Applied Mechanics and Materials Vols. 325-326

Abstract: Through the DC side capacitor voltage unbalance problem of cascaded static synchronous compensator. Put through a theory of active voltage average distribution to balance DC capacitor voltage, using master slave controller to realize controlling requirements. The main controller calculates each phase AC side of H bridge required total active and reactive voltage and grid voltage phase information etc, The slave controller complete each cascade module for active voltage average distribution control. The simulation results show that the method is feasible and effective.

Abstract: The moving-mass hypersonic attitude dynamic model is a strong nonlinear, multivariable, and strong coupling system. Based on the reasonable assumption, a simplified dynamic model is given. According to the time-scale separation theory, a sliding variable structure controller is designed and implemented for the tracking control of angular velocity and angle at the same time. Simulation results demonstrate the effectiveness of controller.

Abstract: For high-accuracy trajectory tracking of manipulator joint, the more realistic dynamic equations, considering reducer flexibility, nonlinear friction and external disturbance, are established and then decomposed into two subsystems in series. A double closed-loop controller, which is mainly used to compensate the flexibility, is designed by using active disturbance rejection control (ADRC) technology. The extended state observers are applied for real-time observation and compensation of the nonlinear terms. Simulation results indicate that the flexibility and friction are simultaneously overcomed, and the proposed controller can greatly improve the tracking accuracy.

Abstract: Based on the energy-saving principle of variable frequency and energy adjustment, problems on application of the optimization table method of voltage vector in AC frequency control of motor speed adjusting are mainly emphasized by analysis on precooling system of air separation in this paper. With the help of Matlab/Simulink simulation software, the simulation model of the control system of the AC induction motor is built, and a method of frequency and speed adjusting control of the motor based on dsPIC is put forward. Furthermore, this technology is applied in the precooling pump system of air separation, and a full digital SPWM variable frequency and speed adjusting system with low energy consumption, high efficiency and good dynamic is constructed.

Abstract: The problem of robust stabilization for a class of SISO uncertain nonlinear Differential-Algebraic Eqyatuion subsystems is considered in this paper. The robust stabilization controller is proposed based on backstepping approach using two-layer Artificial Neural Networks (ANN) whose weights are updated on-line. A new adaptive algorithm is proposed to update the weights of ANN such that all signals in the closed-loop systems are bounded and the states are convergent asymptotically to the equilibrium through the proposed controller.

Abstract: The conventional valves used in the choke manifold for well control usually have intensely nonlinear characteristic of the match between pressure choking and vale opening. Therefore, it is difficult to achieve the precise choking pressure that is essential to the managed pressure drilling (MPD) through a single throttle within the scope of full opening. However, the parallel choke manifold proposed in this paper, i.e. a program of parallel throttling, can enhance the accurate choking wellhead backpressure for MPD. The fine linear choking principle and feasibility of the parallel choke manifold were analyzed in detail by calculating the resistance modulus of bypass valves. The formula calculated the resistance modulus of each valve under different working state. Furthermore, the laboratory tests shown the parallel throttle method can achieve the control of fine choking pressure by switching one or more valves in the branch pipes. Therefore, the proposed parallel choke manifold system can reduce the requirements for the linear capability of valves and provide some references to further study the surface fine choking pressure system for MPD.

Abstract: In the electro-hydraulic servo system for steam turbine, there are many components with nonlinear behaviors. It is difficult to identify these nonlinear parameters with regular identification methods. Particle swarm optimization (PSO) is a relatively new optimization algorithm which has been applied to a variety of problems. However, it may easily get trapped in local optima when solving complex problems. In this study, a nonlinear model including dead zone is established first and a multi-particle swarm optimization (MPSO) method based on double-layer evolution is studied in detail. Then the parameter identification with this optimization method for the electro-hydraulic servo system of steam turbine are discussed in the paper. Moreover, numerical simulation demonstrates that the accuracy of the proposed parameter identification algorithm can be guaranteed.

Abstract: The utility model of early warning system for train operation detects and analysis all the information from the weather detection, photoelectric detection, vibration sensor and signal of the tracks comprehensively. It determines the position of the train by the weighted coefficients and controls the interval signal and locomotive signal accurately. This system should be barely affected by the weather conditions, the results detected by this system are reliable, and it can ensure the train operates safely.

Abstract: District heating process is a complicated dynamic and thermal nonlinear system. For controlling it the system model should be found firstly. Through the research and analysis of the knowledge about heating system, this paper on the basis of mechanism model, researched the establishment of experimental models. Firstly by measuring the response data, the model parameter identification of the heating process can be made to got the heating determining part model, then random part of the system model can be described by the method of Autoregressive Integrated Moving Average Model. Finally using the MATLAB to simulate and make the model step response curve analysis. Simulation results show the model is effective and verified.

Abstract: In this paper, a modified two-step algorithm (MTSA) is applied to an optimization problem in which the objective function is a multi-input single-output nonlinear steady-state model. An on-line searching method for gain-keeping in MTSA is proposed. The simulation results show that the method is effective.