Applied Mechanics and Materials Vols. 260-261

Abstract: Introduce the status of mobile internet application in electric power corporations and current security protection methods. An in-depth analysis is made to demonstrate the possible hidden risks in the electric power smart terminals. Propose a set of electric power smart terminals protect solution and the implementation based on android operating system.

Abstract: The shock effect has been analyzed when the human body touches different types of vehicles in power frequency electric field. It solved the problem of influence of induced voltage generated by high voltage AC Power Lines on human Body. The induced voltage value of the human body and three different types of vehicles has been calculated by the soft of ANSYS in this paper. The results indicate that the human body will be shocked by two processes of transient and steady state. The influence of shock effect of transient and steady state on human body has been selectively analyzed when the human body touches vehicles. The proposed models and algorithm has the advantages of simple calculation procedure, small calculation burden and convenient to engineering application. It can be applied to the shock effect when the human body touches metal objects with different potential in power frequency electric field. It is worth being populated.

Abstract: To assess the oil-paper insulation of transformer, it is necessary to establish the equivalent circuit for it regardless of using the time domain methods or frequency domain methods. Based on the principle of dielectric polarization, the extended Debye model is always adopted for the equivalent circuit of oil-paper insulation in transformer in most cases; however, it is usually difficult to determine the number of relaxation mechanisms in the model. This paper presents a method to determine it by the time domain dielectric spectra, namely, conduct differential operation for the depolarizing current of transformer’s oil-paper insulation to obtain the time domain dielectric spectra, and the number of spectrum peaks is equal to that of relaxation mechanisms. Thereby, the extended Debye model of the equivalent circuit of the oil-paper insulation of transformer can be built. This paper describes the analytical procedures of the time domain dielectric spectra method in detail and presents examples to validate its feasibility and rationality in determining the equivalent circuit model of transformer’s oil-paper insulation.

Abstract: Inductance capacitance parameters value of main circuit devices of independent photovoltaic power system influence stability of system. In this paper, selection the suitable transistors, using a variety of algorithms to match the parameters value of capacitance, inductance. PSIM software was used to carry out modeling for photovoltaic cells, lead-acid battery, electrombile. Simulation of buck and boost DC/DC circuits, through analyzing time-domain waveform, verifys feasibility of design scheme, correctness of the algorithms. These algorithms provide a the oretical basis of main circuit setting of independent photovoltaic power system.

Abstract: Time-domain waveform of partial discharge (PD) signals of generator stator is distorted in enclosed busbar by the influence of distribution parameters of electrical equipment and different connection structure of enclose busbar. To research propagation characteristics of PD signals, a model of enclosed busbar between generator busbar exports and main transformer is established by using EMTP-ATP software. To analyze the propagation characteristics of time-domain waveform, voltage and current wave of PD signals are simulated. Voltage wave and current wave will be carried out fast fourier transform (FFT) algorithm by the use of MATLAB, frequency-domain characteristics are analyzed. It follows that the influence of time-domain waveform and frequency-domain characteristics of PD signals. The basic theories is provided for the location of PD signal monitoring sensor.

Abstract: A multiplex data acquisition system applied in high voltage transmission line based on electronic combined transformers is proposed in the paper. Employing an air-core coil for current measurement and current protection and a SF6 coaxial capacitance for voltage measurement, this paper proposes a method to acquisition signal based on the MSP430F1611 MCU and ADC AD7685. The data acquisition system can collect three channel analog signals (current measurement, current protection, voltage measurement) at the same time, and then pack the data, send them to the merging unit through the optical fiber. The multiplex data acquisition system is at the ground potential, so the optical power source could be abandoned and the reliability is effectively enhanced. The technology of multi-channel acquisition, high-speed communications, anti-electromagnetic interference are mainly introduced. Tests have been done and the experimental results show that this ECT meets the requirement of the 0.2s class for measurement and 5PTE for protection in IEC60044-8, voltage channel meets the requirement of the 0.2 level in IEC60044-7.

Abstract: With the application of large scale nonlinear load in power systems, lots of harmonic are produced, causing the total power factor to decrease. Therefore, it needs to compensate the reactive power of power systems. The disadvantages of the widely applied static var compensator are that the size of the compensator is too large, and the control ability is poor when the capacity of power systems is small. So a reactive power generator based on voltage source inverter is proposed in this paper. The reactive power generator takes series connection of IGBTs as the main circuit structure, the inverter as core and DSP as controller. The close loop framework consists of human-computer interaction, measurements and feedback control. The inverter is controlled by a digital PI close loop controller to feed a phase adjustable current to power systems to compensate reactive power. The system’s structure is simple, the control is flexible, and the size is small. The test results show that the response of this reactive power generator is quick, and it can compensate the power factor to be 1 which means that it has good effect of static reactive compensation.

Abstract: In this study, the relationship between microstructural evolution and mechanical properties of thermal barrier coatings (TBCs) has been investigated through different thermal fatigue systems, electric thermal fatigue (ETF) and flame thermal fatigue (FTF), including the thermal stability through the interface between the bond and top coats. The TBC system with the thicknesses of 300 µm in both the top and bond coats was prepared with METCO 204 NS and AMDRY 962, respectively, with the air plasma spray (APS) system using 9MB gun. To observe the oxidation resistance and thermal stability of TBC, the thermal exposure tests were performed with both thermal fatigue tests at a surface temperature of 850 °C with a temperature difference of 200 °C between the surface and bottom of sample, for 12,000 EOH in designed apparatuses. The hardness values are slightly increased due to the densification of top coat with increasing the thermal exposure time in both thermal fatigue tests. The influence of thermal fatigue condition on the microstructural evolution and interfacial stability of TBC is discussed.

Abstract: Recently, polymer electrolyte membrane (PEM) electrolyzers consist of the layered structure of membrane and electrode assembly (MEA), titanium flow field plate, gasket, end plate, and others. Among these components, MEA and titanium flow field plate take account for most of the device cost. The cost and time for manufacturing device can be reduced with the gasket-integrated 3-D mesh-applied PEM electrolyzer (Fig. 3), while maintaining the same performance as that of the existing titanium flow field plate devices. The 3-D mesh is found to perform the roles of the existing flow plate which ensures the smooth fluid flow and uniform power supply. The voltage shows 19.3V at current density (0.5 A/cm²), a little lower than 19.6V that is 10 times of 1.96V which is the average cell voltage at the same current density. In addition, hydrogen production and stability for performance are equal to or higher than that of the device for titanium flow field plate.

Abstract: In this paper a voltage control strategy based on the optimal control theory, for isotropic rotor permanent magnet synchronous motor (PMSM) drives, is proposed. The complete optimal control of the three phase permanent magnet synchronous machine (PMSM) consists of three components: the state feedback, the feed forward compensation of the load torque and the reference to achieve the desired state. The control assures a smooth dynamic response, in order to achieve the desired state in steady state, the fast compensation of the load torque, and the energy minimization. The obtained solution by integrating the matrix Riccati differential equation (MRDE) is orientated towards the numerical implementation (by using a zero order hold) and it is computed on-line. The optimal control strategy is applied to PMSM drives and verified by simulations.