The silver-palladium(Ag-Pd) alloy coating as a solid lubricant was investigated for its application to the high temperature stud bolts used in nuclear power plants.A hex bolt sample was prepared in the following steps...The silver-palladium(Ag-Pd) alloy coating as a solid lubricant was investigated for its application to the high temperature stud bolts used in nuclear power plants.A hex bolt sample was prepared in the following steps:1) bolt surface treatment using alumina grit blasting for cleaning and increasing the surface area;2) nickel(Ni) film coating as a glue layer on the surface of the bolt;and 3) Ag-Pd alloy coating on the Ni film.The films were deposited by using a direct current(DC) magnetron sputtering system.The thickness and composition of the Ag-Pd alloy film have effect on the friction coefficient,which was determined using axial force measurement.A 500 nm-thick Ag-Pd(80-20,molar ratio) alloy film has the lowest friction coefficient of 0.109.A cyclic test was conducted to evaluate the durability of bolts coated with either the Ag-Pd(80-20) alloy film or N-5000 oil.In a cycle,the bolts were inserted into a block using a torque wrench,which was followed by heating and disassembling.After only one cycle,it was not possible to remove the bolts coated with the N-5000 oil from the block.However,the bolts coated with the Ag-Pd(80-20) alloy could be easily removed up until 15 cycles.展开更多
Reactive power control can control voltage within the proper range from the power network side or from the distribution generation （PV （photovoltaic）） side. Reactive power control from the power network side is si...Reactive power control can control voltage within the proper range from the power network side or from the distribution generation （PV （photovoltaic）） side. Reactive power control from the power network side is simpler because little controlled object apparatus, such as STATCOM, is required. However, it is difficult to optimize the individual voltages of residential consumers because few data have been obtained by the power network side as compared with the power generation side. Energy loss at each residence with PV is different due to the difference in the grid-interconnection condition, such as distribution line impedance when the same operating voltage is set at all residences. Therefore, in this paper, the authors propose an advanced reactive power control method for residential PV systems in order to optimally control the voltage at individual residences so as to minimize energy loss fluctuation. The effectiveness of the proposed reactive power control is demonstrated by numerical simulation.展开更多
There is a danger of power generation efficiency decreasing due to voltage increase when clustered residential PV systems are grid-interconnected to a single distribution line. As a countermeasure, installation of the...There is a danger of power generation efficiency decreasing due to voltage increase when clustered residential PV systems are grid-interconnected to a single distribution line. As a countermeasure, installation of the reactive power control of an inverter at each residence has been considered. However, there are not many types of inverters that can operate reactive power control because there are insufficient effects on a low voltage distribution line with low penetration PV with reactive power control. Therefore, it is necessary to consider how to increase generation efficiency with a lower number of inverters. In this paper, four Japanese standard distribution line structures, for example of a residential area on ＂C1＂, where 2,160 residential PV systems are grid-interconnected, are selected. The optimal setting of reactive power control at each residence is computed on the distribution lines with a greedy method.展开更多
基金Project supported by Power Research and Development Program funded by Ministry of Knowledge Economy and Korea Institute of Materials Science,a subsidiary branch of Korea Institute of Machinery and Materials
文摘The silver-palladium(Ag-Pd) alloy coating as a solid lubricant was investigated for its application to the high temperature stud bolts used in nuclear power plants.A hex bolt sample was prepared in the following steps:1) bolt surface treatment using alumina grit blasting for cleaning and increasing the surface area;2) nickel(Ni) film coating as a glue layer on the surface of the bolt;and 3) Ag-Pd alloy coating on the Ni film.The films were deposited by using a direct current(DC) magnetron sputtering system.The thickness and composition of the Ag-Pd alloy film have effect on the friction coefficient,which was determined using axial force measurement.A 500 nm-thick Ag-Pd(80-20,molar ratio) alloy film has the lowest friction coefficient of 0.109.A cyclic test was conducted to evaluate the durability of bolts coated with either the Ag-Pd(80-20) alloy film or N-5000 oil.In a cycle,the bolts were inserted into a block using a torque wrench,which was followed by heating and disassembling.After only one cycle,it was not possible to remove the bolts coated with the N-5000 oil from the block.However,the bolts coated with the Ag-Pd(80-20) alloy could be easily removed up until 15 cycles.
文摘Reactive power control can control voltage within the proper range from the power network side or from the distribution generation （PV （photovoltaic）） side. Reactive power control from the power network side is simpler because little controlled object apparatus, such as STATCOM, is required. However, it is difficult to optimize the individual voltages of residential consumers because few data have been obtained by the power network side as compared with the power generation side. Energy loss at each residence with PV is different due to the difference in the grid-interconnection condition, such as distribution line impedance when the same operating voltage is set at all residences. Therefore, in this paper, the authors propose an advanced reactive power control method for residential PV systems in order to optimally control the voltage at individual residences so as to minimize energy loss fluctuation. The effectiveness of the proposed reactive power control is demonstrated by numerical simulation.
文摘There is a danger of power generation efficiency decreasing due to voltage increase when clustered residential PV systems are grid-interconnected to a single distribution line. As a countermeasure, installation of the reactive power control of an inverter at each residence has been considered. However, there are not many types of inverters that can operate reactive power control because there are insufficient effects on a low voltage distribution line with low penetration PV with reactive power control. Therefore, it is necessary to consider how to increase generation efficiency with a lower number of inverters. In this paper, four Japanese standard distribution line structures, for example of a residential area on ＂C1＂, where 2,160 residential PV systems are grid-interconnected, are selected. The optimal setting of reactive power control at each residence is computed on the distribution lines with a greedy method.
