Applied Mechanics and Materials Vols. 448-453

Abstract: Applying ecology evolutionary algorithm of food chain which simulates biological energy transfer mode to multistage transmission network planning (MTNP). According to the characteristics of MTNP, a real number encoding method is proposed to solve the problem that decision variables dimension increases as the stage increases. The test is performed on a 19-bus system and demonstrates the method EEAFC-based MTNP is practical and effective.

Abstract: Voltage stability assessment plays a major role in planning and operation of power system. This paper presents an efficient approach to solve reactive power control problem for voltage stability improvement. In this approach the voltage stability index is formulated to identify the most vulnerable bus at various operating conditions. The bus with the value of maximum VSI is considered as the most critical bus. To maintain the stability of the system the severity of the load buses has to be minimized. This can be achieved by the optimal settings of control variables using Differential Evolution Algorithm. The effectiveness of the proposed approach has been examined on the standard IEEE 30 bus test system under stressed and contingency condition.

Abstract: Cascading failure has become the significant factor of the safe and reliable operation of grid with the development of power system. To assess the operation risk of cascading failure, we apply traditonal and improved branching process model to a a 14-year historical outage data from a regional power grid in China, computing probabilities of cascading line outages. Then the probability distribution obtained from the 2 moedls are compared by fitness test. As the simulation result shows, for the historical data, the empirical distribution of the total number of line outages is well approximated by the improved branching process model with propagation parameters and initial outages. The fitness test provide quantitative evidence that the improved model fits the data better than the conventional model.

Abstract: This paper presents an empirical Gramian balanced reduction method which efficiently solves nonlinear power system model reduction problems. This method projects the nonlinear power system dynamic model to a lower dimension subspace and the reduced model can retain the original nonlinear system input and output dynamic behaviors. A four-generator nonlinear power system, combining different factors which form empirical controllable and observable Gramian matrices, is used to analyze how external excitations and outputs affect balanced empirical Gramian reduction. The case verifies the feasibility and effectiveness of balanced empirical Gramian reduction method.

Abstract: There are many factors affected the result of humidity measurement in the resonator wetness steam measuring system .The away of frequency that aroused from the heat expansion of resonator ,the changing of resonance frequency because the thickness of water membrane,errors from the part of frequency measuring are analyzed ,and the compensation measure is introduced separately.The measuring precision of steam humidity can be cffectively increased.

Abstract: This paper presents a novel method for determining the harmonic emission responsibilities of utility and customer at the point of common coupling (PCC). The proposed approach is based on robust partial least squares regression (robust PLS), which estimates system harmonic impedance by utilizing the signals of harmonic voltage and current measured synchronously at PCC. Consequently the harmonic emission responsibilities are calculated. The presented method reduces or removes the effect of outlying data points. The simulation and the practical engineering results indicate that the proposed method is valid and feasible.

Abstract: The functional testing is necessary based on the analysis the shortage of substation equipment on-line monitoring system, such as the problems about difficult interoperability and data sharing in case of the various communication protocols. The substations function is described in detail before introduce the functional testing. In this paper, the system functional testing was given under two kinds of environment. One is the testing platform is used to debugging instrument, another is used to the device for signal-input source and analysis. Finally, a method for substation equipment functional testing of IEC 61850-based system is presented which will contribute to the effectiveness and equivalences of the testing.

Abstract: Equipments for distribution automation terminal and the corresponding back-up power that can be cold started directly without heating equipments in natural environment at -40°C are developed to suit the extremely cold weather in Northeast China. The ultimate goal is to realize normal operation at a temperature ranging from -50°C to +70°C.

Abstract: This paper deals with the study of smart substation system level test. The test include three parts:network performance test,electronic transformer test and conformance testing.Network performance test involves the process layer network and station level networks test, transmission delay and frame loss rate of switch is tested.Electronic transformer test contains accuracy test, absolute delay test and polarity test. Conformance test is a test for model based on IEC 61850,test flow is studied.

Abstract: Reactive power is extremely important in the power system. To do reactive power compensation in place where reactive power is consumed a more reasonable approach. Traditional grading capacity of reactive power compensation determination methods are prone to sub or over-compensation. This paper firstly established a grading capacity of reactive power compensation optimization model; then introduced the artificial fish swarm algorithm(AFSA) method for grading capacity of reactive power compensation; finally the proposed algorithm is verified through an example and compared with those based on other optimization search algorithm. The results show that using AFSA to determine the classification of reactive power compensation capacity leads to higher efficiency.