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Gao K.,Henan Electric Power Research Institute | Zhang Z.N.,Henan Electric Power Research Institute | Zhu Q.S.,Henan Electric Power Research Institute | Yuan L.,Henan Electrical Power Corporation
Applied Mechanics and Materials | Year: 2014

The electric power short circuit breakdown may cause low voltage blocking of frequency-converter giving rise to power unit shutdown accident,three typical coal-fired power units are selected to emulate calculations on low voltage ride ability with considering threephase short-circuit earthing fault, threephase short-circuit earthing fault by impedance, single-phase short-circuit earthing fault,indicating that the short-circuit fault of the lines integrating into power system would result in the voltage of house-service busbar dropping off to 25%-85%,especially threephase short-circuit earthing fault in small operation mode attacks on power unit auxiliary at the most, therefore auxiliary demands complete and dependable low voltage ride through ability. and puts forward to some reform suggestes. © (2014) Trans Tech Publications, Switzerland. Source

Gao K.,Henan Electric Power Research Institute | Yuan L.,Henan Electrical Power Corporation | Zhang Z.N.,Henan Electric Power Research Institute | Wei H.B.,Henan Electric Power Research Institute
Advanced Materials Research | Year: 2014

For sake of analyzing influence on load characteristic of urban low voltage distribution network from extensive popularization of charging equipments of electric vehicles, this paper establishes probability density distribution load characteristic model of charging equipment. Taking representative distribution lines and transformer areas with residential and commercial users for instance, summer daily load curves are described and charging load are forecasted, and basic load curves and charging load additional demand curves are peak-valley superimposed according to respective traits, further more, the influence on distribution lines and transformer areas from charging load of electric vehicles with different ages, finally, suggestions are put forward of urban low voltage distribution network planning and charging equipment supervisions. © (2014) Trans Tech Publications, Switzerland. Source

Yang G.,Shanghai JiaoTong University | Yang G.,Henan Electrical Power Corporation | Tai N.,Shanghai JiaoTong University | Zheng X.,Shanghai JiaoTong University | Zhu Y.,State Grid Corporation of China
Gaodianya Jishu/High Voltage Engineering | Year: 2012

To explore the similarities and differences between the control and protections of ultra-high voltage direct current systems (UHVDC) and conventional high voltage direct current systems (HVDC), the characteristics of UHVDC control and protection system is analyzed in detail. Firstly, taking the Xiangjiaba-Shanghai UHVDC project as an example, we introduced its control and protection framework, configuration features, and its similarities and differences compared with that of HVDC. Then, we analyzed the control algorithm changes in UHVDC, such as changes in the control algorithms of power compensation, valve control, online input and withdrawal strategy of converters, de-icing operation mode and so on. Finally, we discussed the converter transformer saturation protection and the final breaker protection principles which were developed based on HVDC protection, and described the specific protection functions of UHVDC. According to the analysis, the dual 12-pulse valve in series adopted in the UHVDC projects, and the bypass breakers added in the bus area of valve connecting in which UHVDC is different from HVDC in primary connections, as well as the higher protection standard for UHVDC, are the main reasons that cause the difference of UHVDC protection systems from HVDC. A protection system DCC800 is capable of controlling valves in series, enhancing the coordination of control and protection among valves, which will result in more flexibility and diversity of UHVDC operations. In the presented UHVDC protection system, a "Two out of three" protection principle and redundant eTDM buses are adopted in UHVDC, and the problem of main computer stalling is solved well, ensuring that the system has more overall reliability. Source

Liu H.,China Electric Power Research Institute | Zhang X.,China Electric Power Research Institute | Jiang B.,Tsinghua University | Ai S.,China Electric Power Research Institute | Tian Q.,Henan Electrical Power Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2015

In order to carry out the type test of fault location equipment, the relevant standards of transmission line travelling wave fault location equipment are analyzed. In view of the influence factors of range accuracy, functional and performance testing system and test items are proposed. Through detailed introduction of test case, the methods of simulation model establishing and fault setting are introduced in detail. Experimental results demonstrate the validity and practicability of the method of testing. At last, according to the standard DL/T 357-2010 and on the basis of examination of fault recorders throughout the years, an evaluation mechanism of fault location equipment is proposed, which can evaluate software and hardware comprehensive performance of device, and can put forward the device applications scopes that provide technical support and guarantee for device selection. ©, 2015, Power System Protection and Control Press. All right reserved. Source

Wang Q.,Henan Electric Power Research Institute | Chen S.J.,Henan Electrical Power Corporation | Han X.H.,China Agricultural University
Advanced Materials Research | Year: 2014

The thesis describes the loss model of distribution network and gives the transformer loss model and line loss model, Then it proposes some loss reduction measures at the stage of planning and design as well as operation and maintenance. Finally, according to the main problems about the loss reduction measures in China, it puts forward some countermeasures to reduce line loss. Distribution network as part of the end for power configuration which is directly connected with the users of demand side. The loss of distribution network has been high because of feeder radius, complex voltage grade and a large number of devices on the network. The line loss of distribution network represents a major component of the line loss in the whole power system, the line loss of 10kv and below distribution network accounts for about 78% in it according to statistical analysis [1-2]. So, under the current energy shortage situation, there is a great economic and social significance to adopt the reasonable measures to save energy and decrease loss in distribution network. © (2014) Trans Tech Publications, Switzerland. Source

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