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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.

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.

He Y.,Henan Electrical Power Corporation | Hu J.,North China Electrical Power University | Yan Z.,Institute of Disaster Prevention | Shang J.,Henan Electrical Power Corporation
Dianwang Jishu/Power System Technology | Year: 2013

With the rapid development of large-scale wind farms in China, there will be more and more demand on ancillary services in power sector, so the ancillary service is becoming one of the most important factors restricting the grid-integration of large-scale wind farms. The impacts of grid-integration of large-scale wind farms on power grid ancillary service costs, which are mainly caused by the peak-load regulation and reserve capacity, are researched quantitatively. On this basis, in the viewpoint of reformation and development of China's power sector several mechanisms of apportionment and compensation of ancillary service costs due to the grid-integration of large-scale wind farms are proposed, and corresponding policy suggestions are recommended according to the difficulty levels of feasibilities.

Jia X.F.,North China Electrical Power University | Huang S.M.,North China Electrical Power University | She K.,North China Electrical Power University | Cao D.S.,Henan Electrical Power Corporation
Applied Mechanics and Materials | Year: 2013

In view of the present situation of harmonic management at present, put forward the harmonic pollution emissions trading and harmonic insurance contract mechanism of the two methods to manage. We first introduce the basic idea of harmonic pollution emissions trading, the general steps and market supervision. Through emissions trading to the regional total funds management and harmonic environment capacity can achieve optimal allocation. Secondly, introduces the mechanism of harmonic insurance contract, by using the method of electric harmonic insurance contract signed between the two sides of the harmonics management. By concluding an insurance contract will users due to harmonic problem and the loss of risk transfer to the electric power company, the loss of the user can obtain a reasonable compensation. Implementation of the harmonic pollution emissions trading and harmonic insurance contract management method, could make the power network and the user to achieve profit optimization and take the initiative to improve power quality, but also promoted the development and technology of harmonic method. © (2013) Trans Tech Publications, Switzerland.

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.

Liu W.,North China Electrical Power University | Yang N.,North China Electrical Power University | Zhang J.,Henan Electrical Power Corporation | Sun J.,Henan Electrical Power Corporation | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

In condition of adverse weather, the probability of components failure in the power grid was increasing significantly and amplifying the probability of serious grid accidents. In comparison with the evolution of grid self-organized criticality and the section development of failure propagation chain, this paper first proposed that the failure propagation chain could be characterized as an effective tool for expressing the grid self-organized status. Then, after the analysis of traditional cascading failure chain, the complex grid failure propagating chain model, using grid self-organized criticality, in consideration of adverse weather, was established, simulating the potential cascading failure trail during the process of evolution of grid self-organized status in form of failure propagating chain. The introduction of this model can provide a key reference for grid operator in screening the weakness of power grid. The simulation of Henan power grid proves the availability and feasibility of the model. © 2012 Chinese Society for Electrical Engineering.

Liu N.,China Electric Power Research Institute | Tang X.-J.,China Electric Power Research Institute | Zhang W.-C.,China Electric Power Research Institute | Ma S.-Y.,China Electric Power Research Institute | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

The level of three-phase short-circuit current of 500/220 kV bus will exceed standard in Henan power grid after the completion of Ultra-High Voltage (UHV) Yubei station. The opening of 500/220 kV electromagnetic ring network is studied. The solution to electromagnetic ring opening is proposed based on current partitioning mode, and the feasibility of all the schemes is verified. After the ring opening, Henan grid will be divided to 16 areas to supply electric power. Under the premise of grid security and stability, the level of three-phase short-circuit current is lowered, the benefit of gird investment is maximized, and the balanced development of 500/220 kV grid can be facilitated. Based on the above solution , this paper presents the technical principles in dealing with 500/220 kV electromagnetic ring opening under UHV power grid environment. The principle provides reference for mid-long term planning and implementation of power grid.

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.

Zhang S.,China Electric Power Research Institute | Chen Y.,China Electric Power Research Institute | Li F.,China Electric Power Research Institute | Zhang Y.,Liaoning Electric Power Corporation | And 3 more authors.
Dianwang Jishu/Power System Technology | Year: 2012

Based on the calculated data of power grid operation modes, the collaborative system for power grid operation mode calculation implements data management of multi-level parallelly operated dispatching departments in different places and joint operation mode calculation. Overall functional structure of the collaborative system was expounded, and concrete function design schemes for fundamental platform system, intelligent collaborative system for operation modes, supporting system for simulation analysis, assess system of on-line data, high-performance parallel computation system and man-machine visualization system were proposed. This collaborative system had been put into operation and its operation results showed that the proposed system could increase the reliability of power grid data, improve working method of operation mode calculation in dispatching departments effectively and raise working efficiency.

Hu Y.,Henan Electrical Power Corporation | Lu T.,Shandong University | Chu S.,Henan Electrical Power Corporation | An N.,China Electric Power Research Institute | And 2 more authors.
Dianwang Jishu/Power System Technology | Year: 2012

A method to analyze trajectory sensitivity of voltage stability based on quasi-steady state simulation is proposed, by which the sensitivity of system parameters control variables to state quantity can be attained. The trajectory sensitivity is utilized to predict the medium- and long-term trajectory in time-domain under the variation of control quantity and system parameters to assess voltage stability of power system, compare influences of power components on voltage stability and provide information to voltage stability control measures. Trajectory sensitivity method can remedy the defects of poor adaptability of traditional static sensitivity of voltage stability to device models and incapability of incarnating dynamic characteristics of power system as well as such shortcomings of traditional simulation methods as only simple information can be provided and poor analyzability of their conclusions.

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