Applied Mechanics and Materials Vols. 263-266

Abstract: Single-machine infinite-bus system and two-machine system simulation models were built to study the power system transient stability. Based on time domain simulation, the effect of generator inertia time constant (τg), and excitation system ceiling voltage (Ke) on transient stability were analyzed by single-machine infinite-bus system. The changes of transient stability of two-machine system were also compared by means of power system stabilizers (PSS) and static VAR compensator (SVC). In particular, the system transient stability varied greatly in different locations of SVC. Finally, some suggestions concerning the improvement of power system transient stability were put forward.

Abstract: This paper discusses the parameters tuning of fractional-order controller satisfying the desired gain-margin and phase-margin specifications in terms of a stability equation method applicable to fractional-delay systems. The tuning procedure is then applied to the level control of double water tank, which is modeled as a second-order transfer function with time-delay. The Matlab simulations and the experiments on the water tank device show the effectiveness of the tuning and the benefits of using fractional-order controllers.

Abstract: The bearingless motor combined technical characteristics of motor and magnetic bearings. It can simultaneously implemented electromagnet torque control and suspension control all in the motor .Since there are two sets of windings wound on the stator of bearingless motor, two sets of power circuit hardware and controller are required. In the case of most conventional structures, each terminal controller calculate references by themselves and transmits a torque/positon interactively. However, the latency issues of data delivery latency affecting the decoupling between the air-gap flux.The paper proposed the structure for a torque/positon hybrid control through network, torque/positon is transmitted from each terminal controller to a central controller. Then the central controller calculates references that are feedback to the terminal. The delay time is eliminated. In the paper, the hybrid control of bearingless induction motor is realized with the digital system based on the TMS320F2812.

Abstract: In this paper, we study adaptive attitude synchronization of spacecraft formation with switching topology. By introducing a novel adaptive control architecture and by transforming the attitude dynamics into Euler-Lagrange form, decentralized controllers are developed, which allow for parametric uncertainties and unknown external disturbances. Based upon graph theory and Lyapunov stability theory, rigid mathematical analysis on system stability is provided. A distinctive feature of this work is to address the adaptive attitude synchronization with general directed information flow. It is shown that arbitrary desired constant relative orientations within the group or with respect to any external references can be attained. Simulation results are provided to demonstrate the effectiveness of the obtained results.

Abstract: To eliminate the negative effects caused by three-phase unbalanced distribution, a novel soft-switching system based on single-phase inverter is proposed. The system achieves three-phase equilibrium distribution by adjusting the power supply of the electric equipments. This paper presents a track strategy named regulating frequency to promise no impulse current, which means regulating the output frequency of the inverter to make the output voltage of the inverter synchronize with the grid voltage. Firstly, make the output voltage of the inverter synchronize with the voltage of original access phase, then switch the electric equipment to the inverter. Secondly, make the output voltage of the inverter synchronize with the voltage of alternative access phase, then switch the electric equipment to the alternative access phase to accomplish the soft-switching. MATLAB software and experiment are used to carry out verification for this system. The result shows that the impulse current is practically zero when the electric equipments are switching. The system achieves soft-switching.

Abstract: This paper is about using the latest PIC16F876 MCU and PIC16F877 produced by MIROCHIP from United States to realize the roller drive motor in timed accurate turn, reverse, braking and monitoring feedback control through modular design method.

Abstract: Established and simulated a two-dimensional amendment trajectory model for mortar. Theoretical researching and simulation show that using canard control to correct trajectory, we can change the size and direction control by adjusting the control signals. Not only can we correct one-dimensional trajectory, but also correct two-dimensional trajectory which concluding projectile range and lateral displacement, improving shooting accuracy.

Abstract: The problem of robust adaptive stabilization of a class of multi-input nonlinear systems with unknown parameters and structure has been considered. By employing the direct adaptive method to a general nonlinear adaptive system, a robust adaptive controller is designed to complete the global asymptotically stability of the system states. Some simulations are provided to illustrate the effectiveness of the proposed method.

Abstract: In order to predict and control the temperature of continuous casting slab, a mathematical heat transfer model simulating the solidification process of continuous casting slab has been developed based on the realistic roller-layout and spray nozzle distribution. And the accuracy has been verified by comparing with the pin-shooting experiment results. An advanced control strategies are adopted to achieve the optimization of water quantity under different production conditions by the integration of energy saving water distribution module and slab temperature optimization module in the dynamic secondary cooling model. The total water consumption has a trend of dropping off after the utilization of the optimization technique. And the slab surface temperature increases which fits for the down stream direct hot rolling.

Abstract: A new networked control system is modeled, which has global Lipschitz nonlinearity and network-induced uncertainty including time delay, packet dropout and quantization simultaneously. Then, a class of mode-dependent nonlinear controller is designed, which can effectively eliminate the effects of the uncertainty and ensure the stochastic stability of the controlled system. Furthermore, a linear matrix inequality (LMI) is established and proved, which is a sufficient condition for the existence of the desired controller. According to the LMI, the controller can be explicitly given. Finally, an illustrative example is given to show the validity and practicability.