Applied Mechanics and Materials Vol. 737

Abstract: In this paper, based on the requirements of distribution automation system (DAS), the testing method of performance index of remote terminal unit is studied. The standardized test method and testing process with automatic test is discussed. The paper also brings forward a set of feasible testing and evaluation method on the distribution automation terminal device to ensure the safe and stable running of power distribution automation terminal.

Abstract: With the strengthening of interconnected power grid connection, interval oscillation mode damping continue to improve, interval power oscillation accidents still occur, however, the negative damping mechanism of the classic cannot be satisfactorily explain these phenomena, this paper provides the researches forced oscillation mechanism of the low frequency oscillation, the speed control system is likely to form the forced oscillation source, speed regulation system and low frequency oscillation formed an adverse coupling effect. In this paper, based on the mechanism of their method, speed control system are analyzed, the effect of various parameters on the low frequency oscillation in order to avoid speed regulation system to participate in the low frequency oscillation provides technical support.

Abstract: Abstract. Neutral un-effectual grounded system (NUGS) is widely used in Chinese medium voltage power distribution network. However, existing earthed fault location methods in NUGS are not satisfactory in practical application due to weak fault current and unstable arc. Based on analysis of spectrum characteristics of current signals in single-phase earthed fault feeder, this paper proposed an earthed fault location method based on support vector machine (SVM). Firstly, the zero sequence current signal was sampled, and its spectrum was gotten by discrete Fourier transform. Secondly, the three dimensional feature vector that constituted by fundament, harmonic, inter harmonic component, had been extracted as the input of SVM. Furthermore, the SVM was trained with the samples obtained by simulation under different fault distance, different fault resistance and different fault close angle. Finally, the earthed fault feeder is selected using the trained SVM. The simulation results indicate that the fault location by the presented method is more precise.

Abstract: To achieve further optimization of resource utilization, HVDC power transmission project in the proportion of the state grid is growing and the range of applications are more widely. Due to the high cost of converter stations, properly design of DC MOA for DC system insulation coordination and reducing the cost are crucial. Through research and analysis of large amounts of data, applications and test technologies of DC MOA is in-depth expounded, It’s further deepened the staff’s understanding of the DC MOA, there are also some guidance and references to the repair and maintenance of DC MOA.

Abstract: In this paper, we focus on the defects of traditional business model, and give the self-similar process definition and significance of research. The self-similar process and characteristics is introduced, and the affected network performance is presented. In order to better understand the network model, we establish an effective business model based on the Poisson and Markov model. A novel iteration approach is introduced to solve the deficiencies problem of traditional approach, it is quite suitable for the dynamic p-cycle application and can accurately describe the actual network traffic for real network. Finally, the precision of different prediction algorithms are compared and analyzed.

Abstract: TGZ10A-40.5 wall bushing of high voltage switch cabinet from one company was taken as applied research object. Reference the development process of high voltage cable shielding technology, three samples were designed and produced depending on different sets of the shield system. The result show that: surfaces processed by the way that the inner (aluminum cylinder) and the outer (metal mesh ring) shielding components were coated with a semi-conductive material, made little sense to improve the withstand voltage level and reduce the partial discharge; surface processed by the way that inner shield component (aluminum cylinder) was coated with semi-conductive material, the outer shield component (metal mesh ring) was not coated with semi-conductive material, was obviously influenced the improvement of the withstand voltage level and reduction of the partial discharge, compared with traditional technology, the average start voltage of corona increased 23.8%, the average value of partial discharge dropped 27.7%.

Abstract: In order to study the application of Weibull distribution in cable partial discharge pattern recognition. We apply a 10kV 30m XLPE cable for this study. Then design four kinds of typical artificial defect model and analyze each of defect model’s discharge pulse signals. Finally, estimate the Weibull distribution of signals by use of the maximum likelihood method. The results show that Weibull probability distribution is similar to partial discharge amplitude distribution, the shape parameter β can be used to identify different types of discharge.

Abstract: In order to analysis the type of XLPE cable partial discharge, and grasp characteristics of partial discharge caused by different defects. In this paper, we use a 10kV 30-meter-long XLPE cable and design different types of defects. Then we collect the PD data of different defect model by PD data acquisition system. To characterize Partial discharge signals generated by different defect model by use of discharge capacity q_s, discharge times n, the average discharge amount q_n and phase distribution function include the maximum discharge amount distribution H_Qmax (φ), the average discharge amount distribution H_Qmean (φ), the discharge times phase distribution H_N(φ) as well as φ-Q-N distribution map and so on. The results show that the partial discharge signals produced by different defect model have different statistical characteristics.

Abstract: Electric power supply is one of the most important aspects of China’s national energy development strategy (NEDS). As major economic unit as well as major energy consumer, Jiangsu province is facing serious energy supply challenges. Under such circumstances, positive actions are taken by local government in respond to NEDS which put energy saving in the first place, and demand side management (DSM) is implemented. DSM is an important measure which can release rush hour electric supply pressure, enhance energy efficiency, optimize electric power utilization, and it is beneficial for sustainable development. This paper is based on the analysis of the current DSM situation of Nanjing, and green lighting is taken as an example. An empirical analysis is given to cost-effectiveness of the implementation of green lighting. Finally, the conclusion that the cost-effectiveness of the implementation of green lighting is economically viable to power supply companies, electric customers and the whole society is drawn.

Abstract: Taking safety and quality management of power transmission and transformation projects as the main line, this paper studies the practice of construction management of 220kV and above power transmission and transformation projects in Jiangsu province after the system reformation of State Grid Jiangsu Electric Power Company, then refines the experiences and highlights in pre-planning, process management, implementation of management measures and other aspects. The new management mode of power projects with Jiangsu characteristics is established.