In the context of constructing Global Energy Interconnection(GEI), energy storage technology, as one of the important basic supporting technologies in power system, will play an important role in the energy configurat...In the context of constructing Global Energy Interconnection(GEI), energy storage technology, as one of the important basic supporting technologies in power system, will play an important role in the energy configuration and optimization. Based on the most promising battery energy storage technology, this paper introduces the current status of the grid technology, the application of large-scale energy storage technology and the supporting role of battery energy storage for GEI. Based on several key technologies of large-scale battery energy storage system, preliminary analysis of the standard system construction of energy storage system is made, and the future prospect is put forward.展开更多
Construction of Global Energy Interconnection(GEI) is regarded as an effective way to utilize clean energy and it has been a hot research topic in recent years. As one of the enabling technologies for GEI, big data is...Construction of Global Energy Interconnection(GEI) is regarded as an effective way to utilize clean energy and it has been a hot research topic in recent years. As one of the enabling technologies for GEI, big data is accompanied with the sharing, fusion and comprehensive application of energy related data all over the world. The paper analyzes the technology innovation direction of GEI and the advantages of big data technologies in supporting GEI development, and then gives some typical application scenarios to illustrate the application value of big data. Finally, the architecture for applying random matrix theory in GEI is presented.展开更多
The development of Global Energy Interconnection(GEI)is essential for supporting a wide range of basic data resources.The Global Energy Interconnection Development and Cooperation Organization has established a compre...The development of Global Energy Interconnection(GEI)is essential for supporting a wide range of basic data resources.The Global Energy Interconnection Development and Cooperation Organization has established a comprehensive data center covering six major systems.However,methods for accurately describing and scientifically evaluating the credibility of the massive amount of GEI data remain underdeveloped.To address this lack of such methods,a GEI data credibility quantitative evaluation model is proposed here.An evaluation indicator system is established to evaluate data credibility from multiple perspectives and ensure the comprehensiveness and impartiality of evaluation results.The Cloud Model abandons the hard division of comments to ensure objectivity and accuracy in evaluation results.To evaluate the suitability of the proposed method,a case analysis is conducted,wherein the proposed method demonstrates sufficient validity and feasibility.展开更多
In order to meet the pressing demand for wide-area communication required by the Global Energy Interconnection(GEI),accelerating the construction of satellite-terrestrial Integra怕d networks that can achieve network e...In order to meet the pressing demand for wide-area communication required by the Global Energy Interconnection(GEI),accelerating the construction of satellite-terrestrial Integra怕d networks that can achieve network extension and seamless global coverage has become the focus of power communication tech no logy development.In this study,we propose a satellite-terrestrial integrated network model that can support interconnection and interoperation on the IP layer between the satellite system and the怕rrestrial segment of the existing power communication system.First,the composition and function of the satellite-terrestrial collaborative network are explained.Then,the IP-based protocol stack is described,and a typical applicati on experime nt is con ducted to illustrate the particular process of this protocol stack.Fin ally,a use case of IP interconn ection that depends on GEO satellite communication is detailed.The experime ntal study has showed that the satellite-terrestrial collaborative network can efficiently support various IP applications for the GEI.展开更多
Resources scarcity,environmental pollution and climate change pose a great threat to the survival and development of humanity.The fundamental way out is innovation.Chinese President Xi Jinping proposed'discussions...Resources scarcity,environmental pollution and climate change pose a great threat to the survival and development of humanity.The fundamental way out is innovation.Chinese President Xi Jinping proposed'discussions on establishing Global Energy Interconnection,or GEI to facilitate efforts to meet global power demand with clean and green alternatives'at the UN Sustainable Development展开更多
The Global Energy Interconnection Conference will be held in Mar.2019 in Beijing,China. We are collecting research papers worldwide to publish a special issue.1 New Energy Generation Design and Equipment Development o...The Global Energy Interconnection Conference will be held in Mar.2019 in Beijing,China. We are collecting research papers worldwide to publish a special issue.1 New Energy Generation Design and Equipment Development of Photovoltaic, Photothermal, Wind and other New Energy Generation Systems,New Energy Generation Simulation and Planning, Test and Inspection Technology, Power Prediction and展开更多
With the rapid development of technologies such as big data and cloud computing,data communication and data computing in the form of exponential growth have led to a large amount of energy consumption in data centers....With the rapid development of technologies such as big data and cloud computing,data communication and data computing in the form of exponential growth have led to a large amount of energy consumption in data centers.Globally,data centers will become the world’s largest users of energy consumption,with the ratio rising from 3%in 2017 to 4.5%in 2025.Due to its unique climate and energy-saving advantages,the high-latitude area in the Pan-Arctic region has gradually become a hotspot for data center site selection in recent years.In order to predict and analyze the future energy consumption and carbon emissions of global data centers,this paper presents a new method based on global data center traffic and power usage effectiveness(PUE)for energy consumption prediction.Firstly,global data center traffic growth is predicted based on the Cisco’s research.Secondly,the dynamic global average PUE and the high latitude PUE based on Romonet simulation model are obtained,and then global data center energy consumption with two different scenarios,the decentralized scenario and the centralized scenario,is analyzed quantitatively via the polynomial fitting method.The simulation results show that,in 2030,the global data center energy consumption and carbon emissions are reduced by about 301 billion kWh and 720 million tons CO2 in the centralized scenario compared with that of the decentralized scenario,which confirms that the establishment of data centers in the Pan-Arctic region in the future can effectively relief the climate change and energy problems.This study provides support for global energy consumption prediction,and guidance for the layout of future global data centers from the perspective of energy consumption.Moreover,it provides support of the feasibility of the integration of energy and information networks under the Global Energy Interconnection conception.展开更多
In order to quantify the contribution of the mitigation strategies,an extended Kaya identity has been proposed in this paper for decomposing the various factors that influence the CO2 emission.To this end,we provided ...In order to quantify the contribution of the mitigation strategies,an extended Kaya identity has been proposed in this paper for decomposing the various factors that influence the CO2 emission.To this end,we provided a detailed decomposition of the carbon intensity and energy intensity,which enables the quantification of clean energy development and electrification.The logarithmic mean divisia index(LMDI)has been applied to the historical data to quantify the contributions of the various factors affecting the CO2 emissions.Further,the global energy interconnection(GEI)scenario has been introduced for providing a systematic solution to meet the 2℃goal of the Paris Agreement.By combining LMDI with the scenario analysis,the mitigation potential of the various factors for CO2 emission has been analyzed.Results from the historical data indicate that economic development and population growth contribute the most to the increase in CO2 emissions,whereas improvement in the power generation efficiency predominantly helps in emission reduction.A numerical analysis,performed for obtaining the projected future carbon emissions,suggests that clean energy development and electrification are the top two factors that can decrease CO2 emissions,thus showing their great potential for mitigation in the future.Moreover,the carbon capture and storage technology serves as an important supplementary mitigation method.展开更多
There has been an intense discussion on the energy infrastructure cooperation in Northeast Asia.Most studies have focused on the technical feasibility of grid interconnection,deployment of renewable energy,and have ig...There has been an intense discussion on the energy infrastructure cooperation in Northeast Asia.Most studies have focused on the technical feasibility of grid interconnection,deployment of renewable energy,and have ignored the quantitative analysis of social and economic benefits of these proposals.This study uses a computable general equilibrium model to evaluate the effects of energy interconnection in Northeast Asia.Key model development tasks include 1)constructing a new nesting structure,2)econometrically estimating the constant elasticities of substitution(CES)between fossil-and non-fossil-power generation bundles,3)developing a new base-case scenario,and 4)developing the policy scenario.We found that while Northeast Asia will benefit from energy interconnection development with higher GDP than in the base-case;there will be a trade-off between higher investment and lower consumption.Sector results and environmental implications in this region are also discussed.展开更多
Electric interconnection is an essential trend for future large-scale development and utilization of renewable energy.China has proposed the concept of Global Energy Interconnection to realize the clean utilization of...Electric interconnection is an essential trend for future large-scale development and utilization of renewable energy.China has proposed the concept of Global Energy Interconnection to realize the clean utilization of energy through the interconnection of power grids and optimize the allocation of global energy resources.This study proposes the Kazakhstan-China-Republic of Korea networking scheme,analyzing the characteristics of power supply and demand in these countries.Based on the regional economic analysis and power development,four interconnection schemes are proposed utilizing UHVDC technology.Accordingly,existing problems and favorable factors are fully considered.The investment analysis of±1100 kV and±800 kV lines,configuration scheme of the converter station,and investment estimation of four interconnection schemes are given.展开更多
Combining the characteristics of the reverse distribution of solar resources and water resources in North Africa,West Africa and the Sahara,this paper proposes the West Africa-North Africa grid interconnection project...Combining the characteristics of the reverse distribution of solar resources and water resources in North Africa,West Africa and the Sahara,this paper proposes the West Africa-North Africa grid interconnection project to realize the optimal configuration of desert solar resources and surrounding water resources,and introduce the water resources of West Africa's Niger River and North Africa's desalinated seawater to improve the living environment and development conditions in the hinterland of the Sahara Desert;build photovoltaic bases along the route to send clean electricity to North Africa and West Africa.This paper studies the transmission channel path,electricity-water composite transmission technology and project scheme,and analyzes the economics of the project and the water supply and demand conditions of the Niger River.The research results show that it is feasible in hydrological characteristics to lead the Niger River water along the power transmission channel that crosses the Sahara Desert,and the new electricity-water composite transmission technology has obvious economic advantages.展开更多
In recent years,the Middle East region countries have experienced rapid population and economy growth,which has resulted in large increase of energy and power demand.Although the traditional fossil fuels remain the ma...In recent years,the Middle East region countries have experienced rapid population and economy growth,which has resulted in large increase of energy and power demand.Although the traditional fossil fuels remain the majority for supplying the domestic demand,additional generating capacity and fuel supply are necessary according to current situation and future demand forecast.The renewable energy provides an alternative resource for satisfying demand,especially in this region with high potential of solar and wind energy.Besides the development of renewable energy,interconnected electricity networks also enable the cross-border power exchange to fulfil electricity demand.Many Middle East countries have already started developing renewable energy and reforming the national power sector for regional electricityintegration.However,none of them has already implemented their targets and the challenges are still huge.This study reviews current conditions of electricity and energy interconnection development,and analyzes the process of regional electricity network integration and national power sector reforms and provides suggestion for regions’plan.Finally,the technology developments for future power grid interconnection and renewable energy integration are also reviewed.展开更多
For building Global Energy Interconnection(GEI), it is necessary to implement new breakthroughs on largepower system simulation. Key routes for implementing full electromagnetic transient simulation of large-power sys...For building Global Energy Interconnection(GEI), it is necessary to implement new breakthroughs on largepower system simulation. Key routes for implementing full electromagnetic transient simulation of large-power systems are described in this paper, and a top framework is designed. A combination of the new large time step algorithm and the traditional small-time step algorithm is proposed where both parts A and B are calculated independently. The method for integrating the Norton equivalence of the power electronic system to the entire power grid is proposed. A two-level gird division structure is proposed, which executes a multi-rate parallel calculation among subsystems and element parallel calculation in each subsystem. The initialization method of combining load flow derivation and automatic trial-and-error launching is introduced. The feasibility of the method is demonstrated through a practical power grid example, which lays a foundation for further research.展开更多
Northeast Asia is one of world’s major economic and energy consumption centers.Countries in this region are undergoing rapid economic and social development,and energy security and greenhouse gas emission reduction h...Northeast Asia is one of world’s major economic and energy consumption centers.Countries in this region are undergoing rapid economic and social development,and energy security and greenhouse gas emission reduction have become prominent issues.In this region,clean energy resources including hydro,wind,and solar are concentrated in Russia,Mongolia,and Northeast China,whilst electricity load centers are in East China,Korea and Japan.Currently,an energy and electricity model has been developed to project electricity demand through 2030 for each country.Based on the idea of a Global Energy Interconnection,this article proposes to establish a Northeast Asia Grid Interconnection(NEAG),connecting Mongolia,China,Korea,Japan,and Russia with large volumes of transmission lines,in an effort to facilitate optimized resource allocation.The NEAG would be accomplished step by step along with identification of key interconnectors.China is set to play an important role in establishing the NEAG by providing a strong sending grid and necessary technological equipment.Tremendous economic,environmental,and social benefits are expected to be generated by the NEAG.展开更多
HVDC technology has undergone many major developments in the past decades,resulting in higher power ratings,increased efficiency,and the availability of effective means for HVDC grid protection.These developments have...HVDC technology has undergone many major developments in the past decades,resulting in higher power ratings,increased efficiency,and the availability of effective means for HVDC grid protection.These developments have made overlay HVDC grids a viable option to shift towards a carbon-free power system,by enabling optimal use of renewable resources.In particular,overlay HVDC grids greatly increase the prospect of building(trans-)continental supergrids to facilitate global economic development.However,overlay HVDC grids still encounter challenges due to the distance and amount of power involved.This paper focuses on analyzing the readiness of the current technologies and the challenges associated with overlay HVDC grids.An in-depth analysis is carried out to evaluate the applicability of current technologies for overlay HVDC grids.Based on the review of recent research and development efforts,the gaps and challenges towards the realization of a global HVDC grid are summarized.展开更多
基金supported by National Key R&D Program of China(2017YFB0903504)
文摘In the context of constructing Global Energy Interconnection(GEI), energy storage technology, as one of the important basic supporting technologies in power system, will play an important role in the energy configuration and optimization. Based on the most promising battery energy storage technology, this paper introduces the current status of the grid technology, the application of large-scale energy storage technology and the supporting role of battery energy storage for GEI. Based on several key technologies of large-scale battery energy storage system, preliminary analysis of the standard system construction of energy storage system is made, and the future prospect is put forward.
基金supported by National High-technology Research and Development Program of China (863 Program) (2015AA050203)the State Grid Science and Technology Project (5442DZ170019-P)
文摘Construction of Global Energy Interconnection(GEI) is regarded as an effective way to utilize clean energy and it has been a hot research topic in recent years. As one of the enabling technologies for GEI, big data is accompanied with the sharing, fusion and comprehensive application of energy related data all over the world. The paper analyzes the technology innovation direction of GEI and the advantages of big data technologies in supporting GEI development, and then gives some typical application scenarios to illustrate the application value of big data. Finally, the architecture for applying random matrix theory in GEI is presented.
基金supported by the State Grid Science and Technology Project (No. 52450018000H)
文摘The development of Global Energy Interconnection(GEI)is essential for supporting a wide range of basic data resources.The Global Energy Interconnection Development and Cooperation Organization has established a comprehensive data center covering six major systems.However,methods for accurately describing and scientifically evaluating the credibility of the massive amount of GEI data remain underdeveloped.To address this lack of such methods,a GEI data credibility quantitative evaluation model is proposed here.An evaluation indicator system is established to evaluate data credibility from multiple perspectives and ensure the comprehensiveness and impartiality of evaluation results.The Cloud Model abandons the hard division of comments to ensure objectivity and accuracy in evaluation results.To evaluate the suitability of the proposed method,a case analysis is conducted,wherein the proposed method demonstrates sufficient validity and feasibility.
基金supported by the State Grid Science and Technology Project (No. 5455HT160004)
文摘In order to meet the pressing demand for wide-area communication required by the Global Energy Interconnection(GEI),accelerating the construction of satellite-terrestrial Integra怕d networks that can achieve network extension and seamless global coverage has become the focus of power communication tech no logy development.In this study,we propose a satellite-terrestrial integrated network model that can support interconnection and interoperation on the IP layer between the satellite system and the怕rrestrial segment of the existing power communication system.First,the composition and function of the satellite-terrestrial collaborative network are explained.Then,the IP-based protocol stack is described,and a typical applicati on experime nt is con ducted to illustrate the particular process of this protocol stack.Fin ally,a use case of IP interconn ection that depends on GEO satellite communication is detailed.The experime ntal study has showed that the satellite-terrestrial collaborative network can efficiently support various IP applications for the GEI.
文摘Resources scarcity,environmental pollution and climate change pose a great threat to the survival and development of humanity.The fundamental way out is innovation.Chinese President Xi Jinping proposed'discussions on establishing Global Energy Interconnection,or GEI to facilitate efforts to meet global power demand with clean and green alternatives'at the UN Sustainable Development
文摘The Global Energy Interconnection Conference will be held in Mar.2019 in Beijing,China. We are collecting research papers worldwide to publish a special issue.1 New Energy Generation Design and Equipment Development of Photovoltaic, Photothermal, Wind and other New Energy Generation Systems,New Energy Generation Simulation and Planning, Test and Inspection Technology, Power Prediction and
基金supported by National Natural Science Foundation of China(61472042)Corporation Science and Technology Program of Global Energy Interconnection Group Ltd.(GEIGC-D-[2018]024)
文摘With the rapid development of technologies such as big data and cloud computing,data communication and data computing in the form of exponential growth have led to a large amount of energy consumption in data centers.Globally,data centers will become the world’s largest users of energy consumption,with the ratio rising from 3%in 2017 to 4.5%in 2025.Due to its unique climate and energy-saving advantages,the high-latitude area in the Pan-Arctic region has gradually become a hotspot for data center site selection in recent years.In order to predict and analyze the future energy consumption and carbon emissions of global data centers,this paper presents a new method based on global data center traffic and power usage effectiveness(PUE)for energy consumption prediction.Firstly,global data center traffic growth is predicted based on the Cisco’s research.Secondly,the dynamic global average PUE and the high latitude PUE based on Romonet simulation model are obtained,and then global data center energy consumption with two different scenarios,the decentralized scenario and the centralized scenario,is analyzed quantitatively via the polynomial fitting method.The simulation results show that,in 2030,the global data center energy consumption and carbon emissions are reduced by about 301 billion kWh and 720 million tons CO2 in the centralized scenario compared with that of the decentralized scenario,which confirms that the establishment of data centers in the Pan-Arctic region in the future can effectively relief the climate change and energy problems.This study provides support for global energy consumption prediction,and guidance for the layout of future global data centers from the perspective of energy consumption.Moreover,it provides support of the feasibility of the integration of energy and information networks under the Global Energy Interconnection conception.
基金This work was supported by the Science and Technology Foundation of GEIGC(101662227)National Key Research and Development Program of China(2018 YFB0905000).
文摘In order to quantify the contribution of the mitigation strategies,an extended Kaya identity has been proposed in this paper for decomposing the various factors that influence the CO2 emission.To this end,we provided a detailed decomposition of the carbon intensity and energy intensity,which enables the quantification of clean energy development and electrification.The logarithmic mean divisia index(LMDI)has been applied to the historical data to quantify the contributions of the various factors affecting the CO2 emissions.Further,the global energy interconnection(GEI)scenario has been introduced for providing a systematic solution to meet the 2℃goal of the Paris Agreement.By combining LMDI with the scenario analysis,the mitigation potential of the various factors for CO2 emission has been analyzed.Results from the historical data indicate that economic development and population growth contribute the most to the increase in CO2 emissions,whereas improvement in the power generation efficiency predominantly helps in emission reduction.A numerical analysis,performed for obtaining the projected future carbon emissions,suggests that clean energy development and electrification are the top two factors that can decrease CO2 emissions,thus showing their great potential for mitigation in the future.Moreover,the carbon capture and storage technology serves as an important supplementary mitigation method.
基金supported by the Overseas Expertise Introduction Project for Discipline Innovation(B18014)National Natural Science Foundation of China(71733002)Science and Technology Foundation of SGCC(52450018000N)。
文摘There has been an intense discussion on the energy infrastructure cooperation in Northeast Asia.Most studies have focused on the technical feasibility of grid interconnection,deployment of renewable energy,and have ignored the quantitative analysis of social and economic benefits of these proposals.This study uses a computable general equilibrium model to evaluate the effects of energy interconnection in Northeast Asia.Key model development tasks include 1)constructing a new nesting structure,2)econometrically estimating the constant elasticities of substitution(CES)between fossil-and non-fossil-power generation bundles,3)developing a new base-case scenario,and 4)developing the policy scenario.We found that while Northeast Asia will benefit from energy interconnection development with higher GDP than in the base-case;there will be a trade-off between higher investment and lower consumption.Sector results and environmental implications in this region are also discussed.
基金supported by the Technical Assistant 9690 project of Asian Development Bank(ADB).
文摘Electric interconnection is an essential trend for future large-scale development and utilization of renewable energy.China has proposed the concept of Global Energy Interconnection to realize the clean utilization of energy through the interconnection of power grids and optimize the allocation of global energy resources.This study proposes the Kazakhstan-China-Republic of Korea networking scheme,analyzing the characteristics of power supply and demand in these countries.Based on the regional economic analysis and power development,four interconnection schemes are proposed utilizing UHVDC technology.Accordingly,existing problems and favorable factors are fully considered.The investment analysis of±1100 kV and±800 kV lines,configuration scheme of the converter station,and investment estimation of four interconnection schemes are given.
基金supported by National Natural Science Foundation of China(No.72131007)Agent-based modeling and analysis on evolution of the energy technology system for alternative fuel vehiclesScience and Technology Foundation of Global Energy Interconnection Group Co.,Ltd.(No.SGGEIG00JYJS2100027).
文摘Combining the characteristics of the reverse distribution of solar resources and water resources in North Africa,West Africa and the Sahara,this paper proposes the West Africa-North Africa grid interconnection project to realize the optimal configuration of desert solar resources and surrounding water resources,and introduce the water resources of West Africa's Niger River and North Africa's desalinated seawater to improve the living environment and development conditions in the hinterland of the Sahara Desert;build photovoltaic bases along the route to send clean electricity to North Africa and West Africa.This paper studies the transmission channel path,electricity-water composite transmission technology and project scheme,and analyzes the economics of the project and the water supply and demand conditions of the Niger River.The research results show that it is feasible in hydrological characteristics to lead the Niger River water along the power transmission channel that crosses the Sahara Desert,and the new electricity-water composite transmission technology has obvious economic advantages.
基金supported by China EPRI under the State Grid Corporation of China Science and Technology Project“Research on the Framework of Cross-Border Electricity Trading Market”(No.5442DZ150052)the University of Birmingham
文摘In recent years,the Middle East region countries have experienced rapid population and economy growth,which has resulted in large increase of energy and power demand.Although the traditional fossil fuels remain the majority for supplying the domestic demand,additional generating capacity and fuel supply are necessary according to current situation and future demand forecast.The renewable energy provides an alternative resource for satisfying demand,especially in this region with high potential of solar and wind energy.Besides the development of renewable energy,interconnected electricity networks also enable the cross-border power exchange to fulfil electricity demand.Many Middle East countries have already started developing renewable energy and reforming the national power sector for regional electricityintegration.However,none of them has already implemented their targets and the challenges are still huge.This study reviews current conditions of electricity and energy interconnection development,and analyzes the process of regional electricity network integration and national power sector reforms and provides suggestion for regions’plan.Finally,the technology developments for future power grid interconnection and renewable energy integration are also reviewed.
基金supported by key project of smart grid technology and equipment of national key research and development plan of China (2016YFB0900601)
文摘For building Global Energy Interconnection(GEI), it is necessary to implement new breakthroughs on largepower system simulation. Key routes for implementing full electromagnetic transient simulation of large-power systems are described in this paper, and a top framework is designed. A combination of the new large time step algorithm and the traditional small-time step algorithm is proposed where both parts A and B are calculated independently. The method for integrating the Norton equivalence of the power electronic system to the entire power grid is proposed. A two-level gird division structure is proposed, which executes a multi-rate parallel calculation among subsystems and element parallel calculation in each subsystem. The initialization method of combining load flow derivation and automatic trial-and-error launching is introduced. The feasibility of the method is demonstrated through a practical power grid example, which lays a foundation for further research.
基金supported by scientific research program titled Feasibility Study on Northeast Asia Grid Interconnection,funded by State Grid Corporation of China.
文摘Northeast Asia is one of world’s major economic and energy consumption centers.Countries in this region are undergoing rapid economic and social development,and energy security and greenhouse gas emission reduction have become prominent issues.In this region,clean energy resources including hydro,wind,and solar are concentrated in Russia,Mongolia,and Northeast China,whilst electricity load centers are in East China,Korea and Japan.Currently,an energy and electricity model has been developed to project electricity demand through 2030 for each country.Based on the idea of a Global Energy Interconnection,this article proposes to establish a Northeast Asia Grid Interconnection(NEAG),connecting Mongolia,China,Korea,Japan,and Russia with large volumes of transmission lines,in an effort to facilitate optimized resource allocation.The NEAG would be accomplished step by step along with identification of key interconnectors.China is set to play an important role in establishing the NEAG by providing a strong sending grid and necessary technological equipment.Tremendous economic,environmental,and social benefits are expected to be generated by the NEAG.
基金supported in part by the Science and Technology Project of State Grid Corporation of China(HVDC Systems/Grids for Transnational Interconnections)under Grant No.SGTYHT/16-JS-198。
文摘HVDC technology has undergone many major developments in the past decades,resulting in higher power ratings,increased efficiency,and the availability of effective means for HVDC grid protection.These developments have made overlay HVDC grids a viable option to shift towards a carbon-free power system,by enabling optimal use of renewable resources.In particular,overlay HVDC grids greatly increase the prospect of building(trans-)continental supergrids to facilitate global economic development.However,overlay HVDC grids still encounter challenges due to the distance and amount of power involved.This paper focuses on analyzing the readiness of the current technologies and the challenges associated with overlay HVDC grids.An in-depth analysis is carried out to evaluate the applicability of current technologies for overlay HVDC grids.Based on the review of recent research and development efforts,the gaps and challenges towards the realization of a global HVDC grid are summarized.