Applied Mechanics and Materials Vols. 446-447

Abstract: This paper proposes a new nonlinear broadband model of the power transformer which is both fit for steady state and transient simulation in power system. The model consists of high-frequency module and low-frequency module in parallel. Based on the black-box method, the high-frequency block is built in the form of π-type equivalent circuit, and the low-frequency block is in the form of conventional gamma-type circuit, in which core saturation characteristic is expressed by a nonlinear inductor. A power transformer is studied in the laboratory, simulations and experiments are carried out in case of power-frequency steady state, excitation currents distortions, lightning overvoltage, and very fast transient overvoltages (VFTO) respectively. The comparisons between the simulated and measured results verify the feasibility and validity of the model.

Abstract: In this paper, a new simulation model is developed to be able to simulate diesel genset smart grid interconnection by keeping in view future requirements of the grids and grid codes. The simulations are carried out in Matlab/Simulink environment. An example case is based on 1200 kW variable speed diesel genset with permanent magnet synchronous generator (PMSG). The simulations are carried out for various dynamic behaviours of PMSG and their protection and control facilities, which are necessary in normal operating conditions and in a range of disturbed operating conditions in order to preserve or to re-establish system security. Various faults (e.g. disturbances) have been induced in the distribution system and the robustness of the network has been analysed to make sure continuous supply of electricity to the consumers in the future smart grid environment.

Abstract: The calculation of the admittance parameters of the power transformer is the basis of establishing its black-box model and studying its freqency response analysis. An improved calculation method for wide frequency admittance parameters is proposed based on multi-conductor transmission lines model, combined with the finite element method. Firstly, multi-conductor transmission lines model of the transformer windings is established. In order to reduce the order of the parameter matrix, several turns which are continuous in capacitive coupling are treated as a transmission line by applying finite element method. Then after the boundary conditions are applied to the model, zero and non-zero values of the matrix are separated to calculate respectively, which avoids the complex equation solution of the previous calculation method, as well as improves the computational efficiency. At last, a 10kV single-phase two-winding transformer is measured. By the comparisons of the calculated and the measured results the method is proved to be validation.

Abstract: The smart grid has expanded the capacity of clean energy, has made the power grid load consume clean energy reasonably, it can realize the maximization of social benefit, it is a scientific problem to be resolved in the field of energy. This article will apply the interruptible load to the power system with wind power, study the significance of the interruptible load, summarize the research and practice of clean energy carried out at home and abroad, consider the impact of the wind machine on power grid after it is connected to the grid, finally put forward the power package by analyzing the method of the demand response.

Abstract: Commutation Failure is the common fault of HVDC, continuous commutation failure may lead to HVDC block and affect the stability of the power system. Especially in southern power grid, china, its special that the end of four HVDC system are all in Guangzhou. If the AC system occurs serious fault, all of the HVDC system may occur commutation Failure, HVDC block, even occurs large area blackout. So how to avoid continuous commutation failure and restore the stability of HVDC is important for AC and DC parallel power system. This paper based on the mechanism of commutation failure, analyze the reason of commutation failure and identification method, preventive measures. At last, this paper uses actual recorded wave to analyze the diversification of system after commutation failure.

Abstract: Internal combustion engines are widely used in our day. Internal combustion engines first transform fuel energy into heat energy. Afterwards, approximately 30% of this heat energy is transformed into mechanical energy. Approximately 5% of the heat energy is expelled through friction and radiation, 30% through cooling and 35% through the exhaust system. In the present study, electricity was generated by using thermoelectric equipment and the waste heat expelled from the exhaust system. It was observed that as the exhaust temperature increased, the amount of electricity generated also increased.

Abstract: In this paper, a novel bandpass filter (BPF) using the composite right/left-handed transmission line (CRLH-TL) theory is presented.The composite right/left-handed TL with the high-pass characters of left-handed transmission line (LH-TL) and the low-pass characters of right-handed transmission line (RH-TL) are used to construct the bandpass filter.Using this theory,we design a bandpass filter which have an obvious band pass response with a wide passband range from 5.1to 12.9GHz and a low insertion loss of less than 3.1dB. The relative bandwidth is close to 110%. Simulation using ADS demonstrated the viability of the approach.

Abstract: This paper presents total harmonics elimination in H-bridge Multi-Level Inverter. The basic concept of this reduction is to eliminate harmonics in different level with an appropriate choice of switching angles. This paper employs Homotopy algorithm to solve the transcendental equations for finding the switching angles. This method solves the nonlinear transcendental equations. It is much simpler formulation without complex analytical calculations for any number of voltage levels. In this technique, it is not required transformer allows the use of a single dc power source (e.g., a battery or a fuel cell stack) with the remaining n − 1 dc sources being capacitors, which is referred to as hybrid cascaded H-bridge multilevel inverter (HCMLI). It has several informative Mat lab simulation results verify the validity and effectiveness of the proposed algorithm.

Abstract: To solve the hiding problem of hardware Trojan in chip, we first analyzed the self-protection technology of malicious software, and then proposed a trigger mechanism that base on timing finite state machine (TFSM), energy flow, and distributed Trojan design method. As for the trigger mechanism that based on TFSM, one must enter the right pattern on the correct time to activate the Trojan. The mechanism based on energy flow can make the hardware Trojan keep hiding in the RTL code logical analysis. The distributed hardware Trojan design is to divide a complete Trojan into several components, and the Trojan will keep silent if all the components are not in order. The design methods of hardware Trojan have been verified in our self-made hardware threat simulate platform, it can reduce the rate of been detected out, and the possibility of been triggered out by random operations.

Abstract: This paper presents varied CMOS ring oscillator topologies using Silterra 0.13-µm Process. Three topologies of ring oscillators have been designed which is the single-ended ring oscillator, differential ring oscillator and ring oscillator based variable resistor for 2.4 GHz wireless applications. The proposed designs consist of five stages delay cell. The simulation results show that a single-ended ring oscillator obtained the lowest power consumption of 0.41 mW, while differential oscillator achieves phase noise of −64.44 dBc/Hz at 1 MHz offset frequency. However, ring oscillator based variable resistor did not achieve any significant improvement. The proposed design is oscillates at 2.4 GHz.