Applied Mechanics and Materials Vols. 672-674

Abstract: Phasor measurement technology developed rapidly in CHINA, Real time power system dynamic monitoring master station system were built widely in inter-regional power system and provincial power system, With WAMS system of practical ,WAMS master station test specification making is particularly important .The WAMS application ,series standard normative and the need to make a master station system test specification were described .According to the master system in the operation of the power dispatch center ,test content was put forward ,the content include Hardware requirements ,the system function and the application functions .At the same time ,protocol test method ,transmission delay test method ,data formats ,the test methods of system performance and application performance were proposed .Test content and methods research of real time power system dynamic monitoring master station system lay the foundation for the making of the master station system test specification ,provide reference for the development and practical use of real-time dynamic monitoring system.

Abstract: While analyzing the line loss, power supply enterprise always encounters circumstances in which the line loss rate swings heavily, especially during the months when there exists season alternate or long vacations, the fluctuation range of the line loss rate grows larger, and it will be apparently on the high side or on the low side. This text figured out the major factors influencing the fluctuation of the line loss rate, quantitatively analyzing three factors’ effects on line loss rate, which respectively are non-correspondence electric quantity for supplying and selling, the dedicated line which large consumer load transfers and the change of electric quantity which is nondestructive for sale, thus facilitating the grid enterprises dynamically analyzing the line loss in time, providing authentic line loss data for electric power departments at all levels, electricity board, power supply station, improving the accuracy of line loss analysis, dismissing the human factors during the fluctuation of line loss.

Abstract: According to the relay protection rules, 110kV bus and 220kV bus and above, should be installed special bus protection. This paper do a separate research on bus coupler charging protection from the aspects of bus protection principle and logic of action. It was pointed out that the necessity of blocking differential protection in the process of coupling charging and the new problem of blocking differential protection. This paper puts forward improved bus charging protection after research the processing methods of different relay protection manufacturers, and it improves the reliability of bus coupler charging protection

Abstract: The online identification of low frequency oscillation mode based on measured signal from PMU is the base of damping control. Removing nonlinear trend from the signal effectively can ensure the precision of mode identification. A method named smoothness prior approach (SPA) is proposed to remove the nonlinear trend from measured signal. In order to meet the demand of removing nonlinear trend for identification of low frequency oscillation based on analyzing the basic principle of smoothness prior approach, it determines regularization parameter of smoothness prior approach according to its characteristic of frequency response. It is used to analyze the simulation signals from IEEE-39 bus power system and the measured signals in some power grid, and compared with empirical mode decomposition and digital filter method. The results demonstrate that this proposed method can successfully remove nonlinear trend from the signal and improve the speed of computation, as well as the precision of mode identification, which has a relatively high practical value.

Abstract: A spatial load forecasting method based on reliability of load forecasting is proposed. It calculates the correlation of wave comprehensive index, variance, maximum predictable ability of each power supply small area’s historical load data by using the analysis theory of grey degree based on the analysis of load forecasting error last target year. The weight of each factor effected on prediction outcomes according to the gray correlation degree is determined, then the load forecasting reliability model of each power supply area is constructed. Finally, by using the adjustment role of load forecasting reliability, the load of target year is forecasted. Actual example shows that the spatial load forecasting method based on reliability of load forecasting is correct and effective.

Abstract: The power flow calculation is a basic electrical calculation which is to study the steady state operation of power system. Its task is to decide the whole system running state according to the given operating conditions and the network structure. The power flow calculation is the basis of the stability calculation and fault analysis of power system. In this paper, through a four machine 11 node example, we shows that the influence of generator node type on power flow calculation.

Abstract: The access of DG changes the operation and structure of traditional distribution network. This study mainly focused on controlling DG output current to reduce network loss of the system. Select a simple radial distribution system as example for theoretical analysis and derive the expressions of load current and node voltage. Assuming that there exists a real number k between DG output current and load. Then list the network loss and voltage deviation expressions. For the purpose of operation optimization, k can be determined by mathematical calculations. It proves that the method has a certain rationality to be effective in controlling network loss.

Abstract: Distributed protection relay value setting is widely applied in china. There is a graph chaos problem in protection relay model splicing process. Deeply study the characteristic of integrated relay splicing, combined with the substation voltage level, a substation locating method based on improved genetic algorithm is proposed. To enhance the graph splicing, a voltage level based method is applied. At last, a practical example is used to validate the effectiveness of the method.

Abstract: In the matter of huge, widespread, and great workload when facing the issue of loss reduction, finding the wire line loss potential plays a very important role. In this paper data envelopment analysis of C²R model-based, gird line factors as a guide to build the analysis method of loss potential in Gansu power based on DEA, also calculating results according to 2012 Gansu wire line loss statistics. The result is combining with Gansu line loss situation, to discuss and test the validity and reliability of the method.

Abstract: The “five-zone” control theory is a kind of Reactive power integrated control theory With the device as the control object directly which is different from the traditional “nine-zone” theory . It has high control precision and good control effect and has a broad application prospect. However, with the appearance of New type of dynamic reactive power compensation device, the basic five-zone control theory can’t meet the new demand In this paper, on the basis of the traditional "five-zone"theory, considering the dynamic reactive power compensation device, the traditional five area boundary is improved. Based on the improved chart on the basis of the five area, defines a new type of five area chart control method, and finally verifies “improved five-zone” control method by simulation.