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Wang L.,Shandong University | Chen Q.,Shandong University | Li T.,Fujian Electrical Power Co. | Gao Z.,Shandong University | Li Z.,Shandong University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

When a fault takes place on a section in a power grid, the corresponding protective relays will trip the related circuit breakers to cut off the fault current. As a result, one or more outage areas would be formed. If the faulty section is restricted in the outage area, the efficiency of fault diagnosis program will be greatly promoted. On the other side, if the control center can not receive the whole alarm message of circuit beakers, all of the sections must be diagnosed because the outrage area can not be gotten. Furthermore, wrong diagnosis results may be gotten because of the missing of alarm messages. Given this back ground, based on graph theory, one or more outrage area can be partitioned by cut-set of nodes. Multi-objective optimization method skyline query was applied to sort the outrage area decreasingly based on the precision rate of fault section. The developed diagnosis method could make the diagnosis program much faster, and can insure the fault section will not be omitted. Petri net was applied as the diagnosis tool and several examples showed the accuracy of this method. © 2013 Chin. Soc. for Elec. Eng.

Li T.,Fujian Electrical Power Co. | Xue Y.,China University of Petroleum - East China
IET Conference Publications | Year: 2013

The paper presents a new small current grounding fault location method applicable to distribution automation systems (DASs) using fault transient currents. The faulty section is identified by comparing the degree of similarity of transient currents of feeder terminal units (FTUs) (including faulty line selection device) at adjacent switches. If both transient currents are highly similar, then the section is regarded as the sound section, otherwise as the faulty section. The paper also analyzes the adaptability of the transient localization algorithm on DAS, as well as other key technologies such as time synchronization for FTUs, software and hardware processing ability, etc. The prototype system was installed in a typical distribution system in Xiamen Power Supply Bureau, State Grid Company of China. Dozens of grounding fault transients were captured with correct faulty line identification and faulty section localization. The method is reliable, free from the influence of arc suppression coil and easy to be implemented. It makes DASs function more complete, and helps to improve its overall performances.

Li T.,North China Electrical Power University | Li T.,Fujian Electrical Power Co. | Zhao H.,North China Electrical Power University | Ou D.,North China Electrical Power University | Qi J.,North China Electrical Power University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

The causes and characteristics of short interruption and its impact on customers are analyzed. The implication of short interruption is described and suggestions on the definition of short interruption in China are proposed. Through questionnaire and customers interview, an investigation is conducted on the distribution network short interruption situation and relevant customers' short interruption cost in a coastal city. An appraisal method for customers' short interruption cost is proposed. The relationship between the customer cost and the duration of short interruption is dealt with and the characteristics of customers' short interruption cost are indicated. © 2012 State Grid Electric Power Research Institute Press.

Lin F.,North China Electrical Power University | Zeng H.,Fujian Electrical Power Co.
Dianwang Jishu/Power System Technology | Year: 2011

Due to the existence of distributed capacitance and transition resistance in HV transmission lines, existing fault location methods based on one-terminal impedance are not suitable for the one-terminal fault location of HV transmission lines. To solve this problem, a transmission line model based on distributed parameters is built and the calculation formula for operation voltage at reference position is defined. A location function based on phase characteristics and a location function based on amplitude characteristics, which utilize one-terminal data, are given. It is known from theoretical analysis that the voltage loaction function possesses different phase characteristics while the selected reference position is located at the left side or the right side of the faulty point, i. e., an only step abrupt change of the phase characteristic occurs while the reference position moves through the fault point, and when the selected reference position coincides with faulty point, the amplitude of votlage location function reaches its minimum. On this basis a one-terminal phase-based fault location method and a one-terminal amplitude-based fault location method for the fault location of single-phase earth fault of HV transmission line are proposed. Simulation results show that the two proposed fault location method are slightly affected by fault position, transition resistance and load current, their fault location results are accurate for high-resistance earth-fault, thus they can meet the requirement of on-site application.

Jiang X.-B.,Fuzhou University | Huang Y.-J.,Fuzhou University | Lai X.-S.,Fuzhou University | Lai X.-S.,Fujian Electrical Power Co.
Gaodianya Jishu/High Voltage Engineering | Year: 2011

Return voltage measurement is an effective non-destructive testing method for diagnosis of transformer insulation state. Establishing transformer dielectric response equivalent circuit model is an effective way to analyze the relationship between insulation aging and characteristic quantity. Therefore, on the basis of establishing equivalent circuit mathematical model, equivalent circuit parameters identification was transformed into the mathematical optimization, then the improved ant colony algorithm was adopted to identify model parameters. Four test functions proved that using both global optimal solution and each iteration optimal solution in global pheromone updating could improve convergence speed, expand search scope, and using the dynamic local pheromone updating could also strengthen the ability of jumping out of local optimal value. The contrast of polarization spectra between model calculation and practical measurement shows that the solved equivalent model can accurately reflect the medium response characteristics of oil-paper transformer insulation.

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