Fully utilizing the flexibility provided by a district heating system(DHS)can promote wind power accommodation for an electric power system(EPS).However,for privacy or communication reasons,existing power and heat dis...Fully utilizing the flexibility provided by a district heating system(DHS)can promote wind power accommodation for an electric power system(EPS).However,for privacy or communication reasons,existing power and heat dispatch methods are not suitable for practical application.In this paper,a general math formulation of the hierarchical dispatch method is proposed to coordinate EPS and DHS operators based on the feasible region of boundary variables(FRBV),and a method based on the simplicial approximation approach is proposed to obtain a conservative FRBV approximation of a DHS.A simulation based on a real 41-node DHS is constructed to determine the factors that may impact the boundaries of the FRBV,and then the performance of the simplicial approximation approach is displayed by visualizing the approximation process for the FRBV,and finally three dispatch methods are compared to show the advantages of the proposed hierarchical dispatch method.展开更多
In northern China,thermal power units(TPUs)are important in improving the penetration level of renewable energy.In such areas,the potentials of coordinated dispatch of renewable energy sources(RESs)and TPUs can be bet...In northern China,thermal power units(TPUs)are important in improving the penetration level of renewable energy.In such areas,the potentials of coordinated dispatch of renewable energy sources(RESs)and TPUs can be better realized,if RESs and TPUs connected to the power grid at the same point of common coupling(PCC)are dispatched as a coupled system.Firstly,the definition of the coupled system is introduced,followed by an analysis on its characteristics.Secondly,based on the operation characteristics of deep peak regulation(DPR)of TPUs in the coupled system,the constraint of the ladder-type ramping rate applicable for day-ahead dispatch is proposed,and the corresponding flexible spinning reserve constraint is further established.Then,considering these constraints and peak regulation ancillary services,a day-ahead optimal dispatch model of the coupled system is established.Finally,the operational characteristics and advantages of the coupled system are analyzed in several case studies based on a real-world power grid in Liaoning province,China.The numerical results show that the coupled system can further improve the economic benefits of RESs and TPUs under the existing policies.展开更多
An integrated heat and power system(IHPS)is a promising approach for alleviating wind curtailment problems.In an IHPS,the combined heat and power(CHP)plant is the key component,which supplies both heat and electric lo...An integrated heat and power system(IHPS)is a promising approach for alleviating wind curtailment problems.In an IHPS,the combined heat and power(CHP)plant is the key component,which supplies both heat and electric loads,and couples the thermal system and power system.However,existing research commonly ignores or simplifies the internal composition of CHP plants,which could lead to some unavoidable errors.This paper focuses on the internal composition of CHP plants,and models the physical processes in different components and flexible resources in the CHP plant.Furthermore,a joint dispatch problem of an IHPS with the above CHP plant models is formulated,and an iterative algorithm is developed to handle the nonlinearity in this problem.Case studies are performed based on a real CHP plant in Northern China,and the results indicate that the synergistic effect of different energy resources in the CHP plant is realized by the joint dispatch model,which promotes wind power accommodation and reduces fossil fuel consumption.展开更多
1 Introduction Big data application services are very popular nowadays,but the traditional relational databases have become the bottleneck of service performance.NoSQL databases try to find a new way to solve big data...1 Introduction Big data application services are very popular nowadays,but the traditional relational databases have become the bottleneck of service performance.NoSQL databases try to find a new way to solve big data processing problem,which not only can store semi-structured and unstructured data,but also use distributed partition methods and give up traditional ACID properties to improve system performance.However,to carry out big data[1]analysis tasks better,multi-dimensional index[2]technology is demanding,which is not yet supported by most NoSQL databases[3].Since simple secondary index will degrade system query performance,it is a big challenge that how to apply multi-dimensional index to improve query efficiency while ensuring system performance.展开更多
Currently the flexible demand for high proportion penetration of renewable energy depends on coal-fired units(CFUs),and the large-scale phase-out of CFUs in a short time is not realistic in China.Due to urban expansio...Currently the flexible demand for high proportion penetration of renewable energy depends on coal-fired units(CFUs),and the large-scale phase-out of CFUs in a short time is not realistic in China.Due to urban expansion,approximately 458 Chinese coal-fired power plants(CFPPs)are now located in cities.Limited by space,urban CFUs face difficulty in becoming equipped with carbon capture and storage systems.This presents a sizeable challenge for the low-carbon transition of urban CFPPs and carbon neutral processes.Here,we present a ready-to-implement method to reduce the carbon emission of CFPPs in limited space:roof photovoltaic-assisted power generation combined with sludge cocombustion for coal-fired power generation systems(PVSCs).We also consider nonurban CFPPs with the method of roof photovoltaic-assisted power generation(PVs)only.Based on remaining life cycle analysis,we find that the PVSCs could save 28.47 Mt of coal,reduce CO_(2)emissions by 69.76 Mt,treat 125.70 Mt of sludge,and also generate 12.08 billion RMB worth of electricity revenue per year.In addition,our scenario analysis shows that PVSCs are more profitable when choosing an urban CFU with a remaining life of more than 12 years and while the sludge treatment subsidy is set at 100 RMB t1.Under strict and lenient CFU decommissioning policies,CFUs with a remaining life of between 19 and 30 years and between 13 and 24 years should be selected for PVs,respectively.Thus,we conclude that PVSCs can not only generate economic benefits but also facilitate carbon reduction and solid waste treatment.展开更多
基金This work was supported by the National Key Research and Development Program of China under Grant 2017YFB0902100 and State Grid Corporation of China.
文摘Fully utilizing the flexibility provided by a district heating system(DHS)can promote wind power accommodation for an electric power system(EPS).However,for privacy or communication reasons,existing power and heat dispatch methods are not suitable for practical application.In this paper,a general math formulation of the hierarchical dispatch method is proposed to coordinate EPS and DHS operators based on the feasible region of boundary variables(FRBV),and a method based on the simplicial approximation approach is proposed to obtain a conservative FRBV approximation of a DHS.A simulation based on a real 41-node DHS is constructed to determine the factors that may impact the boundaries of the FRBV,and then the performance of the simplicial approximation approach is displayed by visualizing the approximation process for the FRBV,and finally three dispatch methods are compared to show the advantages of the proposed hierarchical dispatch method.
基金supported in part by the National Key Research and Development Program of China(No.2019YFB1505400).
文摘In northern China,thermal power units(TPUs)are important in improving the penetration level of renewable energy.In such areas,the potentials of coordinated dispatch of renewable energy sources(RESs)and TPUs can be better realized,if RESs and TPUs connected to the power grid at the same point of common coupling(PCC)are dispatched as a coupled system.Firstly,the definition of the coupled system is introduced,followed by an analysis on its characteristics.Secondly,based on the operation characteristics of deep peak regulation(DPR)of TPUs in the coupled system,the constraint of the ladder-type ramping rate applicable for day-ahead dispatch is proposed,and the corresponding flexible spinning reserve constraint is further established.Then,considering these constraints and peak regulation ancillary services,a day-ahead optimal dispatch model of the coupled system is established.Finally,the operational characteristics and advantages of the coupled system are analyzed in several case studies based on a real-world power grid in Liaoning province,China.The numerical results show that the coupled system can further improve the economic benefits of RESs and TPUs under the existing policies.
基金supported by the National Key Research and Development Program of China under Grant 2017YFB0902100.
文摘An integrated heat and power system(IHPS)is a promising approach for alleviating wind curtailment problems.In an IHPS,the combined heat and power(CHP)plant is the key component,which supplies both heat and electric loads,and couples the thermal system and power system.However,existing research commonly ignores or simplifies the internal composition of CHP plants,which could lead to some unavoidable errors.This paper focuses on the internal composition of CHP plants,and models the physical processes in different components and flexible resources in the CHP plant.Furthermore,a joint dispatch problem of an IHPS with the above CHP plant models is formulated,and an iterative algorithm is developed to handle the nonlinearity in this problem.Case studies are performed based on a real CHP plant in Northern China,and the results indicate that the synergistic effect of different energy resources in the CHP plant is realized by the joint dispatch model,which promotes wind power accommodation and reduces fossil fuel consumption.
基金This work was supported by the National Natural Science Foundation of China(Grant No.61972209).
文摘1 Introduction Big data application services are very popular nowadays,but the traditional relational databases have become the bottleneck of service performance.NoSQL databases try to find a new way to solve big data processing problem,which not only can store semi-structured and unstructured data,but also use distributed partition methods and give up traditional ACID properties to improve system performance.However,to carry out big data[1]analysis tasks better,multi-dimensional index[2]technology is demanding,which is not yet supported by most NoSQL databases[3].Since simple secondary index will degrade system query performance,it is a big challenge that how to apply multi-dimensional index to improve query efficiency while ensuring system performance.
基金the National Key R&D Program of China(No.2019YFB1505400).
文摘Currently the flexible demand for high proportion penetration of renewable energy depends on coal-fired units(CFUs),and the large-scale phase-out of CFUs in a short time is not realistic in China.Due to urban expansion,approximately 458 Chinese coal-fired power plants(CFPPs)are now located in cities.Limited by space,urban CFUs face difficulty in becoming equipped with carbon capture and storage systems.This presents a sizeable challenge for the low-carbon transition of urban CFPPs and carbon neutral processes.Here,we present a ready-to-implement method to reduce the carbon emission of CFPPs in limited space:roof photovoltaic-assisted power generation combined with sludge cocombustion for coal-fired power generation systems(PVSCs).We also consider nonurban CFPPs with the method of roof photovoltaic-assisted power generation(PVs)only.Based on remaining life cycle analysis,we find that the PVSCs could save 28.47 Mt of coal,reduce CO_(2)emissions by 69.76 Mt,treat 125.70 Mt of sludge,and also generate 12.08 billion RMB worth of electricity revenue per year.In addition,our scenario analysis shows that PVSCs are more profitable when choosing an urban CFU with a remaining life of more than 12 years and while the sludge treatment subsidy is set at 100 RMB t1.Under strict and lenient CFU decommissioning policies,CFUs with a remaining life of between 19 and 30 years and between 13 and 24 years should be selected for PVs,respectively.Thus,we conclude that PVSCs can not only generate economic benefits but also facilitate carbon reduction and solid waste treatment.
