Applied Mechanics and Materials Vols. 668-669

Abstract: A novel robust control scheme for decentralized generator excitation and valve coordinated control systems to improve power system stability is proposed. By utilizing generator terminal voltage magnitude and phase angle to represent the interactions among generators, decentralized generator excitation and valve coordinated control in multi-machine power systems is achieved. The control is realized by robust parametric approach. Simulation results show that the proposed robust parametric coordinated control can improve power system stability.

Abstract: The work is designed and made as a controlled system of rotational inverted pendulum. Small direct current machine is droved by Single chip microcomputer that it controls the angle of swinging of swinging rod when the rotating arm does reciprocating rotation motion. The MC9S12CXS128 single-chip microcomputer is adopted as the master control chip of control system, the Angle of swinging rod is measured by the incremental encoder, power of the rotary arm controlled part provided by PM35S - 048 direct current machine and the motor drive module as a control system. It can realize measurement and control of the rotation angle of the rotating arm and the swinging angle of swinging rod precisely.

Abstract: On account of that common subsynchronous resonance controllers cannot well adapt to the time-varying and nonlinear characteristics of power system, biogeography-based optimization (BBO) algorithm is introduced to design subsynchronous damping controller optimally based on the mechanism of suppressing SSO by static var compensator (SVC). The simulatied results of Jinjie plant indicate that the subsynchronous damping controller optimized by BBO algorithm can remarkably improve the damping of torsional modals and thus effectively depress the multimodal SSO, ensuring the safety and stability of units and power grid operation.

Abstract: The suspension system is one of the most important parts of the automobile. The suspension system has an important influence on the ride comfort and maneuverable stability of the automobile. As structure parameters of traditional passive suspension cannot adaptively change with external conditions, the improvement of dynamic performance is difficult. Tow-DOF and four-DOF suspension of vehicle model is set up in this paper. Under random profiled road input simulated by using Runge-Kutta method, the control laws of fuzzy controller are adjusted by using different weight coefficients and use Matlab software to simulate the performances. Then, the results are compared and the performances are analyzed between passive suspension and semi-active suspension. The simulation results show the semi-active suspension is more effective for decreasing the vibration of vehicle body than the passive suspension, and designed fuzzy controller is effective for controlling the active controller of the semi-active suspension.

Abstract: Active flow control has produced a great many values in the S-shaped inlets. In this study, the pressure gradient is used to characterize the degree of flow reattachment on the S-shaped inlet and be referred as the pressure recovery parameter^[1]. A transfer function is established between an input of frequency of the solenoid valve and an output of the pressure gradient. According to the process of model-based design, one of Simulink model created by Different Control Algorithms which are applied to the established system in the simulation is selected to generate C codes automatically. The generated codes are embedded in the ARM7 processor and the test result of the processor is consistent with simulation.

Abstract: In order to achieve a proper design and control, it is necessary to have an exact model of boost converter. In this paper, the mathematic model of boost converter is proposed by the state-space average method. In the next step, the open-loop transfer function model without compensation is deduced in detail according to the mathematic model of the boost converter, the controller is designed according to frequency domain. The phase margin and magnitude margin of the open-loop system of the boost converter with compensator have both been increased. After compensating, the control system becomes stable. Using Matlab 7.1, the simulation of the control system of boost converter was implemented. The simulation results of control system confirm that the controller can reduce steady state error and resist power supply disturbance.

Abstract: A control system for DC motor should be designed to meet the desired performance objectives with the smallest control energy. LQR controller can satisfy the requirement. In this paper, the state space model of DC motor control system is proposed. The key problem to apply LQR controller is to choose the correct weighted matrix Q and R of performance index. At present, there is no formulaic approach for this problem. This kind of LQR controller based on PSO algorithms, which can obtain satisfying control results, is presented for DC motor control system. Using Matlab 7.1, the simulation of the DC motor control system is implemented. The simulation results of it confirm that the LQR controller can reduce steady state error, improve response speed, and resist power supply disturbance.

Abstract: Aircraft Ditching is related primarily with the aviation safety. Firstly, the full-scaled shape of Boeing 777-200 is modeled according to the lost MH370 aircraft on 8th March. And then an Arbitrary Lagrange-Euler (ALE) fluid-field model is created for water and air domain. Next some simulation cases are implemented related to different vertical velocities using LS-DYNA nonlinear finite-element code, with the same horizontal velocity and attack angle. At the same time, the variations of the velocity of the head and tail are discussed. Consequently, Ditching overload peak occurs at the highest vertical velocity. The simulation results can deeply be applied to accident analysis of aircraft impacting on water.

Abstract: It is significant for the phenomena of bouncing on water to analyze the ditching procedure of any kind of aircraft. The SPH method is employed to achieve a numerical simulation in the architecture of LS-DYNA and PrePost programs. The water domain is modeled by SPH and the boundary condition is discussed too. Through a set of contrastive analysis of different boundary conditions, some constructive suggestions of establishing the boundary conditions are given to deeply simulate aircraft ditching in the future.

Abstract: If you want to simulate and analyze a system by Petri net, you must construct a reliable and accurate Petri net model. Problem of constructing model by Petri net is discussed few at present. Petri net automatic modeling method based on system behavior sequence is presented. This method combines all the behavior sequences of system into the formal language expression. For different system, giving labeled function (giving the relationship between transition and system behaviors) can construct system Petri net model. To illustrate the algorithm, an example of constructing user Petri net model of telephone call service is given. This method has strong formalization and can be used universally. The model constructed by this method is standard and can realize computer automatic modeling. It makes progress in research of system modeling.