased on the system identification. By selecting data upon orthogonal norm , acquiring the system model through Least Squares method, and according to the theory of optimization, the authors obtain the optimal values of controlledparameters.This method can avoid disadvantageboth of searching for the input-output specialty through mechanismmodeling and big data sample space for Manual Neural Network. It is valuable in practice for the ball type pulverizer system operation optimization and economizing energy in power plant.     

Management Information System of Power Based on C/S and B/S Mode Combined

After analyzing the feature of C/S and B/S modes, a kind of MIS for power industry, which combined C/S with B/S, is put forward. The C/ S platform is developed with the Powerbuilder 7.0 and SQL Server 7.0, and the B/ S platform is developed with ASP and IIS5.0+ SQL Server7.0. Electric power management information system should be constituted by the seventh statures mold piece, which are the electricity measures to collecting, electricity charges settling accounting system, the safety system et al. In order to meet the demand of data safety of enterprises, the method of passing data between C/S and B/S is introduced.     

低功耗粮情测控物联网模型研究

以储粮粮情测控为研究背景,以降低粮情测控系统功耗为目标,提出了一种低成本、低功耗、可扩展的弹性粮情测控物联网模型。粮情测控物联网模型包括三层结构:感知层、传输层和汇聚层。感知层支持多参数粮情数据感知;传输层多跳传输粮情数据;汇聚层兼容GPRS、WIFI、WLAN、3G、Enthernet等通信方式,系统结构灵活,扩展性强。实验验证,该模型相较于传统的WSN至少可以延长粮情测控系统的寿命,粮情感知节点在不更换电源情况下可以工作3~5年。