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Zeng Q.,China Electric Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2013

Based on the structure of 1000 kV/±800 kV UHVAC/UHVDC transmission system, a determinacy index based reliability model of series-parallel power transmission system is built and a reliability assessment method, in which the reliability of the two kinds of power transmission system is assessed by actual operational reliability indices of related components and sub-systems, is proposed. The features of the reliability of the two kinds of power transmission systems are compared and analyzed; the comparative analysis on impacts of the forced outage of the two kinds of transmission systems on power grid operation stability as well as the economy of the measures to maintain operation stability of power grid are discussed. Analysis results show that the reliability of high-capacity long-distance 1000 kV AC transmission system is obviously higher than that of ±800 kV DC transmission system; when 1000 kV AC transmission system is operated in double circuit mode and ±800 kV DC transmission system is operated in practical available capacity mode, the power grid stability can be evidently improved by use of linked modulation under monopole blocking.

Su Z.,China Electric Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2013

In the viewpoint of preventing pollution flashover occurred on transmission and distribution equipments, the fog-haze is of the same concept as the traditional concept for wet deposition and dust fog. The research on the influences of fog-haze on external insulation of transmission and distribution equipments mainly includes the physical and chemical features of the fog-haze, the influence of the fog-haze on contamination level of insulator surface, the simulation of the fog-haze and its influence on pollution flashover voltage of insulators. The achievements of experimental research on the fog-haze performed in Shanghai and Beijing since 1990s are emphatically presented: atmospheric pollution easily evolves into the haze or the fog-haze weather, and it makes the increase of wet deposition on external insulation surfaces of transmission and distribution equipments; the smudgy degree caused by fog-haze can be characterized by fog conductivity; the sustained action of fog-haze makes the degree of contamination on insulator surfaces limitedly increased, so the pollution flashover voltage of insulators is decreased to some extent. In recent years, power grids belonging to State Grid Corporation of China persist in the anti-pollution flashover policy of "putting the insulation coordination level in its place and reserving a certain margin", as a result the encroachment on transmission and distribution equipments due to fog-haze whether is successfully resisted and the occurrence of large-area pollution flashover accidents is suppressed, thus the trip-out rate of transmission lines caused by pollution flashover has reduced to the historically lowest level.

Fang Y.,China Electric Power Research Institute
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Based on the 2011 Southwest America blackout inquiry report, this paper presents a description of the event evolution and an analysis of technical causes leading to the cascade development from the point of view of prevention and control of cascading outages, including ineffectiveness of security analysis and preventive control, inadequacy of real-time situational awareness, unreasonability of protection relay settings, inappropriateness of control system design and lack of coordination between protection and control. It concludes that several fundamental measures need to be strengthened, including a complete, thorough and timely understanding of system dynamic characteristics, coordination of protection and control actions, and improvement of simulation analysis.

Li X.,China Electric Power Research Institute
IET Renewable Power Generation | Year: 2012

The energy storage system (ESS) is the current, widely popular means of smoothing intermittent wind power (WP) generation to regulate output power uncertainty in a wind power generation system (WPGS). This study presents a novel Kalman filter (KF) application method for smoothing the power-output fluctuation of a WPGS based on a battery energy storage system (BESS). A fuzzy logic control method was added to a first-order KF with feedback control of the battery state of charge (SOC). On this basis, the smoothing power output of the hybrid wind/battery power system could be adaptively regulated based on the SOC, and consequently, the battery SOC could be effectively managed according to the charge- and WP-output levels. The effectiveness of the proposed control strategy based on the fuzzy adaptive KF was verified using MATLAB/SIMULINK software and simulation tests. © 2012 The Institution of Engineering and Technology.

Zeng Q.,China Electric Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2015

A parameter optimization model of 1 000 kV UHVAC power transmission system to enhance its power transmission capability and decrease its cost is proposed. The techno-economy of 1 000 kV UHVAC and ±800 kV UHVDC transmission systems are analyzed and based on the data from demonstration projects in China their construction costs are estimated, and an improved annual operating cost method and a stability cost method are put forward and applied in techno-economical assessment on 1 000 kV UHVAC power transmission technology and ±800 kV UHVDC power transmission technology. The construction costs for unit power transmission of 1 000 kV UHVAC and ±800 kV UHVDC, 1 500~2 000 km power transmission system are at the same level under the transmitted capacity based on static stability; however, the annual operating cost for 1 000 kV UHVAC power transmission system is obviously lower than that for ±800 kV UHVDC power transmission system. Besides, the construction costs of unit power transmission to keep the transient stability of 1 000 kV UHVAC power transmission system is more evidently lower than that for ±800 kV UHVDC power transmission system. The economy of 1 000 kV power transmission system is better than ±800 kV power transmission system. ©, 2015, Power System Technology Press. All right reserved.

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