Advanced Materials Research Vols. 1070-1072

Abstract: In the previous blackout, overload components out of operation often leaded to the expansion of the accident. One active defense substation domain strategy control system was proposed to prevent the N-1 contingencies to N-2 contingencies caused blackout. Through the substation elements states real time analysis , the active defense control strategy was created by learn from the principles and action messages of backup switching equipment, protection and automatic stability control devices. In order to keep the overall system stability, the active defense control strategy was completed by actively put in the standby element or quit part of the overload elements, to make the system into a new equilibrium state. Contrasting these control strategies by PSCAD/EMTDC simulation software, the results presented that this strategy could quickly change the “Close to collapse” zone into the stability states and the building program simple and practical.

Abstract: A power network disturbance identification system (PNDIS) was developed as a new function module of wide-area security defense system (WASDS), which has been commissioned in the dispatching center of a real power system. This paper describes the implementation of its software platform which consists of three parts: data sharing service, calculation engine and visualization module. The paper focuses on the design of the calculation engine, which is the key part of the platform, and the visualization module. Wavelet transform (WT) is used to identify the time and location of disturbance in the power system. Tests on measured data recorded by WAMS are presented in order to illustrate the benefits of the software platform and show its excellent performance.

Abstract: This paper reviews kinds of 110kV transformer percentage restraint differential protection’s principles from differential types and different manufacturers. Based on the Adobe AIR cross-platform technology, a new system on mobile terminal is carried out to support kinds of transformer protections’ calibration in one auxiliary application. On Android platform and iOS platform, this system is able to calculate testing currents, predict actual action boundary points and draw restraint characteristic curve. All the functions improve calibration efficiency and logic verification reliability greatly.

Abstract: The intelligent dispatch and control of future smart grid demands grasping of any nodal load pattern in the general great grid, therefore to realize the load forecasting of any nodal load is quite important. To solve this problem, focusing on overcoming the weakness of isolated nodal load forecasting and based on the correlation analysis, this paper proposes a multi-dimensional nodal load forecast system and corresponding method for effective prediction of any nodal load of the grid. This system includes topology partitioning of the grid energy flow according to layers and regions, basic forecasting unit composed of each layer’s total amount of load and its nodal loads, and combination forecasting for any node. The forecasting method is based on techniques including the multi-output least square support vector machine, Kalman filtering and the approximate optimal prediction. A case study shows that the multi-dimensional nodal load forecasting model helps to improve the forecasting accuracy, and has practical prospects.

Abstract: The conventional approaches to distribution network fault location has certain drawbacks in terms of complexity, especially the fault occurred in the branch lines. In this paper, a novel fault location method based on D-type traveling wave was proposed. This method choose the measurement point which the initial traveling waves first reached as the reference measurement point, and the distance between multiple failure points received a fault traveling wave signal to the reference measurement point was calculated. Then, the maximum distance between multiple failure points to the reference measurement point was selected as location of the final failure point. The simulation result with ATP simulation software and MATLAB software show that the proposed method can achieve fault location fast and accurately within a very short period. Compared with the existing algorithms, this method was consistent whether the fault occurred in the main line or branch lines, which improved the accuracy and reliability of the traveling wave fault location in distribution network.

Abstract: The extensive usage of power electronic equipments makes harmonic problem increasingly serious. In unbalanced three-phase system, traditional p-q, d-q method ignores the zero sequence currents, resulting in zero sequence harmonic leakage error. This article is based on the basic principle of instantaneous reactive power theory, it proposes a new type of harmonic detection algorithm, this algorithm does not need phase-locked loop nor do a matrix transformation, and can effectively avoid the zero order harmonic leakage error caused by coordinate transformation.In the end, using Matlab/Simulink environment to build models of traditional algorithm and improved algorithm .Through comparison, the simulation result shows that the improved algorithm is more accurate and more effective than the traditional one.

Abstract: This paper presents a novel CPF-GMRES algorithm based on an adaptive preconditioner to overcome the computational bottleneck in the analysis of large-scale power system voltage stability with CPF. Considering the combination details of CPF and GMRES, an adaptive preconditioning structure is proposed to reduce the formation times of preconditioner. Initialize the preconditioning matrix in the predictor of CPF, and modify it with Broyden method in the corrector. Large number add-in strategy and a replenished one are applied to deal with the influence of PVPQ bus-type switching. Numerical results with IEEE 118-bus test system and a real power grid verify the effectiveness of the proposed algorithm, and indicate that a remarkable speed advantage is obtained compared with the conventional CPF-GMRES with the preconditioner of ILU factorization.

Abstract: With the rapid development of the grid scale, there are huge data generated in grid, which include many sample data, alarm data used for real-time monitor and analysis, the traditional dispatching system can’t meet the demands of big capacity storage very well. In recent years, big data technology develop very fast, among it the distributed column-oriented database system is rising gradually with the vigorous development of cloud computing. Considering the character of power data, this paper studies how to use distributed column-oriented database system in power application for storing massive increasing data. The paper design massive data storage structure of power data, design software frame and deployment of massive power data storage. Through experiment it is feasible for distributed column-oriented database to be applied in EMS system through experiment.

Abstract: It is the random and irregular and variable properties of disturbance signal in the detection of power quality, there is lack of mature methods for detection and location of PQ disturbances. An improved morphological undecimated wavelet scheme was presented in this paper and applied to the detection of power quality disturbance. The improved MUDW scheme, which meets signal reconstruction conditions, contains broad open-close or close-open filter and morphological gradient which detect mutations on the top and bottom edges of signal. It used MATLB to detect transient or steady state with single or composite disturbance signals and made comparison with the existing form of sampling wavelet. The result shows that the new MUDW scheme can recognize and detect the signal and has a good anti-noise performance.

Abstract: With the strong and smart grid full development and the unprecedented power scale, the traditional interaction has become increasingly unable to meet the requirements of future grid scheduling system. This paper analyzes the feasibility of speech interactive technology application in the dispatching automation areas, designed the scheduling speech interaction framework to meet the characteristics of grid scheduling. Then it was integrated into the existing human-computer systems to do related validation studies. The human-computer interaction framework is consisted of speech recognition module, semantic storage modules, interactive response modules and integrated human-computer display modules.The results showed that the speech interaction as an Auxiliary interaction, intergrated into human-computer interaction in the future scheduling system that can help dispatchers better to monitor and manage the power grid, which has broad application prospects in future grid scheduling system.