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Li B.,Tianjin University | Fan X.,Tianjin University | Zhang S.,National Power Dispatching and Communication Center | Bo Z.,Alstom
APAP 2011 - Proceedings: 2011 International Conference on Advanced Power System Automation and Protection | Year: 2011

The three-phase transformer will produce great magnetizing inrush current with high secondary harmonic component at the time of energization, while differential protection can effectively block by the second harmonic principle and interval angle principle. For paralleled converter transformers, the differential current of the integral differential protection equals the sum of the differential current of the two partial differential protections. However, the secondary harmonic component in the two partial differential currents is not simple superposition, which may cause the failure of blocking of the integral differential protection, and therefore cause false tripping. Based on a false tripping accident of the integral differential protection, the paper further analyses the occurrence mechanism of magnetizing inrush current and the secondary harmonic component, proves the possibility of the offsetting of secondary harmonic component in the two partial differential current, and proposes solution accordingly. © 2011 IEEE.


Fang C.,Tsinghua University | Xia Q.,Tsinghua University | Hu C.,East China Grid Company | Wang B.,National Power Dispatching and Communication Center
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

This paper presents an integrated generation and transmission monthly maintenance scheduling model and a decomposition-coordination algorithm. The optimization objective is to meet the maintenance requirements as much as possible, which is further transformed into an equivalent wish curve. The maintenance scheduling is decomposed and coordinated based on effective decision variables identification. The analysis and discussions on the results of numerical examples validate the feasibility and effectiveness of the model and algorithm. © 2011 State Grid Electric Power Research Institute Press.


Ji C.,North China Electrical Power University | Pei Z.,North China Electrical Power University | Pei Z.,National Power Dispatching and Communication Center | Zhang Y.,North China Electrical Power University | Zhou T.,North China Electrical Power University
Applied Mechanics and Materials | Year: 2011

The operation of the Three Gorges power station is of the most complex feature in China and even in the world, for it involves many factors such as flood control, power generation, shipping and water supply. This paper takes the experimental reservoir impoundment in 2008 for example, demonstrated its impact on power grid operation, meanwhile, put forward suggestions on impoundment time, impoundment target, impoundment and fluctuating process and adjusting mechanism building, etc. © (2011) Trans Tech Publications.


Mao A.,North China Electrical Power University | Zhang G.,North China Electrical Power University | Lu Y.,National Power Dispatching and Communication Center | Gao J.,National Power Dispatching and Communication Center
Dianwang Jishu/Power System Technology | Year: 2012

On Sept. 8, 2011, a large-scale blackout occurred in South America and North Mexico interconnected power gird. General situation and the process of the blackout as well as its harmful effects are presented. The structure of the power grid where the fault occurred and the features of its operation and dispatching are analyzed, and the main causes leading to the blackout, such as heavy load of power grid due to hot weather, weak structure of power grid, non-uniform power grid security management under joint dispatching mode and weak supervision and monitoring ability of grid dispatching centre, are dissected. On the basis on analyzing the large-scale blackout and considering actual situation of dispatching and administration of power grids in China, the lessons from the large-scale blackout for power grid dispatching and administration in China are summarized.


Shen X.,China Electric Power Research Institute | Shu Z.,National Power Dispatching and Communication Center | Liu Y.,National Power Dispatching and Communication Center | Lu P.,National Power Dispatching and Communication Center | Zhang L.,China Electric Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2011

The operation situation of protective relayings belonging to the State Grid Corporation of China in 2009 is presented, including a brief description on the operation situation of primary equipments in 220 kV and above power systems and the statistics and analysis on faults occurred in these systems as well as the operation situation of line protections, transformer protections, busbar protections and generator protections. It is pointed out that the operation department should bear the primary responsibility for the maloperation and misoperation of protections, and the manufacturers and design departments should bear the secondary responsibility, and the lacking in responsibility appears as false wiring, poor overhaul and maintenance of equipment and bad manufacturing quality, thus the life-cycle management of protective relayings should be further enhanced according to the demands of fine management and standardization construction.

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