Responsiveness is a challenge for space systems to sustain competitive advantage over al-ternate non-spaceborne technologies.For a satellite in its operational orbit,in-orbit responsiveness is defined as the capabilit...Responsiveness is a challenge for space systems to sustain competitive advantage over al-ternate non-spaceborne technologies.For a satellite in its operational orbit,in-orbit responsiveness is defined as the capability of the satellite to respond to a given demand in a timely manner.In this paper,it is shown that Average Wait Time(AWT) to pick up user demand from ground segment is the ap-propriate metric to evaluate the effect of ground segment location on in-orbit responsiveness of Low Earth Orbit(LEO) sunsynchronous satellites.This metric depends on pattern of ground segment access to satellite and distribution of user demands in time domain.A mathematical model is presented to determine pattern of ground segment access to satellite and concept of cumulative distribution function is used to simulate distribution of user demands for markets with different total demand scenarios.Monte Carlo simulations are employed to take account of uncertainty in distribution and total volume of user demands.Sampling error and standard deviation are used to ensure validity of AWT metric obtained from Monte Carlo simulations.Incorporation of the proposed metric in the ground segment site location process results in more responsive satellite systems which,in turn,lead to greater customer satisfaction levels and attractiveness of spaceborne systems for different applications.Finally,simula-tion results for a case study are presented.展开更多
Accurate topology information is crucial to management and application in an active low-voltage distribution network(LVDN).Existing topology identification(TI)methods mostly lack a systematic framework to obtain preci...Accurate topology information is crucial to management and application in an active low-voltage distribution network(LVDN).Existing topology identification(TI)methods mostly lack a systematic framework to obtain precise hierarchical relations and consumers’segment locations.Their performances are usually deteriorated by introduction of incomplete and tampered smart meter data.To address the problem of TI with penetration of PV prosumers,non-consumption users,and electricity thieves,a data-driven algorithm is proposed via measurements of nodal voltage magnitude and active power,without any prior network information.Inspired by engineering applications of graph theory knowledge,we cast connection problems of LVDN into the solution of adjacency matrices.Up-down and parallel relations of branches are first identified using active power,based on feature extraction of frequency domain filtering and correlation.Correlation factor analysis is subsequently adopted to assign multiple consumers to specific subnetworks,and then consumers’segments are precisely located by combining regression analysis and association strategy.The proposed algorithm is successfully examined on in a complex LVDN,and results show higher robustness under different scenarios.展开更多
基金Supported by the Research Council of Shahid Beheshti University,G. C.
文摘Responsiveness is a challenge for space systems to sustain competitive advantage over al-ternate non-spaceborne technologies.For a satellite in its operational orbit,in-orbit responsiveness is defined as the capability of the satellite to respond to a given demand in a timely manner.In this paper,it is shown that Average Wait Time(AWT) to pick up user demand from ground segment is the ap-propriate metric to evaluate the effect of ground segment location on in-orbit responsiveness of Low Earth Orbit(LEO) sunsynchronous satellites.This metric depends on pattern of ground segment access to satellite and distribution of user demands in time domain.A mathematical model is presented to determine pattern of ground segment access to satellite and concept of cumulative distribution function is used to simulate distribution of user demands for markets with different total demand scenarios.Monte Carlo simulations are employed to take account of uncertainty in distribution and total volume of user demands.Sampling error and standard deviation are used to ensure validity of AWT metric obtained from Monte Carlo simulations.Incorporation of the proposed metric in the ground segment site location process results in more responsive satellite systems which,in turn,lead to greater customer satisfaction levels and attractiveness of spaceborne systems for different applications.Finally,simula-tion results for a case study are presented.
文摘Accurate topology information is crucial to management and application in an active low-voltage distribution network(LVDN).Existing topology identification(TI)methods mostly lack a systematic framework to obtain precise hierarchical relations and consumers’segment locations.Their performances are usually deteriorated by introduction of incomplete and tampered smart meter data.To address the problem of TI with penetration of PV prosumers,non-consumption users,and electricity thieves,a data-driven algorithm is proposed via measurements of nodal voltage magnitude and active power,without any prior network information.Inspired by engineering applications of graph theory knowledge,we cast connection problems of LVDN into the solution of adjacency matrices.Up-down and parallel relations of branches are first identified using active power,based on feature extraction of frequency domain filtering and correlation.Correlation factor analysis is subsequently adopted to assign multiple consumers to specific subnetworks,and then consumers’segments are precisely located by combining regression analysis and association strategy.The proposed algorithm is successfully examined on in a complex LVDN,and results show higher robustness under different scenarios.
