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Chen Z.,Sichuan University | Xiao X.,Sichuan University | Xiao X.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | Li C.,Sichuan University | And 3 more authors.
Neural Computing and Applications | Year: 2015

Real-time transient stability status prediction (RTSSP) is very important to maintain the safety and stability of electrical power systems, where any unstable contingency will be likely to cause large-scale blackout. Most of machine learning methods used for RTSSP attempt to attain a low classification error, which implies that the misclassification costs of different categories are the same. However, misclassifying an unstable case as stable one usually leads to much higher costs than misclassifying a stable case as unstable one. In this paper, a new RTSSP method based on cost-sensitive extreme learning machine (CELM) is proposed, which recognizes the RTSSP as a cost-sensitive classification problem. The CELM is constructed pursuing the minimum misclassification costs, and its detailed implementation procedures for RSSTP are also researched in this work. The proposed method is implemented on the New England 39-bus electrical power system. Compared with three cost-blind methods (ELM, SVM and DT) and two cost-sensitive methods (cost-sensitive DT, cost-sensitive SVM), the simulation results have proved that the lower total misclassification costs and false dismissal rate with low computational complexity can be achieved by the proposed method, which meets the demands for the computation speed and the reliability of RTSSP. © 2015 The Natural Computing Applications Forum


Liu Y.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | Liu Y.,University of Sichuan | Liu J.-Y.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | Liu J.-Y.,University of Sichuan | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

In this paper, the dynamic model for limit induced bifurcation in wind power systems is constructed, and it is used to locate the bifurcation point in WSCC-9Bus system with wind farms connected. For the sake of system stability, the limit induced bifurcation is investigated under different wind speed conditions. Moreover, the initial condition of an optimal model is calculated through the method of Quasi Steady-State Analysis(QSS). It is safe to conclude that wind farms operating with increasing wind velocity can increase the load margins. Therefore, high wind speed more easily leads to limit induced bifurcation. The wind system with large hard-limit for dynamic devices and large fluctuations in wind speed can lead to transformation between limit induced bifurcation and saddle node bifurcation, which more easily leads to voltage collapse.


Wei Z.,University of Sichuan | Wei Z.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | Liu J.,University of Sichuan | Liu J.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | And 8 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2011

As the operating and managing information of distribution network is incomplete, inconsistent, non-timely, inaccurate and enslaved to GIS, a dispatch support system based on visualization technology is designed for distribution network. Based on the design and realization of system functions, which takes the thinking mode of dispatcher as the framework, the visual interface as the functional model, and the interactive calculation as the system core, the operational interfaces, such as basal graphic display, connection-graph management, graphic function, etc., and data interfaces are introduced in detail. Research results and applications show that, it could be a reference for the design and application of next generation intelligent dispatch support system for distribution network.


Xu X.,Chengdu Electric Power Bureau | Wei Z.,University of Sichuan | Wei Z.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | Liu J.,University of Sichuan | And 8 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2011

A support system of distribution network dispatch is studied in the environment of smart grid and the present situation of power distribution network development is analyzed. Eight functions are designed based on visualization technology for the support system: the equipment parameter entry based on graphic and model integration, the intelligent presentation of equipment status, the intelligent search, the graphic and model integration of preplan creation, query and demonstration, the intelligent shift log, the evaluation and intelligent prompt of risk points and weak points, the web publishing, the historical events query and intelligent list generation. The application experiments are carried out in actual power distribution network.


Shen X.,University of Sichuan | Shen X.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | Liu J.,University of Sichuan | Liu J.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | Liu Y.,University of Sichuan
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

By turning the power security control of power transfer into non-linear programming, a new power flow transferring control algorithm based on node lopsided powers is proposed. The equality constraints are transformed into power mismatch and processed as the optimization target. It avoids the drawback of the conventional intelligent optimization algorithm that optimal solution must succeed to the satisfaction of power flow equations, thus improving the computing speed. Then a particle swarm optimization (PSO) algorithm with fully communicated information is utilized to solve the optimization problem. In order to avoid premature in PSO optimization process, chaotic sequence is used to initiate individual position, so as to strengthen the diversity of searching. Constraints of the optimization problem can be effectively handled by the proposed method. When system is heavily loaded, conventional methods cannot be used, but the algorithm proposed is still valid. New England 39-bus system is employed to verify the effectiveness of the proposed method. © 2012 State Grid Electric Power Research Institute Press.


Zhang Y.,University of Sichuan | Zhang Y.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | Yang H.,University of Sichuan | Yang H.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | And 4 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

To solve the parsing program's compatibility issues caused by the different definitions of power quality data interchange format (PQDIF) between the manufacturers and provincial standards in the field of domestic power quality, a general parsing scheme for PQDIF files is proposed and implemented. By summarizing tag groups of the known PQDIF files and their corresponding power quality measurement types, the scheme structures a channel series definition table stored in the extensible markup language (XML) format. When parsing a PQDIF file, the Hash table is applied to quickly match the tag groups with the known groups and corresponding measurement types in the channel series definition table, and at the same time differently match the unknown tag groups with the most similar groups. Without modifying the source code of the parsing program, not only the known PQDIF files which have different definition structures could be parsed quickly and correctly, but also the PQDIF files with unknown tag groups could be parsed through simple configurations made by users. The reliability and practicality of the parsing scheme are proved through applications in Sichuan power quality integrated data platform. © 2012 State Grid Electric Power Research Institute Press.


Ma C.,Sichuan University | Xiao X.-Y.,Sichuan University | Li C.-S.,Sichuan University | Li C.-S.,Intelligent Electrical Power Grid Key Laboratory of Sichuan Province | And 3 more authors.
International Journal of Electrical Power and Energy Systems | Year: 2014

Catastrophic accidents in power system are characterized by complex and significant uncertainties. The existing risk assessment methods based on probability theory require adequate historical statistic data to ensure the precision of probability model and parameter identification regardless of the rareness of catastrophic accidents. Alternatively, the catastrophic accident can be treated as a fuzzy event, and then a new uncertain risk assessment model to identify the most possible catastrophic accident sequences is presented in this paper. According to physical propagation process and mathematical modeling principle of the catastrophic accident, a risk evaluation system consisting of the credibility measure, global fuzzy severity measure and risk measure is provided based on the credibility theory. The risk assessment model starts from N-1 contingencies, and the most possible catastrophic accident sequences are identified by the risk ranking of all N-k contingencies in each stage. Some numerical cases of the WSCC 9-bus and practical regional power system are simulated to demonstrate the applicability, validity and accuracy of the proposed method. © 2014 Published by Elsevier Ltd.

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