Cascading failure is a potential threat in power systems with the scale development of wind power,especially for the large-scale grid-connected and long distance transmission wind power base in China.This introduces a...Cascading failure is a potential threat in power systems with the scale development of wind power,especially for the large-scale grid-connected and long distance transmission wind power base in China.This introduces a complex network theory(CNT)for cascading failure analysis considering wind farm integration.A cascading failure power flow analysis model for complex power networks is established with improved network topology principles and methods.The network load and boundary conditions are determined to reflect the operational states of power systems.Three typical network evaluation indicators are used to evaluate the topology characteristics of power network before and after malfunction including connectivity level,global effective performance and percentage of load loss(PLL).The impacts of node removal,grid current tolerance capability,wind power instantaneous penetrations,and wind farm coupling points on the power grid are analyzed based on the IEEE 30 bus system.Through the simulation analysis,the occurrence mechanism and main influence factors of cascading failure are determined.Finally,corresponding defense strategies are proposed to reduce the hazards of cascading failure in power systems.展开更多
Research on the permeability and pressure distribution characteristics of the roadway surrounding rock in the excavation damaged zone(EDZ) is beneficial for the development of gas control technology. In this study, an...Research on the permeability and pressure distribution characteristics of the roadway surrounding rock in the excavation damaged zone(EDZ) is beneficial for the development of gas control technology. In this study, analytical solutions of stress and strain of the roadway surrounding rock were obtained, in which the creep deformation and strain softening were considered. Using the MTS815 rock mechanics testing system and a gas permeability testing system, permeability tests were conducted in the complete stress-strain process, and the evolution characteristics of permeability and strain were studied over the whole loading process. Based on the analytical solutions of stress and strain and the governing equation of gas seepage flow, this paper proposes a hydro-mechanical(HM) model, which considers three different zones around the roadway. Then the gas flow process in the roadway surrounding rock in three different zones was simulated according to the engineering geological conditions, thus obtaining the permeability and pressure distribution characteristics of the roadway surrounding rock in three different zones. These results show that the surrounding rock around the roadway can be divided into four regions-the full flow zone(FFZ), flow-shielding zone(FSZ), transitive flow zone(TFZ), and in-situ rock flow zone(IRFZ). These results could provide theoretical guidance for the improvement of gas extraction and gas control technology.展开更多
基金This work was financially supported by a grant from the National Basic Research Program of China(973 Program)(No.2012CB215204)the Key Project of the CAS Knowledge Innovation Program“Research and demonstration of the coordinated control system based on multi-complementary energy storage”(No.KGCX2-EW-330).
文摘Cascading failure is a potential threat in power systems with the scale development of wind power,especially for the large-scale grid-connected and long distance transmission wind power base in China.This introduces a complex network theory(CNT)for cascading failure analysis considering wind farm integration.A cascading failure power flow analysis model for complex power networks is established with improved network topology principles and methods.The network load and boundary conditions are determined to reflect the operational states of power systems.Three typical network evaluation indicators are used to evaluate the topology characteristics of power network before and after malfunction including connectivity level,global effective performance and percentage of load loss(PLL).The impacts of node removal,grid current tolerance capability,wind power instantaneous penetrations,and wind farm coupling points on the power grid are analyzed based on the IEEE 30 bus system.Through the simulation analysis,the occurrence mechanism and main influence factors of cascading failure are determined.Finally,corresponding defense strategies are proposed to reduce the hazards of cascading failure in power systems.
基金financially supported by the Natural Science Foundation of Jiangsu Province,China(No.BK20140189)the Postdoctoral Science Foundation of China(No.2014M550315)
文摘Research on the permeability and pressure distribution characteristics of the roadway surrounding rock in the excavation damaged zone(EDZ) is beneficial for the development of gas control technology. In this study, analytical solutions of stress and strain of the roadway surrounding rock were obtained, in which the creep deformation and strain softening were considered. Using the MTS815 rock mechanics testing system and a gas permeability testing system, permeability tests were conducted in the complete stress-strain process, and the evolution characteristics of permeability and strain were studied over the whole loading process. Based on the analytical solutions of stress and strain and the governing equation of gas seepage flow, this paper proposes a hydro-mechanical(HM) model, which considers three different zones around the roadway. Then the gas flow process in the roadway surrounding rock in three different zones was simulated according to the engineering geological conditions, thus obtaining the permeability and pressure distribution characteristics of the roadway surrounding rock in three different zones. These results show that the surrounding rock around the roadway can be divided into four regions-the full flow zone(FFZ), flow-shielding zone(FSZ), transitive flow zone(TFZ), and in-situ rock flow zone(IRFZ). These results could provide theoretical guidance for the improvement of gas extraction and gas control technology.
