Applied Mechanics and Materials Vols. 260-261

Abstract: This paper studies on the electromagnetic transient model of doubly-fed wind turbine grid-side converter under the imbalanced grid condition. And on this basis, the paper analysis the impact of doubly-fed converter when grid voltage asymmetric drop. It puts forward a dual PLL and dual current control combination of doubly-fed converter grid side control strategy. This strategy achieves grid voltage positive and negative sequence fast separation when asymmetric grid voltage drop occur, achieves the active output power secondary fluctuate suppression under the imbalanced grid voltage condition, avoids DC voltage rise at the fault moment and also achieves converter reactive power support under the imbalanced grid fault. The simulation and experimental results show that the proposed control strategy is correct and with the application value of engineering

Abstract: The microstructural evolution related to the thickness of thermal barrier coating (TBC) and their thermal stabilities have been investigated with a specific attention to defect species as well as to its morphology with the thermal exposure time. The TBCs with different thicknesses of 600 and 2,000 µm were prepared by air plasma spray (APS) process and the thermal exposure tests were performed at 950^C in a furnace with a dwell time of 100 hrs till 500 hrs. The thickness of thermally grown oxide (TGO) layer in the TBC with 2,000 µm is thinner than that with 600 µm. Also, the TBC with 2,000 µm is more efficient in improving the oxidation resistance of bond coat than that with 600 µm. Vickers indentation methods are used to evaluate the interfacial stabilities. Indentation impression and crack formation of the TBC of 600 µm is easily occurred in comparison with that of 2,000 µm, showing relatively longer cracks, independent of thermal exposure. However, the crack formation and propagation through the interface does not observed in the TBC with 2,000 µm, showing crack propagation through the top coat near the interface. These results imply that the interfacial stability of TBC can be also improved with increasing the coating thickness.

Abstract: The government and the power grid corporations pay close attention how to evaluate the peak power load shifting ability of electric thermal storage air-conditioning system scientifically and rationally. The evaluation method of existing standard was analyzed briefly, and a new operable evaluation model based on the field tests was put forward. Based on the above analysis, the peak power load shifting of four projects was analyzed. Example shows that the analysis model can provides the basis for calculating the power load shifting indicator of electric thermal storage air-conditioning project.

Abstract: Community energy management system is the development trend and an important part of the future intelligent community. For the construction objective, this paper introduces the general construction scheme of community energy management system, and the specific design schemes of the system's hardware structure, software architecture,communication mode are described in detail. The system will implement information integration and monitoring of the intelligent community, optimal allocation and coordinate control of energy, so as to provide users with safe and green electric power service.

Abstract: Arc-fault protection is a new circuit protection technology and its function is breaking the circuit in time when arc-fault appears and protecting distribution line from electric fire. This paper introduces the arc-fault signal characteristics, detection method and the hardware and software design of AFCI. Through analysis and research, arc-fault signal has asymmetry waveform: the positive and the negative half cycles, the waveform at the zero crossing of a steep shoulder and waveform characteristics. Wavelet transform can detect characteristics of arc-fault effectively. AFCI detects the signal of current by using the current transform and puts the current signal into MCU through the filter and amplifier. The software mainly uses the DB4 wavelet transform to process the arc-fault signal. The arc-fault detection is the advantages of accurateness, fast detection and low rate of wrong judgment.

Abstract: The micro-grid structure and operation mode are analyzed in this paper. By listing micro-grid typical operation mode, and explains the energy management system, micro-grid controller, electric primary equipment is how to coordinate between control. Analysis of the usual method for the energy management system optimization control strategy will be passed to the micro-grid controller. A kind of brand-new control command transmission mode is put forward for improving the micro-grid control strategy by the efficiency.

Abstract: The basic principle of three-phase PWM rectifier is analyzed and the mathematic model is established.Based on traditional voltage and current double feedback loops control structure, according to the balance of power relations between the input and output,feedforward compensation control of the grid voltage component is added in current loop,and feedforward compensation control of the load current is added in voltage loop.The design methods of current regulator and voltage regulator are given. This control strategy is effective to improve dynamic response of DC bus voltage when the load or grid voltage changes.Finally,simulation results show the effectiveness and correctness of the proposed control strategy.

Abstract: The basis is a device that contains tension sensor. The output of tension sensor is associated with the input control unit. The tension sensor is connected between the two loads. The sensing signal is processed using a PC measuring card with special software. The resulting device will be part of trains. Data sensing by this device will be transmitted from the PC to the control unit.

Abstract: In a diaphragm electrolyze system with a Ti/RuO2/IrO2 anode and the Pd/MWNTs gas diffusion cathode, the degradation of 2-chlorophenol was fully studied by the electrochemical reduction and the simultaneous oxidation of the cathode and anode. The results indicated that the Cl- removal reached 90.5% after 80 min electrolysis with H2 feeding. After 120 min electrolysis, the removal of 2-chlorophenol in the anodic and cathode compartments were 88.8% and 98.5%, respectively. Additionally, the TOC removal reached 75% and 85.6% in the anodic and cathodic compartment respectively after 140 min. By the UV scanner analysis of the electrolyte, the 4-chlorophenol and benzoquinone were oxidized by the oxides formed on the cathode, while the benzoquinone was found accumulated in the anodic compartment. Based on the analysis of electrolysis intermediates using high performance liquid chromatography (HPLC) and ion chromatography (IC), the electrolysis degradation of 2-chlorophenol was proposed containing the intermediates, such as phenol, hydroquinone, benzoquinone, maleic acid, fumaric acid, succinic acid, malonic acid, oxalic acid, acetic acid and formic acid.

Abstract: Demand for CRH (China Railways High-Speed) trains, both in quantity and types, is increasing because of the rapid development of high-speed railway in China. To support the improvement and development the AC transmission system of these trains, a study platform is proposed in this paper. Target of the platform is supporting the study which contains design, verification, display etc. in detail. Platform framework is described in this paper. And the results of study on transmission system temperature rise and energy-saving operation strategy of high-speed train based on the platform are displayed. Availability of the study platform is verified.