Applied Mechanics and Materials Vols. 513-517

Abstract: With expansion of the scale of wind power used in grid, its impact on the power grid has become more and more apparent. Because of its characteristics of intermittency and randomness, it is necessary to study the effect of wind power fluctuation on power system risk. The large scale wind power farm is connected to the power grid, the influence of its output fluctuation on static security of power grids is studied in this paper, and corresponding evaluation risk index of the power grid security is built. A new type of power system analysis software (PSAT) is used for the simulation analysis, and the results show that output fluctuation of wind power has great influence on low voltage and overload risk of power system.

Abstract: The aim of this study was to investigate the use of a model to determine harvest area of Eichhornia crassipes in environmental phytoremediation. A logistic model was constructed to eatimate the area of Eichhornia crassipes and tested in Eichhornia crassipes samples. The area of Eichhornia crassipes was measured nine times in experiment period using GPS and satellite remote sensing images. The measurements were shown to lead to a determination of the parameters of accurate logistic model with an overall Goodness of Fit Index of 0.9753. This indicates that there is a possibility of obtaining maximum harvest area of Eichhornia crassipes from the logistic model and suggests that it is possible to implement environmental phytoremediation with the continuous harvest at the maximum sustainable area of Eichhornia crassipes.

Abstract: The aim of this study was to investigate the use of two linear programming models to optimize protection, development, and ecological restoration of coastal mud flat, in particular maximizing ecosystem service values and minimizing ecological restoration cost. Such two linear programming models for Dafeng City, Jiangsu Province, China were constructed to represent all ecosystem and ecological restoration services in a decision support model and given the optimal protection, development, and ecological restoration decision for the coastal mud flat. This indicates that there is a possibility of obtaining a decision support system from the linear programming models and suggests that it is possible to improve decisions of restoration programs of the coastal mud flat by selecting areas of protection and development in which multiple service benefits can be maximized and ecological restoration cost can be minimized simultaneously.

Abstract: The blade is an important component in wind turbines, and the detection and diagnosis of its defects has become an important subject in wind power industry. This paper introduces the principles of the existing methods for state detection and fault diagnosis in wind blades, and then discusses the deficiency of each method. The existing difficulties and some key problems to be solved are also pointed out in this paper. Finally, the trend of its future development has been discussed.

Abstract: The off-line test method which is generally employed in modeling of generator excitation system has parameter lag and does not fully reflect dynamic characteristics. This article established an online identification and dynamic modeling for the excitation system by smart component technique combined with particle swarm optimization algorithm. It studied the principles of dynamic modeling, taking model parameters corresponding to the minimum objective function as the output result of the identification, also set up implementation steps and flowcharts of the parameter identification based on particle swarm optimization algorithm. An example case was given based on the measured data, and the identification results of the case were taken as the set value of the simulation model. The article compared simulation results to the field test data of 5% step response condition. The comparative results indicated that particle swarm optimization algorithm based on synchronization intelligent component data had the ability to adapt to online identification decently and high identification accuracy.

Abstract: The basic concept of constructing the Steiner triple systems of order is described. The detinition of edges matrix of the complete graph is given. A method of constructing Steiner triple system of order is proposed. The errtire procedure of constructing Steiner triple systems of orderand is presented respectively, The enumeration problem of Steiner triple systems of order is discussed ^[1-1.

Abstract: According to the process of PD radar target tracking, the radial motion of target has a significant impact on velocity measurement. Simulation shows that there is an apparent relation between radial velocity and non-coherent accumulated waveform. Based on the calculation of the entropy of non-coherent accumulated waveform, a method based on waveform entropy in velocity measurement is proposed. Experiments show that the new method can achieve high measurement accuracy, and is insensitive to velocity. At the same time, a rough estimation of velocity is used to shorten the running time.

Abstract: The voltage stability can be maintained by the series compensation equipment while the voltage sag of distribution system side occurs. The series compensation equipment of cascade H-bridge type has many advantages such as lower harmonic injection into the power system, lower switching losses, easily to be extended and so on. However, due to the complexity of structure and control of the multilevel converter increase the possibility of device failure. In order to improve the reliability of series compensation equipment, this paper analyzes the possible fault type of series compensation devices and combined with the characteristics of different types of faults, proposing a fault diagnosis method for the series compensation equipment of cascade H-bridge type. This method only needs to detect the voltage and current of output side in series compensation equipment, the fault can be successfully dignosed by a certain equivalent and computation .This method is not affected by voltage and current changes, and easy to implement. This device can rapidly diagnosis and remove faults device in continuous operation, then by changing the modulation of inverter makes the series compensation device work normally. The simulation examples proves the validity of this method.

Abstract: Ro-ro turn dam transportation has advantages of easy to assemble and unassembled, low cost, large capacity, etc. It plays a positive role in relieving the existing pressure of coal transportation, therefore, it is necessary to research the Ro-ro transportation schemes. This paper takes Yanjia-Tian'e line for example, proposed 27 parking spaces, 32 parking spaces, 38 parking spaces, 59 parking spaces and 250t self-propelled shipping for a total of five schemes. It establishes the evaluation index system, do correlation analysis to the data of the questionnaire, analysis of the evaluation factor by Confirmatory Factor Analysis (CFA). Conclusion shows that 59 parking spaces is the optimal solution.

Abstract: In order to meet the need of modern experimental teaching, improve experiment of openness and flexibility. Constructing digital circuit experiment system, fully embodies the virtual instruments in experimental operation of the advantage based on the virtual instrument technology, LabVIEW. Through the analysis of digital circuit experiment in actual effect of virtual instrument technology, shows the digital experiment system more simple and convenient, and some characteristics of relative stability and performance and experiments small errors and use convenient and save costs etc,so can be widely used in experiment teaching. Not only expanded experiment scope and space, but also can exert students' initiative and creativity.