Applied Mechanics and Materials Vols. 433-435

Abstract: The design is to control DC servo motor and design a DC servo control system by the computer.It measures the DC servo motors parameter by measuring element (displace sensor) and transforms some forms of information by using A/D conventer to the CPU.The CPU will compare the input signal and measuring signal and if there is error, according to the predetermined control law to produce a control signal to control motor ,the system makes input signal and measuring signal keep consistent. Control algorithm use digital PID controller .

Abstract: Compared with the transmission transformer condition assessment, less data is one of the major problems that limit distribution transformer condition assessment work. This paper intends to solve this problem through reducing state variables dimensionality. First, through analyzing the principle of every state variables of distribution transformer by use of the maximum Eigen-value approach, the core state collection of assessing the distribution transformer is formed and the state variables dimensionality is reducing. Then, the initial results of distribution transformer condition assessment are obtained by using core state variables. Thirdly, the sensitivity of the non-core state variables to the evaluation results is calculated. Finally, the initial assessment result is modified considering the non-core state variables change and the sensitivity to get the final result. Through the above proposed method, the evaluation process need only consider the core state variables and the change of non-core state variables. This method not only reduces the demand for data, but also ensures accuracy of the results using the sensitivity correction. The results of a condition assessment instance of distribution transformer verify the validity of the method.

Abstract: A duty ratio perturbation based on improved genetic algorithm is proposed in this paper. It can overcome some shortcomings of traditional MPPT method, and can perfectly achieve a real-time adjustment for maximum power output. A simulation model is established on Matlab, feasibility and validity of the method is verified.

Abstract: This paper analyzes the network features of power grid with buses’ cascading failures based on the theories and methods of complex networks. And it concludes detailed vulnerability analysis of buses in Huazhong power grid under three forms of attack (maximum load attack, maximum degree attack and random attack) .It provides technical means for the prevention of cascading failure .

Abstract: In this paper, the influence of gird-side and inverter-side inductance on LCL-filter performance is studied. The design method of LCL-filter applied in three-phase shunt active power filter (SAPF) is proposed. An active damping strategy using the current feedback of the filter capacitor is adopted to suppress the resonance. A practical example is designed using the proposed design procedure. Finally, Simulation and experimental results verify the feasibility of the design method.

Abstract: Abstract: The point of the micro-grid distributed power's control is grid-connected inverter. The flexible grid-connection control technology provided an optimizing control method between distributed power and micro-grid and between micro-grid and power system. The flexible grid-connection control strategy includes flexible grid-connection control and flexible islanding control. The flexible grid-connection control achieves the good performance by means of regulation of the active and reactive power of micro-grid, while inhibiting the impact of impulse current, smooth power output, forecasting load and micro-grid power capacity. Based on the flexible grid-connection technology research of distributed power in micro-grid, the flexible master-slave method was presented based on PQ control, and the balance of power and the flexible control in micro-grid has been reached by it. The emulation and experiment results verify that the flexible master-slave method is effective; the balance of power, the flexible control when micro-grid is in islanding mode has been reached; the feasibility of the flexible master-slave method to stabilize the system was showed.

Abstract: This paper introduces a novel design of three-phase AC-voltage regulation trigger circuitry using silicon controlled rectifier (SCR), and presents its application in an energy-saving design of oil extractor control system. The design employs photoelectric isolation technique and the inter-phase of three-phase power supply itself, only three groups of triggering signals are required to control the six thyristors conducting angles. The generation of high-precision triggering signals and PID control regulator functions are realized by programming the multiple high-performance timers and the AD interface of a STM32 microprocessor. Experiments and in-field tests have shown the feasibility of the proposed scheme.

Abstract: Towards the problem of power quality disturbance detecting and localization in the power system, this paper proposed a new method based on improved TT-transform. Amplitude’s mutation in maximum element sequence of the TT- module matrix’s row is detected to locate beginning and ending time of power quality disturbances. This method can not only detect single power quality disturbance, but also detect composite disturbance accurately. The simulation results show that the method proposed can accurately detect the common power quality disturbance signal.

Abstract: This paper studies the synchronous control and disturbance rejection problem for a simple interconnected power system subjecting to a periodic disturbance with uncertain amplitude and frequency. By constructing a new exosystem, the synchronous control and disturbance rejection problem can be solved with output regulation theory. Designing an internal model for the complicated system and introducing an appropriate transformation, the output regulation problem is changed into the stabilization problem of a new augmented system. With the help of adaptive output feedback control technique, the designed dynamic energy storage controller can solve stabilization problem of the augmented systems as well as the synchronous control and disturbance rejection problem for the original system. Finally, the simulation results show the effectiveness of the proposed control strategy.

Abstract: Wind energy is one of the most competitive renewable energies, load has become the problem which has to be taken into consideration with larger capacity and flexibility. Due to drive-train damping was small and torsional load was large by traditional constant torque control (CTC) at above rated wind speed, a dynamic torsional load control (DTLC) was presented based on state feedback and sliding mode control. The method reduced the fluctuation of low speed shaft torque by decreasing equivalent torsional displacement difference. The model and controller were simulated in MATLAB/Simulink, the results demonstrate its effectiveness.