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Liu Y.,Tongji University | Lin J.,Tongji University | Guo L.,Tianjin Electrical Power Dispatch Center | Cai N.,Tianjin Electrical Power Design Institute | And 4 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015

To focus on the drawbacks of existing robust state estimation methods and algorithms, a novel robust state estimation algorithm based on adaptive kernel density estimation was hereby proposed. The new robust state estimation model based on adaptive kernel density estimation theory was firstly presented. In order to determine the bandwidth of adaptive kernel density, the approximative expression of optimal kernel bandwidths is deduced using mean integral square error of probability density estimation, and the characteristic of the state variable components having stronger correlation with the local direct measurements than with all un-direct measurements; and the constraints of kernel bandwidths for state variable components, including initial constraint, modified constraint and standard deviation constraint, are further designed, for insuring measurement redundancy and system observability and overcoming the issue of misidentification and unidentification of bad data; based on the above expression and constraints, the composite determination method of kernel bandwidths is finally made. Successful application of practice power system of the algorithm illustrate that: the new state estimation model, the expression of approximative optimal kernel bandwidths, constraints of kernel bandwidths and its composite determination method are all effective and reasonable. © 2015 Chinese Society for Electrical Engineering. Source

Yu M.,North China Electrical Power University | Li L.,Tianjin Electrical Power Design Institute | Xie G.,Peking University | Shi H.,Beijing Institute of Petrochemical Technology
Mathematical Problems in Engineering | Year: 2014

This paper mainly investigates the average consensus of multiagent systems with the problem of packet losses when both the first-order neighbors' information and the second-order neighbors' information are used. The problem is formulated under the sampled-data framework by discretizing the first-order agent dynamics with a zero-order hold. The communication graph is undirected and the loss of data across each communication link occurs at certain probability, which is governed by a Bernoulli process. It is found that the distributed average consensus speeds up by using the second-order neighbors' information when packets are lost. Numerical examples are given to demonstrate the effectiveness of the proposed methods. © 2014 Mei Yu et al. Source

Li B.,Tianjin University | Guo F.,Tianjin University | Li X.,Tianjin Electrical Power Design Institute | Bo Z.,State Grid Corporation of China
IEEE Transactions on Power Delivery | Year: 2014

This paper elaborates on the reasons for current unbalance in extremely high voltage/ultra-high voltage (UHV) double-circuit transmission-line systems based on analyses of a typical tower structure and feasible phase arrangements. In addition to the studies of the system under normal operation condition, the unbalanced currents of the double-circuit line under the condition of external faults are first investigated. The frequency-dependent model of UHV double-circuit lines is built using the ElectroMagnetic Transients Program including DC (EMTDC) software package. Simulation results and real data obtained from the power utility show that the circulating unbalanced currents in both cases of normal operation and external fault conditions cannot be ignored due to their high magnitude. The significant influence of the circulating unbalanced currents on pilot directional protection of double-circuit lines is proven and verified by various simulation tests and real field data. Consequently, an improved scheme is proposed to overcome the influence of circulating unbalanced current and significantly improve the reliability of pilot directional protection. © 1986-2012 IEEE. Source

Li J.-X.,Tianjin Electrical Power Design Institute | Li J.-X.,Jilin University | Wang C.-M.,Jilin University | Wang G.-C.,Jilin University
Yantu Lixue/Rock and Soil Mechanics | Year: 2013

Landslide susceptibility assessment and prediction are the important contents of the first solution for the decision-making of prevention and mitigation of disaster. Starting from the geological environmental conditions within Longzi county in Tibet, the 13 influencing factors are selected, including elevation, slope and so on. According to landslide risk classification standards established, landslide risk rating is divided into high, moderate and low. Based on combination weighting-unascertained measure theory coupled evaluation model, 20 landslides' risks in study area are assessed and analyzed by unascertained measure function, combination weighting and confidence criterion. Each landslide risk is obtained. Compared with evaluation results of fuzzy matter-element and catastrophe theory, the evaluation results are consistent with actual situation and reasonable. Therefore, the model can provide a new idea for landslide risk prediction. Source

Guo Y.-C.,Tianjin Electrical Power Design Institute | Wu G.,Tianjin Institute Geotechnical Investigation and Surveying | Zhou Y.-M.,Tianjin Institute Geotechnical Investigation and Surveying | Qin H.-J.,Tianjin Electrical Power Design Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The general situations, ambient environmental conditions of planning site as well as engineering geological conditions of Nailun International Trade Building are introduced. The structural design of bracings and calculation of deep excavation are expounded. The practical effect of the bracing design for the deep excavation is explained. The engineering practices show that this bracing design resultin favorable social and economic benefits and can offer reference for other similar projects. Source

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