Advanced Materials Research Vols. 433-440

Abstract: In order to balance reactive power, reduce line losses, prevent excessive power frequency and switching over-voltage and adjust and control the line voltage etc. The long-distance and high voltage transmission lines are needed reactive power compensation. High voltage overhead transmission lines and high voltage submarine cable (including mixed-submarine) transmission lines are different, for example, the capacitance in the submarine cable lines is larger than in the conventional overhead lines. Therefore, the reactive power compensation on the EHV transmission lines which contains submarine cable lines is focus on the compensation of submarine cable lines. The reactive power compensation in 500 kV AC submarine cable interconnection project for Hainan power grid and Guangdong power grid[1], which is the first 500 kV long-distance and high-capacity sea trails interconnection project in China and which is just completed soon, is researched by Electro-Magnetic Transient Program——PSCAD/EMTDC (Power System Computer Aided Design/ Electro Magnetic Transient in DC System in this paper). The simulation results verifies that the role of shunt reactor which could absorb charging power and suppress the power frequency overvoltage for the long-distance and high-capacity hybrid submarine cable lines. The conclusions can offer references to suppress power frequency overvoltage and the reactive power compensation in extra high voltage transmission lines which is the mixed mode of overhead transmission lines and submarine cables.

Abstract: A microgrid is an excellent supplement for both urban and rural utility grids. It assists in the integration of different kinds of renewable and distributed generation and it has the potential to make the distribution system more flexible and reliable. A microgrid is a combination of two or several energy resources like natural gas, wind, photovoltaic, biomass or diesel generators. Different energy resources together with battery storage system can complement one another to provide a more continuous power output. Two microgrid prototypes are discussed and, optional configurations are estimated using the economic analysis tool HOMER. Economic benefits and greenhouse-gas emissions of microgrids are calculated and compared. Results show that microgrids with optimal sizing and operation can achieve both cost efficiency and lower emissions.

Abstract: To reduce the computing complexity of Shannon wavelet entropy(WE), Tsallis WE algorithm was proposed and implemented by combining Tsallis entropy with lifting wavelet transform(LWT), which provided a new method to extract features of transient signals in transmission system. By adjusting the nonextension index, the property of Tsallis entropy was analyzed, and the relations between Tsallis entropy and Shannon entropy were discussed. Taking for instance Tsallis wavelet energy entropy(WEE), the computing complexity of Tsallis WE was analyzed and compared with Shannon WE. In order to verify the practicality of the new algorithm, the paper carried out not only the simulation test for transient faults in transmission system model, but also the processing of practical harmonics and lighting signal based on DSP, which showed that in comparison with Shannon WE the new algorithm can ensure the accuracy of feature extraction for transient signals , but its runtime has been partially reduced.

Abstract: A Fuzzy controller is suitable for controlling certain objects which are hard to be modelled mathematically. A controller based on fussy technology is set up for household electric appliance. The advantages are quick to response and efficient in energy conservation.

Abstract: This paper presents the analysis, design and implementation of a novel open-winding permanent magnetic starter-generator using the open-winding permanent magnetic machine for overcoming the difficulties of voltage regulation, narrow speed range and low power factor of the permanent magnetic machine for the vehicles applications. In the proposed method, one side of the open-winding permanent magnetic machine is connected to rectifier for the DC voltage output, the other is connected to the inverter for the regulation of the DC voltage. And the open-winding machine can be reconstructed to be the conventional machine as the starter. In contrast to the conventional starter-generator for the vehicle, the speed range of the generation process and efficiency of the machine are improved obviously. A new control algorithm of double-loop for regulation of the DC voltage and current of machine is developed and verified by the simulation results.

Abstract: Analysis of the mine wireless channel research status, comprehensive description of the radio transmission channel characteristics. through the analysis of the wave attenuation characteristics ,This paper presents a wireless channel model for underground coal mines. In this paper, an empty straight rectangular tunnel, for example, using the ray tracing method to research the mine wireless channel characteristics and analyzes the other factors of impact the Ray Field Strength In the near field zone. Finally, through the simulation tests of Fading in the Coal Mine Tunnel and use Matlab to simulate the experimental data and simulation curves by contrast, come to this theoretical method is reasonable.

Abstract: Wind speed forecasting is important to both wind plant and electrical system’s operation. Improving the prediction accuracy can not only effectively eliminate the disadvantageous impact to the power system but also enhance the wind’s permeability and competitiveness against the other kinds of power in electricity market. The random and intermittent wind directly causes the same characteristics of the wind power. The maximum entropy principle information principle was introduced to construct an integrated forecasting model. In this model, all individual forecasting models’ results and historical forecasting error were regarded as constraints. The forecasting values were educed by the integrated model based on the maximum entropy principle. Application result in a real wind plant showed that the integrated model had a higher forecasting accuracy compared with individual models and combined models.

Abstract: This paper describes a practical method of Online Risk Assessment (ORA) on urban power system. It includes a set of models for online risk analysis of urban power system, the Online Probabilistic Risk Indices (OPRI) & their arithmetic, and the models for computing parameters varying with operating conditions which are used for Probabilistic Risk Indices calculation. The ability of the method can provide operators in control center the near term identification on security level, weak point, and riskiest event of urban power system. Further more, the system architecture of Online Risk Assessment (ORA) is presented, which is the preparation of software implementation of Online Risk Assessment System (ORAS) on Urban Power System

Abstract: The concept of logistics system simulation and the basic applications of Witness are introduced in this paper. By a specific example, the simulation model is found about the production process of steel logistics system by Witness. The relationship of production process and computer simulation is illustrated, further, the simulation model is ran and outcome is obtained. Based on the example of the production process of BF-BOF region in iron and steel enterprise simulation model, the method of the production process with WITNESS is analyzed. By setting the parameters to achieve the purpose of the actual production process is optimized. Finally, more feasible solution is put forward by simulation analysis

Abstract: Recently, frequent torrential floods cause tremendous casualties and economic losses to the national people in China. In this paper, six 1:6 scale rural building models made of PMMA are tested to research the flow pressure of flood, which will provide the basic data for the flood-resistant design of rural buildings. The experiment of flood on buildings is carried on the large wave-current tank. The height of water is 0.6, 0.9 and 1.2 meters and the distances between the building and floodgate are 3, 6 and 9 meters respectively. The flow pressure is obtained by the sensor transducer. Based on the experimental results, the distribution of the flow pressure and some effect factors are investigated. Results show that the variation of flow pressure distributions decreases gradually with the vertical distance from bottom to top in the vertical direction. The flow pressure in the horizontal direction is different because of the boundary and holes effect.