通过在调度自动化系统(EMS)中实时监视与统计各电压层级负荷总和、电厂出力及厂用电、与相邻地区电网及地方电力公司电力交换、网络损耗等情况,可加强电网负荷管理,掌握电网负荷分布及特性,分析电网运行损耗,提高电网安全、经济、优质...通过在调度自动化系统(EMS)中实时监视与统计各电压层级负荷总和、电厂出力及厂用电、与相邻地区电网及地方电力公司电力交换、网络损耗等情况,可加强电网负荷管理,掌握电网负荷分布及特性,分析电网运行损耗,提高电网安全、经济、优质、环保运行水平。文章提出了220 k V^500 k V电压等级线路损耗、变压器损耗、网损损耗的工程计算公式以及在系统中的实现手段,并介绍了在EMS系统中对任一时间范围内的网损均值的统计和查询方式。通过分析EMS系统采集数据的特性,探索日常数据维护工作中提高网损统计准确性的措施。处理好数据同步性和采样精度等所造成的偏差问题,有利于电网运行调控中分析网损指标,明确降损原则和调控措施,达到提高资源利用率、增加经济效益、减少能源损耗、改善环境的目的。展开更多
Boundary layer separation and reattachment is often an unavoidable feature of low pressure (LP) turbine,one of the main causes of this phenomenon is the high altitude low Reynolds number experienced by the modern LP t...Boundary layer separation and reattachment is often an unavoidable feature of low pressure (LP) turbine,one of the main causes of this phenomenon is the high altitude low Reynolds number experienced by the modern LP turbine stage in aero-engine.Although an excellent turbine airfoil design can avoid flow separation on certain extent,but within flight envelope,LP turbine's characteristic Reynolds number may varied greatly,so it will be still under the risk of the presence of separation bubble.In this two parts paper a new concept of slotted-blade was raised to testify the gain of the blade slotting.A high aerodynamic loading LP turbine blade IET-LPTA was under investigated with different Reynolds number.Computational results reveal that the blade slotting could be a way of choice to suppress separation bubble and reduce profile loss under the condition of low Reynolds number,although its position and geometry need to be further investigated.展开更多
Accurately and efficiently predicting the load sharing of multi^bolt thick laminate joints is necessary to quicken the optimization of the large-scale structures over various design variables, and a two-dimensional ...Accurately and efficiently predicting the load sharing of multi^bolt thick laminate joints is necessary to quicken the optimization of the large-scale structures over various design variables, and a two-dimensional （2D） finite element method （FEM） is introduced to meet such a demand. The deformation contributions of the joint zone are analyzed and calculated separately, including the shearing deformation of the fasteners shank, the bending deformation of the fasteners shank, and the bearing deformation of the fasteners and joint plates. These deformations are all transferred and incorporated into the components of the fastener＇s flexibility. In the 2D finite element model, the flexibilities of the beam elements and bush elements are used to simulate different components of the fastener＇s flexibility. The parameters of the beam elements which include the bending moment of inertia and intersection area, and the parameters of the bush elements which include the stiffness in different directions, are all obtained through equalizing the fasteners flexibilities. In addition, the secondary bending effect introduced by the single-lap joints is also taken into account to verify the flexibilities of the fasteners in practical application. The proposed FEM is testified to be more accurate than the traditional 2D FEMs and more efficient than the three-dimensional （3D） FEM in solving load sharing problem of multi-bolt single-lap thick laminate joints. With the increase of joint plates＇ thickness, the advantages of the proposed method tend to be more obvious. The proposed 2D FEM is an effective tool for designing bolted joints in large-scale composite structures.展开更多
文摘通过在调度自动化系统(EMS)中实时监视与统计各电压层级负荷总和、电厂出力及厂用电、与相邻地区电网及地方电力公司电力交换、网络损耗等情况,可加强电网负荷管理,掌握电网负荷分布及特性,分析电网运行损耗,提高电网安全、经济、优质、环保运行水平。文章提出了220 k V^500 k V电压等级线路损耗、变压器损耗、网损损耗的工程计算公式以及在系统中的实现手段,并介绍了在EMS系统中对任一时间范围内的网损均值的统计和查询方式。通过分析EMS系统采集数据的特性,探索日常数据维护工作中提高网损统计准确性的措施。处理好数据同步性和采样精度等所造成的偏差问题,有利于电网运行调控中分析网损指标,明确降损原则和调控措施,达到提高资源利用率、增加经济效益、减少能源损耗、改善环境的目的。
基金provided by the Supercomputing Center of Chinese Academy of Sciences and the National Natural Science Foundation of China’s sponsorship
文摘Boundary layer separation and reattachment is often an unavoidable feature of low pressure (LP) turbine,one of the main causes of this phenomenon is the high altitude low Reynolds number experienced by the modern LP turbine stage in aero-engine.Although an excellent turbine airfoil design can avoid flow separation on certain extent,but within flight envelope,LP turbine's characteristic Reynolds number may varied greatly,so it will be still under the risk of the presence of separation bubble.In this two parts paper a new concept of slotted-blade was raised to testify the gain of the blade slotting.A high aerodynamic loading LP turbine blade IET-LPTA was under investigated with different Reynolds number.Computational results reveal that the blade slotting could be a way of choice to suppress separation bubble and reduce profile loss under the condition of low Reynolds number,although its position and geometry need to be further investigated.
文摘Accurately and efficiently predicting the load sharing of multi^bolt thick laminate joints is necessary to quicken the optimization of the large-scale structures over various design variables, and a two-dimensional （2D） finite element method （FEM） is introduced to meet such a demand. The deformation contributions of the joint zone are analyzed and calculated separately, including the shearing deformation of the fasteners shank, the bending deformation of the fasteners shank, and the bearing deformation of the fasteners and joint plates. These deformations are all transferred and incorporated into the components of the fastener＇s flexibility. In the 2D finite element model, the flexibilities of the beam elements and bush elements are used to simulate different components of the fastener＇s flexibility. The parameters of the beam elements which include the bending moment of inertia and intersection area, and the parameters of the bush elements which include the stiffness in different directions, are all obtained through equalizing the fasteners flexibilities. In addition, the secondary bending effect introduced by the single-lap joints is also taken into account to verify the flexibilities of the fasteners in practical application. The proposed FEM is testified to be more accurate than the traditional 2D FEMs and more efficient than the three-dimensional （3D） FEM in solving load sharing problem of multi-bolt single-lap thick laminate joints. With the increase of joint plates＇ thickness, the advantages of the proposed method tend to be more obvious. The proposed 2D FEM is an effective tool for designing bolted joints in large-scale composite structures.
