Applied Mechanics and Materials Vols. 397-400

Abstract: With the rapid development and huge requirements of wireless communication systems, microwave-monolithic Integrated circuits (MMIC) with high performance and reliability have become very popular and been developed rapidly. The nitride quality and the reliability of the metal-insulator-metal (MIM) capacitor can be also researched based on time-dependent dielectric breakdown (TDDB) theory. In this paper, the various Si₃N₄ capacitors having different area sizes, aspect ratios and corners were designed with respect to nitride quality and lifetime evaluation. All of MIM capacitors used in this study are manufactured using a special reliability mask, and the test structures include various sizes of capacitors ranging from 10Kμm2 to 250Kμm2 as well as capacitor corner check. The ramp voltage and the constant voltage tests are destructive oftentimes to identify the cause of dielectric failure. Combining these breakdown marks with an optical microscope inspection and cross section check of the 10Kμm² capacitors as well as corner-structure check are reported in this paper. That can make the identification and classification of dielectric breakdown mechanisms. When the capacitor size is larger than that of 65K-um², the factor of failure acceleration raises significantly.

Abstract: In order to solve the problems in existing protection for high voltage direct current (HVDC) transmission lines, such as insufficient sensitivity for main protection and slow operation for backup protection, a novel pilot protection for HVDC transmission lines based on model error function is proposed in this paper. In the principle, through analyzing the fault component networks, external fault is equivalent to a capacitance model, while the internal fault is equivalent to a inductance model. Taking capacitance model as a benchmark, the model error function was defined to describe the degree of consistency between actual fault data and the benchmark. When an external fault occurs, fault data agree with the capacitance model and model error equals zero. When an internal fault occurs, fault data do not agree with the capacitance model and model error does not equal zero. According to this, a protection criterion is constructed. Theoretical analysis and simulation show that the new principle, not affected by transition resistance and line distributed capacitance current, can identify internal faults and external faults reliably and rapidly.

Abstract: The instability and intermittency of wind makes the output power of the wind turbine randomness and volatility. Due to its fast pulse response and high charge-discharge rate, the flywheel energy storage can effectively reduce the power fluctuations caused by the wind farm. This article optimized the control strategy for the permanent magnet synchronous motor (PMSM) based flywheel energy storage system to reduce the active power fluctuations. Fuzzy inference method is used to make the desired smoothing active power value more precise. The rotor flux oriented vector control strategy with improved proportional resonant controller (PR controller) is proposed based on the mathematical model of PMSM to improve the robustness of the system in current control.

Abstract: The integrated half-bridge IGBT driver need compact, high efficiency and high power density isolated DC-DC power supply, a set of two magnetic cores share a high-frequency full-bridge switches are designed. A simple circuit generates four channel drive signals, without isolation, to achieve compact on-board power supply and the best combination with the integrated half-bridge IGBT driver. The key signals are simulated, and experimental results show that the power supply is simple, reliable.

Abstract: In the paper hybrid electrode capacitor self-healing circuit is simulated through ATP. It illustrates the equivalent circuit of self-healing is correct, so self-healing process can be analysised quantitatively. The results are that the smaller is the plasma resistance, the larger is self-healing waveform amplitude, The larger is the experimental capacitor, the longer is self-healing time.

Abstract: As an important part of the smart grid, smart meters and advanced metering infrastructures are given the newly missions connected network. Along with Ethernet development smart meters with measurements and networks, meter with BOA can become reality. In this paper a system of smart meter BOA and its smart meter networking has developed. It has real time displays and storage of smart meter data. The system uses a ARM9 (S3C2440) chip with a Linux operation system. Gathering from breaker via RS232, Data are sent to BOA server through named pipes to be displayed on web. At the same time, these data are stored in embed data base SQLite, for feature managements.

Abstract: In order to restrain harmonic pollution of power grid, the structure and control strategy of APF was researched. The structural parameters and method of direct current control of the most widely used APF with three-phase VSI was discussed. Decoupling control of active and reactive current on the dq plane was realized by dq transforming. Harmonic of load current was detected by Ip-Iq algorithm based on the instantaneous reactive power theory. Double closed-loop control was applied and PWM drive signals of IGBT were got through comparison of triangle wave and modulation wave. The simulation results demonstrate that the kind of control method make APF good dynamic response and static compensation.

Abstract: There are three modes of reactive compensation. Analysis on the present situation of oilfield distribution, the on-spot mode is adopted in this paper. An approach for 10kV lines reactive power compensators of oil field distribution networks is put forward. At the same time, combined with the concentrated compensation and grouping compensation, the total number of capacitors and the investment are calculated. The feasibility of the proposed method is showed by the results of an example. the power factor is improved, the quality and reliability are also mended.

Abstract: Based on Nios II embedded processor control module, a digital control system was designed for wire feeding control of gas tungsten arc welding(GTAW). In the control system FPGA wave module is used to control the movement of the DC servo motor, and the digital control of pulsed wire feeder for GTAW was achieved. One and the same control module with Nios II embedded processor is used to control the wire feeder and the welding power source. Thus, the current parameter of pulsed welding arc can be obtained and used directly for controlling the speed of wire feeding. At last, the experiment results are provided to verify the validity.

Abstract: This paper is aimed at designing a special pulse power amplification system for an ultrahigh-speed pulser that is used in Brillouin optical fiber sensing system. This amplification system consists of three parts, that is, signal receiving part, power amplifying part and 180 degree phase shifting part. Considering the fact that signals produced by the pulser are 1.2V differential PCML square wave signals and have ultrafast rising and falling transition time, high speed op-amps were adopted to receive signals and isolate pulser and amplifier. Since square wave signals have ultralow duty ratio, the power amplifier was designed with only one transistor working in switch-mode. As the effective frequency component of the pulse is up to 1500MHz, this design made use of a high speed high voltage operational amplifier to shift phase for signals. The eventually result indicates that, this amplification system can amplify square wave signals whose pulse width ranges from 2ns to 5ns, and voltage amplitude 1V of square wave signals with maximum duty ratio 5:10⁵ and minimum duty ratio 1:10⁶ up to 8V.