Applied Mechanics and Materials Vols. 494-495

Abstract: Accurate Partial discharge (PD) detection and location is of great significance for the power cable insulation condition monitoring. To achieve this, an adequate cable model to analyze pulse propagation is needed. Considering the complex structure of the cable, the equivalent circuit model is no longer applicable. In this paper a numerical electromagnetic method, FDTD, is applied. To analysis wave propagation characteristics in time domain, a well-established cable model is constructed. By simulating the electromagnetic (EM) field propagation inside the cable and the cable joint, the components of the electric fields excited by the PD source in different directions are calculated in order to evaluate the influence of the cable joint in practice, the calculated PD waveforms in the cable are compared with those of the cable joint model in FDTD.

Abstract: Taking into account the controlling over average circulating supercurrent, we theoretically investigate the dynamic features of the superconducting charge qubit driven by ac gate voltage. By means of treating ac voltage as a perturbation and considering the nonadiabatic case, the average circulating supercurrents are obtained with/without the effect of decoherence and dissipative factors. It is found that average circulating supercurrents can be controlled for above two cases by modulating the frequency of ac voltage.

Abstract: Partial discharge (PD) diagnosis techniques are widely used in the insulation condition monitoring for power cables. In this paper, the damped AC (DAC) voltage method was used to study the PD characteristics in the heat-shrinkable cable accessories. Four different cases of artificial defects in cross-linked polyethylene (XLPE) cables were investigated, and these defects include termination without stress tube, incorrect use of insulation tape as the semi-conductive adhesive tape in the middle joint, void and metal particles on the surface of XLPE insulation. Furthermore, the PD inception voltage and patterns obtained under the DAC voltage are compared with the AC test results.

Abstract: A new control system of vibrating screen invert power source was designed according to the question of step regulation of current and power in vibrating screen in the use of MCU. Zero-voltage switching inverter is used to reduce the loss of switching devices in the main circuit and MSP430 MCU is the core of the control circuit. A PI voltage regular with a filter and a feedback type, IGBT over-voltage protection circuit and PWM pulse generating and drive circuit are designed. Experimental results show that the inverter power has high precision, fast response, and anti-interference ability, and the system can obtain better steady state accuracy and dynamic characteristics and greatly improve the efficiency of shaker.

Abstract: On the basis of introducing the working principle of the electrical fast transient pulse/burst generator, the method of combination of AC inverting and DC boosting is adopted to design a kind of DC high voltage power supply used for the electrical fast transient pulse/burst generator after the further study about the key technology of the high voltage DC power supply according to the requirements of IEC61000-4-4. The experiments show that the power output voltage reaches 5 KV, meanwhile the range of output voltage is from 0.1 KV to 5.0 KV within the linearity is about 5%, the electric power can be up to 250 watts. Above all, the design meets the requirements of the high voltage power supply for the electrical fast transient pulse/burst generator.

Abstract: Based on the analysis of traditional electric energy metering cubicle, there are still a lot of disadvantages in operation. This paper presents a new type of electric energy metering cubicle. The composite intelligent terminal wiring device, intelligent locking device and image monitoring equipment are applied to the traditional standard electric energy metering cubicle. It is suggested that the new electric energy metering cubicle can effectively ensure the safety of the staff, prevent power loss caused by incorrect wiring and avoid electricity theft.

Abstract: The paper propose an outer-rotor permanent magnet synchronous motor (PMSM) with peak torque of 3000N.m. The position measuring system based on CPLD and dual magnetic sensor is developed. This system can handle two channel signals obtained from two sensor heads, and provides correct and reliable position feedback signals for the motor control. According to the mathematical model of the PMSM, full digital high precision control system with triple feedback closed loops are designed and implemented in experimental evaluation. The test results validate that the system is feasible and the control precision can reach 1.5 arc-second.

Abstract: In order to study and improve the track circuit system,we preliminary study and model for ZPW-2000A no track circuit transmission network of automatic block for in china, through the insulation of domestic ZPW-2000 no track circuit transmission network system model and simulation,we verified that the simulation results and field device test results is consistent . Simulation results show that the track circuit transmission network mathematical model is correct and effective, for further study made ZPW-2000 laid the foundation for the track circuit.

Abstract: In order to better research and design track circuit system, this paper analysis and calculated compensation capacitor of the ZPW2000 no insulation track circuit, and verified the consistency of the experimental results and the practical installation situation. Analysis results also show that, through the appropriate compensation capacitor, the no insulation track circuit transmission distance significantly increased.

Abstract: This paper describes the structure and the principle of the NI DAQ based measurement system used for investigating the frequency dependent behavior of instrument transformers in the high voltage system. A computer based NI DAQ card is utilized as the data acquisition system in the new measurement system. The software digital filter and the phase locked loop are implemented to obtain the magnitude and phase angle, respectively. With this measurement system, we investigated frequency responses of several voltage and current transformers at the converter station of the Germany railway.