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Nanjing, China

Chen X.,Nanjing Southeast University | Chen X.,Wiscom System Co. | Zheng J.,Nanjing Southeast University | Mei J.,Nanjing Southeast University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014

Power capacitor bank is an important device, when it occurs a minor fault, if not be found in time, will gradually develop into a serious malfunction, causing damage to the capacitor bank. To solve this problem, this paper proposes a new method of early capacitor bank internal component failure warning: the LC oscillation frequency variation method based on early theoretical characteristics of a single component damage analysis. The method calculates the oscillation frequency by collecting discharge PT voltage and bus voltage, records the frequency of initial value, and then compares the variation in the process to propose early warning. The advantages of this method are of high detection precision, and can judge the fault phase and avoid the system voltage fluctuation. According to the warning method needs, an on-line monitoring and early warning device of capacitor bank is designed to realize the engineering applications of this method. A variety of data after the field operation also verify this warning method. Thus this device is convenient for the operation and the management of the capacitor banks, and provides a new way to find the early fault in time. ©, 2015, Power System Protection and Control Press. All right reserved.

Jia P.,Nanjing University | Xu W.,Wiscom System Co. | Ma J.,Nanjing University | Fu G.,Nanjing University
2011 International Conference on Remote Sensing, Environment and Transportation Engineering, RSETE 2011 - Proceedings | Year: 2011

As a lot of earthquakes all around the world showing, most destructive earthquakes cause secondary disasters. The loss that secondary disasters brought often goes beyond earthquake disaster itself. The oil tanks with flammable and explosive oil often cause secondary destructive damage when they leak, are fired, and thus exploded. The paper studies the characteristics of oil tanks secondary disasters of earthquake and the relationship between the damage of oil tanks secondary disasters and the seismic intensity. And it studies the modeling of the seismic affecting field and the oil tanks hazard caused by earthquake. And it excogitates technique theory of GIS-based perspective assessment system for oil tanks secondary disasters of earthquake that is designed to rate oil tanks hazard in urban area, to help relocate and reconstruct oil tanks in earthquake resistant design, to supply technical supports for administrator's decision-making in earthquake disaster, and to prevent the oil tanks secondary disasters, fire and explosion, when or before urban earthquake happens. © 2011 IEEE.

Wang X.,Wiscom System Co. | Jin H.,Wiscom System Co. | Zong H.,Wiscom System Co. | Gu J.,Wiscom System Co. | And 2 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2012

VxWorks, a kind of embedded real-time operating system, is applied in the design of the integrated digital protection, measuring and control devices to meet the requirements of smart grid for the high performance of bay-level devices in digital substations. Its hardware platform is introduced and the realization of its high reliability and real-time performance is explained, which divides all functions into various interrupts and tasks with different priorities and applies the semaphore and message queue to properly dispatch the tasks. The implementation of the embedded Ethernet technique based on IEC61850 is discussed, which adopts the MMS+TCP/IP+Ethernet application mode to communicate with the station-level devices. The design has been applied in real projects.

Feng X.,Sinopec | Li J.,Wiscom System Co. | Miao S.,Wiscom System Co. | Yu Z.,Sinopec
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2011

The high-speed bus transfer device is mainly used in power plant auxiliary system, which has been improved to fit the industrial substations. It identifies the single bus connection or sectionalized single bus connection by setting and adapts to different running modes according to the self-acquired breaker status, which reduces the complexity of design and operation. It applies substation-specific fast starting modes, such as no-current starting, reverse-power starting and frequency-voltage-change starting. With the consideration of different working conditions, comprehensive blocking functions are designed, including the directional over-current blocking function. Its excellence and applicability are validated by some industrial substation applications.

Han J.,Wiscom System Co. | Huang J.,Wiscom System Co.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013

Two common sync-capture algorithms are analyzed. Algorithm 1 predicts the closing time according to the relationship among phase angle difference, slip frequency and slip frequency acceleration, while algorithm 2 applies the contemporary forecast theory to predict the closing time based on the phase angle difference order. Both are improved. For algorithm l, the phase angle difference between short time interval is estimated with interpolation principle and the closing command is issued if the closing condition is satisfied, otherwise continue the algorithm. For algorithm 2, the parabolic curve fitting prediction algorithm combined with the residual analysis is added, which is more accurate than linear fitting, and the measuring system of phase angle difference, which has direct influence on algorithm, is improved by acquiring the original data at the zero-crossing-point of square wave and by increasing the data density through data interpolation. Experimental results prove that the improved algorithms enhance obviously the quality of synchronous closing.

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