Improvement Methods of Fuzzy Control with Intelligent Integration

Fuzzy controller can achieve satisfactory dynamic performance even for complicated process without mathematical model of the process.Its main imperfection is the existence of steady state error and ultimate oscillatory in the process output. This limits its application area. How to eliminate the steady state error while keep its good dynamic performance has been paid much attention. The strategy to introduce integral function to the conventional fuzzy control system is put forward in this paper to overcome the above problem. After expound two key factors on introducing integral action,an intelligent integral algorithm has been employed,and two methods on introduction of the intelligent integral to the fuzzy control system are proposed. Their characteristics and applied situations are summarized.     

Application of Fuzzy Control in Direct Torque Control of an Induction Motor

The key of motor control is to control motor's torque essentially.Direct torque control,which emerged after the field-oriented control,directly stresses the instantaneous torque control of induction machine,which avoids some problems existing in field-oriented control,thus,it gets more attention.In conventional direct torque control system,switch vector is selected directly by the errors of stator flux-linkage and torque,after introducing fuzzy logic,optimal selecting switch state is realized by various strategies by distinguishing the grade of the errors of stator flux-linkage and torque,the dynamic and steady state performances of induction motors are improved.This paper presents a design method of the fuzzy controller.Simulation results demonstrate that it is effective,the stator currents pulsation at start-up and the torque pulsation are decreased.     

Analysis on Control Strategy for a Kind of Uncertain Complexity System

In practical industrial fields, it is very difficult to control uncertain complexity object effectively, because there are various uncertainties from internal dynamic characteristic and external, surroundings disturbance for controlled object. Its complexity is not only shown in structure, but also in information relation, so it is uneasy to implement it on technology. Aimed at selecting puzzle of control strategy for uncertain complexity system control, the authors describe cybernetics model based on analysis on some kinds of control strategy and contrastive research, and the model is applied in physical engineering system successfully. Finally, the authors point out that intelligent control strategy should be selected for uncertain complexity system control, and that Human Simulation Intelligent Control is a wise choice.     

DECENTRALIZED LOAD FREQUENCY CONTROL OF HYDROTHERMAL POWER SYSTEM

The decentralized load frequency control (LFC) of hydrothermal power system is designed with overlapping information set. The conflicts among the generation regulation constraint (GRC) ,the process of reheat steam turbines,the governor dead-band effects,and the dynamic response of LFC have been coordinated.     

Fuzzy Adaptive Variable Structure Control of Speed Process of DC Motor

The load changed of motor affects normal run. If it is not adjusted, the state of motor will become poor, while it affects steady of the system. This paper presents an efficient method for the motor speed controlling, it applies Tacagi-Sugeno's method that each linear submodels are connected for fuzzy algorithm, an algorithm of the fuzzy model identifying and fuzzy control is fulfilled through whole nonlinear model which are replaced with local linear models. It makes speed of motor to maintain steady, and variable structure control is applied to guarantee performance of dynamic flowing for process controlled, the design of stability and robustness is proposed in the scheme. Practice running results show that it is efficient that uncertain dynamic processes are controlled.     

Improvement and simulation on direct torque control system of permanent magnet synchronous motor

To solve the problems of large flux, torque ripple and inconstant inverter switching frequency in conventional direct torque control (DTC), a space vector modulation (SVM) technique is introduced to the conventional PMSM-DTC system and analyzed thoroughly based on the mathematical model. This novel control method which enjoys the advantages of VC and DTC has only one easy adjustable PI regulator and is easy to realize. The simulation verifies that this control system is capable of effectively improving the steady state performance and keeping the excellent dynamic performance of the PMSM-DTC system simultaneously and remain the switching frequency constant.     

Temperature Control of High Temperature Melt Viscosity Test Instrument

The construction and function of high temperature melt viscosity test instrument are introduced in this paper. And the character of temperature control system is given. In order to improve dynamic and static performance of the temperature control system, a new method is proposed which combines threshold control with adaptive fuzzy PID control. While the current temperature of the heating furnace is much lower than the given temperature, threshold control works in order to protect system and improve dynamic performance. When the current temperature is close to the given value, adaptive fuzzy PID control works to improve static performance. At last, simulation and experiment results validate the proposed control method.     

Vehicle Lateral Stability Control Based on Sliding Model Control

In view of the vehicle cornering or path changing under ultimate handling maneuver, a 3-DOF nonlinear vehicle dynamics model which takes the vehicle lateral velocity, yaw rate and body roll angle as the State variables is presented. Based on the dynamic analysis, the method which using additional yaw moment produced by different longitudinal braking force among each wheels to improving vehicle handling stability in emergency situations is discussed. Considering the sideslip angle as one of the vehicle state variables is difficult to measuring, the sideslip angle estimation based on vehicle dynamic model and kinematics is designed. And then, based on the theory of siding model control, the combining sliding model control system is founded, which taking the vehicle yaw rate and body side-slip angle errors between the estimated and the real as the input variables, and taking the braking torque and the steering angle as control aims. The simulation results indicate that the control method can effectively improve the vehicle lateral handling stability.     

Analysis of Unified Power Flow Controller in Damping Low Frequency Oscillation of Power System

With the development and complication of power system, the problem of low frequency oscillation in electric network becomes obvious. Unified Power Flow Controller is one of the most powerful facilities in Flexible AC Transmission Systems, which can improve the transient stability and damp the low oscillation in power system with suitable control. Considering the characteristics of inverter's output voltage magnitude, adjustment of phase and process of charge and discharge of dc capacitance, the dynamic model of UPFC is proposed by a series of nonlinear differential coefficient equations. Based on UPFC's dynamic model, the linear optimal controller of UPFC with state feedback is proposed. In this way, the low frequency oscillation is damped effectively. A simulation is processed basing the theory.     

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.     

Simulation Research of Control Parameters in Induction Motor Vector Control System

In order to obtain the effect rules of control parameters of speed regulator on performance indexes of induction vector-controlled system and the setting rules of control parameters of speed regulator,according to rotor flux oriented control principle,a vector control model of induction motor is established and simulated with the software of Matlab/Simulink.This vector control system is proved that it possesses good static and dynamic performance.This paper analyzes the effect of control parameters' variations of speed regulator on performance indexes and gives simulation results.     

Analysis on Correlated Problem with Control of Uncertainty System

The majority difficulty for uncertainty system control is that agreements haven't been arrived in concept of uncertainty information and its characteristics, uncertainty system and its properties. Therefore some control problems have discussed based on some confused concepts, and the result shows that the study on uncertainty system control hasn't made great progress yet. In addition, problems concerning uncertainty system control are very wide in the practical engineering. Aimed at above problems the concept of uncertainty information and its classification, basic properties of uncertainty system and desired control strategy based on own practical experience are studied. Finally, that intelligent control strategy is wise choice for uncertainty system control based on successful engineering application.     

Optimal Control System for UPFC

This paper first analyzes the internal dynamic process of the UPFC,then a five order differential equation is presented to describe dynamic behavior of UPFC. In term of this,a optimal control system is designed.Dynamic simulation of a transmission system demonstrates the effectiveness.     

THE OVERLAPPING DECOMPOSITION DECENTRALIZED CONTRAL FOR GENERATOR''S EXCITER/GOVERNOR SYSTEMS

In this paper the generator's exciter/governor system are decomposed by using the overlapping decomposition method, and an overlapping decomposition decentralized control (ODDC) system is designed for the exciter /governor systems. In or.dar to enhance the dynamic qualities of the decentralized control system, the concept of the second feedback system is introduced to modify the first feedback gain matrix on the condition of the structure of the original decentralized control system maintaining unchanged. The practical decentralized control system design and its; simulation results show that this method greatly improves the control effect of the ODDC system and also holds all the advantages of the ODDC system. Besides, this paper indicates that it is a simple and effective method to control excitor/governor system by overlapping decomposition decentralized control strategy.     

The design of torque dynamic sliding mode controller in permanent magnet synchronous generator for wind turbine

Permanent magnet synchronous generator for wind turbine is a multivariable nonlinear system with strong coupling. Considering the influence of the volatile parameters of the generator on the performance of vector control, the torque dynamic sliding-mode control strategy is further studied. The proposed first order dynamic sliding-mode control strategy reduces the chattering by using a new switch function constituted with derivative element. With the dynamic sliding-mode controller in the power outer loop, the PMSG vector control system shows excellent robustness and insensitivity to the parameters and disturbance, which is confirmed by simulation.     

Control Strategy for Asychronized Turbogenerators

Asynchronized Generator can better solve the excessive reactive and stability problem in power system.In order to improve the dynamic and transient performances of an asynchronized turbogenerator(ASTG),excitation control equation of it in the dynamic synchronous reference frame is presented.Control results are simulated in the synchronous and dynamic synchronous reference frames for ASTG.It is shown that the dynamic and transient performances in the dynamic synchronous reference frame are better than those in the synchronous reference frame.Consequently,the control strategy of dynamic synchronous reference frame can shorten more time on the dynamic process of ASTG.     

AN EXPERT TYPE CONTROLLER FOR INDUSTRIAL PROCESS

In this paper an expert system concept in AI is introduced to the industrial process control. Specific structures and features of expert control system are discussed. An expert controller directly applicable to industrial process is designed. The simulation of control system indicates that the expert controller has strong information precssing capability and versatile control strategies with desirable control performance. Thus, expert control approach is an effective means towards the realization of intelligent Control.     

ON THE PROBLEM OF SWITCHING CONDITIONS FOR A KIND OF MINIMUM-TIME CONTROL SYSTEMS

The paper provides a detailed study of switching conditions of minimum-time control systems based on application in engineering. By analysis in theory and experiment, the authors deduce a set of switching conditions with state and control variabes inequality constraints, the variations of system parameters and the time-delay of computer in real time control. As an example, a DC motor speed control system is considered. By digital simulation and physical experiments,these conditions proved to be correct. The method in this paper is also suitable for other control systems using compound control algorithm.     

The Research and Simulation of the Fuzzy-PID Control System for Ball Mill Pulverizing of Power Plant

This paper focuses on the main problems in the operation control for ball mill pulverizing system, proposes the dynamic mathematical model for the steel ball mill pulverizing system , simulates and analyzes the dynamic character of the system. A Fuzzy-PID controller with on-line self-tuning parameters based on fuzzy control technology is proposed .The simulation results show that the Fuzzy-PID control system can improve the controlling effect and the ability of suppressing disturbances.     

Design and Implementation of Role-based Access Control in a Teaching System

This paper discusses how to design and implement a security subsystem, which based on the Role-based Access Control technology. By taking a teaching web system as a practical example, the paper establishes an access control matrix, so dynamic menu, page jump, and data access control are loaded. The experimental shows that, the system can controls the access authorized data, and to avoid the illegality access. The practicability and robust in the system is evident.