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Ding M.,Hefei University of Technology | Wang B.,Hefei University of Technology | Zhao B.,Zhejiang Electrical Power Test and Research Institute | Chen Z.,Anhui Electrical Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2013

Standalone PV-wind-diesel-battery hybrid microgrid supplies power to local loads by power sources within the microgrid, and the primary target is to enhance the accouplement between the generated power and the load maximally. To improve the economy of whole microgrid while the power supply reliability is ensured, it is necessary to perform optimal design of capacity configuration of the microgrid according to existing conditions in whether and resources and to choose optimal source capacity combination. Mathematical models for different kinds of power sources within the standalone PV-wind-diesel-battery hybrid microgrid are established respectively, and two economic models of investment cost and different expenses are built too. Based on the dispatching strategy and constraints of this hybrid system, the numbers of different power sources are taken as variables and the minimum composite cost and expenses as optimization objective, and then the optimal capacity configurations of different power sources in the system are solved by genetic algorithm. The reasonableness of the proposed models is verified by case study results. Source


Zhang X.-S.,Zhejiang Electrical Power Test and Research Institute
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

Electromagnetic transients simulation model is set up for analysis of DC magnetic bias induced current of transformer based on PSCAD/EMTDC. Related technology detail is explained, such as the model and parameters selection of transformer and the simulate principle of DC magnetic bias. By this model, DC magnetic bias induced current of transformer is analyzed under different kinds of conditions including normal operation, no-load switching, sympathetic inrush, internal and external faults and faults recovery. Results show that DC magnetic bias of transformer has small effect on related relay protection, but it may refuse to operate for internal fault when the larger transition resistance or slight interturn fault occurs. Source


Wang S.-H.,Zhejiang Electrical Power Test and Research Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2011

Based on the length variation as a result of galloping, in this paper, the varying tensile force of conductors was calculated, and the influences of galloping amplitude, number of loops, span and sag on varying tensile force were analyzed. The results show that both the horizontal tension and the vertical component of the axial tension at the suspension point increase with the increase of the galloping amplitude, the decrease of span, and the increase of the sag. The one-loop galloping can lead to the most extensive variation range. The parity of the number of loops has great influence on the relative variation ratio. The deflection of insulator sting as a result of severe conductor galloping may greatly decrease clearance distance between the conductors and cross arm. Source


Wang S.-H.,Zhejiang Electrical Power Test and Research Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2010

Conductor galloping phenomena on overhead transmission lines are of great danger to the security of service of electrical power system. Based on several typical iced conductor galloping phenomena occurring in China, this paper summarizes and analyzes the characteristics, reasons and preventing techniques of conductor galloping. The results show that the galloping phenomena occurring in China have such characteristics as high strength, larger and larger coverage area, etc. The formation of conductor galloping mostly relies on icing, wind as well as configuration and parameters of transmission lines. The harm resulting from conductor galloping can be effectively avoided, resisted or restrained if some measures are taken. Galloping-avoidable measure is to choose appropriate line path as far as possible to avoid the microclimate and micro-terrain which possess special conditions of galloping. Galloping-resistable measure is to enhance the mechanical and electric strength of transmission lines so as to ensure that conductors and other components will not be damaged when conductor galloping occurs. Galloping-restrainable measures is to install anti- galloping devices on transmission lines so as to destroy the formative conditions of galloping phenomena, restrain the amplitude of galloping and ensure the security of service of transmission lines. Source


Wang S.-H.,Zhejiang Electrical Power Test and Research Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2010

Atmospheric ice deposits on transmission lines are of great danger to the security of service of electrical power system. Based on several typical severe ice accidents occurring in China, this paper summarizes and analyzes the characteristics, reasons and preventing techniques of severe ice accidents. The results show that the ice accidents occurring in China have such characteristics as large coverage area, coexistence of mechanical failures and electrical failures, etc. Overload caused by the severe icing, tensile force difference caused by asymmetrical icing or asynchronous ice shedding, ice flashovers, and conductor galloping are the main reasons for ice accidents. Anti-icing, anti-flashovers, and anti-galloping are the main technical orientation of preventing transmission lines from severe ice accidents. Source

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