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Zhang X.-Y.,Power Dispatching Control Center
Journal of China Universities of Posts and Telecommunications | Year: 2013

Existing data network risk assessment methodology concerned about the safety analysis of the data network components lack of analysis of the overall network security features. With the maturing of the complex network theory to study, more and more researchers will combine theory with reality system to describe the analysis of complex data networks. The complex network theory is applied to the field of complex structured risk analysis of the data network, data network connectivity and efficacy of two aspects of the analysis, and the vulnerability of the network structure of the complex data analysis. The methods adopted to study the unique characteristics of the network traffic on the data network to make up for the one-sidedness of the general complex network theory to evaluate the efficacy of the data network, and at the same time to make up for the blank data network structure overall vulnerability analysis. © 2013 The Journal of China Universities of Posts and Telecommunications. Source

Zhang J.,Guangdong Power Grid Corporation | Li P.,Power Dispatching Control Center | Guo Q.,China Electric Power Research Institute
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014

The low frequency oscillation incident occurred between Pingban power plant and Guangxi power grid on December 2, 2010. Prior to the oscillation, Guangxi Baise area 220 kV Pingbai line experienced a phase A fault of three jumps following unsuccessful reclosing. Scene investigation and analysis results show that the angular rate signal in the PSS2A model was mistakenly shielded, leading to the power system stabilizer (PSS) providing negative damping in active state. China Southern Power Grid Corporation attached great importance to this oscillation incident, which was reproduced by simulation on power system analysis software BPA and real-time digital simulation (RTDS). By interconnecting the actual excitation regulator device and RTDS for closed-loop simulation test, not only the low frequency oscillation incident is reproduced, but also the phenomenon of the PSS2A model providing positive damping in the high frequency band (above 1 Hz) and negative damping in the low frequency band (below 1 Hz) due to inaccurate calculation is exposed. This paper analyzes the causes of the negative damping phenomenon from the point of view of the mechanism of the PSS2A model, and studies the limitations of the field test method in testing the PSS2A model's effect of damping in the low-frequency band, and expounds the necessity of the PSS2A model for RTDS power grid access. © 2014 State Grid Electric Power Research Institute Press. Source

Wang L.,Beijing University of Posts and Telecommunications | Rui L.,Beijing University of Posts and Telecommunications | Qiu X.,Beijing University of Posts and Telecommunications | Li W.,Beijing University of Posts and Telecommunications | Jiang K.,Power Dispatching Control Center
Proceedings - International Symposium on Computers and Communications | Year: 2013

Service composition has been introduced to exploit heterogeneous resources of distributed nodes for purpose of supplying ubiquitous services in ubiquitous stub environments, especially in MANETs. However, due to the characteristics of infrastructure-less, the limited resources of the nodes and dynamic topology caused by the mobility of nodes, service composition faces great risk of failure. Therefore, service recovery handling failure is crucial to guarantee composite service's successful execution. In this paper, we propose a novel recovery selection function which incorporates device effective rate, individual capability and cooperative capability. Then we elaborate an original heuristic thought-based backup recovery algorithm: Dynamic Local Backup Recovery Algorithm (DLBRA). Finally, simulation results demonstrate that the proposed strategy ensures high performance, effectively guarantees the sustainability and significantly reduces the response time of the composite service. © 2013 IEEE. Source

Wu W.,South China University of Technology | Wen F.,Zhejiang University | Xue Y.,NARI Group | Zhou H.,Power Dispatching Control Center | Li X.,Alstom
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

Based on the criteria for electrical data, protective relays and circuit breakers, a weighted fuzzy Petri net based model with time-delay constraints for power system fault diagnosis employing information from multiple sources is presented, in which the temporal features of the three criteria are taken into account. First, the candidate fault components are identified by analyzing the power network topologies before and after the occurrence of a fault or faults. Then, the action paths can be found by the backward reasoning routing, thus the fault diagnosing model based on the weighted fuzzy Petri net is developed to identify the fault components. The electrical data and their temporal features are exploited in the development of the Petri net as well. The time-delay constraints between faulty components and operating protective relays as well as between operating protective relays and tripped circuit breakers, and the malfunctions of protective relays and circuit breakers, can be accommodated. A matrix operation based method is employed for fault diagnosis reasoning. The backward reasoning is next used to identify the malfunctioning protective relays and/or circuit breakers. Finally, the IEEE 39-bus power system and an actual fault scenario of Xingren substation in Guizhou Province are used for demonstrating the feasibility and efficiency of the fault diagnosis model and method developed. © Right. Source

Wu W.,South China University of Technology | Wen F.,Zhejiang University | Xue Y.,NARI Group | Zhao X.,Power Dispatching Control Center | Hu R.,Power Dispatching Control Center
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

Several blackouts and large-area outages around the globe were caused by cascading failures in the past several years. The ability to forecast cascading failures has become one of the most important research topics in power systems. The existing methods of forecasting cascading failures do not systematically and comprehensively address some important influencing factors such as the network topology, the relevance between two consecutive failures, and the uncertainties in the system operations. Given this background, based on the initial failure probabilities of lines and the transition probability between two consecutive failures, a Markov chain based model for forecasting cascading failures is presented. In this model, the transferring power flow, malfunctions of protective relays and circuit breakers, and the failure rates of components are considered. At first, the next failure is forecasted by the Markov chain based method, and the set of possible failures is identified, followed by the paths of cascading failures with the time sequence determined. Then, three criteria used to evaluate the vulnerability of follow-up failures are presented, and employed to monitor and quickly control possible cascading failures. Finally, the IEEE 10-unit 39-bus system is used for demonstrating the essential features of the developed model and method. ©2013 State Grid Electric Power Research Institute Press. Source

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