Advanced Materials Research Vols. 1092-1093

Abstract: A framework of comprehensive risk assessment for Electric Cyber-Physical System (ECPS) is proposed in this paper. Risk factors of information system and their impact on the gird are analyzed and the method of obtaining the fault probability considering risk factors from information system is discussed. A comprehensive risk assessment model is presented and related software is developed. Research work in this paper provides a theoretical basis and software framework support to the following system development.

Abstract: The simulation of distribution automation troubleshooting and the functional design of training system software is discussed by this article, Including: basic platform capabilities, the Decision Analysis of Auxiliary power failure, Power operation mode for load transfer analysis, the ring analysis of Grid operation mode , the Training Simulator of Distribution Network and the data synchronization of The simulation system diagram and mode .the simulation of Distribution Automation Troubleshooting and the effect of training system operation Show the validity and effectiveness of the method.

Abstract: With chaotic dynamics analysis to the mechanical vibration signals of on-load tap changers(OLTC) operations, a geometric feature extraction scheme is developed for phase portrait structure based on a multi-dimensional coordinate space. The fuzzy set theory is further introduced into OLTC mechanical fault diagnosis, with a view to establishing the normal distribution membership function of every condition fuzzy set. Regarding two sample categories, i.e. single analyte sample and analyte sample sets, both principles of the largest membership and the optional nearly are used for fuzzy reasoning to finally realize mechanical fault diagnosis of OLTC.

Abstract: This paper analyzed high capacity high speed switch’s works and structures, proposed a parallel structure of high capacity high speed switch (FSR) with current limiting reactor. Through analysis of its action process, this paper used EMTP/ATP to simulate FSR action process, analyzed line current and voltage changes in normal and short circuit station. Simulation results show that the method can effectively limit short circuit current level.

Abstract: Since distribution lines have relatively weak insulation compared to power transmission lines, it is more liable to lightning damages. This paper reports a study of how overhead ground wire height and impulse ground resistance affect the lightning protection performance. The results obtained in this paper show that high overhead ground wire worsen the lightning protection performance while reducing the impulse ground resistance improves the lightning protection performance. Therefore, it is recommended to set the overhead ground wire lower and take necessary measures to reduce impulse ground resistance. The results obtained also confirm the crucial role of the overhead ground wire as a protection of distribution lines.

Abstract: In the past few decades, power system has developed into a large-scale network system of centralized electricity generation and long-distance transmission. But in recent years, electrical load has increasing, while the grid has not developed simultaneously, it makes transmission capacity of long-distance transmission lines increase, so as the decline of stability and security of power grid. In order to achieve the goal of not only increasing utilization of renewable energy, but also solving the drawbacks of large-scale power systems, implementing distributed power generation is an effective way. Despite the advantages of distributed generation, there are many problems in itself, for example, the high cost of distributed generation stand-alone access and control difficulties. In addition, distributed generation is a non-controllable source for large grid. Then in the beginning of this century, scholars have proposed the concept of micro-grid.

Abstract: With the rapid development of UHV technology, Electric field measurement technique has attracted lots of people's attention.Electro-optical sensors for measuring the electric field to become the main method due to the crystal optical fiber preparation and mature technology. This article describes the basic principles that Mach - Zehnder of lithium niobate optical modulator for electric field measurements.Designing the Mach - Zehnder electro-optic sensors in the Comsol Multiphysics oftware, the calculation model for the simulation results of bending radius that the optical waveguide transmission power loss minimum, a 3dB directional coupler to determine the length of the arm and finally adding a signal voltage, the applied voltage is obtained a linear relationship between the output power.

Abstract: To reduce the tubular hydro-generator no-load voltage waveform distortion,some different design schemes of stator slot skewing degree in a 36MW fractional slot tubular hydro-generator (q=1¹/₂ ) are calculated and compared. Then, the relation of the no-load voltage waveform harmonic distortion factor (HDF) and stator slot skewing degree are revealed. The research provides the important reference informations for the optimization of no-load voltage waveform , and it is helpful for improving the industral design and manufacture standard of tubular hydro-generator.

Abstract: Optical current transformer (OCT) measured current signal which is mixed with strong random noise. The measured readings can’t accurately reflect the value of the measured current. Since the optical current transformer noise inside the band is basically where the measured current signal overlap,we can not use the traditional method to filter it out. This paper describes the measurement principle based on the Faraday effect of optical current transformer and signal to noise characteristics. Considering optical current transformer for low SNR characteristics, and embedded systems do not have the characteristics of a matrix library, we proposed using sequential Kalman filter to improve the real-time output signal to noise ratio. In the measured current for DC and AC conditions,we established an appropriate state space model Kalman filter.,and conduct simulation on matlab. Practice shows that the sequential Kalman filter algorithm can effectively improve the output signal to noise ratio and accuracy.

Abstract: Surge arrester is an effective measure to protect distribution lines from lightning strikes. But high costs will be spent on the maintenance of a great many surge arresters in 10kV distribution line. Taking the relationship between reliability and economical efficiency into consideration, aiming at installation density of surge arrester, this paper established the effective simulation models of direct lightning stroke overvoltage and induced overvoltage by ATP-EMTP. Finally, this paper presented the optimal installation scheme of surge arrester on the basis of the simulation and analysis of the lightning withstand level. The simulation results provide references for the optimal installation scheme of surge arrester on the distribution network.