Simulation Investigation for the Regulating Characteristics of Real and Reactive Power of Asynchronized Turbogenerators

This paper discuas the controlling principle of asynchronized turbogenerators,deduces their mathematical model,and studies their regulating characteristics of real and reactive power(or voltage)by means of simulation calculation of operating characteristics for a 200MW asychronlzed turbogenerator.The conclusion is that the asychronlzed tubogenerators not only can regulate real and reactive power independently but also has an excellent dynamic performance.     

Low frequency oscillation restraint in power systems that include asynchronized turbogenerators

Yangtze River is abundant of water and can provide enough water as cooling and heating source for water source heat pumps (WSHP). A pair of contrast experiments with open loop system and close loop system of WSHP were finished in order to get the heat pump's COP, the system's COP and the distribution of water temperature in the heat exchanger etc. This paper compared the characteristic and the COP of these two kinds of system. The heat pump's COP of the open loop system and close loop System are 3.08 and 3.77 respectively, and the system's COP are 2.83 and 2.80 respectively. At last, applications of open loop system and close loop System of WSHP at Yangtze River were analyzed and the key problem for attention was pointed out in the paper.      

Modeling and Simulation of the Doubly Fed Generatorwith the Matrix AC-AC Converter as an Exciter

According to the space vector modulation method of the AC DC AC converter,the switch control scheme of the matrix AC AC converter is deduced,and the model of a three phase matrix AC AC converter is constructed. According to the mathematic model of the doubly fed generator and the excitation control principle based on dynamical synchronous reference frame,the simulation model of the generator and excitation controller are established,then the modeling and simulation of the doubly fed generator system with the matrix AC AC converter as an exciter are implemented.The steady state and transient characteristics of the system are simulated,the harmonics of the EMF and stator?rotor current are researched.     

富硒猪肉脯生产中HACCP体系的建立

对富硒猪肉脯生产过程中各个环节可能存在的潜在危害进行了分析,根据HACCP原理确定了相应的关键控制点(CCP)和关键限值,并制定了相应的预防措施,建立了监控方法,将加工过程中的危害风险降低到最低程度,从而最大限度的提高富硒猪肉脯的食用安全性。     

Passive Lossless Forward Converter with Current Double Rectifier

To reset transformer excitation flux reliably,reduce the switching losses and improve influence of EMI noises in high frequency forward converters,several kinds of methods have been proposed,including RCD snubbers,active snubbersand resonant converters,and so on.These methods have many shortages.In consideration of these shortages,this paper puts forward a passive lossless forward converter with current double rectifier(CDR).The circuit does not require an extra switch or additional control circuit,and can resets the transformer excitation flux reliably,and does not include lossy components.So the circuit has higher reliability and higher performance/price ratios than above several kinds of methods. The paper analyzes the frame and operating principle of main circuit in detail.The key parameters design principles of the circuit are given.The simulation results confirm validity of the theoretical analysis results.     

Design of Excitation Control System of A.C.Excited Generator

Dual-passage excitation control method based on dynamical synchronous reference frame is analysed according to the base theory of A.C. excited generator. Using the dual-CPU project basing on the high speed DSP, excitation control system of A.C. excited generator is realized. Considering the characteristic of this control system, taking full advantage of the high speed and the convenient peripherals of DSP, the hardware and software of the control system are designed appropriately. Dual-passage excitation control system is realized using the dual-CPU method. Dual-passage excitation control strategy based on dynamic synchronous reference frame is proved with the experiment.     

Dual-pasSage Excitation Control of Asynchronized Turbogenerator

n this paper,the principle structure and basic model of dual-passage excitationcontroller of asynchronized turbogenerator are presented.The control effect of each feedback termare analyzed.Two improved control schemes are proposed and testified by simulation in vestigation.     

Discussion on the Secondary Moment of Prestressed Frame

The secondary moment of prestressed concrete frame is different from that of continuous beam. In this paper,the principle and calculation method of equivalent load secondary moment and axial secondary moment are discussed,and the infection of secondary moment in moment modulation is analyzed,together with the suggestions of moment modulation for prestressed concrete frame with adopting the total control. The suggestions would be able to distinguish the advantageous and disadvantageous effect of secondary moment. Some helpful advises for moment modulation design are given in this paper.     

Study on Single-chip Computer Control Systems in Miniature Water Works

In order to enhance automation and to design low price and performance reliable control systems for the miniature water works, the single-chip computer control system was adopted to control the work. The single chip computer control system in the miniature water works, the principle of the hardware and a part of software block diagram were discussed in this paper. Finally, the data acquisition and control network were introduced.     

Study on the Integration Framework of Urban Planning Information System Based on Web Services

Web Services is a service-oriented structure and which is really platform-independent and language-independent.In this paper, its system and key technology are analyzed,then aiming at the main problems in information sharing of urban planning information system(UPIS),a UPIS integration framework based on the Web Services is proposed and its principle is studied.Furthermore,an example with realization of UPIS system by ASP.NET in Visual Studio.NET is given.     

A SENSITIVITY METHOD FOR THE WEIGHTING MATRIX SELECTION OF LINEAR OPTIMAL CONTROL

The paper analyses the relations between closed-loop system dynamic qualities and linear optimal control weighting matrix Q and offers a sensitivity method for selecting weighting matrix Q. As a practical example, a linear optimal supplement excitation control system is designed for a single machine-infinite bus power system using the presented method. Theoretical . analysis and simulation results have shown that the dynamic qulities of the control system are very satisfactory.     

速冻青刀豆HACCP体系中微生物控制效果的研究

为了提高出口速冻青刀豆产品的安全卫生质量,验证HACPP体系对产品微生物的控制效果,在青刀豆产品生产过程中运用HACCP原理,确定关键控制点及其控制措施,建立了完整的HACCP体系;并对执行该体系后的产品进行菌落总数、大肠菌群和大肠杆菌的检测,数据用数学建模方式分析。结果显示,产品菌落总数符合维布尔分布,以104cfu/g为标准,菌落总数指标的合格率达到99.22%;大肠菌群指标的合格率为98.33%;大肠杆菌(致病菌)指标的合格率为100%;证明HACCP体系在产品微生物总数的控制方面具有很好的效果,值得在速冻蔬菜产品中推广应用。     

Type Selection of Grit Clarifier without Primary Sedimentation Tank

In view of existing features of activated sludge process without primary sedimentation tank and the requirements on grit removing sedimentation tank,in this paper,two types of grit clarifier-horizontal and whirling one are suggested with consideration of grit removal efficiency for fine particle size during its design.Then,according to the sedimentation theory,the principle of grit removal,control of key technical parameters and type choice of grit discharge equipment are analyzed.It can serve as reference for the design of grit clarifier.     

Dynamic signatures method for analysis of vehicle bridge resonance

The dynamic behavior of railway bridges (dynamic deflection and acceleration) is one of the running safety control indices for high speed trains. Therefore, the dynamic behavior of railway bridges is studied based on the concept of the dynamic signatures of the train and the bridge. By simplifying the train excitation as a series of moving concentrated forces, the mathematical expressions of the dynamic signatures of the train are obtained through theoretical derivations, and then a method is presented for calculating the resonance speed of trains and the maximum vertical acceleration of the bridge. With this method, the dynamic responses of the simple supported bridge can be calculated quickly. The feasibility of this method is validated through some examples, in which the resonance mechanism of train bridge system and the influencing factors are investigated. In addition, the effect of high frequency components to the bridge acceleration is also analyzed.     

Unbalance response analysis of high speed aerostatic motorized spindle rotor system

According to the high speed of aerostatic motorized spindle, the complex dynamic behavior and the unbalance incentive, dynamical model is built up on the basis of Lagrange equation. And it is includes the differential equatioan of free vibration and forced vibration.Then, the residual unbalanced inertial centrifugal force and the mechanism of unbalanced magnetic pull are analyzed. Finally, a motorized spindle rotor-gas bearings system with the highest working speed of 250 000 r/min is simulated in the way of the unbalance excitation harmonic analysis. The dynamic behavior of high-speed aerostatic motorized spindle is revealed in supercritical mode at unbalance excitation.A theoretical basis is provided for the optimization design, vibration control to the rotor system of high-speed aerostatic motorized spindle in engineering application.     

Principle and Key Technology of Full Automatic Vicat Apparatus

In this paper the working principle and performance character of both the manual and automatic Vicat apparatuses in existence are compared and analyzed,and their existing weakness and the urgent problem to be solved are pointed out.On this basis,adopting the technology of mechatronics and modern sensors,a new sort of full automatic Vicat apparatus that can fully satisfy the national standard in testing the setting time of the cement has been developed.This apparatus can be operated expediently with high precision,the test results are to be analyzed and computed automatically.This paper presents the working principle,performance character,key technology and prospect of application for the full automatic Vicat apparatus.     

Approach to Effective Control on the Project Investment

In this paper, in allusion to the three kinds of serious overvaluation (the budgetary estimate of project construction exceeds the rough estimate, the budget exceeds the budgetary estimate and the final accounts exceed the budget) causing uncontrollable project investment often appeared in domestic project construction,the main causes for that are analyzed. That is, the frequent project change and the malpractice of the cost managing system. In this paper, according to some real projects,the kinds and causes of project change are clarified and the malpractice of the cost managing system is analyzed. The effective approaches of reducing the project change, especially the united surveying and improving the cost managing system in order to make the effective control of the project investment are realized.     

A Digital Thyristor Trigger Control System of Three Phase Full-control-bridge on the Base of Singlechip Controller

A new type of digital trigger control system on the base of Singlechip Controller is proposed for water power station control system. The trigger use the singlechip controller's highspeed output port skillfully, and this system included controller and trigger,so as to reduce the component, reduce the cost and make the system more integrated, more precise and more reliable and advanced the hydro excitation control system. In this system, we use new electric technology, new detection technology and new automatic theory, so as to make the system more perfect and more intelligent. It has overcome the disadvantage of simulation integrate circuit in above.     

The Electric Control System of Mechanical Transmission Test-bed With Mechanical Closed Cycle And Electric Colsed Cycle

This paper presented the principle and combinations of the mechanical transimssion test-bed with mechanical closed cycle and electric closed cycle. This system is composed of variable velocity driver, motor, generator, inverter and computer. It can be used both in mechanical closed cycle test-bed and electric ciooed cycle test-bed. The test-bed can keep a realting monitoring over the system and control the rotational speed and torque by computer. It can also simulate the real work condition of the test and to do the test. In this paper,the diminishable magnetization velocity modulation,invertiable control,the test data and curve,and the inverting efficiency as well as control scheme and presented.     

Assessment and Suggestion on Management System of Vehicle Exhaust

This paper analyzes the deep reasons why the benefits are always poor though China has controlled the vehicle exhaust for more than ten years, as well as a successful experience of the developed countries. Contrasting the deficiencies of the previous Air Pollution Control Law and advantages of the present Air Pollution Control Law , the paper indicates the organization structure and management system of the EPA are not entirely eligible for the tasks though the new law entitles environmental administrations to strengthening the exhaust control. It calls for that, according to principle that a structure results in a function, China must establish the management system of vehicle emission control in metropolises as soon as possible. So we can implement this law and improve urban air quality that has deteriorated due to vehicle exhaust. This paper puts forward organization form, functions, tasks and effect of this system.