Li S.,Shandong University |
Han X.,Shandong University |
Wang M.,Shandong University |
Wang Y.,Jinan Power Supply Company |
Zhang Q.,Shandong Electrical Power Dispatching and Control Center
IEEE Region 10 Annual International Conference, Proceedings/TENCON | Year: 2017
Reference network model determines the optimal transmission line capacities by minimizing the generation cost and investment cost of transmission lines, in which line flow constraints under contingency events should be respected. However, the number of these constraints is tremendous and this makes the impediment when reference network model is applied for real large power systems. In this paper a new method is proposed to solve reference network efficiently based on line outage distribution factor (LODF). Firstly, the power flow without contingency events is calculated. Next, the line flow under contingency events is calculated based on LODF. For each contingency event, the line flow constraint which possesses the most severe overload level is added into the reference network model. The optimization procedure proceeds until all the overload flows are eliminated. The efficiency and validity of the proposed method is verified by IEEE test systems and a real large power system. © 2016 IEEE.
Ni Z.-R.,North China University of Water Conservancy and Electric Power |
Wang Y.-A.,Jinan Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014
The synchronization of merging unit in smart substation and limitations of the method of validating whether the current at each side of differential protection is synchronous by using on-site phase and differential current check are analyzed. The design requirements of field testing instrument with merging unit delay characteristics of smart substation is proposed. The system structure and the detailed design of field testing instrument is introduced based on the design requirements. Finally, the detailed calculation and comparative analysis of tester time granularity and the time response with the merging unit is done. Analysis shows that, the tester can validate that the merging unit delay parameters are set correctly, which can prevent incorrect setting and accord with the site acceptance requirements.
Gong M.-F.,Shandong University of Science and Technology |
Xia W.-H.,Zaozhuang Power Supply Company |
Zhang X.-M.,Jinan Power Supply Company |
Li G.-L.,Zaozhuang Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013
Aiming at the problem that CT saturation will affect transformer differential protection's accuracy and speed, this paper proposes to use Hilbert Huang Transform (HHT) to identify transformer fault under CT saturation condition. The waveform of transformer's external fault current contains some catastrophe points; in contrast, internal fault current's waveform is continuous. The new method is just based on this waveform characteristic. Firstly, a group of intrinsic mode functions (IMF) which are different in characteristic scale are obtained from Empirical Mode Decomposition (EMD). Then, Hilbert transform is applied for the first decomposed IMF to get the instantaneous frequency. Instantaneous frequency's catastrophe points just reflect current's catastrophe points. According to time interval between the two adjacent catastrophe points, it can identify transformer's external fault, internal fault and transferring fault accurately. PSCAD simulation results verify that under CT saturation condition, this method can identify all kinds of faults of transformer in 12 ms. Besides, it can block the inrush current.
Du B.X.,Tianjin University |
Xiao M.,Tianjin University |
Zhang J.,Jinan Power supply Company
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2013
Epoxy (EX) is widely used as insulating materials in electric devices with its excellent insulating properties in spite of its weak ability of thermal conduction. One possible way to obtain high thermal conductivity for Epoxy is the use of an inorganic filling material. Tracking failure is a typical dielectric breakdown performance on polymer surface. Thermal conductivity is associated with the tracking failure performance. In this paper, it is attempted to clarify whether the addition of Boron Nitride (BN) particles can achieve the aim of improving resistance to tracking failure of Epoxy by the way of increasing its thermal conductivity. Prior to test, samples were prepared by dispersing BN particles into EX with shear force. Tracking failure tests were performed at room temperature. The thermal conductivity effects on the time to tracking failure, the discharge quantity of discharge current and the thermal photographs were discussed. Obtained results show that with increasing the concentration of BN particles, the maximum temperature and the discharge quantity decrease, but the time to tracking failure increases. The experimental results suggest that the concentration of BN particles plays a main role in the result of the tracking failure. The resistance to tracking is improved by the filler of BN particles, which is due to the improvement of thermal conductivity. © 1994-2012 IEEE.
Liu N.,Shandong University of Finance and Economics |
Zhang Q.,Jinan Power Supply Company
Journal of Convergence Information Technology | Year: 2012
It is importance of the parameter estimation of asymmetric stochastic volatility model in financial econometrics; this paper proposes an improved Markov Chain Monte Carlo estimation method, it conducts logarithmic and squared conversion for the basic asymmetric stochastic volatility mode. This paper carried out simulation experiment to check the finite sample properties of the improved method. The experimental results show that the proposed algorithm is effective.
Zuo P.,Tsinghua University |
Li J.,Beijing Institute of Technology |
Song X.,Jinan Power Supply Company |
Yuan J.,Tsinghua University
IEEE Transactions on Plasma Science | Year: 2013
The railguns can be classified into three types by the interior surface shape of rails, which are the type of plane-rail, convex-rail, and concave-rail. In this paper, the characteristics of current distribution in rails and armature are analyzed and compared for those three types, during the rising, dropping, and the flat part of the exciting current source. This current distribution is simulated by the finite element software ANSYS. The convex-rail type gun is of the weakest opposite direction current phenomenon, and its current distribution on the rail section is the most even. The evenness of the current distribution can be adjusted by changing the height of the convex part. The current density at the corner of armature is very large in the plane-rail and the concave-rail types, which results in stress concentration and probably damage of armature or rail surfaces. © 1973-2012 IEEE.
Zhou K.,University of Canterbury |
Qiu Z.,Jinan Power Supply Company |
Watson N.R.,University of Canterbury |
Liu Y.,University of Canterbury
IET Power Electronics | Year: 2013
The mechanism of harmonic current injection from single-phase grid-connected converters is comprehensively investigated. The measurable impacts from grid voltage, converter commutation, power factor, PWM modulation and control strategy are demonstrated on the harmonic current injection. According to the mechanism, a tailor-made control solution which employs a low pass voltage-loop filter and internal model principle-based hybrid current controller, is proposed to eliminate the harmonic current injection from the single-phase grid-connected converters. Experiments are performed to verify the validity of the mechanism and the proposed control method. It not only presents an effective tailor-made solution to the elimination of harmonic current injection from grid-connected power converters, but also provides a mechanism-based benchmark tool to further develop rational grid requirements on the harmonic injection levels in the grid integration of distributed generation units. © The Institution of Engineering and Technology 2013.
Xiao M.,Jinan Power supply Company |
Xiao M.,Shandong University |
Du B.X.,Tianjin University
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2016
Epoxy resin is widely used for insulation in cast dry-type transformers, in spite of its weak ability of thermal conduction. One approach to obtain a higher thermal conductivity is to introduce inorganic fillers with high thermal conductivity. The purpose of this paper is to study the effect of high thermal conductivity on temperature rise of epoxy cast windings. In this paper, micro and nano boron nitride (BN) particles were mixed into epoxy with idfferent mass fraction. Then the composite was cast into mold to make different transformer windings. Thermal distribution was calculated and simulated by finite element analysis. An then experiments were carried out to verify the simulation results and investigate the effects of the improved thermal conductivity on temperature rise. Obtained results showed that the thermal conductivity had a significant effect on temperature rise. With increasing the thermal conductivity, the maximum temperature decreased obviously. The maximum temperature difference and time to reach thermal equilibrium state were decreased. It is concluded that the ability of thermal conduction of the transformer can be improved by using the epoxy with high thermal conductivity. Dielectric breakdown strength (BD strength) of different windings were also investigated and it was found that pure epoxy resin had the highest BD strength, while the composites filled with BN particles were all lower than neat epoxy. © 1994-2012 IEEE.
Zhang B.-D.,Tianjin University |
Li G.-F.,Jinan Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010
An accurate model of the distribution network is indispensable to calculate line loss and optimize the structure correctly for a 10 kV distribution network. Because the power flow calculation sequence of the model is huge and time-consuming for creating, all loads between breakers are simplified by a generalized node, and its interior structure is described with the help of a group of the power flow calculation subsequences. A kind of method for creating power flow calculation sequence by district is proposed. At the same time, in view of multistep loads, the heuristic rules of the branch-exchange algorithm are modified and the method of revising power flow calculation sequence is designed. These suggestions have been adopted successfully in the system of operation optimization and assistant decision of the 10 kV distribution network, which is located in Shangqiu power supply bureau, Henan Province.
Sun Q.,Jinan Power Supply Company |
Dong X.,Jinan Power Supply Company
China International Conference on Electricity Distribution, CICED | Year: 2012
During the course of upgrading urban and rural power grids at large scale in China, distribution automation construction of Jinan Power Supply Company has some success. This thesis analyzes technical limitations of Jinan Power Supply Company ten years ago and points out four problems of traditional distribution automation system. In order to solve the problems, this thesis proposes intelligent distribution automata ion system. The system is divided into three subsystems and its integration design including distribution control SCADA system, distribution GIS system and distribution management system. Data platform is used to achieve stable and reliable data interaction of each module so as to improve practicability of distribution automation system. This thesis introduces general construction mode of distribution automation system designed on the basis of this idea, including distribution automation master station system construction, distribution automation information interaction bus construction and distribution production management command platform construction. Therefore, it forms distribution network regulation and control integration construction mode. © 2012 IEEE.