Applied Mechanics and Materials Vol. 392

Abstract: Metal halide lamp (MH) is widely used in stadium lighting because of its significant advantages. But this high-intensity gas discharge lamp circuit contains the arcand such negative resistance characteristics lead to harmonic current. In addition, electronic ballasts of MH with rectifier circuit and inverter also produced a large number of electrical harmonics, becoming the main harmonic sources. In this paper, piecewise linearization method is used to establish the electrical model of 2500W metal halide lamp and a three-level model of electronic ballasts with the PSCAD/EMTDC. This paper analyzed the grid side harmonic current when the model is running. Comparing the simulation results to the measured data of Shenzhen Universiade venues lighting circuit, we can verify the accuracy of the model.

Abstract: This paper builds the mathematical model of a doubly-fed wind power generator (DFIG) which is widely used in wind power generation. Based on stator magnetic field orientation vector technique, active and reactive power decoupling control strategy is constructed. Based on the software package PSCAD/EMTDC, the grid-connected system of DFIG is modeled, and the dynamic response characteristics of generators active and reactive power on ramp change of wind speed conditions is simulated and analyzed. The simulation results show that the variable pitch DFIG has good operating characteristics and the model is correct.

Abstract: In the new electricity market environment, PV project investment faces more investment risks. For photovoltaic power generation characteristics of the project and with the integrated current research, we put forward the investment decision-making framework based on real option theory; we enrich and develop the applications of real options theory about investment decisions in the electricity, there are certain theoretical and practical significances.

Abstract: This paper studies the fast On-Load Tap Changer (OLTC) technology of contactless switch without transition resistance or transition reactor. It not only provides the equivalent circuit of OLTC, the impact current calculation formula and the OLTC simulation waveform based on the inductive load but also supplies with the main electrical circuit and the waveform recorded in the experiments. The MJN3 contactless voltage-controlled power source has been developed with MCT801D intelligent module, which can accomplish to rapidly switch in voltage-controlled gears based on the inductive load. Its output current is continuous with no impact, no over-voltage and voltage-drop, which can achieve the high performance and high reliability.

Abstract: Through the analysis of 2 single-phase grounding over voltage accidents caused by capacitive over current in 10 kV power grid in this paper, the causes and damages of arc grounding over voltage are illustrated, and the necessity of capacitive current test and effective methods are pointed out. The test and assessment to the 29 substations capacitor currents provides a scientific basis for the correct selection of the neutral point operation mode, and the strengths and weaknesses of the neutral Point grounding through the arc suppression circle and the mode trends of 10kV grid neutral grounding are demonstrated.

Abstract: The paper described selection principle of the device, carried out a detailed analysis and the design of the diagram of the high-frequency transformer. At the same time, the PCB layout design was put forward. Experimental results show that the power supply would still be able to output stable DC in the case of grid voltage fluctuation and larger load disturbance, had the characteristic of good stability and high precision, all parameters can meet the system requirements.

Abstract: In this paper includes an approach to implement Three Dimensional Space Vector Pulse width Modulation (3D-SVPWM) for multilevel inverter/Converter. The Proposed 3D-SVM scheme finds the reference vector by using simple mathematical equations for selecting switching states without redundant switching vectors. Moreover, the proposed PWM strategy satisfies the constraint that the output voltage vector should be only changed by one switching action. Not requiring extra hardware, the NPC inverter with the proposed PWM results are remarkable. The proposed algorithm is simulated by MATLAB and Implemented by FPGA-DSP Processor.

Abstract: According to the structure and characteristics of HVDC system, this paper used the FTA (fault tree analysis) method to divide fault results of DC system into five transmission capacities: 0%, 25%, 50%, 75% and 100%, calculated results by incorporating DC system into AC system and used Monte Carlo simulation method to evaluate reliability of AC/DC hybrid system. Whats more, this paper established the model, algorithm and index system for risk assessment of AC/DC hybrid power system and developed corresponding software. Finally, an example was given to prove the correctness and validity of the proposed algorithm and software.

Abstract: A small size cylindrical Molten Carbonate Fuel Cell stack was installed at Giugliano landfill in Italy. The stack was constituted by 16-cells with a 300 W nominal power. Preliminary tests were performed in order to verify the possibility to supply the stack by the landfill biogas, characterized by low methane content (32%). Results showed that the proposed plant is able to correctly operate also when supplied with low methane content biogas.

Abstract: Optimization of voltage and reactive power in substation is important for improve voltage stability and power quality. In order to avoid the frequent actions of on load tap changer, it is come up with a new control strategy for optimization of voltage and reactive power in substation based on probabilistic forecasting. In this paper the objective function is built to maximize the probability of the voltage qualification, with the times of equipments actions as constraint conditions. To establish the probability model of voltage firstly, the load on low-voltage bus and system voltage are forecasted with the method of forecasting error statistics. In this paper the objective function is built to maximize the probability of the voltage qualification, with the times of equipments actions as constraint conditions. The tap operating times are limited by estimating the risk of the loss of the voltage qualification; Otherwise, capacitors could turn on or turn off by turns, so their operating times is not need to limit. This method applies to 35kV distribution system a town of northern China,and the result demonstrates that it is feasible and effective.