Electric system planning with high variable renewable energy(VRE)penetration levels has attracted great attention world-wide.Electricity production of VRE highly depends on the weather conditions and thus involves lar...Electric system planning with high variable renewable energy(VRE)penetration levels has attracted great attention world-wide.Electricity production of VRE highly depends on the weather conditions and thus involves large variability,uncertainty,and low-capacity credit.This gives rise to significant challenges for power system planning.Currently,many solutions are proposed to address the issue of operational flexibility inadequacy,including flexibility retrofit of thermal units,inter-regional transmission,electricity energy storage,and demand response(DR).Evidently,the performance and the cost of various solutions are different.It is relevant to explore the optimal portfolio to satisfy the flexibility requirement for a renewable dominated system and the role of each flexibility source.In this study,the value of diverse DR flexibilities was examined and a stochastic investment planning model considering DR is proposed.Two types of DRs,namely interrupted DR and transferred DR,were modeled.Chronological load and renewable generation curves with 8760 hours within a whole year were reduced to 4 weekly scenarios to accelerate the optimization.Clustered unit commitment constraints for accommodating variability of renewables were incorporated.Case studies based on IEEE RTS-96 system are reported to demonstrate the effectiveness of the proposed method and the DR potential to avoid energy storage investment.展开更多
In recent years,renewable energy(RE)penetration has become an important target in power systems.However,RE power is affected by climate change and has strong randomness and volatility.Adequate transmission capacity an...In recent years,renewable energy(RE)penetration has become an important target in power systems.However,RE power is affected by climate change and has strong randomness and volatility.Adequate transmission capacity and energy storage systems(ESSs)are conducive to the integration of RE.Therefore,coordinated transmission renewable–storage expansion planning(TRSEP)is an effective decision-making approach to cope with the impacts of climate change and achieve the development tar-get of RE penetration.Electricity trading between different systems is common;therefore,in addition to the penetration of RE into the internal loads of the system,the proportion of RE generation in tie lines is gaining attention,making analyses of the RE transmission path necessary.Referring to the flow of carbon emissions,this paper defines the RE power flow density to track the transmission path of RE.Next,a TRSEP model is proposed that can clearly distinguish the RE transmission path into internal loads,exter-nal loads,and energy losses.To address the presence of bilinear terms in the proposed model,the McCormick method is applied,and a customized feasibility correction strategy is designed to obtain a good feasible solution.Numerical results from case studies are provided to verify the rationality and effectiveness of the approach proposed in this paper.展开更多
Under the pressure of environmental issues,decarbonization of the entire energy system has emerged as a prevalent strategy worldwide.The evolution of China’s power system will increasingly emphasize the integration o...Under the pressure of environmental issues,decarbonization of the entire energy system has emerged as a prevalent strategy worldwide.The evolution of China’s power system will increasingly emphasize the integration of variable renewable energy(VRE).However,the rapid growth of VRE will pose substantial challenges to the power system,highlighting the importance of power system planning.This letter introduces Grid Optimal Planning Tool(GOPT),a planning tool,and presents the key findings of our research utilizing GOPT to analyze the transition pathway of China’s power system towards dual carbon goals.Furthermore,the letter offers insights into key technologies essential for driving the future transition of China’s power system.展开更多
The high penetration of variable renewable energy raises a flexibility challenge in the power system.This raises the necessity of considering the adequacy of flexibility in power system planning.However,the flexibilit...The high penetration of variable renewable energy raises a flexibility challenge in the power system.This raises the necessity of considering the adequacy of flexibility in power system planning.However,the flexibility of the power system covers a wide range of timescales,from seconds to months.This poses difficulties in planning of multi-timescale flexible resources.This paper proposes a new perspective on the modeling and planning of multi-timescale flexible resources in power systems with high penetration of variable renewable energy.The operational boundaries of flexible resources are transformed into a characteristic domain,where flexibility at different timescales can be added and the balance of flexible supply and demand can be expressed as algebraic equations.Such modeling facilitates rigorous multi-timescale flexibility balance metrics.Furthermore,a planning method for multi-timescale flexibility is proposed based on the model in the characteristic domain.The proposed planning method is tested using data from China's Xinjiang provincial power grid.Results show the proposed method can characterize multi-timescale flexibility with high accuracy,thus making it possible to fully account for flexibility at different timescales.展开更多
Concerning the integration of large-scale wind power,an integrated model of generation and transmission expansion planning is proposed based on the assessment of the value of steady state and dynamic security.In the a...Concerning the integration of large-scale wind power,an integrated model of generation and transmission expansion planning is proposed based on the assessment of the value of steady state and dynamic security.In the assessment of security value,the unit commitment simulation based on the predicted hourly load and wind power output data in the planning horizon is used to evaluate the costs of preventive control,emergency control and social losses due to the uncertainty of load and wind power.The cost of preventive control consists of the fuel cost of power generation,the environmental cost and the load shedding cost.This not only provides a systematic method of security assessment of power system expansion planning schemes,but also broadens the perspective of power system planning from the technology and economic assessment to the measure of the whole social value.In the assessment process,the preventive control and emergency control of cascading failures are also presented,which provides a convincing tool for cascading failure analysis of planning schemes and makes the security assessment more comprehensive and reasonable.The proposed model and method have been demonstrated by the assessment of two power system planning schemes on the New England 10-genarator 39-bus System.The importance of considering the value of security and simulating hourly system operation for the planning horizon,in expansion planning of power system with integration of large-scale wind power,has been confirmed.展开更多
Renewable generation is rapidly increasing and transforming power systems toward“new-type power systems”.The integration of renewable energy resources necessitates a shift from conventional grid-following converters...Renewable generation is rapidly increasing and transforming power systems toward“new-type power systems”.The integration of renewable energy resources necessitates a shift from conventional grid-following converters(GFLs)to advanced grid-forming controls.Although grid-forming converters(GFMs)provide grid support and enhance system stability under weak grid conditions,their deployment requires more robust hardware,complex control algorithms and system operation constraints,resulting in planning and operational trade-offs between system stability and cost efficiency.This paper studies the underexplored question of how many GFMs are needed from a techno-economic perspective.The holistic analysis integrates long-term planning,short-term operational strategies and dynamic stability considerations,thereby supporting large-scale renewable integration while ensuring system security and economic benefits.展开更多
Adequacy is a key concern of power system planning,which refers to the availability of sufficient facilities to meet demand.The capacity value(CV)of variable renewable energy(VRE)generation represents its equivalent c...Adequacy is a key concern of power system planning,which refers to the availability of sufficient facilities to meet demand.The capacity value(CV)of variable renewable energy(VRE)generation represents its equivalent contribution to system adequacy,in comparison to conventional generators.While VRE continues to grow and increasingly dominates the generation portfolio,its CV is becoming non-negligible,with the corresponding impact mechanisms becoming more complicated and nuanced.In this paper,the concept of CV is revisited by analyzing how VRE contributes to power system balancing at a high renewable energy penetration level.A generalized loss function is incorporated into the CV evaluation framework considering the adequacy of the power system.An analytical method for the CV evaluation of VRE is then derived using the statistical properties of both hourly load and VRE generation.Through the explicit CV expression,several critical impact factors,including the VRE generation variance,source-load correlation,and system adequacy level,are identified and discussed.Case studies demonstrate the accuracy and effectiveness of the proposed method in comparison to the traditional capacity factor-based methods and convolution-based methods.In the IEEERTS79 test system,the CV of a 2500 MW wind farm(with40%renewable energy penetration level)is found to be 6.8%of its nameplate capacity.Additionally,the sensitivity of CV to various impact factors in power systems with high renewable energy penetration is analyzed.展开更多
Multi-energy system(MES)is crucial for the development of smart cities.This paper summarises the research progress and achievements from an engineering case study in China which aims at enhancing MES energy efficiency...Multi-energy system(MES)is crucial for the development of smart cities.This paper summarises the research progress and achievements from an engineering case study in China which aims at enhancing MES energy efficiency.Key theories and technologies were tested at an MES demonstration site in Hunan,China,using both software and hardware systems which improve significantly in energy efficiency,carbon savings,environmental and economic benefits.Specifically,the optimal operation modes proposed in this paper achieves a best-case scenario of 9.97 tons of CO_(2) savings,26.4%lower than conventional systems.The findings provide crucial guidance for policymakers and industry stakeholders which aims to implement sustainable energy solutions in future urban planning.展开更多
Following the deregulation of the power industry,transmission expansion planning(TEP)has become more complicated due to the presence of uncertainties and conflicting objectives in a market environment.Also,the growing...Following the deregulation of the power industry,transmission expansion planning(TEP)has become more complicated due to the presence of uncertainties and conflicting objectives in a market environment.Also,the growing concern on global warming highlights the importance of considering carbon pricing policies during TEP.In this paper,a probabilistic TEP approach is proposed with the integration of a chance constrained load curtailment index.The formulated dynamic programming problem is solved by a hybrid solution algorithm in an iterative process.The performance of our approach is demonstrated by case studies on a modified IEEE 14-bus system.Simulation results prove that our approach can provide network planners with comprehensive information regarding effects of uncertainties on TEP schemes,allowing them to adjust planning strategies based on their risk aversion levels or financial constraints.展开更多
voltage direct current(HVDC)transmission lines are being constructed throughout the world,aided by advancements in power electronics and the potential value to transfer power between distant areas and off-shore locati...voltage direct current(HVDC)transmission lines are being constructed throughout the world,aided by advancements in power electronics and the potential value to transfer power between distant areas and off-shore locations.Multiple HVDC lines within and across large AC interconnections could bring about economic benefits such as interregional capacity exchange and transfer of low-cost,distant electric energy directly to load centers.In addition,network configuration of HVDC lines could result in additional benefits that have not been deeply studied.This paper describes the modeling process for continentallevel power system interconnections with the addition of multiple HVDC lines configured as a macrogrid.The models used for study are based on industry-accepted power-flow and dynamic system models for the North American Eastern and Western Interconnections.The model provides insight on feasibility and initial steady-state and stability tests of the HVDC macrogrid and its interactions with the existing electricity infrastructure,opening the door to analysis of the technical value of such a macrogrid.展开更多
We address the problem of optimally re-routing the feeders of urban distribution network in Milano,Italy,which presents some peculiarities and significant design challenges.Milano has two separate medium-voltage(MV)di...We address the problem of optimally re-routing the feeders of urban distribution network in Milano,Italy,which presents some peculiarities and significant design challenges.Milano has two separate medium-voltage(MV)distribution networks,previously operated by two different utilities,which grew up independently and incoordinately.This results in a system layout which is inefficient,redundant,and difficult to manage due to different operating procedures.The current utility UNARETI,which is in charge of the overall distribution system,aims at optimally integrating the two MV distribution networks and moving to a new specific layout that offers advantages from the perspectives of reliability and flexibility.We present a mixed-integer programming(MIP)approach for the design of a new network configuration satisfying the so-called 2-step ladder layout required by the planner.The model accounts for the main electrical constraints such as power flow equations,thermal limits of high-voltage(HV)/MV substation transformers,line thermal limits,and the maximum number of customers per feeder.Real power losses are taken into account via a quadratic formulation and a piecewise linear approximation.Computational tests on a small-scale system and on a part of the Milano distribution network are reported.展开更多
The energy conservation plays an important role for low carbon development.In order to evaluate the energy conservation in the full life-cycle,a scheme to estimate the energy consumption,or alternatively the energy pa...The energy conservation plays an important role for low carbon development.In order to evaluate the energy conservation in the full life-cycle,a scheme to estimate the energy consumption,or alternatively the energy pay,in constructing an overhead transmission line is proposed in this paper.The analysis of a typical projection is given for demonstration.With new additional overhead transmission lines,the energy consumption,known as the power loss in power network,is expected to be decline,which is defined in this paper as the energy payback.In order to estimate this kind of contribution,the scheme that consisted of load forecast,production simulation for generating systems,load flow simulation and power loss calculation has been proposed.Case studies,based on the IEEE 24-bus test system,are given to demonstrate the efficacy of the schemes.Moreover,several presumptive scenarios are deployed and analysed with the presented schemes for comparison.展开更多
基金jointly supported by Youth Program of National Natural Science Foundation of China(No.51907100)Technical Program of Global Energy Interconnection Group Co.,Ltd(No.1100/2020-75001B)
文摘Electric system planning with high variable renewable energy(VRE)penetration levels has attracted great attention world-wide.Electricity production of VRE highly depends on the weather conditions and thus involves large variability,uncertainty,and low-capacity credit.This gives rise to significant challenges for power system planning.Currently,many solutions are proposed to address the issue of operational flexibility inadequacy,including flexibility retrofit of thermal units,inter-regional transmission,electricity energy storage,and demand response(DR).Evidently,the performance and the cost of various solutions are different.It is relevant to explore the optimal portfolio to satisfy the flexibility requirement for a renewable dominated system and the role of each flexibility source.In this study,the value of diverse DR flexibilities was examined and a stochastic investment planning model considering DR is proposed.Two types of DRs,namely interrupted DR and transferred DR,were modeled.Chronological load and renewable generation curves with 8760 hours within a whole year were reduced to 4 weekly scenarios to accelerate the optimization.Clustered unit commitment constraints for accommodating variability of renewables were incorporated.Case studies based on IEEE RTS-96 system are reported to demonstrate the effectiveness of the proposed method and the DR potential to avoid energy storage investment.
基金supported by State Key Laboratory of Electrical Insulation and Power Equipment(EIPE22119).
文摘In recent years,renewable energy(RE)penetration has become an important target in power systems.However,RE power is affected by climate change and has strong randomness and volatility.Adequate transmission capacity and energy storage systems(ESSs)are conducive to the integration of RE.Therefore,coordinated transmission renewable–storage expansion planning(TRSEP)is an effective decision-making approach to cope with the impacts of climate change and achieve the development tar-get of RE penetration.Electricity trading between different systems is common;therefore,in addition to the penetration of RE into the internal loads of the system,the proportion of RE generation in tie lines is gaining attention,making analyses of the RE transmission path necessary.Referring to the flow of carbon emissions,this paper defines the RE power flow density to track the transmission path of RE.Next,a TRSEP model is proposed that can clearly distinguish the RE transmission path into internal loads,exter-nal loads,and energy losses.To address the presence of bilinear terms in the proposed model,the McCormick method is applied,and a customized feasibility correction strategy is designed to obtain a good feasible solution.Numerical results from case studies are provided to verify the rationality and effectiveness of the approach proposed in this paper.
基金supported by the National Natural Science Foundation of China(No.52130702,No.52177093)。
文摘Under the pressure of environmental issues,decarbonization of the entire energy system has emerged as a prevalent strategy worldwide.The evolution of China’s power system will increasingly emphasize the integration of variable renewable energy(VRE).However,the rapid growth of VRE will pose substantial challenges to the power system,highlighting the importance of power system planning.This letter introduces Grid Optimal Planning Tool(GOPT),a planning tool,and presents the key findings of our research utilizing GOPT to analyze the transition pathway of China’s power system towards dual carbon goals.Furthermore,the letter offers insights into key technologies essential for driving the future transition of China’s power system.
基金supported by the Science and Technology Project of State Grid Corporation of China"The technology and application of model refinement and aggregation to support multi-level,multiagent and multiperiod dispatch"(5100-202099497A-0-0-00).
文摘The high penetration of variable renewable energy raises a flexibility challenge in the power system.This raises the necessity of considering the adequacy of flexibility in power system planning.However,the flexibility of the power system covers a wide range of timescales,from seconds to months.This poses difficulties in planning of multi-timescale flexible resources.This paper proposes a new perspective on the modeling and planning of multi-timescale flexible resources in power systems with high penetration of variable renewable energy.The operational boundaries of flexible resources are transformed into a characteristic domain,where flexibility at different timescales can be added and the balance of flexible supply and demand can be expressed as algebraic equations.Such modeling facilitates rigorous multi-timescale flexibility balance metrics.Furthermore,a planning method for multi-timescale flexibility is proposed based on the model in the characteristic domain.The proposed planning method is tested using data from China's Xinjiang provincial power grid.Results show the proposed method can characterize multi-timescale flexibility with high accuracy,thus making it possible to fully account for flexibility at different timescales.
文摘Concerning the integration of large-scale wind power,an integrated model of generation and transmission expansion planning is proposed based on the assessment of the value of steady state and dynamic security.In the assessment of security value,the unit commitment simulation based on the predicted hourly load and wind power output data in the planning horizon is used to evaluate the costs of preventive control,emergency control and social losses due to the uncertainty of load and wind power.The cost of preventive control consists of the fuel cost of power generation,the environmental cost and the load shedding cost.This not only provides a systematic method of security assessment of power system expansion planning schemes,but also broadens the perspective of power system planning from the technology and economic assessment to the measure of the whole social value.In the assessment process,the preventive control and emergency control of cascading failures are also presented,which provides a convincing tool for cascading failure analysis of planning schemes and makes the security assessment more comprehensive and reasonable.The proposed model and method have been demonstrated by the assessment of two power system planning schemes on the New England 10-genarator 39-bus System.The importance of considering the value of security and simulating hourly system operation for the planning horizon,in expansion planning of power system with integration of large-scale wind power,has been confirmed.
基金supported in part by the Carbon Neutrality and Energy System Transformation project and in part by EPSRC under Grant EP/Y025946/1.
文摘Renewable generation is rapidly increasing and transforming power systems toward“new-type power systems”.The integration of renewable energy resources necessitates a shift from conventional grid-following converters(GFLs)to advanced grid-forming controls.Although grid-forming converters(GFMs)provide grid support and enhance system stability under weak grid conditions,their deployment requires more robust hardware,complex control algorithms and system operation constraints,resulting in planning and operational trade-offs between system stability and cost efficiency.This paper studies the underexplored question of how many GFMs are needed from a techno-economic perspective.The holistic analysis integrates long-term planning,short-term operational strategies and dynamic stability considerations,thereby supporting large-scale renewable integration while ensuring system security and economic benefits.
基金supported in part by the National Key R&D Program of China(No.2022YFB2403300)in part by the Scientific&Technical Project of State Grid Shanghai Electric Power Company(No.SGSHDK00DWJS2310470)in part by the Scientific&Technical Project of China Electric Power Planning&Engineering Institute(No.K202316)。
文摘Adequacy is a key concern of power system planning,which refers to the availability of sufficient facilities to meet demand.The capacity value(CV)of variable renewable energy(VRE)generation represents its equivalent contribution to system adequacy,in comparison to conventional generators.While VRE continues to grow and increasingly dominates the generation portfolio,its CV is becoming non-negligible,with the corresponding impact mechanisms becoming more complicated and nuanced.In this paper,the concept of CV is revisited by analyzing how VRE contributes to power system balancing at a high renewable energy penetration level.A generalized loss function is incorporated into the CV evaluation framework considering the adequacy of the power system.An analytical method for the CV evaluation of VRE is then derived using the statistical properties of both hourly load and VRE generation.Through the explicit CV expression,several critical impact factors,including the VRE generation variance,source-load correlation,and system adequacy level,are identified and discussed.Case studies demonstrate the accuracy and effectiveness of the proposed method in comparison to the traditional capacity factor-based methods and convolution-based methods.In the IEEERTS79 test system,the CV of a 2500 MW wind farm(with40%renewable energy penetration level)is found to be 6.8%of its nameplate capacity.Additionally,the sensitivity of CV to various impact factors in power systems with high renewable energy penetration is analyzed.
基金supported by the National Nature Science Foundation of China,Grant No:U22B20104the International Science and Technology Cooperation Program of China,Grant No:2022YFE0129300.
文摘Multi-energy system(MES)is crucial for the development of smart cities.This paper summarises the research progress and achievements from an engineering case study in China which aims at enhancing MES energy efficiency.Key theories and technologies were tested at an MES demonstration site in Hunan,China,using both software and hardware systems which improve significantly in energy efficiency,carbon savings,environmental and economic benefits.Specifically,the optimal operation modes proposed in this paper achieves a best-case scenario of 9.97 tons of CO_(2) savings,26.4%lower than conventional systems.The findings provide crucial guidance for policymakers and industry stakeholders which aims to implement sustainable energy solutions in future urban planning.
文摘Following the deregulation of the power industry,transmission expansion planning(TEP)has become more complicated due to the presence of uncertainties and conflicting objectives in a market environment.Also,the growing concern on global warming highlights the importance of considering carbon pricing policies during TEP.In this paper,a probabilistic TEP approach is proposed with the integration of a chance constrained load curtailment index.The formulated dynamic programming problem is solved by a hybrid solution algorithm in an iterative process.The performance of our approach is demonstrated by case studies on a modified IEEE 14-bus system.Simulation results prove that our approach can provide network planners with comprehensive information regarding effects of uncertainties on TEP schemes,allowing them to adjust planning strategies based on their risk aversion levels or financial constraints.
基金This work was supported by the Pacific Northwest National Laboratory operated by Battelle for the U.S.Department of Energy under contract DE-AC05-76RL01830.
文摘voltage direct current(HVDC)transmission lines are being constructed throughout the world,aided by advancements in power electronics and the potential value to transfer power between distant areas and off-shore locations.Multiple HVDC lines within and across large AC interconnections could bring about economic benefits such as interregional capacity exchange and transfer of low-cost,distant electric energy directly to load centers.In addition,network configuration of HVDC lines could result in additional benefits that have not been deeply studied.This paper describes the modeling process for continentallevel power system interconnections with the addition of multiple HVDC lines configured as a macrogrid.The models used for study are based on industry-accepted power-flow and dynamic system models for the North American Eastern and Western Interconnections.The model provides insight on feasibility and initial steady-state and stability tests of the HVDC macrogrid and its interactions with the existing electricity infrastructure,opening the door to analysis of the technical value of such a macrogrid.
文摘We address the problem of optimally re-routing the feeders of urban distribution network in Milano,Italy,which presents some peculiarities and significant design challenges.Milano has two separate medium-voltage(MV)distribution networks,previously operated by two different utilities,which grew up independently and incoordinately.This results in a system layout which is inefficient,redundant,and difficult to manage due to different operating procedures.The current utility UNARETI,which is in charge of the overall distribution system,aims at optimally integrating the two MV distribution networks and moving to a new specific layout that offers advantages from the perspectives of reliability and flexibility.We present a mixed-integer programming(MIP)approach for the design of a new network configuration satisfying the so-called 2-step ladder layout required by the planner.The model accounts for the main electrical constraints such as power flow equations,thermal limits of high-voltage(HV)/MV substation transformers,line thermal limits,and the maximum number of customers per feeder.Real power losses are taken into account via a quadratic formulation and a piecewise linear approximation.Computational tests on a small-scale system and on a part of the Milano distribution network are reported.
基金This work was supported by the National Science Fund for Distinguished Young Scholars(No.51325702)the China Postdoctoral Science Foundation(No.2014M560968).
文摘The energy conservation plays an important role for low carbon development.In order to evaluate the energy conservation in the full life-cycle,a scheme to estimate the energy consumption,or alternatively the energy pay,in constructing an overhead transmission line is proposed in this paper.The analysis of a typical projection is given for demonstration.With new additional overhead transmission lines,the energy consumption,known as the power loss in power network,is expected to be decline,which is defined in this paper as the energy payback.In order to estimate this kind of contribution,the scheme that consisted of load forecast,production simulation for generating systems,load flow simulation and power loss calculation has been proposed.Case studies,based on the IEEE 24-bus test system,are given to demonstrate the efficacy of the schemes.Moreover,several presumptive scenarios are deployed and analysed with the presented schemes for comparison.
