Applied Mechanics and Materials Vols. 325-326

Abstract: The distribution network is mostly the ungrounded neutral system or the resonant grounded system in many countries. Selecting the fault line as soon as possible is of great significance to power systems. This paper proposes a parameter identification method in frequency domain to solve this problem. By using the matrix pencil method to extract frequency-points and their information in zero-sequence voltage and zero-sequence current, spectral leakage in DFT is avoided. With the estimated frequency points, an equation in frequency domain is established which will help to calculate the capacitance value and thus to identify the fault line. This method requires a low sampling rate and has high accuracy. In addition, the frequency-band in this new method is wider than the SFB's frequency-band. Verified by simulation in ATP-EMTP and data from RTDS, the new method is quite effective in fault line selection with an ability to overcome transition resistor and is immune from the impact of arc-suppression.

Abstract: Through analyzing maintenance characteristics of various phases in life cycle, it can be found maintenance is essential in each phase of the system. Therefore, it is important to change the traditional maintenance concept, research on the selective maintenance system in life cycle, instead of considering maintenance only in running phase. Based on the PHM (prognostic and health management) in marine power system, defines optimization maintenance timing of the equipment as objective, and set reliability and economy as evaluation criteria for the maintenance program, this article establishes selective maintenance system for marine power system in life cycle.

Abstract: In order to give online voltage monitoring and stability margin judgment, a radial basis function (RBF) is used in this paper to predict the node voltage amplitude. Using BPA build IEEE9 network and input the processed data to RBF neural network, compared the results with the actual voltage amplitude, got a accurate prediction result. So as to stand out the accuracy of RBF, compared the relative error of prediction results between RBF and the second exponential smoothing model (SES). It testified the accuracy of RBF was more superior.

Abstract: Based on the characteristics of overhead distribution lines, according to the principles and methods of the 3ds Max software to create 3D model, this paper introduces how to solve the key issues for the visualization of the management system of overhead distribution lines. The process of the study shows that use 3ds Max turning, lofting and boolean functions, to draw 3D model of the overhead distribution line irregular shape parts is simple and feasible, make whole 3D model and video, can display a vivid of the various components of overhead distribution line. Enables managers to query data more intuitive, and provide a reference for management decision-making, research results can be applied in other electric power information management system design.

Abstract: In this paper, shaft monitoring data in condition monitoring system of hydropower units was used to build the fault classification model based on the least square support vector machine (LS-SVM). By the wavelet packet signal decomposition for unit vibration signal, setting the signal energy components as the study sample, learning of fault diagnosis classifier was conducted, to achieve the diagnosis of common faults in shaft running of hydropower unit.

Abstract: Power quality problems could cause enormous amounts of economic cost to electricity consumers. Taking voltage dips as an example, this paper presents a general overview of methods to quantify economic impact of power quality problems. It also presents in detail several ways how to collect power quality economic data. At last, suggestions on how such researches could be done in China are represented.

Abstract: Lightning is a special and spectacular phenomenon of the sound, light and electricity in the nature. Due to lightning discharge releasing a huge energy in a very short time and forming a large current and high voltage with strong destructive, it will take a great threat to people, equipment and facilities. From a long time, the lightning protection is always an important question in the electrical construction engineering design and construction, which scientists in the countries all over the world must consider in. This paper analyses the thunder and lightning causes of a civil aviation airport, according to the average annual lightning days we calculate the lightning activity intensity in some region, on this foundation, we establish the lightning threat model of the civil automatic charging station, and provide the theory basis for the lightning protection design and the analysis of the lightning threat model of the automatic charging station.

Abstract: 500kV EHV transmission networks have become the main one of the national grid, carring out live working for 500kV EHV transmission lines is the objective requirements to ensure the stable operation of the grid system. This paper uses a new system to simulate and analyse the way of entering the high electric area on 500kV transmission line. The system has built the ZM1 transmission tower and line model, accurately accounted the complex gap and satety distance. The simulation results show that the system can effectively get the best secure route and determine the way to enter into the equipotential with the safety margin.

Abstract: Hybrid active power filter has been used widely in the engineering application. It often be in idle and low power working state. The grid inverter can't keep in real-time rated output conditions, the output capacity of it got wasted. A kind of new-type HAPF device of microgrid was put forward. This device can realize grid-connected power generation of distributed generation and do not affect the original improve power quality function of HAPF. An improved id-iq composite instructions current detection and synthesis method was used, the simulation results were given in the end.

Abstract: The area of vulnerability (AOV) of point of common coupling (PCC) can directly reflect the issue of voltage sag caused by faults in power system. In order to calculate the area of vulnerability more accurately and faster, this paper proposes a new fault positions method based on interpolation, which overcomes the blindness of setting fault points. The influence of transformer winding connections on voltage sag is also taken into account. Short-circuit calculation is adopted and transfer matrix representing the transfer law of transformer on voltage sag is deduced firstly. Then, the principle and implementation flow of the new method are presented in detail. Finally, the new method is applied to a regional power system of China, and graphic result of the area of vulnerability is displayed under balanced and unbalanced faults.