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Liu H.,North China University of Water Conservancy and Electric Power | Zhang Y.,Shanghai JiaoTong University | Jiang C.,Shanghai JiaoTong University | Liu S.,Yunnan Power Dispatching and Control Center
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

In an electricity market, hydropower producers pay more attention to the revenue risk due to the stochastic characteristic of inflows and electricity generation. How to consider risk management in the process of hydro scheduling is an important problem to be solved. In this paper, multiple scenarios were utilized to represent the stochastic market prices. Risk penalization mode and risk constraint mode were combined to construct short-term optimal hydro scheduling model based on dynamic risk management. A new algorithm combing the improved fast evolutionary algorithm (IFEP) and genetic algorithm (GA) was proposed, in which Gaussian and Cauchy mutation were combined, and penalizing and repairing mechanism were combined to deal with the constraints, therefore the algorithm has good performance in search and convergence. The analysis results about the influence of various risk management modes on optimal hydro scheduling show that, dynamic risk management can obtain a better trade-off among expected profit, risk and violation of end reservoir storage, and can obtain more expected profit with less risk, and can provide theory reference for flexible scheduling decisions based on its acceptable risk level. ©2012 Chin. Soc. for Elec. Eng. Source

Wu Y.,Nanjing University of Science and Technology | Wu Y.,NARI Group | Xue Y.,NARI Group | Lu J.,Hunan Electric Power Company | And 5 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2016

According to the ways and mechanisms of electrical equipment faults caused by forest fire, a modified model of transmission line fault probability is developed. And an early-warning defense method based on the spatial-temporal distribution of power grid fault probability is proposed. Firstly, by combining forest fire information, geographic environments and meteorological information, the method is able to predict the forest fire behaviors and dynamically assess the transmission line flashover probability. Then, the spatial-temporal distribution fault probability can be obtained so that the higher the risk of potential faults is, the greater concern they will receive, thus raising the early-warning ability of power grids to prevent the forest fire. © 2016 Automation of Electric Power Systems Press. Source

Wu Y.,Nanjing University of Science and Technology | Wu Y.,NARI Group | Xue Y.,NARI Group | Xie Y.,Nanjing University of Science and Technology | And 4 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2016

The ways of electrical equipment fault probability influenced by typhoons and rainstorms are analyzed in detail. The scope of data acquisition of blackout defense system is expanded to macroscale meteorological forecast information as well as local meteorological data. A spatial-temporal early-warning method against these natural disasters is proposed. Firstly, according to the information of meteorology, environment, topography and geomorphology, the spatial-temporal evolution trends of typhoons and rainstorms can be predicted and modified. Then, the probability of faults such as broken lines, collapsed towers, flashover caused by adverse weather or derivative disasters such as landslide, debris flow and flood is forecasted on line. Through the module interface between natural disaster evaluation and power system stability analysis, the predictive fault set of online security analysis which was fixed can now be dynamically modified. Therefore, the blackout defense system against typhoon and rainstorm has definite ability of early warning and decision support. © 2016, Automation of Electric Power Systems Press. Source

Bao W.,Zhejiang University | Zhu T.,Yunnan Power Dispatching and Control Center | Zhao C.,Yunnan Power Dispatching and Control Center | Wu T.,China Electric Power Research Institute | Guo R.,Zhejiang University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2016

Proper network partition for secondary voltage control is the prerequisite for the application of three levels or “soft” three levels voltage control. Good partition should satisfy the conditions that each partition contains at least one reactive power source while maintaining connexity itself. This paper proposes a three-stage network partition method for secondary voltage control based on network structure and electrical distance. Firstly, the method proposed merges the reactive power source nodes connected by radial branches into one and the same partition according to the network structure. Secondly, the controlled nodes are classified into two types, and then merged into the partition to which the nearest reactive power source in electrical distance belongs while keeping the connexity of partitions. Finally, an agglomerative analysis is made on the initial partitions according to WARD distance to determine the final network partitions. Allowing for merger to be performed only between the connected partitions guarantees the connexity of the final partition while greatly reducing the scale of agglomerative computation. The method proposed meets the demand of secondary voltage control as the partition results are related only to the network structure while having nothing to do with the operation conditions, such as power flow distributions. The partition results of an IEEE 39-bus system and Yunnan power system have verified the rationality and efficiency of the proposed method, showing that the method is of definite application value to the secondary voltage control of power systems. © 2016 Automation of Electric Power Systems Press. Source

Chen L.,North China Electrical Power University | Gu X.,North China Electrical Power University | Li W.,Yunnan Power Dispatching and Control Center | Zhu T.,Yunnan Power Dispatching and Control Center | Zhao C.,Yunnan Power Dispatching and Control Center
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014

As none of the currently used restoration methods of the black-start stage for power systems has retained the restoration security margin while intent only on the maximization of profitability indices, serious security risks may result in the restoration process. At the same time, the preference factors of decision makers and the actual situation of system restoration cannot be well synthesized in the existing black-start decision-making methods. An extended black-start multi-objective optimization method considering both power support and restoration security margin is proposed. The optimization goals are designed to maximize the total weighted power generation output of the black-start system and voltage stability margin, while maintaining bus voltage at a satisfactory level. A multi-objective optimization model is developed for the black-start schemes by comprehensive consideration of all the constraints of the unit start-up time and system operation. The fast and elitist non-dominated sorting genetic algorithm (NSGA-II) and the Dijkstra algorithm are employed to solve the Pareto-optimal solutions of the extended black-start schemes. By using the Vague set multi-attribute decision-making method based on fuzzy entropy weight and considering the preference factors of decision makers and objective information of decision matrix, the most satisfactory solution is identified. The effectiveness of the proposed method is validated by optimization results on the New England 10-unit 39-bus power system and the Southern power system of Hebei Province. © 2014 State Grid Electric Power Research Institute Press. Source

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