We propose a quasi-deterministic proxy for the net work-constrained stochastic unit commitment(SUC)problem.The proposed proxy can identify very similar commitment deci sions as those obtained by solving the SUC proble...We propose a quasi-deterministic proxy for the net work-constrained stochastic unit commitment(SUC)problem.The proposed proxy can identify very similar commitment deci sions as those obtained by solving the SUC problem with a large scenario set.Its computational performance,though,is close to that of a deterministic unit commitment problem.The proposed proxy has the same formulation as the SUC problem but only includes one or two envelope scenarios,generated based on the original scenario set.The two envelope scenarios capture the maximum and minimum net-load conditions in the original scenario set.We use a systematic method to assess the quality of commitment decisions obtained by the proposed proxy.The considered case study is based on the Illinois 200-bus system.展开更多
The electricity distribution network is experiencing a profound transformation with the concept of the smart grid,providing possibilities for selfish consumers to interact with the distribution system operator(DSO)and...The electricity distribution network is experiencing a profound transformation with the concept of the smart grid,providing possibilities for selfish consumers to interact with the distribution system operator(DSO)and to maximize their individual energy consumption utilities.However,this profitseeking behavior among consumers may violate the network constraints,such as line flows,transformer capacity and bus voltage magnitude limits.Therefore,a network-constrained energy consumption(NCEC)game among active load aggregators(ALAs)is proposed to guarantee the safety of the distribution network.The temporal and spatial constraints of an ALA are both considered,which leads the formulated model to a generalized Nash equilibrium problem(GNEP).By resorting to a well-developed variational inequality(VI)theory,we study the existence of solutions to the NCEC game problem.Subsequently,a two-level distributed algorithm is proposed to find the variational equilibrium(VE),a fair and stable solution to the formulated game model.Finally,the effectiveness of the proposed game model and the efficiency of the distributed algorithm are tested on an IEEE-33 bus system.展开更多
Spatio-temporal databases aim at appropriately managing moving objects so as to support various types of queries. While much research has been conducted on developing query processing techniques, less effort has been ...Spatio-temporal databases aim at appropriately managing moving objects so as to support various types of queries. While much research has been conducted on developing query processing techniques, less effort has been made to address the issue of when and how to update location information of moving objects. Previous work shifts the workload of processing updates to each object which usually has limited CPU and battery capacities. This results in a tremendous processing overhead for each moving object. In this paper, we focus on designing efficient update strategies for two important types of moving objects, free-moving objects(FMOs) and network-constrained objects(NCOs), which are classified based on object movement models. For FMOs, we develop a novel update strategy, namely the FMO update strategy(FMOUS), to explicitly indicate a time point at which the object needs to update location information. As each object knows in advance when to update(meaning that it does not have to continuously check), the processing overhead can be greatly reduced. In addition, the FMO update procedure(FMOUP) is designed to efficiently process the updates issued from moving objects. Similarly, for NCOs, we propose the NCO update strategy(NCOUS) and the NCO update procedure(NCOUP) to inform each object when and how to update location information. Extensive experiments are conducted to demonstrate the effectiveness and efficiency of the proposed update strategies.展开更多
Network-constrained unit commitment(NCUC)is one of the most widely used applications in power system and electricity market operations.According to empirical evidence,some of the transmission constraints in a NCUC are...Network-constrained unit commitment(NCUC)is one of the most widely used applications in power system and electricity market operations.According to empirical evidence,some of the transmission constraints in a NCUC are inactive.Identifying and eliminating these inactive constraints can improve the efficiency.In this paper,an efficient method is first proposed for identifying the inactive transmission constraints.The physical and economic insights of NCUC are carefully considered and utilized.Both the generating costs and power transfer distribution factor(PTDF)are considered.Not only redundant constraints but also non-binding constraints can be identified via the proposed method.An acceleration method that combines relaxation-based neighborhood search and improved relaxation inducement is proposed for further reducing the computation time.The case study shows that the proposed method can significantly reduce the number of transmission constraints and substantially improve the efficiency of NCUC without impacting the optimality.展开更多
The network-constrained flow is defined as the movement between two locations along road networks,such as the residence-workplace flow of city dwellers.Among flow patterns,clustering(i.e.the origins and destinations a...The network-constrained flow is defined as the movement between two locations along road networks,such as the residence-workplace flow of city dwellers.Among flow patterns,clustering(i.e.the origins and destinations are aggregated simultaneously)is one of the cities’most common and vital patterns,which assists in uncovering fundamental mobility trends.The existing methods for detecting the clustering pattern of network-constrained flows do not consider the impact of road network topology complexity on detection results.They may underestimate the flow clustering between networks of simple topology(roads with simpler shapes and fewer links,e.g.straight roads)but with high network intensity(i.e.flow number per network flow space),and determining the actual scale of an observed pattern remains challenging.This study develops a novel method,the lengthsquared L-function,to identify clustering patterns of networkconstrained flows.We first use the L-function and its derivative to examine the clustering scales.Further,we calculate the local L-function to ascertain the locations of the clustering patterns.In synthetic and practical experiments,our method can identify flow clustering patterns of high intensities and reveal the residents’main travel behavior trends with taxi OD flows,providing more reasonable suggestions for urban planning.展开更多
基金supported in part by the Advanced Research Projects AgencyEnergy(ARPA-E)of U.S.Department of Energy(No.2171-1618)。
文摘We propose a quasi-deterministic proxy for the net work-constrained stochastic unit commitment(SUC)problem.The proposed proxy can identify very similar commitment deci sions as those obtained by solving the SUC problem with a large scenario set.Its computational performance,though,is close to that of a deterministic unit commitment problem.The proposed proxy has the same formulation as the SUC problem but only includes one or two envelope scenarios,generated based on the original scenario set.The two envelope scenarios capture the maximum and minimum net-load conditions in the original scenario set.We use a systematic method to assess the quality of commitment decisions obtained by the proposed proxy.The considered case study is based on the Illinois 200-bus system.
基金This work was supported in part by the Science and Technology Project of SGCC“Research on Morphologies and Pathways of Future Power System”。
文摘The electricity distribution network is experiencing a profound transformation with the concept of the smart grid,providing possibilities for selfish consumers to interact with the distribution system operator(DSO)and to maximize their individual energy consumption utilities.However,this profitseeking behavior among consumers may violate the network constraints,such as line flows,transformer capacity and bus voltage magnitude limits.Therefore,a network-constrained energy consumption(NCEC)game among active load aggregators(ALAs)is proposed to guarantee the safety of the distribution network.The temporal and spatial constraints of an ALA are both considered,which leads the formulated model to a generalized Nash equilibrium problem(GNEP).By resorting to a well-developed variational inequality(VI)theory,we study the existence of solutions to the NCEC game problem.Subsequently,a two-level distributed algorithm is proposed to find the variational equilibrium(VE),a fair and stable solution to the formulated game model.Finally,the effectiveness of the proposed game model and the efficiency of the distributed algorithm are tested on an IEEE-33 bus system.
基金supported by the National Science Council of Taiwan(Nos.NSC-102-2119-M-244-001 and MOST-103-2119-M-244-001)
文摘Spatio-temporal databases aim at appropriately managing moving objects so as to support various types of queries. While much research has been conducted on developing query processing techniques, less effort has been made to address the issue of when and how to update location information of moving objects. Previous work shifts the workload of processing updates to each object which usually has limited CPU and battery capacities. This results in a tremendous processing overhead for each moving object. In this paper, we focus on designing efficient update strategies for two important types of moving objects, free-moving objects(FMOs) and network-constrained objects(NCOs), which are classified based on object movement models. For FMOs, we develop a novel update strategy, namely the FMO update strategy(FMOUS), to explicitly indicate a time point at which the object needs to update location information. As each object knows in advance when to update(meaning that it does not have to continuously check), the processing overhead can be greatly reduced. In addition, the FMO update procedure(FMOUP) is designed to efficiently process the updates issued from moving objects. Similarly, for NCOs, we propose the NCO update strategy(NCOUS) and the NCO update procedure(NCOUP) to inform each object when and how to update location information. Extensive experiments are conducted to demonstrate the effectiveness and efficiency of the proposed update strategies.
基金National Natural Science Foundation of China(No.51777102)Chinese Association of Science and Technology Young Elite Scientists Sponsorship Program(2017QNRC001)the State Grid Corporation of China(Risk Quantization and Active Control for Power Grid Operations Considering Large-scale Meteorological Data).
文摘Network-constrained unit commitment(NCUC)is one of the most widely used applications in power system and electricity market operations.According to empirical evidence,some of the transmission constraints in a NCUC are inactive.Identifying and eliminating these inactive constraints can improve the efficiency.In this paper,an efficient method is first proposed for identifying the inactive transmission constraints.The physical and economic insights of NCUC are carefully considered and utilized.Both the generating costs and power transfer distribution factor(PTDF)are considered.Not only redundant constraints but also non-binding constraints can be identified via the proposed method.An acceleration method that combines relaxation-based neighborhood search and improved relaxation inducement is proposed for further reducing the computation time.The case study shows that the proposed method can significantly reduce the number of transmission constraints and substantially improve the efficiency of NCUC without impacting the optimality.
基金supported by the National Key R&D Program of China[Grant No.2022YFC3800803]the National Natural Science Foundation of China[Grant No.42071436]the Innovation Project of LREIS[Grant No.KPI002].
文摘The network-constrained flow is defined as the movement between two locations along road networks,such as the residence-workplace flow of city dwellers.Among flow patterns,clustering(i.e.the origins and destinations are aggregated simultaneously)is one of the cities’most common and vital patterns,which assists in uncovering fundamental mobility trends.The existing methods for detecting the clustering pattern of network-constrained flows do not consider the impact of road network topology complexity on detection results.They may underestimate the flow clustering between networks of simple topology(roads with simpler shapes and fewer links,e.g.straight roads)but with high network intensity(i.e.flow number per network flow space),and determining the actual scale of an observed pattern remains challenging.This study develops a novel method,the lengthsquared L-function,to identify clustering patterns of networkconstrained flows.We first use the L-function and its derivative to examine the clustering scales.Further,we calculate the local L-function to ascertain the locations of the clustering patterns.In synthetic and practical experiments,our method can identify flow clustering patterns of high intensities and reveal the residents’main travel behavior trends with taxi OD flows,providing more reasonable suggestions for urban planning.
