High penetration of distributed renewable energy promotes the development of an active distribution network(ADN).The power flow calculation is the basis of ADN analysis.This paper proposes an approximate linear three-...High penetration of distributed renewable energy promotes the development of an active distribution network(ADN).The power flow calculation is the basis of ADN analysis.This paper proposes an approximate linear three-phase power flow model for an ADN with the consideration of the ZIP model of the loads and PV nodes.The proposed method is not limited to radial topology and can handle high R/X ratio branches.Case studies on the IEEE 37-node distribution network show a high accuracy and the proposed method is applicable to practical uses such as linear or convex optimal power flow of the ADN.展开更多
Distribution system analysis(DSA)currently faces several challenges due to inclusion of distributed energy resources(DERs),which have many characteristics,such as inherent variability,uncertainty,possibility of flexib...Distribution system analysis(DSA)currently faces several challenges due to inclusion of distributed energy resources(DERs),which have many characteristics,such as inherent variability,uncertainty,possibility of flexible four quadrant converter operations with distributed generation(DG),and the need for efficient operations to improve reliability of the supply system.This article argues for a high degree of case-specificity and discusses its implications in distribution networks with increasing DG penetration.The research is based on the exhaustive yearly simulation analyses of 132 candidate scenarios and investigates the effects of feeder-specific factors,such as geo-electric size and feeder spread,load density,and phase unbalancing.Nineteen(19)feeder variants—with phase-domain detailed modeling of all feeder components,including DGs,are subjected to increasing penetration of photovoltaic generation without altering the type and location of DGs.The objective is to analyze the role of feederspecific factors on feeder response characteristics in terms of annualized operational parameters,such as energy losses,feeder voltage profile,average power factor,and peak demand at a substation node,as well as tap-changer operations of voltage regulating equipment and their interaction with shunt compensation.Recorded annual load profiles—industrial,commercial,and residential—as well as location specific weather data are used to simulate the candidate scenarios based on three IEEE test feeders and one actual spot network in India.Results signify the consideration of feeder-specific factors in the planning exercise of grouping“similar”feeders for formulating the strategies that can improve daily operations of distribution feeders.The demonstrated case-specificity also implies that optimization algorithms for improved operations with DGs will need to be based on an integrated approach that accounts for feeder-specific factors as well as cyclic variability of DERs.展开更多
Although Zn metal is an ideal anode candidate for aqueous batteries owing to its high theoretical capacity,lower cost,and safety,its service life and efficiency are damaged by severe hydrogen evolution reaction,self-c...Although Zn metal is an ideal anode candidate for aqueous batteries owing to its high theoretical capacity,lower cost,and safety,its service life and efficiency are damaged by severe hydrogen evolution reaction,self-corrosion,and dendrite growth.Herein,a thickness-controlled ZnS passivation layer was fabricated on the Zn metal surface to obtain Zn@ZnS electrode through oxidation–orientation sulfuration by the liquid-and vapor-phase hydrothermal processes.Benefiting from the chemical inertness of the ZnS interphase,the as-prepared Zn@ZnS electrode presents an excellent anti-corrosion and undesirable hydrogen evolution reaction.Meanwhile,the thickness-optimized ZnS layer with an unbalanced charge distribution represses dendrite growth by guiding Zn plating/stripping,leading to long service life.Consequently,the Zn@Zn S presented 300 cycles in the symmetric cells with a 42 mV overpotential,200 cycles in half cells with a 78 mV overpotential,and superb rate performance in Zn||NH;V;O;full cells.展开更多
In addition to increasing penetration of distributed generation(DG),the distribution system power flow may be significantly impacted by direction and magnitude.This paper proposes a method for optimal placement of win...In addition to increasing penetration of distributed generation(DG),the distribution system power flow may be significantly impacted by direction and magnitude.This paper proposes a method for optimal placement of wind DG considering the unbalanced operation of distribution systems.The objective function includes static voltage stability index,three-phase unbalance index,system reliability index,and DG investment cost.The untransposed distribution lines and unbalanced load are modelled,and corresponding static voltage stability index and system reliability considering DG penetrations are derived.The expected and stochastic daily distributed generation and demand profiles in four seasons are calculated to improve the accuracy.To solve this multi-objective optimization model,a fuzzy membership function is used to integrate the four individual objectives,and a sensitivity-based method is proposed to solve the model efficiently.Case study on IEEE 13-bus distribution 3-phase networks and 123-node test feeder successfully verifies the performance of the proposed approach.展开更多
基金supported in part by the National Key R&D Program of China(No.2016YFB0900100)the National Science Foundation of China(No.51325702,51677096).
文摘High penetration of distributed renewable energy promotes the development of an active distribution network(ADN).The power flow calculation is the basis of ADN analysis.This paper proposes an approximate linear three-phase power flow model for an ADN with the consideration of the ZIP model of the loads and PV nodes.The proposed method is not limited to radial topology and can handle high R/X ratio branches.Case studies on the IEEE 37-node distribution network show a high accuracy and the proposed method is applicable to practical uses such as linear or convex optimal power flow of the ADN.
基金This work was supported in part by Indian Institute of Technology Gandhinagar in the form of“Additional Fellowship”to Kalpesh Joshi.
文摘Distribution system analysis(DSA)currently faces several challenges due to inclusion of distributed energy resources(DERs),which have many characteristics,such as inherent variability,uncertainty,possibility of flexible four quadrant converter operations with distributed generation(DG),and the need for efficient operations to improve reliability of the supply system.This article argues for a high degree of case-specificity and discusses its implications in distribution networks with increasing DG penetration.The research is based on the exhaustive yearly simulation analyses of 132 candidate scenarios and investigates the effects of feeder-specific factors,such as geo-electric size and feeder spread,load density,and phase unbalancing.Nineteen(19)feeder variants—with phase-domain detailed modeling of all feeder components,including DGs,are subjected to increasing penetration of photovoltaic generation without altering the type and location of DGs.The objective is to analyze the role of feederspecific factors on feeder response characteristics in terms of annualized operational parameters,such as energy losses,feeder voltage profile,average power factor,and peak demand at a substation node,as well as tap-changer operations of voltage regulating equipment and their interaction with shunt compensation.Recorded annual load profiles—industrial,commercial,and residential—as well as location specific weather data are used to simulate the candidate scenarios based on three IEEE test feeders and one actual spot network in India.Results signify the consideration of feeder-specific factors in the planning exercise of grouping“similar”feeders for formulating the strategies that can improve daily operations of distribution feeders.The demonstrated case-specificity also implies that optimization algorithms for improved operations with DGs will need to be based on an integrated approach that accounts for feeder-specific factors as well as cyclic variability of DERs.
基金supported by the National Research Foundation funded by the government of the Republic of Korea (Nos. 2020R1I1A1A01072996 and 2021K 2A9A2A06044652)the National Natural Science Foundation of China (Nos. 52111540265 and 51874272)
文摘Although Zn metal is an ideal anode candidate for aqueous batteries owing to its high theoretical capacity,lower cost,and safety,its service life and efficiency are damaged by severe hydrogen evolution reaction,self-corrosion,and dendrite growth.Herein,a thickness-controlled ZnS passivation layer was fabricated on the Zn metal surface to obtain Zn@ZnS electrode through oxidation–orientation sulfuration by the liquid-and vapor-phase hydrothermal processes.Benefiting from the chemical inertness of the ZnS interphase,the as-prepared Zn@ZnS electrode presents an excellent anti-corrosion and undesirable hydrogen evolution reaction.Meanwhile,the thickness-optimized ZnS layer with an unbalanced charge distribution represses dendrite growth by guiding Zn plating/stripping,leading to long service life.Consequently,the Zn@Zn S presented 300 cycles in the symmetric cells with a 42 mV overpotential,200 cycles in half cells with a 78 mV overpotential,and superb rate performance in Zn||NH;V;O;full cells.
基金supported in part by the 2015 Science and Technology Project of China Southern Power Grid(WYKJ00000027)in part by funding from mid-career researcher development scheme,the Faculty of Engineering&Information Technologies,The University of Sydney.
文摘In addition to increasing penetration of distributed generation(DG),the distribution system power flow may be significantly impacted by direction and magnitude.This paper proposes a method for optimal placement of wind DG considering the unbalanced operation of distribution systems.The objective function includes static voltage stability index,three-phase unbalance index,system reliability index,and DG investment cost.The untransposed distribution lines and unbalanced load are modelled,and corresponding static voltage stability index and system reliability considering DG penetrations are derived.The expected and stochastic daily distributed generation and demand profiles in four seasons are calculated to improve the accuracy.To solve this multi-objective optimization model,a fuzzy membership function is used to integrate the four individual objectives,and a sensitivity-based method is proposed to solve the model efficiently.Case study on IEEE 13-bus distribution 3-phase networks and 123-node test feeder successfully verifies the performance of the proposed approach.
