Applied Mechanics and Materials Vols. 556-562

Abstract: Optically powered system is a revolutionary new power delivery system, in which optical power is delivered over fiber to photovoltaic power converter, where optical power is transformed into electrical power. Therefore the system is inherently immune to RF, EMI, high voltage and lighting effects. Capable of powering electronic circuitry by optical fiber, this technology has been validated in industries such as electric power, communications, remote sensing and aerospace. To a large extent, photovoltaic power converter is a key component that decides the performance of optically powered system. In this paper, the commonly used GaAs photovoltaic power converter is studied and tested. Parameter values like open circuit voltage, short circuit current, maximum output power, conversion efficiency and the optimum load resistance are obtained through experiment, which can be severed as important reference while choosing or designing DC-DC converter.

Abstract: By analyzing three-point oscillator of inductance feedback with the loss resistance of the inductor,we found the loss resistance of the inductor is a major factor in affecting circuit performance. Negative resistance in series with loss resistance can offset the impact of the loss resistance in the circuit. Oscillation circuit Start-up easilier. The quality factor Q increases and the selectivity is better.The oscillation shape closer to the ideal oscillator.

Abstract: The effects of total voltage level number (TVLN) on behaviors of the modular multilevel converter (MMC) are analyzed in this paper. First, it gives a brief introduction on the MMC system for how the converter generates multilevel staircase waveform. Second, the operation characteristics during the start process are analyzed. The capacitor voltage of a SM, the DC voltage, the exchanging power, and the DC loop current would be all influenced by different TVLNs. Third, the harmonic components in steady state are discussed to reveal the reason why the total harmonic distortion (THD) of the output voltage of MMC reduces when the TVLN increases. Simulation results show the validation of the conclusions drawn in this paper. Furthermore, when the TVLN is small, the THD in SUPWM method is lowest. However, when the TVLN increases, especially greater than 11, the THD in CPS-SPWM method is lowest.

Abstract: There are many information sharing problems and integrated management difficulties in the radio & TV transmitting stations, and there are also networked digital construction demands in these stations. In view of the above, this paper puts forward a management information system (MIS) construction scheme. And then this paper does deep research on technique methods and system architecture. Furthermore, this paper illustrates the detailed functions implementation and the practical application of the system. Finally, the paper summarizes the radio & TV transmitting station MIS’s application and performance, and gives some suggestions about the system’s optimization and improvement.

Abstract: This paper includes the topology and operating principle of matrix converter, and switching function modulation algorithm of the matrix converter is analyzed in detail. Simulation results based on Simulink7.11 are also provided, the result shows a good verification of theoretical analysis, and it provides a theoretical basis for the next research and software/hardware design of matrix converter.

Abstract: For any second-order system, so long as it can be proved that it can be controlled and observed, it can be arbitrary pole configuration. The article selects a typical second-order system, and the first the paper writes the block diagram of transfer function, and proves its controllability, and then carries pole assignment with it. The paper writes the transfer function based on pole assignment of equation, and then writes its hardware simulation diagram, finally validates by computer simulation software and hardware platform. The experimental results show that the dynamic characteristic of the system is obviously better than before pole assignment.

Abstract: The paper build the large region grid model of ultra-high voltage in electro-magnetic and electro-mechanical hybrid simulation system, and researched the effectiveness of ultra-high voltage transmission line to large region grid, especially the N-1 short tripping fault caused transient stability problems.

Abstract: The linear array CCD spectral acquisition system for a Photoelectric Direct Reading Spectrometer is presented. The spectral acquisition circuit, data processing and shortage circuit are designed. Taking microcontroller MSP430 as a control chip, Using PWM signals generated by MSP430 timer, the correct timing of CCD clock pulse, ADC clock and FIFO write enable signal was established. The experiment shows that the synchronization of spectral acquisition, data conversion and shortage was achieved, and the spectral acquisition system is feasible and reliability.

Abstract: With the increasing use of non-linear electrical loads in power system, the harmonic pollution has become a severe problem. In this paper, we proposed a simple method for power system harmonic analysis. Cascaded adaptive comb filter is designed specifically to suppress the electric harmonic pollution. And a high-precision but easily implemented frequency estimation algorithm is presented based on least square estimation method. So the electric signal frequency fluctuation can be real-time tracked, and coefficients of the comb filters can be adaptively updated with this algorithm.

Abstract: First of all, this paper speculates that the essence of the space vector pulse width modulation (SVPWM) is the injection of some kind of zero sequence component through the theoretical analysis. Increasing the range of output voltage and reducing the switching loss are the optimization it can realize, the essential realization method is implemented by changing the placement of zero space vector. Then the method is applied to the cascade multilevel carrier modulation. The main work of this paper is to analyze the relation between SVPWM and the carrier PWM in the two level converter, then add the discrete modulation into the cascade multilevel carrier modulation to verify that the space vector modulation can be realized in cascade multilevel and can get similar results with the two level.