Applied Mechanics and Materials Vols. 701-702

Abstract: A fractional-order hyperchaotic system was proposed and some basic dynamical properties were investigated to show chaotic behavior. These properties include instability of equilibria, sensitivity to initial conditions, strange attractor, Lyapunov exponents, and bifurcation. The fractional-order system presents hyperchaos, chaos, and periodic behavior when the parameters vary continuously. Then, an analog circuit is designed on Multisim 11 and the Multisim results are agreed with the simulation results.

Abstract: The distribution system is at the end of the power system and is directly connected to the energy consumers, which makes the distribution network a vital part of the power system. When a substation suffers an outage, electricity service restoration measures must be taken as soon as possible to reduce the loss. Traditional restoration methods have disadvantages such as poor stability and bad convergence. This paper proposed an approach to resume the power supply after a 35kV substation outage with the help of Dijkstra’s shortest path algorithm. The proposed method is tested on a real distribution system. The result shows that the method is effective to solve the problem of electricity service restoration.

Abstract: The power energy storage in battery transfers to capacitors through thyristor in hybrid energy storage, which makes the instantaneous power amplified. As the switch in Hybrid energy storage, the thyristor must satisfy its opening requirements , besides, the characteristics of the hybrid energy storage system is considered to design the width of trigger pulse, otherwise the thyristor can’t be opened that leads to failure of energy transfer. In this paper, the model of the system is established, the function of current to time is derived from the model, and then the minimum width of trigger pulse is calculated out. The simulation and experiment results are presented, which match with the designation well.

Abstract: Impedance matching is a basic requirement for high frequency signal transmission, but also a relatively complicated aspect in circuit design. In this article, from the perspective of impedance matching, structure principle and characteristics of Smith chart are introduced. On the basis of Smith chart software, its process of impedance matching is described with a simple example to show the advantages of convenient and fast calculation of Smith chart for impedance matching.

Abstract: Aimed at resources shortage and extensive management of transmission line operation and maintenance, this paper proposes a differentiated operation and maintenance (DOM) method. This approach divides DOM strategy into basis strategy and criteria problem based strategy. An multi-objective DOM scheduling optimized model is presented, which contains three objective function including economy, safety and reliability. Based on the current electric power enterprise management requirements, personal safety factor is incorporated into safety objective function. Multi-objective Artificial Physics Optimization algorithm (MOAPO) based on feasible rules of law is used to solve the problem with an excellent diversity and high efficiency. The model is used to optimize yearly differentiated operation and maintenance scheduling in a certain area’s transmission system, the result verifies the feasibility of the model and method.

Abstract: The voltages of between the battery and the ultra-capacitor are not equal in the energy storage system of the electric vehicle. DC/DC converter is researched in order to balance the voltages between the battery and the ultra-capacitor. The traditional control method is not ideal. The model of bidirectional DC/DC converter is established on the basis of the working principle of the DC/DC converter. And it is in the double closed loop PI control mode. The results of simulation indicate that the control method has fast response speed, small overshoot and strong ability of anti-interference. It can also balance the energy between the battery and the ultra-capacitor.

Abstract: The way of calculating the currents and voltages in nonlinear resistive electrical circuits , based on the use of power series (Taylor, Maclaurin) is considered . The advantage of this method lies in the fact that while it implementation it is not necessary to a system of nonlinear equations. To determine the numerical values ​​of the coefficients of the power series corresponding system of linear algebraic equations are solved. Nonlinear operations are limited to the calculation of the numerical values ​​of currents, voltages and their derivatives with respect to the pole equations of nonlinear elements.

Abstract: The effect of thermal resistans on I_C-V_BE fly-back characteristic of power SiGe heterojunction bipolar transistor is studied through theoretical analysis, computer simulations, and experimental measurements. It is found that a suitable thermal resistans can make the collector current achieve the second fly-back point before transistors are burned-out, and then returns to a stable situation. Such a thermal resistans is beneficial to the thermal stability. When the thermal resistans is small, the curve of I_C-V_BE fly-back characteristic of HBT has no fly-back point. While the thermal resistans increases, the curve of I_C-V_BE fly-back characteristic of HBT has two fly-back points.

Abstract: Voltage regulator is designed to automatically maintain the constant of regular voltage level. Every automotive IC has its own regulator module for analog and logic circuit power supply. The output load regulation and current consumption are directly related to the IC’s performance, or even the whole application module. The performance of regulator is not only related with the output parameters, but also the protection character. The over voltage protection feature guarantees the IC’s working environment within specific voltage input range. This article use one IDC’s (Intelligent Distribution Controller) regulator module to describe the design theory for regulator over voltage performance improvement. The test investigation and verification on ATE (Automatic Test Equipment) are demonstrated. The parameter of over voltage threshold is optimized obviously by 2% yield increasing.

Abstract: Lightning strokes are the main cause for the trip fault of transmission line with a rated voltage of 110 kV and above. The counterattack trip and the shielding failure trip were thought to be the two kinds of fault type caused by lightning strokes. According to the development process of the two fault types, a few effective lightning protection methods are proposed. However, there is no relative report about the case that the ground wire and the conductor are stricken simultaneously. Therefore, no specific protection method is presented. In this paper, the possibility of the both stroke is analyzed, according the the mechanism of lightning stroke and the characteristics of lightning strokes. Then, a series of simulation test were designed and carried out. The observation results recorded by high-speed camera indicate that the downward leader could strike grounded wire and conductor simultaneously. At last, based on the intelligent monitoring system of transmission line, the traveling wave current of a lightning stroke was recorded. And after comparing the current with the simulation results by ATP/EMTP, the stroke was thought to be a both stroke. The photos in the fault point indicate that there are discharge points both on the grounded wire and conductor. And this field data clarified that the trip fault was caused by both stroke. A new lightning stroke fault was presented and verified in this paper, this report will supply important reference for lightning protection of transmission line.