High voltage direct current (HVDC) transmission is an economical option for transmitting a large amount of power over long distances. Initially, HVDC was developed using thyristor-based current source converters (CSC)...High voltage direct current (HVDC) transmission is an economical option for transmitting a large amount of power over long distances. Initially, HVDC was developed using thyristor-based current source converters (CSC). With the development of semiconductor devices, a voltage source converter (VSC)-based HVDC system was introduced, and has been widely applied to integrate large-scale renewables and network interconnection. However, the VSC-based HVDC system is vulnerable to DC faults and its protection becomes ever more important with the fast growth in number of installations. In this paper, detailed characteristics of DC faults in the VSC-HVDC system are presented. The DC fault current has a large peak and steady values within a few milliseconds and thus high-speed fault detection and isolation methods are required in an HVDC grid. Therefore, development of the protection scheme for a multi-terminal VSC-based HVDC system is challenging. Various methods have been developed and this paper presents a comprehensive review of the different techniques for DC fault detection, location and isolation in both CSC and VSC-based HVDC transmission systems in two-terminal and multi-terminal network configurations.展开更多
Lithium-sulfur batteries(LSBs)have drawn significant attention owing to their high theoretical discharge capacity and energy density.However,the dissolution of long-chain polysulfides into the electrolyte during the c...Lithium-sulfur batteries(LSBs)have drawn significant attention owing to their high theoretical discharge capacity and energy density.However,the dissolution of long-chain polysulfides into the electrolyte during the charge and discharge process(“shuttle effect”)results in fast capacity fading and inferior electrochemical performance.In this study,Mn_(2)O_(3)with an ordered mesoporous structure(OM-Mn_(2)O_(3))was designed as a cathode host for LSBs via KIT-6 hard templating,to effectively inhibit the polysulfide shuttle effect.OM-Mn_(2)O_(3)offers numerous pores to confine sulfur and tightly anchor the dissolved polysulfides through the combined effects of strong polar-polar interactions,polysulfides,and sulfur chain catenation.The OM-Mn_(2)O_(3)/S composite electrode delivered a discharge capacity of 561 mAh g^(-1) after 250 cycles at 0.5 C owing to the excellent performance of OM-Mn_(2)O_(3).Furthermore,it retained a discharge capacity of 628mA h g^(-1) even at a rate of 2 C,which was significantly higher than that of a pristine sulfur electrode(206mA h g^(-1)).These findings provide a prospective strategy for designing cathode materials for high-performance LSBs.展开更多
Subsurface geothermal energy storage has greater potential than other energy storage strategies in terms of capacity scale and time duration.Carbon dioxide(CO_(2))is regarded as a potential medium for energy storage d...Subsurface geothermal energy storage has greater potential than other energy storage strategies in terms of capacity scale and time duration.Carbon dioxide(CO_(2))is regarded as a potential medium for energy storage due to its superior thermal properties.Moreover,the use of CO_(2)plumes for geothermal energy storage mitigates the greenhouse effect by storing CO_(2)in geological bodies.In this work,an integrated framework is proposed for synergistic geothermal energy storage and CO_(2)sequestration and utilization.Within this framework,CO_(2)is first injected into geothermal layers for energy accumulation.The resultant high-energy CO_(2)is then introduced into a target oil reservoir for CO_(2)utilization and geothermal energy storage.As a result,CO_(2)is sequestrated in the geological oil reservoir body.The results show that,as high-energy CO_(2)is injected,the average temperature of the whole target reservoir is greatly increased.With the assistance of geothermal energy,the geological utilization efficiency of CO_(2)is higher,resulting in a 10.1%increase in oil displacement efficiency.According to a storage-potential assessment of the simulated CO_(2)site,110 years after the CO_(2)injection,the utilization efficiency of the geological body will be as high as 91.2%,and the final injection quantity of the CO_(2)in the site will be as high as 9.529×10^(8)t.After 1000 years sequestration,the supercritical phase dominates in CO_(2)sequestration,followed by the liquid phase and then the mineralized phase.In addition,CO_(2)sequestration accounting for dissolution trapping increases significantly due to the presence of residual oil.More importantly,CO_(2)exhibits excellent performance in storing geothermal energy on a large scale;for example,the total energy stored in the studied geological body can provide the yearly energy supply for over 3.5×10^(7) normal households.Application of this integrated approach holds great significance for large-scale geothermal energy storage and the achievement of carbon neutrality.展开更多
Energy consumption in urban environment in the EU accounts for about 40%of the total energy consumption,and the majority of this energy is utilised for heating and air conditioning of buildings.Hence the process of in...Energy consumption in urban environment in the EU accounts for about 40%of the total energy consumption,and the majority of this energy is utilised for heating and air conditioning of buildings.Hence the process of insulating and retrofitting of relatively old buildings is essential to enhance the thermal performance and hence contribute to energy and carbon emission reduction.There is a need to enhance people’s engagement and education in relation to such issues to inspire and encourage positive actions and investment from the public.This paper presents an approach of combining a novel training process using a low-cost infrared thermal camera with small scale building model to promote DIY(Do-It-Yourself)infrared survey for the public to evaluate the performance of their own homes in order to identify any issues related to insulation or air leaks from the building envelop to encourage them to take corrective actions.The work included the engagement of 50 people to survey their own homes to capture the technical findings as well as their personal reaction and feedback.The results show that 88%of participants have found the educational session helpful to understand the infrared thermography;and 92%have considered the infrared camera to be an effective tool to indicate location of heat losses.Additionally,90%of participants trust that the thermal camera has helped them to identify insulation defects that cause heat losses in their homes.Moreover,84%believe that the thermal imaging has convinced them to think more seriously about the heat losses of their homes and what they could do to improve that.The experimental thermography surveys have shown that many houses have limitations in terms of thermal insulation which have been identified by the participants.This DIY interaction has provided enhanced public engagement and energy awareness via the use of the technology.The financial issues are also found to be critical,as none of the participants would have done the survey if they had to pay for it.Hence,this paper pr展开更多
The provision of wind farm(WF)grid codes(GCs)has become imperative for sustained grid operations,especially for WFs with permanent-magnet synchronous generator(PMSG)wind energy conversion system.Numerous techniques ha...The provision of wind farm(WF)grid codes(GCs)has become imperative for sustained grid operations,especially for WFs with permanent-magnet synchronous generator(PMSG)wind energy conversion system.Numerous techniques have been developed for executing GC requirements in the event of grid faults.Among the methods,an intriguing strategy is to enhance the performance of back-to-back(BTB)converter controllers.In this research,the PID-type terminal sliding mode control(PID-TSMC)scheme is implemented for both machine-side and grid-side converter-modified controllers of BTB-converter,to reinforce the nonlinear relationship among the state-variable and the control input.The application of this control scheme decreases the response time and improves the robustness of the BTB-converter controllers regarding uncertainty of parameters and external disturbances.The grid-side converter tracks the maximum power point,contributing to the rapid decrease of generator active power output during faults.This frees up converter capacity for injecting GC-compliant reactive current into the grid.Besides,the machine-side converter regulates DC-link voltage,in which its variations during external disturbances decrease substantially with the PID-TSMC.The discussions on the simulations contemplate on the robustness and efficiency of the implemented PID-TSMC strategy in comparison to other BTB-converter control strategies.展开更多
Today,there is a growing interest in developing energy efficient buildings since it is estimated that buildings account for about 40%of the total primary energy consumption in the world.In relation to existing buildin...Today,there is a growing interest in developing energy efficient buildings since it is estimated that buildings account for about 40%of the total primary energy consumption in the world.In relation to existing buildings,energy efficiency retrofits have become an important opportunity to upgrade the energy performance of commercial,public and residential buildings that may reduce the energy consumption,demand and cost.In this paper we cover the energy efficiency deep retrofit process that has been carried out for Nottingham Playhouse theatre building for the aim of enhancing its environmental performance and analysing the energy efficiency gained after implementing certain proposed modifications.It is a nationally protected historic building,listed as Grade II*on The National Heritage List for England(NHLE).The building has had insulation enhancement,doors modifications,solar energy installations,energy-saving lights,in addition to improved heating and air conditioning system.The paper presents a novel methodology;and its results indicate significant improvements in the building’s energy performance which is demonstrated using infrared thermographic images and data logger sensors where significant energy savings to the building’s thermal performance are obtained.The energy saving measures have been completed while maintaining the heritage building’s general appearance and architectural features,which have received a Commendation Certificate from The Nottingham Civic Society for this achievement.展开更多
The Energy-related Severe Accident Database(ENSAD)is the most authoritative resource for comparative risk analysis of accidents in the energy sector.Although ENSAD contains comprehensive,worldwide data,it is a non-spa...The Energy-related Severe Accident Database(ENSAD)is the most authoritative resource for comparative risk analysis of accidents in the energy sector.Although ENSAD contains comprehensive,worldwide data,it is a non-spatial database in Microsoft Access format.Therefore,spatial characteristics of the data cannot be fully utilised as well as analysed directly.Based on these premises,a new web-based version of ENSAD with GIS-capabilities–named ENSAD v2.0–is designed and developed using state-of-the-art,open source technologies.The ENSAD v2.0 consists of two main components,i.e.a spatial database and a responsive web application.For the spatial database,the current accident data are georeferenced and migrated from Microsoft Access,using a tiered approach.The responsive web application can be accessed from desktops as well as mobile devices,and provides both a 2D and 3D mapping platform that is developed on cloud-based,serverless architecture.ENSAD v2.0 also allows assigning different user roles with specific access rights,and a public version with advanced visualisation capabilities has also been developed.Lastly,a case study was carried out using a spatial analysis to visualise the potential impact radius of a natural gas pipeline explosion and to assess its consequences in terms of economic damage and casualties.展开更多
With the availability of distributed generation (DG), clusters that can autonomously manage their energy profile are emerging in the power grid. These autonomous clusters manage their load profiles by orchestrating th...With the availability of distributed generation (DG), clusters that can autonomously manage their energy profile are emerging in the power grid. These autonomous clusters manage their load profiles by orchestrating their energy resources, such as DG, storage, flexible energy consuming appliances, etc. The performance of such an autonomous cluster depends on the composition of its energy resources. In this paper, we study how the performance of a cluster is affected by adding energy resources such as generating units, storage systems or consuming appliances. First, we characterize the energy resources by parameters that describe their relevant properties. Afterwards, we describe a comprehensive set of performance indicators of a cluster that capture the economical, environmental, and social aspects. We present a model that shows how the energy resources influence the performance indicators of the cluster. We have tested our model with a case study, revealing its effectiveness to evaluate the value added by an energy resource to a cluster.展开更多
文摘High voltage direct current (HVDC) transmission is an economical option for transmitting a large amount of power over long distances. Initially, HVDC was developed using thyristor-based current source converters (CSC). With the development of semiconductor devices, a voltage source converter (VSC)-based HVDC system was introduced, and has been widely applied to integrate large-scale renewables and network interconnection. However, the VSC-based HVDC system is vulnerable to DC faults and its protection becomes ever more important with the fast growth in number of installations. In this paper, detailed characteristics of DC faults in the VSC-HVDC system are presented. The DC fault current has a large peak and steady values within a few milliseconds and thus high-speed fault detection and isolation methods are required in an HVDC grid. Therefore, development of the protection scheme for a multi-terminal VSC-based HVDC system is challenging. Various methods have been developed and this paper presents a comprehensive review of the different techniques for DC fault detection, location and isolation in both CSC and VSC-based HVDC transmission systems in two-terminal and multi-terminal network configurations.
基金Ministry of Trade,Industry and Energy,Grant/Award Number:20010095Korea Evaluation Institute of Industrial Technology,Grant/Award Number:20012341。
文摘Lithium-sulfur batteries(LSBs)have drawn significant attention owing to their high theoretical discharge capacity and energy density.However,the dissolution of long-chain polysulfides into the electrolyte during the charge and discharge process(“shuttle effect”)results in fast capacity fading and inferior electrochemical performance.In this study,Mn_(2)O_(3)with an ordered mesoporous structure(OM-Mn_(2)O_(3))was designed as a cathode host for LSBs via KIT-6 hard templating,to effectively inhibit the polysulfide shuttle effect.OM-Mn_(2)O_(3)offers numerous pores to confine sulfur and tightly anchor the dissolved polysulfides through the combined effects of strong polar-polar interactions,polysulfides,and sulfur chain catenation.The OM-Mn_(2)O_(3)/S composite electrode delivered a discharge capacity of 561 mAh g^(-1) after 250 cycles at 0.5 C owing to the excellent performance of OM-Mn_(2)O_(3).Furthermore,it retained a discharge capacity of 628mA h g^(-1) even at a rate of 2 C,which was significantly higher than that of a pristine sulfur electrode(206mA h g^(-1)).These findings provide a prospective strategy for designing cathode materials for high-performance LSBs.
基金supported by the National Key Research and Development Program of China under grant(2022YFE0206700)the financial support by the National Natural Science Foundation of China(52004320)the Science Foundation of China University of Petroleum,Beijing(2462021QNXZ012 and 2462021YJRC012)。
文摘Subsurface geothermal energy storage has greater potential than other energy storage strategies in terms of capacity scale and time duration.Carbon dioxide(CO_(2))is regarded as a potential medium for energy storage due to its superior thermal properties.Moreover,the use of CO_(2)plumes for geothermal energy storage mitigates the greenhouse effect by storing CO_(2)in geological bodies.In this work,an integrated framework is proposed for synergistic geothermal energy storage and CO_(2)sequestration and utilization.Within this framework,CO_(2)is first injected into geothermal layers for energy accumulation.The resultant high-energy CO_(2)is then introduced into a target oil reservoir for CO_(2)utilization and geothermal energy storage.As a result,CO_(2)is sequestrated in the geological oil reservoir body.The results show that,as high-energy CO_(2)is injected,the average temperature of the whole target reservoir is greatly increased.With the assistance of geothermal energy,the geological utilization efficiency of CO_(2)is higher,resulting in a 10.1%increase in oil displacement efficiency.According to a storage-potential assessment of the simulated CO_(2)site,110 years after the CO_(2)injection,the utilization efficiency of the geological body will be as high as 91.2%,and the final injection quantity of the CO_(2)in the site will be as high as 9.529×10^(8)t.After 1000 years sequestration,the supercritical phase dominates in CO_(2)sequestration,followed by the liquid phase and then the mineralized phase.In addition,CO_(2)sequestration accounting for dissolution trapping increases significantly due to the presence of residual oil.More importantly,CO_(2)exhibits excellent performance in storing geothermal energy on a large scale;for example,the total energy stored in the studied geological body can provide the yearly energy supply for over 3.5×10^(7) normal households.Application of this integrated approach holds great significance for large-scale geothermal energy storage and the achievement of carbon neutrality.
文摘Energy consumption in urban environment in the EU accounts for about 40%of the total energy consumption,and the majority of this energy is utilised for heating and air conditioning of buildings.Hence the process of insulating and retrofitting of relatively old buildings is essential to enhance the thermal performance and hence contribute to energy and carbon emission reduction.There is a need to enhance people’s engagement and education in relation to such issues to inspire and encourage positive actions and investment from the public.This paper presents an approach of combining a novel training process using a low-cost infrared thermal camera with small scale building model to promote DIY(Do-It-Yourself)infrared survey for the public to evaluate the performance of their own homes in order to identify any issues related to insulation or air leaks from the building envelop to encourage them to take corrective actions.The work included the engagement of 50 people to survey their own homes to capture the technical findings as well as their personal reaction and feedback.The results show that 88%of participants have found the educational session helpful to understand the infrared thermography;and 92%have considered the infrared camera to be an effective tool to indicate location of heat losses.Additionally,90%of participants trust that the thermal camera has helped them to identify insulation defects that cause heat losses in their homes.Moreover,84%believe that the thermal imaging has convinced them to think more seriously about the heat losses of their homes and what they could do to improve that.The experimental thermography surveys have shown that many houses have limitations in terms of thermal insulation which have been identified by the participants.This DIY interaction has provided enhanced public engagement and energy awareness via the use of the technology.The financial issues are also found to be critical,as none of the participants would have done the survey if they had to pay for it.Hence,this paper pr
文摘The provision of wind farm(WF)grid codes(GCs)has become imperative for sustained grid operations,especially for WFs with permanent-magnet synchronous generator(PMSG)wind energy conversion system.Numerous techniques have been developed for executing GC requirements in the event of grid faults.Among the methods,an intriguing strategy is to enhance the performance of back-to-back(BTB)converter controllers.In this research,the PID-type terminal sliding mode control(PID-TSMC)scheme is implemented for both machine-side and grid-side converter-modified controllers of BTB-converter,to reinforce the nonlinear relationship among the state-variable and the control input.The application of this control scheme decreases the response time and improves the robustness of the BTB-converter controllers regarding uncertainty of parameters and external disturbances.The grid-side converter tracks the maximum power point,contributing to the rapid decrease of generator active power output during faults.This frees up converter capacity for injecting GC-compliant reactive current into the grid.Besides,the machine-side converter regulates DC-link voltage,in which its variations during external disturbances decrease substantially with the PID-TSMC.The discussions on the simulations contemplate on the robustness and efficiency of the implemented PID-TSMC strategy in comparison to other BTB-converter control strategies.
文摘Today,there is a growing interest in developing energy efficient buildings since it is estimated that buildings account for about 40%of the total primary energy consumption in the world.In relation to existing buildings,energy efficiency retrofits have become an important opportunity to upgrade the energy performance of commercial,public and residential buildings that may reduce the energy consumption,demand and cost.In this paper we cover the energy efficiency deep retrofit process that has been carried out for Nottingham Playhouse theatre building for the aim of enhancing its environmental performance and analysing the energy efficiency gained after implementing certain proposed modifications.It is a nationally protected historic building,listed as Grade II*on The National Heritage List for England(NHLE).The building has had insulation enhancement,doors modifications,solar energy installations,energy-saving lights,in addition to improved heating and air conditioning system.The paper presents a novel methodology;and its results indicate significant improvements in the building’s energy performance which is demonstrated using infrared thermographic images and data logger sensors where significant energy savings to the building’s thermal performance are obtained.The energy saving measures have been completed while maintaining the heritage building’s general appearance and architectural features,which have received a Commendation Certificate from The Nottingham Civic Society for this achievement.
基金The research was conducted at the Future Resilient Systems(FRS)at the Singapore-ETH Centre(SEC),which was established collaboratively between ETH Zurich and Singapore’s National Research Foundation(FI 370074011)under its Campus for Research Excellence And Technological Enterprise(CREATE)programme.
文摘The Energy-related Severe Accident Database(ENSAD)is the most authoritative resource for comparative risk analysis of accidents in the energy sector.Although ENSAD contains comprehensive,worldwide data,it is a non-spatial database in Microsoft Access format.Therefore,spatial characteristics of the data cannot be fully utilised as well as analysed directly.Based on these premises,a new web-based version of ENSAD with GIS-capabilities–named ENSAD v2.0–is designed and developed using state-of-the-art,open source technologies.The ENSAD v2.0 consists of two main components,i.e.a spatial database and a responsive web application.For the spatial database,the current accident data are georeferenced and migrated from Microsoft Access,using a tiered approach.The responsive web application can be accessed from desktops as well as mobile devices,and provides both a 2D and 3D mapping platform that is developed on cloud-based,serverless architecture.ENSAD v2.0 also allows assigning different user roles with specific access rights,and a public version with advanced visualisation capabilities has also been developed.Lastly,a case study was carried out using a spatial analysis to visualise the potential impact radius of a natural gas pipeline explosion and to assess its consequences in terms of economic damage and casualties.
文摘With the availability of distributed generation (DG), clusters that can autonomously manage their energy profile are emerging in the power grid. These autonomous clusters manage their load profiles by orchestrating their energy resources, such as DG, storage, flexible energy consuming appliances, etc. The performance of such an autonomous cluster depends on the composition of its energy resources. In this paper, we study how the performance of a cluster is affected by adding energy resources such as generating units, storage systems or consuming appliances. First, we characterize the energy resources by parameters that describe their relevant properties. Afterwards, we describe a comprehensive set of performance indicators of a cluster that capture the economical, environmental, and social aspects. We present a model that shows how the energy resources influence the performance indicators of the cluster. We have tested our model with a case study, revealing its effectiveness to evaluate the value added by an energy resource to a cluster.
