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.     

Overall control strategy and operational performances of a doubly fed wind turbine generator system

In order to comprehensively and correctly analyze the real-time operational characteristics of a grid-connected wind turbine generator system, it is necessary to analyze the overall control strategies and operation performances of the wind turbine generator system. According to the type of a doubly fed wind turbine generator system, the mathematical models of wind turbine, drive train and doubly fed induction generator (DFIG) are presented. From the viewpoints of the maximum wind energy capture and safe operation of the wind turbine, a maximum power output control strategy is proposed by considering the DFIG loss minimization, and a variable pitch control strategy is also presented by considering generator rotational speed restriction and the output power restriction. Combined with a power decoupling strategy of DFIG, the overall operational performances of the doubly fed wind turbine generator system are simulated. By comparing the simulation, theoretical analysis and actual operational data, the results show that the presented model and overall control strategies of the doubly fed wind turbine generator system are valid.     

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.     

A new control design for grid integration ofDFIG wind farm with VSC-HVDC

This paper proposes a control scheme for a doubly-fed induction generator (DFIG) wind farm with VSC-HVDC grid integration to ensure secure and reliable operation of power system with fluctuated wind power penetration. The whole system dynamic models are respectively described. Based on vector control system with a virtual voltage orientation, a steady-state voltage control block and a dynamic voltage control block with a cross-product term of d-q currents are separately designed for WFVSC to control the corresponding parts of the wind farm voltage. Meanwhile, with the consideration of AC and DC side parameter variation and external disturbance, an improved backstepping control scheme with Lyapunov stability provement is also proposed for the GSVSC. The combination of the two schemes makes up the new control design of this study. Besides, to verify the performance of the proposed new control design, three different cases are suggested which contain the AC and DC side parameter variation and external disturbance such as local load cut off-in, grid voltage harmonics. Finally, numerical simulations using MATLAB/Simulink are presented for a 200MW DFIG wind farm with VSC-HVDC grid integration to validate the proposed control scheme and demonstrate the improved system operation performance. Moreover, the corresponding discussions are also presented for further illustrations.     

含旋转电机接口和逆变器接口的微网小信号稳定性分析

提出了一种包含了逆变器接口（voltage source inverter,VSI）、同步电机接口（synchronous generator,SG）的独立微网控制策略,并分析了其小信号稳定性。VSI接口和SG接口的分布式电源均采用下垂控制策略,二者之间无需实时通信,可实现负荷功率共享。建立了系统的小信号状态空间模型,主要包括：同步发电机及其控制器的小信号模型、逆变器及其控制器的小信号模型、电网络及负荷小信号模型。计算了下垂增益变化时的根轨迹,得到了系统主特征值随参数变化的根轨迹,计算了不同状态变量对特征值的参与因子。稳定性分析结果表明：当所有分布式电源采用下垂控制时,引入同步发电机接口的分布式电源,系统频率小信号稳定性大大增强。PSCAD时域仿真验证了特征值计算的正确性。     

Vector control of permanent magnet synchronous motor with variable DC-link voltage

As for the drive of control system in electric vehicles, if the inverter power is supplied by a constant DC-link voltage, there are some disadvantages in the system, such as small utilization of the voltage, big current harmonic distortion of the motor windings. A new strategy for vector control of permanent magnet synchronous motor (PMSM) with variable DC-link voltage is proposed, which is suitable for electric vehicles. According to the reference voltage amplitude of the inverter, the new system uses bidirectional DC/DC converter to adjust the DC-link voltage to improve the performance of the vector control system. At last, the whole system is simulated with MATLAB software. The simulation results show that the new strategy for vector control can increase voltage utilization, decrease torque ripple, improve current waveform effectively and decrease the total harmonic distortion of motor current. The results also verify the effectiveness and feasibility of the new strategy.     

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.     

Control strategy of regenerative braking for hybrid electric vehicle based on engine braking

Focusing on a continuously variable transmission(CVT) hybrid electric vehicle with integrate starter generator(ISG), modeling and simulating of engine braking was conducted. An optical control strategy of regenerative braking was put forward. When there is no regenerative braking, engine brake force can be used effectively by changing the CVT ratio to reduce the braking force requirements for wheel brakes based on the calculated results of engine braking. When there is regenerative braking, the braking priority sequence is generator braking, engine braking, and finally frictional braking. A forward simulation model for regenerative braking system of hybrid electric vehicle was built. The simulation and analysis under typical driving cycles was conducted. The result shows the control strategy and the models are reasonable and feasible.     

Dynamics Simulation of ISG-HEV Engine During Starting

The behavior of engine automatic starting and stop under idle speed is an important working model for HEV(hybrid electric vehicle), which can avoid engine running under idle speed. So it can reduce engine fuel consumption, exhaust gas emission and wear efficiently. The ISG(integral starter/generator) motor control strategy is given by dynamic research of the HEV engine starting, based on the model and simulation of resistant characters during engine starting, then an ISG motor-engine integral control model is built up and simulated. The result shows that the ISG motor can drive engine quickly and the simulation meets well with the need of starting time.     

Adaptive Inverse Control for Feed Water and Superheated Steam Temperature of Supercritical Pressure Boiler

An adaptive inverse control method for feed water and superheated steam temperature of supercritical pressure boiler is investigated. Through the analysis of the boiler system ,s dynamic characteristics, the input vector structure of inverse dynamics model of feed water and superheated steam temperature is constructed. The adaptive inverse control system is realized through on-line identification of inverse dynamic model with recursive least squares support vector machine. In the control process, the demand for feed water and spray water flow to the outlet steam temperature and micro-superheated steam temperature is considered to realize the integrated control of feed water and superheated steam temperature. Simulation results show that this control system has good control performance and adaptability and can void the repeated oscillation phenomena of control variables which appear in present two section control system.     

Modeling and simulation of a grid connected wind turbine withdoubly fed induction generator

In order to fully research the effects of external excitations, such as wind speed, wind direction and voltage disturbance, on a grid connected wind turbine with doubly fed induction generator, a co-simulation model of MW-class wind turbine system is established by using Simpack and Matlab/Simulink software. Also, by considering the actual control strategies in the process of simulation, the relationship between external excitations and mechanical system is studied. According to time-domain simulation under the turbulent wind condition, the dynamic meshing forces of gears are analyzed. Besides, the vibration responses of tower are calculated under the different external excitations. Research results lay a foundation for dynamic performance optimization and reliability design of a wind turbine.     

Control strategy and parameters optimization outsourcing production inventory system under uncertainty

This paper proposes a control strategy for the optimal control of the outsourcing production inventory system based on production point and production batch. The statistical probability distribution is used to describe the uncertainty of the production capacity of cooperative enterprises and the transportation time. The optimization model of the control parameters is developed with random production capacity for cooperative enterprises and random transportation time in order to minimize the holding cost,setup cost as well as the cost of production capacity waste. A simulation-based control parameters optimization algorithm is designed to solve the proposed model. The control strategy of production inventory system and the control parameters optimization algorithm proposed are validated by an example. We analyze the influence of the variation of the production point and production batch to the performance of the outsourcing production inventory system.     

AN AUTOMATIC VOLTAGE REGULATOR USING IDENTIFIED MODELS

This paper obtains the mathematical model of a single machine infinite bus power system using the idea of parameter identifications. Because the noise is considered in parameter identification process, the model reflects the real system more exactly. On the base of the identified model this paper also presents a discrete automatic voltage regulator by minimum variance control principles. In order to avoid the static error, we combine discrete minimum variance control with continuous integral control and get very satisfactory effects. This proposed control strategy is very easy to realize. The simulation results show that in every case the dynamic qualities of the proposed control strategy are incomparably superior to that of the conventional PI regulator, which means the proposed control strategy has great practical values.     

Vibration control of active constrained layer damping structure

A finite element dynamic model for plates with active constrained layer damping (ACLD) treatments is derived based on the constitutive equations of elastic, viscoelastic and piezoelectric materials by application of Hamilton principle. The closed loop control system considering displacement and velocity feedback of self sensing voltage from sensor layer is developed. The dynamic behaviors of active constrained layer damping (ACLD) plates including nature frequencies, loss factors and responses in frequency domain are investigated. The influence of control gains on vibration suppression is discussed. Numerical examples demonstrate the validity of the finite element model and the control strategy approach. The proposed control strategy can be widely used to structure vibration control with ACLD patches due to its simple scheme and easy implementation.     

Application of state feedback and observer inmulti-axle vehicle steering system

A 3-degrees of freedom multi-axle vehicle dynamic model is established.Taking account of the practical difficulties for measuring the sideslip,rolling angles and rolling angle speed,a Luenberger observer is designed,and the simulation and analysis of the Luenberger observer are performed.The results show that the Luenberger observer has excellent characteristics in the considered speed range in tracking path.Then,a state feedback controller is designed on the basis of the Luenberger observer,and simulation of a multi-axle vehicle is also carried out.The results show that the performances of a multi-axle vehicle with the proposed control strategy is better than a multi-axle vehicle with front wheel steering strategy,and its control system has fine dynamic characteristic and strong robustness,so multi-axle vehicle with the proposed control strategy can improve vehicle handling stability and security.     

A SELF-TUNING CONTROL FOR A PARALLEL AC/DC POWER SYSTEM

Based on a non-linear system model, an adaptive control methodology is presented for a parallel AC/DC power system by means of on-line recursive parameter identifications. Taking the advantage of rapid power regulatiing ability of the DC power system and combining with the generalized minimum variance self-tuning control principles, the dynamic qualities of the controlled system has been greatly improved. Using SISO form makes the control system very simple to implement. Through the design, simulation and analysis of the self-tuning control system for a practical example, it shows that the self-tuning control strategy is very promising for AC/DC power systems.     

Simulation analysis on braking system of hybrid vehicle with ISG

A hydraulic braking system of the hybrid vehicle is designed based on braking force distribution and brake pressure coordination control strategy of integrated startor and generator(ISG) hybrid electric vehicle(HEV). Simulation model of hydraulic braking system has been established using AMESim software platform. Dynamic performance simulation and analysis to the key components and systems are performed. The results verify the correctness and feasibility of system program and provide evidence for designing and optimizing of HEV braking system.     

Application of Power Spectral Density Analysis in STM

The tunneling-current signals which acquired by STM,include both the sample's molecular structure and the dynamic characteristics of STM system.The Short Time Fourier Transform(STFT) is utilized to estimate the power spectral density(PSD)of the tunneling-current signals and the data's feature vector was extracted in the frequency space.The results obtained by PSD estimation reveal that spectral-space-based feature vector can distinguish the interference from power line(50 Hz),and it can explain and analyze the dynamic characteristics of STM efficiently by using a damped harmonic oscillator model.Meanwhile,the recognition is helpful in the control of the practice scanning condition of STM and the 3-D recreation for the images of STM.     

Coordinated pressure control of a regenerative braking system based on a hybrid electric vehicle with an integrated startor and generator

With a focus on a Changan hybrid electric vehicle (HEV) with an integrated startor and generator (ISG), strategies for braking force distribution and coordinated pressure control are put forward, and a dynamic braking control model is constructed for off     

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.