Applied Mechanics and Materials Vol. 740

Abstract: Permanent magnet generator has the advantages of simple structure, reliable operation and low loss, but it is not easy to adjust voltage, which restricts its wide application. This paper presents a new type of hybrid excitation synchronous generator (HESG) and establishes the mathematical model and simulation of vector control based on its AC excitation system to control the output voltage as the expectation. In application, DSP, as the control system, is traditionally programmed and debugged off-line, which requires heavy workload. Whereas, the design based on model greatly shortens the development cycle. By connecting MATLAB simulation environment to the CCS development environment, the simulation model can be translated into code and downloaded to the targeted DSP through an emulator. This implementation will have specific and indispensable significance for the hardware development and software debugging of motor control system.

Abstract: Control strategy under unbalanced grid voltage conditions is one of the most important issues for grid-connected inverter. Under unbalanced grid voltage conditions, the 2^nd active and reactive power ripples generate, they pollute the grid. To meet the demands of IEEE Std.929-2000, this paper proposed a modified power compensation control strategy; the proposed solution is based on direct power control. To provide accurate compensating power, the power model of three-phase inverter under unbalanced grid voltage conditions is given, using the positive sequence current component and the negative sequence voltage component, the compensating powers are calculated in details. Theoretical analysis and comparative simulation verification are presented to demonstrate the effectiveness of the proposed control strategy.

Abstract: In recent years, the proportion of pumped storage power station in the power grid is increasing, which has many special advantages. The pumped storage motor has two kinds of working condition of generator and motor, not only can the system regulate the reactive power, but also can modify the power factor of the grid resulting in the reduction of the investment on the reactive-power-compensation equipment. On the other hand, the above system is able to enhance both the stability and the overall efficiency. Pumped storage motor start-stop and working condition switch frequently. The test will be analysis and researched with the Time-stepping FEM Consequently, this paper analyses the large disturbance characteristics of the pumped storage motor.

Abstract: Permanent magnet synchronous motor mathematical models of synchronous rotating coordinate system are decoupled by rotor field orientation. Then, the speed regulator, current regulator and space vector control system are designed. The current inner ring and speed outer ring ensure the accurate tracking of current and the accurate control of speed. To reduce the control algorithm computation, SVPWM control strategy based on the 60^o coordinate system is used on the permanent magnet synchronous motor control system. Simulation results show that the space vector control system has good dynamic characteristics and the control scheme is feasible.

Abstract: In the full power wind power system, the cage induction wind generator-rectifier system can be regarded as a independent part if the DC voltage could be always controlled constant by inverter part. The prospective AC voltage and frequency of induction generator is dependent on the specific speed and input power, which is obtained by use of SPWM. All rectifier switching state and the alternating moments can be calculated by switching function given by SPWM control. This paper focuses on how to use analytical methods to calculate the process of alternately switching the state of the system. Furthermore, the dynamic mathematical model of induction generator is studied and derived under different states, which is suitable for analytical method on base of Laplace transform.

Abstract: This paper mainly discusses the applications of real-time data mining technology in fault prediction of power plant generator. Massive real-time historical data of thermal power plant turbine generator equipment is stored to realize comprehensive quantitative assessment of thermal power plant turbine generator’s online security status and potential failure Early Warning. It is based on the Real-time data mining analysis and modeling techniques.

Abstract: In this paper, the mathematical model of induction motor based on stator field orientation in synchronous frame is introduced. To resolve the question of relay, the d-axis current direct calculation is adopted to replace traditional decoupler. Fix threshold double-integrator based on coordinate transformation is used to eliminate integrator saturation. SVPWM based on 60⁰ coordinate system is developed to simplify calculation. The control system based on stator flux orientation is simulated by MATLAB. The simulation result shows that the system has a fast dynamic response and steady characteristics.Nomenclature

Abstract: The TCR single-phase to three-phase power converter has been widely used in electrified railway system as its simple control raw and high reliability. The research on main circuit parameters and its control law is necessary to design suitable TCR single phase to three phase power converter. This paper analyses the main circuit of TCR single phase to three phase power converter, and acquires the parameters configuration theory of each element in main circuit and control law of converter when the power factor varies from 0.7 to 0.9.

Abstract: Conventionally, the fault signal of motor thermal overload in a non-periodic component is not effectively filtered with Full-wave Fourier Algorithm (or FFA). In this paper, a design which combined Complex Morlet Wavelet Algorithm with Subtraction (or CMWAS) filter is presented. The design gives system model of overload and algorithm analysis It is verified that the new algorithm is better than the FFA algorithm in terms of filtering decaying DC component.

Abstract: The running state of different induction motor in the load group will be moved toward two directions when it was occurred the large disturbance in the power system, one is to keep on running, another is out of step or stall. If the quantity of stall induction motor in the group is a large number, the dynamic of stall motors will effect on the stability of power system obviously. So it is necessary to develop the detailed load model to simulate the complicated dynamic characteristic of the load group. An improved synthesis load model which combines two kinds of induction motor is proposed, and the improved genetic algorithm is used to identify the parameter of load model. The case is studied to illustrate the effective and comprehensive adaptability of the proposed identification model.