Applied Mechanics and Materials Vols. 556-562

Abstract: Range eclipse is a serious problem in high pulse repetition frequency (PRF) pulse doppler (PD) terminal guidance radar. In this paper, we propose a new scheme, which exploits multi-group of dual-frequency pulse waveform, for anti-range eclipse. Each group contains two pulse waveforms with different PRF, which has its own range region of anti-range eclipse and anti-range ambiguity simultaneously. In the scheme, only one pulse group works at a moment, which can avoid range eclipse and effectively measure target distance. According to the changing of target distance, radar switches the pulse group to other group to guarantee target in the range region of no eclipse in the tracking term. Simulation results show that this method can effectively prevent high PRF PD radar seeker from range eclipse.

Abstract: For the problem of unequal grouping of parallel compensation capacity in substation, this paper proposes a new optimization method based on curve segmentation and clustering. Firstly, calculate reactive power demand curve by transformer parameters and load curve, partition this curve into several segments. Then cluster these segmentation results into K clusters by using modified FCM (fuzzy C-means clustering) algorithm, in which K means the number of capacitor groups. Take the difference between two adjacent cluster centers as the capacity of each group. Furthermore, study the relationship between segment number and grouping centers in order to get the steady grouping results. After the grouping plan is determined, take the nine-area figure as control strategy. Finally, simulating with an equivalent practical power grid and load profile, the results show both the availability and rationality of this method that power loss is less and power factor is higher compared with the equal grouping method when capacitor is divided into 3 groups.

Abstract: In order to improve the calculation efficiency, active power and reactive power are usually optimized separately in optimal power flow considering the decoupling characteristic. However, this would decrease the economy performance of power system. This paper proposed a weighting factor to formulate a multi-objective model, combining the generation cost and system network loss together. The optimization problem is performed using genetic algorithms and quadratic programming respectively. Finally, the feasibility and efficiency of the proposed model are verified with the IEEE 14 Bus test system.

Abstract: Owing to the scale of power distribution system’s continuously expanding, the closing loop operation is usually needed to meet the demand for the reliability of power supply. However, during the course of this operation, a larger AC surge current with 4~5 times of normal value will be induced, and the surge current can cause the equipped over-current protection take action incorrectly. In this paper, a hybrid type superconducting fault current limiter (SFCL) is suggested to installing into the distribution system, which will take action to inhibit the closing-loop transient surge current by using current-limiting impedance during the transient process. Furthermore, the simulation model of a typical distribution network with the hybrid type SFCL is built through PSCAD/EMTDC software. From the simulation results, it is verified that the suggested hybrid type SFCL can obviously reduce the surge current and improve the power system’s operational stability.

Abstract: In order to ensure the linear array CCD normally and stably working in the spectral measurement, the data acquisition and storage circuit is presented. On the basis of analyzing the ILX511 driving timing, the circuit of data acquisition, processing, and storage based on CCD was designed. The CPLD was used to establish the correct sequence for the CCD clock pulse, AD converter clock, and FIFO writing signal, so the data acquisition, converter, and storage synchronously are achieved. The experiments show that the designed circuit is feasible.

Abstract: The study mainly presents a research on drilling down the power communication data from massive amounts of the basic repository in communication resource management system, and uses advanced technological method to enhance the intelligent analysis level of communication resources, which solves the problem such as information share difficult between power communication network annual planning and management data. The study further diminishes the mapping difficulty by providing an intelligent mapping aids for annual operation mode and device report which resolves the problems such as long cycle mapping, low degree automation and low intelligent level of communication annual operation mode, and it also seeks to establish an effective mapping design system for detail, real and scientific program design of annual operation mode by exploring the models of intelligent aided designing system to meet the specific needs in power communication network operation mode optimization.

Abstract: This paper analyzes the negative influence of dead-time,point out the shortcomings of traditional dead-time compensation methods , and then present a dead-time compensation method. Simulink simulation shows that the proposed method is effective. The proposed method is applied to a 15kW inverter which is controlled by STM32F103 MCU,and it can significantly reduce the THD value of the inverter output voltage waveform. The experiment proved that this method is simple and reliable, with good results.

Abstract: Aided equipment statistics & analysis platform can solve several problems for electric power communication equipment statistics, such as, large amount of statistics, long cycle of analysis, low degree of automation and low level of intelligent evaluation. The statistics & analysis model of communication equipment with the features of advanced, safe and efficient, allows for rapid response to dynamic altering of the network traffic and the equipment operation state, as well as the comprehensive analysis of evaluation index. So the operational status of communication equipment and the health status of communication network can be reflected scientifically. Scientific analysis and effective assessment on forecasting and diagnosing the network will help make an intelligent analysis on the weak link of communication network, which can also obtain reasonable optimization of network system structure, eliminate the hidden danger and provide a guidance for the planning and readjustment on next year’s operation mode. It also seeks to establish an analysis & design system for electric power communication equipment, which can solve the problem of equipment analysis and design. And the system would meet the growing demand of power communication operation in Smart Grid.

Abstract: The effect of liquid crystal (LC) vertical alignment on phase separation dynamics of liquid crystal optical devices with different cell gaps is investigated in this paper. As the cell gap increases, the surface effect on the bulk LC droplets is reduced due to the longer distance. It is found in this experiment that the vertical alignment film can influence the LC droplets in the middle of the gap, and in the meanwhile the surface effect is not too strong to disturb phase separate. In that case, the LC droplets separate at a fixed position during phase separation and also can flow to form good morphology. The surface vertical alignment has a significant effect on the morphology of liquid crystal optical devices.

Abstract: Electricity is the foundation of modern industrial and people’s daily life,as the most basic energy. The higher desire for power supply quality and reliability has been advanced along with the rapid development of national economy.Given the importance of electrical safety in the application of electric energy,it’s necessary to be aware of electricity protective measures,especially the protective earthing ways as the indirect contact protective measures.