The increasing adoption of gas-fired power plants directly strengthens the coupling between electric power and natural gas systems. Current industrial practice in optimal power flow for electric power systems has not ...The increasing adoption of gas-fired power plants directly strengthens the coupling between electric power and natural gas systems. Current industrial practice in optimal power flow for electric power systems has not taken the security constraints of gas systems into consideration, resulting in an overly-optimistic solution. Meanwhile, the operation of electric power and natural gas systems is coupled over multiple periods because of the ramp rate limits of power generators and the slow dynamical characteristics of gas systems. Based on these motivations, we propose a multi-period integrated natural gas and electric power system probabilistic optimal power flow(M-GEPOPF) model, which includes dynamic gas flow models. To address the uncertainties originating from wind power and load forecasting, a probabilistic optimal power flow(POPF) calculation based on a three-point estimate method(3 PEM) is adopted. Moreover, power-togas(Pt G) units are employed to avoid wind power curtailment and enable flexible bi-directional energy flows between the coupled energy systems. An integrated IEEE RTS 24-bus electric power system and the Belgian 20-node natural gas system are employed as a test case to verify the applicability of the proposed M-GEPOPF model, and to demonstrate the potential economic benefits of Pt G units.展开更多
The increasing interdependency of electricity and natural gas systems promotes coordination of the two systems for ensuring operational security and economics.This paper proposes a robust day-ahead scheduling model fo...The increasing interdependency of electricity and natural gas systems promotes coordination of the two systems for ensuring operational security and economics.This paper proposes a robust day-ahead scheduling model for the optimal coordinated operation of integrated energy systems while considering key uncertainties of the power system and natural gas system operation cost. Energy hub,with collocated gas-fired units, power-to-gas(Pt G) facilities, and natural gas storages, is considered to store or convert one type of energy(i.e., electricity or natural gas)into the other form, which could analogously function as large-scale electrical energy storages. The column-andconstraint generation(C&CG) is adopted to solve the proposed integrated robust model, in which nonlinear natural gas network constraints are reformulated via a set of linear constraints. Numerical experiments signify the effectiveness of the proposed model for handling volatile electrical loads and renewable generations via the coordinated scheduling of electricity and natural gas systems.展开更多
Power-to-Gas(P2G)plays an important role in enhancing large-scale renewable energy integration in power systems.As an emerging inter-disciplinary subject,P2G technology requires knowledge in electrochemistry,electrica...Power-to-Gas(P2G)plays an important role in enhancing large-scale renewable energy integration in power systems.As an emerging inter-disciplinary subject,P2G technology requires knowledge in electrochemistry,electrical engineering,thermodynamic engineering,chemical engineering and system engineering.Aiming at P2G modeling and operational problems concerning the research field of power systems and the energy internet,this paper briefly reviews the main technologies and application potentials of the P2G system,and makes systematic summaries of major progresses related to P2G’s integration into the power grid in a bottom-top manner,including the modeling of high/room-temperature electrolysis cells,steady-state/dynamic optimization control of the P2G system,P2G’s integrated model and operational strategies at the grid level.In the final part of this paper,suggestions are put forward on future research directions of P2G systems from the aspects of modeling and operational optimization.展开更多
Concerning the rapid development and deployment of Renewable Energy Systems(RES)and Energy Storage System(ESS)including Power-to-Gas(PtG)technology can significantly improve the friendliness of the integration of rene...Concerning the rapid development and deployment of Renewable Energy Systems(RES)and Energy Storage System(ESS)including Power-to-Gas(PtG)technology can significantly improve the friendliness of the integration of renewable energy.The purpose of this paper is to develop a coordination strategy between a battery energy storage and a PtG system.A simulation case is created with an electrical and a natural gas grid as well as steady-state models of RES and PtG.Charging strategies are developed accordingly for the ESS as well as production strategies for the PtG system.The size of the ESS is then observed with regards to the RES and PtG systems.As a result,it is found that surplus energy from RES can be stored and then used to support the electrical grid and the natural gas grid.It is also concluded that the capacity of the ESS can be affected,given a proper charging and production strategy,which needs to be tailored to each system.As shown in the paper,due to an improper charging strategy in the first quarter of a month,the ESSPC size has increased from its optimal size of 314 MWh to roughly 576 MWh.It can also be seen that given a proper charging strategy,this capacity can be less than 200 MWh.展开更多
With the widespread penetration of renewable energy sources and energy storage systems,the problem of energy management has received increasing attention.One of the systems that network owners consider today is the po...With the widespread penetration of renewable energy sources and energy storage systems,the problem of energy management has received increasing attention.One of the systems that network owners consider today is the power-to-gas(P2G)system.This system causes surplus electricity generated from renewable energy resources or batteries in the network to be converted into gas and sold to the gas network.Two reasons for the existence of gas distributed generation resources and P2G systems cause the two power and gas networks to interact.Energy management and profit making considering these two networks,as a co-optimization of integrated energy systems,is a topic that has been discussed in this study to achieve the best optimal answer.Since the production of renewable energy resources and the purchase price of energy are uncertain,a scenario-based method has been chosen for modelling.Demand-side management is also one of the important problems in optimal operation of the electricity network,which can have a significant impact on reducing peak load and increasing profits.In this paper,a mixed-integer quadratic programming model for co-optimization of electric distribution and gas networks in the presence of distributed generation resources,P2G systems,storage facilities,electric vehicles and demand-side management is presented.The 33-bus distribution network is intended to analyse the proposed model.The results of different scenarios show the efficiency of the proposed model.Several key points are deduced from the obtained results:(i)demand-side management is able to reduce the peak load of the network,(ii)the presence of renewable resources and batteries can cause the network to convert excess electricity into gas and sell it to the gas network in the market and(iii)distributed generation can reduce the purchase of energy from the upstream network and cause a 36% reduction in the cost function.展开更多
Integrated energy systems(IESs)can improve energy efficiency and reduce carbon emissions,essential for achieving peak carbon emissions and carbon neutrality.This study investigated the characteristics of the CHP model...Integrated energy systems(IESs)can improve energy efficiency and reduce carbon emissions,essential for achieving peak carbon emissions and carbon neutrality.This study investigated the characteristics of the CHP model considering P2G and carbon capture systems,and a two-stage robust optimization model of the electricity-heat-gascold integrated energy system was developed.First,a CHP model considering the P2G and carbon capture system was established,and the electric-thermal coupling characteristics and P2G capacity constraints of the model were derived,which proved that the model could weaken the electric-thermal coupling characteristics,increase the electric power regulation range,and reduce carbon emissions.Subsequently,a two-stage robust optimal scheduling model of an IES was constructed,in which the objective function in the day-ahead scheduling stage was to minimize the start-up and shutdown costs.The objective function in the real-time scheduling stage was to minimize the equipment operating costs,carbon emission costs,wind curtailment,and solar curtailment costs,considering multiple uncertainties.Finally,after the objective function is linearized with a ψ-piecewise method,the model is solved based on the C&CG algorithm.Simulation results show that the proposed model can effectively absorb renewable energy and reduce the total cost of the system.展开更多
In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evalu...In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated.It is shown,that Pr^(3+)ions can substitute Ce^(4+)ones in the support lattice,thereby introducing a high population of oxygen vacancies,which act as active sites for CO_(2) chemisorption.Pr doping can also act to reduce the crystallite size of metallic Ni,thus promoting the active metal dispersion.Catalytic performance evaluation evidences the promoting effect of low Pr loadings(5 at%and 10 at%)towards a higher catalytic activity and lower CO_(2) activation energy.On the other hand,higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population,thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.展开更多
With increasing reforms related to integrated energy systems(IESs),each energy subsystem,as a participant based on bounded rationality,significantly influences the optimal scheduling of the entire IES through mutual l...With increasing reforms related to integrated energy systems(IESs),each energy subsystem,as a participant based on bounded rationality,significantly influences the optimal scheduling of the entire IES through mutual learning and imitation.A reasonable multiagent joint operation strategy can help this system meet its low-carbon objectives.This paper proposes a bilayer low-carbon optimal operational strategy for an IES based on the Stackelberg master-slave game and multiagent joint operation.The studied IES includes cogeneration,power-to-gas,and carbon capture systems.Based on the Stackelberg master-slave game theory,sellers are used as leaders in the upper layer to set the prices of electricity and heat,while energy producers,energy storage providers,and load aggregators are used as followers in the lower layer to adjust the operational strategy of the system.An IES bilayer optimization model based on the Stackelberg master-slave game was developed.Finally,the Karush-Kuhn-Tucker(KKT)condition and linear relaxation technology are used to convert the bilayer game model to a single layer.CPLEX,which is a mathematical program solver,is used to solve the equilibrium problem and the carbon emission trading cost of the system when the benefits of each subject reach maximum and to analyze the impact of different carbon emission trading prices and growth rates on the operational strategy of the system.As an experimental demonstration,we simulated an IES coupled with an IEEE 39-node electrical grid system,a six-node heat network system,and a six-node gas network system.The simulation results confirm the effectiveness and feasibility of the proposed model.展开更多
Power-to-gas technology uses temporary surplus electricity to create either renewable hydrogen or renewable natural gas,which can then be stored in natural-gas pipelines and used when needed.As a result,P2G transforms...Power-to-gas technology uses temporary surplus electricity to create either renewable hydrogen or renewable natural gas,which can then be stored in natural-gas pipelines and used when needed.As a result,P2G transforms conventional one-way coupling of a power/heat/natural-gas system into twoway coupling.Furthermore,its operating characteristics makes it possible to more effectively utilize wind-power.This paper describes a new optimal dispatch model for integrated electricity/gas/heat energy systems.The model considers the effective use of surplus wind-energy with electricity-to-gas equipment.First,a multi-energy network model is built,taking into account both equipment and network constraints.Then,we apply a novel two-layer optimization method,which uses P2G,to“absorb”wind power.While the top-layer model is used for the dayahead dispatch of the natural-gas network containing P2G,the bottom-layer model describes the day-ahead economic dispatch of the electricity/heat system,which includes wind power.Based on the Karush-Kuhn-Tucher conditions of the bottom-layer model,the two-layer model is transformed into a single-layer model,and we linearize the nonlinear equation to convert the nonlinear model into a mix-integer linear programming problem,which is solvable using the General Algebraic Modeling System.Finally,numerical case-studies are performed to evaluate the accuracy and effectiveness of the proposed method.展开更多
By optimal sizing of a wind/photovoltaic hybrid renewable-energy(RE)system,trimming the surplus capacity to reduce the fluctuations in the electricity supplied to the grid,and using it to produce green hydrogen throug...By optimal sizing of a wind/photovoltaic hybrid renewable-energy(RE)system,trimming the surplus capacity to reduce the fluctuations in the electricity supplied to the grid,and using it to produce green hydrogen through electrolysis,a stable output with maximum possible capacity factor(CF)is generated to maintain the electricity grid stability.Simultaneously,the trimmed energy is used in a secondary conversion path that minimizes the weighted average cost of the energy generated from the entire plant.This surplus power-to-gas conversion allows the use of green hydrogen to produce electricity,methanol,or ammonia subject to the resource availability,site characteristics,and financial feasibility.Based on robust site selection criteria,the best performance is obtained at two sites:Ras Ghareb and Minya,achieving the lowest energy cost with some variance in their performance.For the Ras Ghareb site,the optimally sized RE plant provided the grid with a quasi-steady capacity of 423 MW with a CF of 80.04%and was capable of injecting 2965.8648 GWh throughout the year with the lowest cost of 2.4355¢/kWh.A surplus of 3.9%of the total energy produced from the plant was directed to produce 1922-ton H_(2)/year,achieving the lowest cost of hydrogen production of$1.9745/kg H_(2).For the other selected site,Minya,the clipped energy is used to produce 3330.47-ton H_(2)/year with an optimized lowest cost of$3.5268/kg H_(2).The difference in hydrogen costs was attributed to the number of full operating hours of the electrolyser in both sites.The cost is mainly affected by the electricity price and the electrolyser cost.With both tending to decrease,future forecasts show hydrogen cost reductions.展开更多
To enhance multi-energy complementarity and foster a low carbon economy of energy resources,this paper proposes an innovative low-carbon operation opti-mization method for electric-thermal-gas regional inte-grated ene...To enhance multi-energy complementarity and foster a low carbon economy of energy resources,this paper proposes an innovative low-carbon operation opti-mization method for electric-thermal-gas regional inte-grated energy systems.To bolster the low-carbon operation capabilities of such systems,a coordinated operation framework is presented that integrates carbon capture devices,power to gas equipment,combined heat and power units,and a multi-energy storage system.To address the challenge of high-dimensional constraint imbalance in the optimization process,a novel low-carbon operation opti-mization method is then proposed.The new method is based on an adaptive single-objective continuous optimiza-tion spiking neural P system,specifically designed for this purpose.Furthermore,simulation models of four typical schemes are established and employed to test and analyze the economy and carbon environmental pollution degree of the proposed system model,as well as the performance of the operation optimization method.Finally,simulation results show that the proposed method not only considers the economic viability of the target integrated energy sys-tem,but also significantly improves the wind power utilization and carbon reduction capabilities.展开更多
As the proportion of wind power generation increases in power systems,it is necessary to develop new ways for wind power accommodation and improve the existing power dispatch model.The power-to-gas technology,which of...As the proportion of wind power generation increases in power systems,it is necessary to develop new ways for wind power accommodation and improve the existing power dispatch model.The power-to-gas technology,which offers a new approach to accommodate surplus wind power,is an excellent way to solve the former.Hence,this paper proposes to involve power-to-gas technology in the integrated electricity and natural gas systems(IEGSs).To solve the latter,on one hand,a new indicator,the scale factor of wind power integration,is introduced into the wind power stochastic model to better describe the uncertainty of grid-connected wind power;on the other hand,for quantizing and minimizing the impact of the uncertainties of wind power and system loads on system security,security risk constraints are established for the IEGS by the conditional value-at-risk method.By considering these two aspects,an MILP formulation of a security-risk based stochastic dynamic economic dispatch model for an IEGS is established,and GUROBI obtained from GAMS is used for the solution.Case studies are conducted on an IEGS consisting of a modified IEEE 39-bus system and the Belgium 20-node natural gas system to examine the effectiveness of the proposed dispatch model.展开更多
Multiple energy carriers can be coupled as an Integrated Energy System (IES) through interconnection tech- nologies. Unexpected risks will be transferred with the growing coupling of energy systems, mainly stemming fr...Multiple energy carriers can be coupled as an Integrated Energy System (IES) through interconnection tech- nologies. Unexpected risks will be transferred with the growing coupling of energy systems, mainly stemming from the uncertain- ties in different energy sectors. It is imperative to coordinate the operation of different energy systems to improve energy efficiency and ensure energy security. With the close integration of different energy systems, it is necessary to couple these different energy markets to achieve the holistic energy supply economy. On the other hand, uncertainties in the energy systems will bring the financial risk for the operator of IES. A risk-averse stochastic market clearing model for the IES is proposed to study the operating strategy aiming at minimizing the operation cost. While the financial risk imposed by the wind power uncertainties is restricted to a predefined level. Simulations results are provided to verify that the proposed model can improve market efficiency and handle the trade-off between cost and risk.展开更多
Together with a huge number of other countries, Germany signed the Paris Agreements in 2015 to prevent global temperature increase above 2℃. Within this agreement, all countries defined their own national contributio...Together with a huge number of other countries, Germany signed the Paris Agreements in 2015 to prevent global temperature increase above 2℃. Within this agreement, all countries defined their own national contributions to CO2 reduction. Since that, it was visible that CO2 emissions in Germany decreased, but not so fast than proposed in this German nationally determined contribution to the Paris Agreement. Due to increasing traffic, CO2 emissions from this mobility sector increased and CO2 emission from German power generation is nearly constant for the past 20 years, even a renewable generation capacity of 112 GW was built up in 2017, which is much higher than the peak load of 84 GW in Germany. That is why the German National Government has implemented a commission (often called "The German Coal Commission") to propose a time line: how Germany can move out of coal-fired power stations. This "Coal Commission" started its work in the late spring of 2018 and handed over its final report with 336 pages to the government on January 26th, 2019. Within this report the following proposals were made:①Until 2022: Due to a former decision of the German Government, the actual remaining nuclear power generation capacity of about 10 GW has to be switched off in 2022. Besides, the "Coal Commission" proposed to switch off additionally in total 12.5 GW of both, hard coal and lignite-fired power plants, so that Germany should reduce its conventional generation capacity by 22.5 GW in 2022.②Until 2030: Another 13 GW of German hard coal or lignite-fired power plants should be switched off.③Until 2038:The final 17 GW of German hard coal or lignitefired power plants should be switched off until 2038 latest. Unfortunately the "Coal Commission" has not investigated the relevant technical parameter to ensure a secured electric power supply, based on German's own national resources. Because German Energy Revolution mainly is based on wind energy and photovoltaic, this paper will describe the negligible contribution of these sources to the secured generation capacity, which will be needed for a reliable power supply. In addition, it will discuss several technical options to integrate wind energy and photovoltaic into a secured power supply system with an overall reduced CO2 emission.展开更多
As a form of hybrid multi-energy systems,the integrated energy system contains different forms of energy such as power,thermal,and gas which meet the load of various energy forms.Focusing mainly on model building and ...As a form of hybrid multi-energy systems,the integrated energy system contains different forms of energy such as power,thermal,and gas which meet the load of various energy forms.Focusing mainly on model building and optimal operation of the integrated energy system,in this paper,the dist-flow method is applied to quickly calculate the power flow and the gas system model is built by the analogy of the power system model.In addition,the piecewise linearization method is applied to solve the quadratic Weymouth gas flow equation,and the alternating direction method of multipliers(ADMM)method is applied to narrow the optimal results of each subsystem at the coupling point.The entire system reaches its optimal operation through multiple iterations.The power-thermal-gas integrated energy system used in the case study includes an IEEE-33 bus power system,a Belgian 20 node natural gas system,and a six node thermal system.Simulation-based calculations and comparison of the results under different scenarios prove that the power-thermal-gas integrated energy system enhances the flexibility and stability of the system as well as reducing system operating costs to some extent.展开更多
The integrated energy system is an important development direction for achieving energy transformation in the context of the low-carbon development era,and an integrated energy system that uses renewable energy can re...The integrated energy system is an important development direction for achieving energy transformation in the context of the low-carbon development era,and an integrated energy system that uses renewable energy can reduce carbon emissions and improve energy utilization efficiency.The electric power network and the natural gas network are important transmission carriers in the en-ergy field,so the coupling relationship between them has been of wide concern.This paper establishes an integrated energy system considering electricity,gas,heat and hydrogen loads;takes each subject in the integrated energy system as the research object;anal-yses the economic returns of each subject under different operation modes;applies the Shapley value method for benefit allocation;and quantifies the contribution value of the subject to the alliance through different influencing factors to revise the benefit allocation value.Compared with the independent mode,the overall benefits of the integrated energy system increase in the cooperative mode and the benefits of all subjects increase.Due to the different characteristics of different subjects in terms of environmental benefits,collaborative innovation and risk sharing,the benefit allocation is reduced for new-energy subjects and increased for power-to-gas sub-jects and combined heat and power generation units after revising the benefit allocation,to improve the matching degree between the contribution level and the benefit allocation under the premise of increased profit for each subject.The cooperative mode effectively enhances the economic benefits of the system as a whole and individually,and provides a useful reference for the allocation of benefits of integrated energy systems.The analysis shows that the revised benefit distribution under the cooperative model increases by 3.86%,4.08%and 3.13%for power-to-gas subjects,combined heat and power generation units,and new-energy units,respectively,compared with the independent function model.展开更多
基金supported by the National Natural Science Foundation of China(No.51277052,No.51407125)
文摘The increasing adoption of gas-fired power plants directly strengthens the coupling between electric power and natural gas systems. Current industrial practice in optimal power flow for electric power systems has not taken the security constraints of gas systems into consideration, resulting in an overly-optimistic solution. Meanwhile, the operation of electric power and natural gas systems is coupled over multiple periods because of the ramp rate limits of power generators and the slow dynamical characteristics of gas systems. Based on these motivations, we propose a multi-period integrated natural gas and electric power system probabilistic optimal power flow(M-GEPOPF) model, which includes dynamic gas flow models. To address the uncertainties originating from wind power and load forecasting, a probabilistic optimal power flow(POPF) calculation based on a three-point estimate method(3 PEM) is adopted. Moreover, power-togas(Pt G) units are employed to avoid wind power curtailment and enable flexible bi-directional energy flows between the coupled energy systems. An integrated IEEE RTS 24-bus electric power system and the Belgian 20-node natural gas system are employed as a test case to verify the applicability of the proposed M-GEPOPF model, and to demonstrate the potential economic benefits of Pt G units.
基金supported in part by the U.S.National Science Foundation Grant(No.CMMI-1635339)
文摘The increasing interdependency of electricity and natural gas systems promotes coordination of the two systems for ensuring operational security and economics.This paper proposes a robust day-ahead scheduling model for the optimal coordinated operation of integrated energy systems while considering key uncertainties of the power system and natural gas system operation cost. Energy hub,with collocated gas-fired units, power-to-gas(Pt G) facilities, and natural gas storages, is considered to store or convert one type of energy(i.e., electricity or natural gas)into the other form, which could analogously function as large-scale electrical energy storages. The column-andconstraint generation(C&CG) is adopted to solve the proposed integrated robust model, in which nonlinear natural gas network constraints are reformulated via a set of linear constraints. Numerical experiments signify the effectiveness of the proposed model for handling volatile electrical loads and renewable generations via the coordinated scheduling of electricity and natural gas systems.
基金This work was supported by the Key Program for International S&T Cooperation Projects of China(2016YFE0102600)National Natural Science Foundation of China(51577096,51761135015)National Key Research and Development Program of China(2018YFB0905200).
文摘Power-to-Gas(P2G)plays an important role in enhancing large-scale renewable energy integration in power systems.As an emerging inter-disciplinary subject,P2G technology requires knowledge in electrochemistry,electrical engineering,thermodynamic engineering,chemical engineering and system engineering.Aiming at P2G modeling and operational problems concerning the research field of power systems and the energy internet,this paper briefly reviews the main technologies and application potentials of the P2G system,and makes systematic summaries of major progresses related to P2G’s integration into the power grid in a bottom-top manner,including the modeling of high/room-temperature electrolysis cells,steady-state/dynamic optimization control of the P2G system,P2G’s integrated model and operational strategies at the grid level.In the final part of this paper,suggestions are put forward on future research directions of P2G systems from the aspects of modeling and operational optimization.
文摘Concerning the rapid development and deployment of Renewable Energy Systems(RES)and Energy Storage System(ESS)including Power-to-Gas(PtG)technology can significantly improve the friendliness of the integration of renewable energy.The purpose of this paper is to develop a coordination strategy between a battery energy storage and a PtG system.A simulation case is created with an electrical and a natural gas grid as well as steady-state models of RES and PtG.Charging strategies are developed accordingly for the ESS as well as production strategies for the PtG system.The size of the ESS is then observed with regards to the RES and PtG systems.As a result,it is found that surplus energy from RES can be stored and then used to support the electrical grid and the natural gas grid.It is also concluded that the capacity of the ESS can be affected,given a proper charging and production strategy,which needs to be tailored to each system.As shown in the paper,due to an improper charging strategy in the first quarter of a month,the ESSPC size has increased from its optimal size of 314 MWh to roughly 576 MWh.It can also be seen that given a proper charging strategy,this capacity can be less than 200 MWh.
文摘With the widespread penetration of renewable energy sources and energy storage systems,the problem of energy management has received increasing attention.One of the systems that network owners consider today is the power-to-gas(P2G)system.This system causes surplus electricity generated from renewable energy resources or batteries in the network to be converted into gas and sold to the gas network.Two reasons for the existence of gas distributed generation resources and P2G systems cause the two power and gas networks to interact.Energy management and profit making considering these two networks,as a co-optimization of integrated energy systems,is a topic that has been discussed in this study to achieve the best optimal answer.Since the production of renewable energy resources and the purchase price of energy are uncertain,a scenario-based method has been chosen for modelling.Demand-side management is also one of the important problems in optimal operation of the electricity network,which can have a significant impact on reducing peak load and increasing profits.In this paper,a mixed-integer quadratic programming model for co-optimization of electric distribution and gas networks in the presence of distributed generation resources,P2G systems,storage facilities,electric vehicles and demand-side management is presented.The 33-bus distribution network is intended to analyse the proposed model.The results of different scenarios show the efficiency of the proposed model.Several key points are deduced from the obtained results:(i)demand-side management is able to reduce the peak load of the network,(ii)the presence of renewable resources and batteries can cause the network to convert excess electricity into gas and sell it to the gas network in the market and(iii)distributed generation can reduce the purchase of energy from the upstream network and cause a 36% reduction in the cost function.
基金supported by the National Natural Science Foundation of China(Grant number 51977154)。
文摘Integrated energy systems(IESs)can improve energy efficiency and reduce carbon emissions,essential for achieving peak carbon emissions and carbon neutrality.This study investigated the characteristics of the CHP model considering P2G and carbon capture systems,and a two-stage robust optimization model of the electricity-heat-gascold integrated energy system was developed.First,a CHP model considering the P2G and carbon capture system was established,and the electric-thermal coupling characteristics and P2G capacity constraints of the model were derived,which proved that the model could weaken the electric-thermal coupling characteristics,increase the electric power regulation range,and reduce carbon emissions.Subsequently,a two-stage robust optimal scheduling model of an IES was constructed,in which the objective function in the day-ahead scheduling stage was to minimize the start-up and shutdown costs.The objective function in the real-time scheduling stage was to minimize the equipment operating costs,carbon emission costs,wind curtailment,and solar curtailment costs,considering multiple uncertainties.Finally,after the objective function is linearized with a ψ-piecewise method,the model is solved based on the C&CG algorithm.Simulation results show that the proposed model can effectively absorb renewable energy and reduce the total cost of the system.
基金support of this work by the project“Development of new innovative low carbon energy technologies to improve excellence in the Region of Western Macedonia”(MIS 5047197)which is implemented under the Action“Reinforcement of the Research and Innovation Infrastructure”funded by the Operational Program“Competitiveness,Entrepreneurship and Innovation”(NSRF 2014-2020)co-financed by Greece and the European Union(European Regional Development Fund)。
文摘In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated.It is shown,that Pr^(3+)ions can substitute Ce^(4+)ones in the support lattice,thereby introducing a high population of oxygen vacancies,which act as active sites for CO_(2) chemisorption.Pr doping can also act to reduce the crystallite size of metallic Ni,thus promoting the active metal dispersion.Catalytic performance evaluation evidences the promoting effect of low Pr loadings(5 at%and 10 at%)towards a higher catalytic activity and lower CO_(2) activation energy.On the other hand,higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population,thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.
基金supported by the National Natural Science Foundation of China(Grant No.62063016)。
文摘With increasing reforms related to integrated energy systems(IESs),each energy subsystem,as a participant based on bounded rationality,significantly influences the optimal scheduling of the entire IES through mutual learning and imitation.A reasonable multiagent joint operation strategy can help this system meet its low-carbon objectives.This paper proposes a bilayer low-carbon optimal operational strategy for an IES based on the Stackelberg master-slave game and multiagent joint operation.The studied IES includes cogeneration,power-to-gas,and carbon capture systems.Based on the Stackelberg master-slave game theory,sellers are used as leaders in the upper layer to set the prices of electricity and heat,while energy producers,energy storage providers,and load aggregators are used as followers in the lower layer to adjust the operational strategy of the system.An IES bilayer optimization model based on the Stackelberg master-slave game was developed.Finally,the Karush-Kuhn-Tucker(KKT)condition and linear relaxation technology are used to convert the bilayer game model to a single layer.CPLEX,which is a mathematical program solver,is used to solve the equilibrium problem and the carbon emission trading cost of the system when the benefits of each subject reach maximum and to analyze the impact of different carbon emission trading prices and growth rates on the operational strategy of the system.As an experimental demonstration,we simulated an IES coupled with an IEEE 39-node electrical grid system,a six-node heat network system,and a six-node gas network system.The simulation results confirm the effectiveness and feasibility of the proposed model.
基金sponsored by Shanghai Sailing Program(20YF1418800)Outstanding PhD Graduate Development Scholarship of Shanghai Jiao Tong University.
文摘Power-to-gas technology uses temporary surplus electricity to create either renewable hydrogen or renewable natural gas,which can then be stored in natural-gas pipelines and used when needed.As a result,P2G transforms conventional one-way coupling of a power/heat/natural-gas system into twoway coupling.Furthermore,its operating characteristics makes it possible to more effectively utilize wind-power.This paper describes a new optimal dispatch model for integrated electricity/gas/heat energy systems.The model considers the effective use of surplus wind-energy with electricity-to-gas equipment.First,a multi-energy network model is built,taking into account both equipment and network constraints.Then,we apply a novel two-layer optimization method,which uses P2G,to“absorb”wind power.While the top-layer model is used for the dayahead dispatch of the natural-gas network containing P2G,the bottom-layer model describes the day-ahead economic dispatch of the electricity/heat system,which includes wind power.Based on the Karush-Kuhn-Tucher conditions of the bottom-layer model,the two-layer model is transformed into a single-layer model,and we linearize the nonlinear equation to convert the nonlinear model into a mix-integer linear programming problem,which is solvable using the General Algebraic Modeling System.Finally,numerical case-studies are performed to evaluate the accuracy and effectiveness of the proposed method.
文摘By optimal sizing of a wind/photovoltaic hybrid renewable-energy(RE)system,trimming the surplus capacity to reduce the fluctuations in the electricity supplied to the grid,and using it to produce green hydrogen through electrolysis,a stable output with maximum possible capacity factor(CF)is generated to maintain the electricity grid stability.Simultaneously,the trimmed energy is used in a secondary conversion path that minimizes the weighted average cost of the energy generated from the entire plant.This surplus power-to-gas conversion allows the use of green hydrogen to produce electricity,methanol,or ammonia subject to the resource availability,site characteristics,and financial feasibility.Based on robust site selection criteria,the best performance is obtained at two sites:Ras Ghareb and Minya,achieving the lowest energy cost with some variance in their performance.For the Ras Ghareb site,the optimally sized RE plant provided the grid with a quasi-steady capacity of 423 MW with a CF of 80.04%and was capable of injecting 2965.8648 GWh throughout the year with the lowest cost of 2.4355¢/kWh.A surplus of 3.9%of the total energy produced from the plant was directed to produce 1922-ton H_(2)/year,achieving the lowest cost of hydrogen production of$1.9745/kg H_(2).For the other selected site,Minya,the clipped energy is used to produce 3330.47-ton H_(2)/year with an optimized lowest cost of$3.5268/kg H_(2).The difference in hydrogen costs was attributed to the number of full operating hours of the electrolyser in both sites.The cost is mainly affected by the electricity price and the electrolyser cost.With both tending to decrease,future forecasts show hydrogen cost reductions.
基金supported by the National Natural Science Foundation of China(No.61703345)the Chunhui Project Foundation of the Education Department of China(No.Z201980).
文摘To enhance multi-energy complementarity and foster a low carbon economy of energy resources,this paper proposes an innovative low-carbon operation opti-mization method for electric-thermal-gas regional inte-grated energy systems.To bolster the low-carbon operation capabilities of such systems,a coordinated operation framework is presented that integrates carbon capture devices,power to gas equipment,combined heat and power units,and a multi-energy storage system.To address the challenge of high-dimensional constraint imbalance in the optimization process,a novel low-carbon operation opti-mization method is then proposed.The new method is based on an adaptive single-objective continuous optimiza-tion spiking neural P system,specifically designed for this purpose.Furthermore,simulation models of four typical schemes are established and employed to test and analyze the economy and carbon environmental pollution degree of the proposed system model,as well as the performance of the operation optimization method.Finally,simulation results show that the proposed method not only considers the economic viability of the target integrated energy sys-tem,but also significantly improves the wind power utilization and carbon reduction capabilities.
基金This work was supported by National Natural Science Foundation of China(No.51777077)Natural Science Foundation of Guangdong Province(2017A030313304).
文摘As the proportion of wind power generation increases in power systems,it is necessary to develop new ways for wind power accommodation and improve the existing power dispatch model.The power-to-gas technology,which offers a new approach to accommodate surplus wind power,is an excellent way to solve the former.Hence,this paper proposes to involve power-to-gas technology in the integrated electricity and natural gas systems(IEGSs).To solve the latter,on one hand,a new indicator,the scale factor of wind power integration,is introduced into the wind power stochastic model to better describe the uncertainty of grid-connected wind power;on the other hand,for quantizing and minimizing the impact of the uncertainties of wind power and system loads on system security,security risk constraints are established for the IEGS by the conditional value-at-risk method.By considering these two aspects,an MILP formulation of a security-risk based stochastic dynamic economic dispatch model for an IEGS is established,and GUROBI obtained from GAMS is used for the solution.Case studies are conducted on an IEGS consisting of a modified IEEE 39-bus system and the Belgium 20-node natural gas system to examine the effectiveness of the proposed dispatch model.
基金This work was supported in part by the Science and Technology Project of State Grid Corporation of China(No.5211JY180014)the fund of China Scholarship Council(CSC).
文摘Multiple energy carriers can be coupled as an Integrated Energy System (IES) through interconnection tech- nologies. Unexpected risks will be transferred with the growing coupling of energy systems, mainly stemming from the uncertain- ties in different energy sectors. It is imperative to coordinate the operation of different energy systems to improve energy efficiency and ensure energy security. With the close integration of different energy systems, it is necessary to couple these different energy markets to achieve the holistic energy supply economy. On the other hand, uncertainties in the energy systems will bring the financial risk for the operator of IES. A risk-averse stochastic market clearing model for the IES is proposed to study the operating strategy aiming at minimizing the operation cost. While the financial risk imposed by the wind power uncertainties is restricted to a predefined level. Simulations results are provided to verify that the proposed model can improve market efficiency and handle the trade-off between cost and risk.
文摘Together with a huge number of other countries, Germany signed the Paris Agreements in 2015 to prevent global temperature increase above 2℃. Within this agreement, all countries defined their own national contributions to CO2 reduction. Since that, it was visible that CO2 emissions in Germany decreased, but not so fast than proposed in this German nationally determined contribution to the Paris Agreement. Due to increasing traffic, CO2 emissions from this mobility sector increased and CO2 emission from German power generation is nearly constant for the past 20 years, even a renewable generation capacity of 112 GW was built up in 2017, which is much higher than the peak load of 84 GW in Germany. That is why the German National Government has implemented a commission (often called "The German Coal Commission") to propose a time line: how Germany can move out of coal-fired power stations. This "Coal Commission" started its work in the late spring of 2018 and handed over its final report with 336 pages to the government on January 26th, 2019. Within this report the following proposals were made:①Until 2022: Due to a former decision of the German Government, the actual remaining nuclear power generation capacity of about 10 GW has to be switched off in 2022. Besides, the "Coal Commission" proposed to switch off additionally in total 12.5 GW of both, hard coal and lignite-fired power plants, so that Germany should reduce its conventional generation capacity by 22.5 GW in 2022.②Until 2030: Another 13 GW of German hard coal or lignite-fired power plants should be switched off.③Until 2038:The final 17 GW of German hard coal or lignitefired power plants should be switched off until 2038 latest. Unfortunately the "Coal Commission" has not investigated the relevant technical parameter to ensure a secured electric power supply, based on German's own national resources. Because German Energy Revolution mainly is based on wind energy and photovoltaic, this paper will describe the negligible contribution of these sources to the secured generation capacity, which will be needed for a reliable power supply. In addition, it will discuss several technical options to integrate wind energy and photovoltaic into a secured power supply system with an overall reduced CO2 emission.
基金supported by the Arc Research Hub for Integrated Energy Storage Solutions(Project ID:IH180100020).
文摘As a form of hybrid multi-energy systems,the integrated energy system contains different forms of energy such as power,thermal,and gas which meet the load of various energy forms.Focusing mainly on model building and optimal operation of the integrated energy system,in this paper,the dist-flow method is applied to quickly calculate the power flow and the gas system model is built by the analogy of the power system model.In addition,the piecewise linearization method is applied to solve the quadratic Weymouth gas flow equation,and the alternating direction method of multipliers(ADMM)method is applied to narrow the optimal results of each subsystem at the coupling point.The entire system reaches its optimal operation through multiple iterations.The power-thermal-gas integrated energy system used in the case study includes an IEEE-33 bus power system,a Belgian 20 node natural gas system,and a six node thermal system.Simulation-based calculations and comparison of the results under different scenarios prove that the power-thermal-gas integrated energy system enhances the flexibility and stability of the system as well as reducing system operating costs to some extent.
文摘The integrated energy system is an important development direction for achieving energy transformation in the context of the low-carbon development era,and an integrated energy system that uses renewable energy can reduce carbon emissions and improve energy utilization efficiency.The electric power network and the natural gas network are important transmission carriers in the en-ergy field,so the coupling relationship between them has been of wide concern.This paper establishes an integrated energy system considering electricity,gas,heat and hydrogen loads;takes each subject in the integrated energy system as the research object;anal-yses the economic returns of each subject under different operation modes;applies the Shapley value method for benefit allocation;and quantifies the contribution value of the subject to the alliance through different influencing factors to revise the benefit allocation value.Compared with the independent mode,the overall benefits of the integrated energy system increase in the cooperative mode and the benefits of all subjects increase.Due to the different characteristics of different subjects in terms of environmental benefits,collaborative innovation and risk sharing,the benefit allocation is reduced for new-energy subjects and increased for power-to-gas sub-jects and combined heat and power generation units after revising the benefit allocation,to improve the matching degree between the contribution level and the benefit allocation under the premise of increased profit for each subject.The cooperative mode effectively enhances the economic benefits of the system as a whole and individually,and provides a useful reference for the allocation of benefits of integrated energy systems.The analysis shows that the revised benefit distribution under the cooperative model increases by 3.86%,4.08%and 3.13%for power-to-gas subjects,combined heat and power generation units,and new-energy units,respectively,compared with the independent function model.