Advanced Materials Research Vols. 732-733

Abstract: In order to analyze the process of mechanical-electric brake of electric drive tracked vehicles accurately, a dynamic/kinematic model which based on multi-body dynamics software RecurDyn, and a control system model based on Matlab/Simulink were established. Both of the two models are co-simulated through the software interface technology. The brake process of the drive motor that based on vector control technology is analyzed.

Abstract: In the summer peak load operation mode of the interconnected power grid which is integrated with HVDC transmission lines from Central China power grid to East China power grid, security and stability emergency control strategies based on generator shedding and EDCPS (Emergency DC Power Support) are studied to cope with system instability caused by Tuanlin-Fengjing DC line unipolar block fault. Simulation results show that interconnected system cannot maintain the transient stability effectively by using EDCPS only. A coordinated control strategy which combines generator shedding with EDCPS is proposed to reduce the number of generators to be shed and ensure the transient stability. Through optimizing EDCPS which two or more HVDC lines participate in, an optimal coordinated control strategy is proposed. Simulation results present that the strategy which combines GC shedding with Longzheng DC bipolar supporting is the optimal strategy.

Abstract: The DC-bus voltage control is critical for stable operation of the three-phase four-wire Active Power Filter. DC-bus stable voltage loop and balance voltage loop are established based on the small signal model. Considering the disadvantages of the traditional PI control, second-order low-pass filter is introduced into the proposed controller. Simulation and experimental results are conducted to validate the effectiveness of the proposed strategy.

Abstract: Wireless sensor network has many advantages while energy supplying is a main limit. However, energy scavenging technology affords an efficient solution, especially in high voltage substations, there is swarmed with strong electromagnetic field, and the scavenging device based on electric field has an irreplaceable advantage. An equivalent mathematical model of the converter was established to study the energy harvesting effect. Another model of conditioning circuitry was further built to analyze the factors affecting charging current. Finally, several main factors and corresponding methods are analyzed to improve the energy scavenging efficiency.

Abstract: In this research, a high-voltage direct current zero voltage switching (ZVS) PWM half-bridge converter is proposed. The parameters of the converter as follows: the input voltage is up to 4000V;the output voltage is 600V.The new ZVS PWM TL converter has neutral point clamping diodes and flying capacitor. This research is going to analyze the working principle of circuit witch thus realizing the zero voltage switching and the circuit parameters selection. Moreover, circuits simulation is carried out by MATLAB to verify the reliability and feasibility of this DC/DC converter topology.

Abstract: Electrostatic Discharge (ESD) is a serious threat to electronic equipment. It can couple into equipment and disturb or even damage internal circuit. In the paper, the coupling of ESD to electronic equipment is presented. It includes the coupling of ESD to EUT and that to PCB. In the coupling of ESD to EUT, there gives five conduction interferences and shows that it’s important to obstruct ESD current and lead its route bypassing sensitive circuit. There also presents the coupling of ESD radiated field to EUT and PCB. It shows unintentional antenna structures and parasitic parameter circuits play important role in ESD interference. They need to be removed and restrained.

Abstract: The structure of the uncontrolled rectifier + Boost circuit + PWM inverter is taken for direct-drive permanent magnet synchronous generator (PMSG) wind-power system. on the basis of the analysis for two different traditional control strategies for the grid side converter, a new control strategy Based on active and reactive power for the low voltage ride through running is proposed and described in detail. The simulation results verify that the given control strategy can be better to provide a reliable guarantee for the system low voltage ride through capability and to provide some reference for the actual control system design.

Abstract: A new method for measuring and identifying characteristic parameters of moving-coil geophones is proposed in this paper, where sine sweeping signal is considered as the electric excitation instead of the traditional vibrational excitation. A mathematical model of moving-coil geophone is constructed and the frequency response of 6-parameter is obtained in this paper. Using the expression as the objective function for fitting measured amplitude-frequency curve, geophones characteristic parameters are obtained. Finally, verification test is performed and the factors affecting measure accuracy are analyzed. The experimental results indicate that the presented method is suitable for production and maintenance, especially for in-situ calibration of geophones. This work provides a new way to design and manufacture portable geophone parameter testers.

Abstract: High temperature superconducting magnetic energy storage system (SMES) is a strong electromagnetic source with serious leakage magnetic field. Leakage magnetic field can cause certain effect to environment, which should be taken into consideration in the design process of high temperature SMES. Direct cooling high temperature SMES device was seen as research object. Two dimensional model of high temperature SMES device was built by using ANSYS, and the leakage magnetic field of SMES devices, whose cryostat are of different magnetic permeability, were compared. The security scope of SMES device was determined under operating condition. Research results can provide important guidelines for the design of the SMES device.

Abstract: Geo-magnetically Induced Current (GIC) is not only flowing in conductors such as power grid and pipeline, but also flowing in earth and GIC in earth will affect GIC in conductors. Thus studying the relationship between GIC in earth and earth conductivity is significant to understand the impacts of conductivity on GIC in earth and conductors. This paper uses Maxwell equations and plane wave method to analyze GIC density lever and distribution characteristics in different earth depth of uniform/layered earth conductivity model and gives the relationship between conductivity and GIC in earth. The results indicate that, the smaller the earth conductivity, the deeper earth GIC distributes, and earth conductivity structure has great impact on GIC. At last, this paper proposes that to calculate GIC in power grid accurately, we need to establish more accurate earth conductivity models.