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Zheng T.,North China Electrical Power University | Pan Y.-M.,North China Electrical Power University | Wang Y.-N.,Shenyang Power Supply Company | Wang L.,Weifang Power Supply Company | Wang Z.-P.,North China Electrical Power University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014

In order to realize robust fault location and isolation of distribution systems under the condition of incomplete information, this paper proposes using the relevance among each phase of fault information, three-phase fault currents and both reported by each feeder switch after fault to amend the omitted and false fault information reported by terminal equipment. And then, a method is proposed to achieve rapid fault location of distribution system's fault section by analyzing the topology, dividing the system into independent minimum distribution area and combining the corrected fault information reported by the above minimum distribution area. The simulation results show that the algorithm can effectively correct the missing and false fault information in order to achieve rapid fault-tolerant location of distribution system's fault section. Source

Zhang G.,Xian Jiaotong University | Huang X.,Weifang Power Supply Company | Tian J.,Shenzhen Power Supply Bureau | Zhan J.,Xian Jiaotong University | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

Surface flashover phenomena in vacuum often occur along the insulator, with its onset flashover voltage much lower than the breakdown voltage of either the insulator or the vacuum gap with the same length, so it seriously limits the development of high voltage electro-vacuum devices. Introducing a kind of machinable ceramic (MC) with excellent machinable performance and good surface dielectrical capability into vacuum insulation system, and considering the commonly used insulation stack structure, multiple layers machinable ceramic samples were established. Their surface flashover voltage were investigated under nanosecond pulsed voltage in vacuum, and the surface electric field distributions and electron trajectory in different structure were simulated. The experimental results indicate that, the flashover voltage of multiple layer insulators is better than that of the cylinder, and it improves with the increase of ratio of insulation to metal (I/M), the radial electric field of multiple layer insulators decreases with the increase of I/M. The flashover stability of truncated cone MC multiple layer insulators is better than that of truncated cone MC with the same angle, and the electrons are not easy to impact the surface of samples. © 2013 Chin. Soc. for Elec. Eng. Source

Zhan J.-Y.,Xian Jiaotong University | Mu H.-B.,Xian Jiaotong University | Huang X.-Z.,Xian Jiaotong University | Huang X.-Z.,Weifang Power Supply Company | Zhang G.-J.,Xian Jiaotong University
Journal of Applied Physics | Year: 2013

Recently, the cathode-like luminescence phenomena are observed from the surface of solid dielectrics under steady-state high voltage excitation in vacuum, which is closely related to the self-stabilizing secondary electron emission (SSEE) occurring on insulator surface. In this paper, the theoretical analysis about surface charging based on the SSEE is made, and a one-dimensional Mont Carlo simulation on surface charge accumulation under DC voltage excitation is provided. The results reveal that surface charging process can be divided into three stages including initial accumulation, fast multiplication, and final stable stage. In the final stage, the SSEE phenomena are achieved and surface charges are invariable and reach up to a stable distribution. The simulated stable surface charge distribution is consistent with the theoretical deduction results, which confirms the existence of SSEE process. © 2013 American Institute of Physics. Source

Luo J.,Chongqing University | Ren C.-J.,Chongqing University | Feng S.-H.,Weifang Power Supply Company | Chen T.,Chongqing Electric Power Research Institute | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

This paper presents a linear state-space equation for a single machine-infinite system based on Park model, which is used for the design of optimal excitation control law. Applying this equation on the basis of optimal control theory, a new excitation controller is designed, in which the terminal voltage, active power, reactive power, angular velocity and angle are the feedback. Load angle and reactive power are introduced to excitation control law, which are closely related to stability and quality. At the same time, in order to improve the terminal voltage regulation accuracy, the integral control is introduced to the excitation control law. The result of MATLAB simulation indicates that compared with other methods, the proposed excitation control can effectively improve the power system's stability in large and small disturbance, as well as voltage regulation precision. Source

Tang K.,Chongqing University | Kang L.,Chongqing University | Yin J.,Chongqing Electrical Power Corporation | Feng S.,Weifang Power Supply Company
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2014

The immeasurable variables of synchronous generator model make its parameter identification difficult. Based on Park model, a parameter identification model only with measurable state variables is derived for synchronous generator, based on which and according to the two-step strategy, the generator parameters are identified by applying the direct integral least square principle. With the proposed model and algorithm, all state variables are directly obtained by integration and the complex differential equations are avoided, which simplifies the parameter identification, improves the identification efficiency and decreases the impact of noise on identification results. Case simulation is carried out on MATLAB and the comparison among the proposed model, Park model and a reference model shows that, the proposed model and algorithm are correct, simple and more accurate. Source

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