Applied Mechanics and Materials Vols. 325-326

Abstract: The dynamic characteristics of the power system will be a sharp deterioration near the second order resonance point. In-depth study of the Power system dynamic characteristics near the second order resonance point, and then how to cause the dynamic characteristics of the system worse at the second order resonance point near the stable boundary, need to quickly search system of second order resonance point. Based on the principle of minimal expansion system method, this paper presents the direct method for search the second order resonance point in power system. For the N dimensions differential dynamic system was established in the 4N+4 dimension expansion equations. The power system second order resonance point search is changed into expanding equation fixed point solution. Significantly reduce computational load, improve the search accuracy for solving second order resonance point calculation. For in-depth study of power system dynamic characteristics near the second order resonance point have a certain value.

Abstract: Transmission lines is an important part of the power system. Transmission line condition monitoring system can enhance the operational reliability of the grid line level of safety, at the same time lay the foundation for intelligent transmission line. Insulator contamination monitoring , lightning monitoring, environmental monitoring, wire breeze vibration monitoring online monitoring technology on the existing transmission line condition monitoring technologies , including comparative analysis of the far-reaching. It can reduce the workload of the artificial line inspection , to reduce the occurrence of pollution flashover to improve power supply reliability. To reduce the pollution flashover occurred to improve the reliability of power supply. Condition based maintenance decision support and sharing of information with other systems. HOMER and MATLAB simulation software , simulation , historical data analysis . Export real - time wind speed data, provide data to support the conductor galloping and aeolian vibration of monitoring and environmental monitoring.

Abstract: In view of their own limitations of GA[1] and ACA[2][3] in the fault location of distribution network, this paper presents a new group intelligent optimization method which is simple and easy to implement, fast convergence rate, more global optimization ability, etc, and this is the PSO. Then the basic principles of the PSO algorithm and the Standard algorithm of PSO are discussed in details, on the base of that, this paper continues to introduce the principle of PSO algorithm which is used in the fault location of distribution network. This section mainly introduces the structure of distribution network, then makes a brief introduction of the fault location algorithm, finally writes out the detailed steps of PSO algorithm. When already understood the principles and algorithms, a detailed analysis of the distribution network. This paper makes use of this method in the process of the location of transformer combined with the high accuracy of fault location which avoid the possibility of local convergence. Finally this paper gives the analysis of case, the result shows that the proposed method of distribution network fault location is feasible.

Abstract: PD in cable accessories will inspire EM waves of ultra-high frequency (UHF) at hundreds of MHZ to GHZ. To study the characteristics of EM wave inspired by PD in cable accessories, a three-dimension model of 110kV cable joints is established. Based on the propagation theory of EM waves in coaxial waveguide, finite element method (FEM) is used to analyze the effect of cable joints composite interfaces on UHF signal propagation, and simulation analysis of relations between PD UHF signal's energy distribution, pulse frequency, propagation distance. Simulation results show that the main transmission mode of EM waves is TEM mode in the joints; Energy of EM waves descends rapidly as the PD pulse's frequency increases; Energy of TEM waves descends rapidly with the increasing detection distance. Simulation analysis of UHF signal's propagation characteristics provides the theoretical basis for UHF PD detection in cable accessories.

Abstract: Spacers, for example, this paper introduces the developing process of energy efficient transmission line modular electrical fittings in distribution network. It uses glass fiber composite materials and non-magnetic as the main material which does not produce or produce very little hysteresis and eddy current losses. It has no corona and its energy saving effect is obvious; anti-dancing, high mechanical strength. Refer to the knowledge of aerodynamics to design the structure, not only effectively prevent the connection joint of different materials connected to the wear and tear, and can effectively reduce wind noise, thus reducing friction and shock losses .It not only replaces the expensive and rare metal materials such gold, and provide simple and economical solution for upgrading the distribution network. It meets the transmission line spacers technical indicators, economic and social benefits significantly.

Abstract: Combined with the characteristics of power engineering projects, the paper introduces a kind of theoretical model that leads gray relational analysis and risk analysis into AHP appraisal method. This article describes the application steps of the model by a case. This article's main focus is the membership of risk index and the index weight. In the risk comprehensive evaluation model, the paper adopts the risk analysis method and gray relational analysis method to determine the membership and the weight of risk index. This model is considered to be the virtue of the subjective weight and the objective one. It can improve the accuracy of the evaluation.

Abstract: when the photovoltaic power generation and thermoelectric power factory connect into the distribution network , the system change from one source to several sources. it will change the construction of the system and the system power flow ,and also the size and direction of short-circuit current. It is harder to prepare the grid protection devices and set value for the protection. This paper studied the complex electronic systems which contains wind farms and thermoelectric power factory, analysis the change of voltage and current of each bus when the fault happen after the photovoltaic power generation connected into the system, and also talk about how the fault location affect the system fault component .Then conduct the expression of the fault current of each line to provide the basis for the study of multiterminal supply network protection strategy.

Abstract: Electric vehicle charging stations are high-power load after they are accessed to the grid. Therefore it may result in the redistribution of the grid load, which leads to the change of the power flow and the grid loss increases. The load model of charging stations is established in a typical distribution network model in this paper. The impact on the distribution network power flow after the electric vehicle charging stations accessed to the grid is calculated. And then some measures to reduce the network loss are brought up, which are proved by relational calculation cases.

Abstract: A dynamic comprehensive evaluation method of power quality based on incentive and punishment mechanism is proposed. At the beginning, the index system is designed and unified. Next, the incentive and punishment mechanism model of each index is established. Then, the vertical and horizontal scatter degree method and minimal variability theory are applied to calculate the comprehensive evaluation value of all the indices on every time period and on the whole time series respectively. Finally, the realistic example demonstrates that this method can easily differentiate the quality of different evaluation objects.

Abstract: AMI (Advanced Metering Infrastructure) is the first step of the implementation of the smart grid. The communication network is the important part of AMI. The reasonable communication network architecture and effective cyber security measures are the keys of the realization of AMIs functions. The components, functions and communication network architecture are studied. Communication technologies that can be used in AMI are analyzed. Based on ZigBee, fieldbus/industrial EtherNet and GPRS, a typical AMI are constructed. The cyber security threats, communication data types and cyber security requirement of AMI are analyzed. The cyber security strategy and implementing scheme are offered. The communication standards and cyber security standards that can be referred while constructing AMI are analyzed. The necessity that publishes AMIs communication standard and cyber security is put forward.