To meet the challenge of mismatches between power supply and demand,modern buildings must schedule flexible energy loads in order to improve the efficiency of power grids.Furthermore,it is essential to understand the ...To meet the challenge of mismatches between power supply and demand,modern buildings must schedule flexible energy loads in order to improve the efficiency of power grids.Furthermore,it is essential to understand the effectiveness of flexibility management strategies under different climate conditions and extreme weather events.Using both typical and extreme weather data from cities in five major climate zones of China,this study investigates the energy flexibility potential of an office building under three short-term HVAC management strategies in the context of different climates.The results show that the peak load flexibility and overall energy performance of the three short-term strategies were affected by the surrounding climate conditions.The peak load reduction rate of the pre-cooling and zone temperature reset strategies declined linearly as outdoor temperature increased.Under extreme climate conditions,the daily peak-load time was found to be over two hours earlier than under typical conditions,and the intensive solar radiation found in the extreme conditions can weaken the correlation between peak load reduction and outdoor temperature,risking the ability of a building’s HVAC system to maintain a comfortable indoor environment.展开更多
Highly transparent,durable,and flexible liquid-repellent coatings are urgently needed in the realm of transparent materials,such as car windows,optical lenses,solar panels,and flexible screen materials.However,it has ...Highly transparent,durable,and flexible liquid-repellent coatings are urgently needed in the realm of transparent materials,such as car windows,optical lenses,solar panels,and flexible screen materials.However,it has been difficult to strike a balance between the robustness and flexibility of coatings constructed by a single cross-linked network design.To overcome the conundrum,this innovative approach effectively combines two distinct cross-linked networks with unique functions,thus overcoming the challenge.Through a tightly interwoven structure comprised of added crosslinking sites,the coating achieves improved liquid repellency(WCA>100°,OSA<10°),increased durability(withstands 2,000 cycles of cotton wear),enhanced flexibility(endures 5,000 cycles of bending with a bending radius of 1 mm),and maintains high transparency(over 98%in the range of 410 nm to 760 nm).Additionally,the coating with remarkable adhesion can be applied to multiple substrates,enabling large-scale preparation and easy cycling coating,thus expanding its potential applications.The architecture of this fluoride-free dual cross-linked network not only advances liquid-repellent surfaces but also provides valuable insights for the development of eco-friendly materials in the future.展开更多
Customer segmentation according to load-shape profiles using smart meter data is an increasingly important application to vital the planning and operation of energy systems and to enable citizens’participation in the...Customer segmentation according to load-shape profiles using smart meter data is an increasingly important application to vital the planning and operation of energy systems and to enable citizens’participation in the energy transition.This study proposes an innovative multi-step clustering procedure to segment customers based on load-shape patterns at the daily and intra-daily time horizons.Smart meter data is split between daily and hourly normalized time series to assess monthly,weekly,daily,and hourly seasonality patterns separately.The dimensionality reduction implicit in the splitting allows a direct approach to clustering raw daily energy time series data.The intraday clustering procedure sequentially identifies representative hourly day-unit profiles for each customer and the entire population.For the first time,a step function approach is applied to reduce time series dimensionality.Customer attributes embedded in surveys are employed to build external clustering validation metrics using Cramer’s V correlation factors and to identify statistically significant determinants of load-shape in energy usage.In addition,a time series features engineering approach is used to extract 16 relevant demand flexibility indicators that characterize customers and corresponding clusters along four different axes:available Energy(E),Temporal patterns(T),Consistency(C),and Variability(V).The methodology is implemented on a real-world electricity consumption dataset of 325 Small and Medium-sized Enterprise(SME)customers,identifying 4 daily and 6 hourly easy-to-interpret,well-defined clusters.The application of the methodology includes selecting key parameters via grid search and a thorough comparison of clustering distances and methods to ensure the robustness of the results.Further research can test the scalability of the methodology to larger datasets from various customer segments(households and large commercial)and locations with different weather and socioeconomic conditions.展开更多
Pressure has been introduced into power systems owing to the intermittent and uncertain nature of renewable energy.As a result,energy resource aggregators are emerging in the electricity market to realize sustainable ...Pressure has been introduced into power systems owing to the intermittent and uncertain nature of renewable energy.As a result,energy resource aggregators are emerging in the electricity market to realize sustainable and economic advantages through distributed generation,energy storage,and demand response resources.However,resource aggregators face the challenge of dealing with the uncertainty of renewable energy generation and setting appropriate incentives to exploit substantial energy flexibility in the building sector.In this study,a risk-aware optimal dispatch strategy that integrates probabilistic renewable energy prediction and bi-level building flexibility engagements is proposed.A natural gradient boosting algorithm(NGBoost),which requires no prior knowledge of uncertain variables,was adopted to develop a probabilistic photovoltaic(PV)forecasting model.The lack of suitable flexibility incentives is addressed by a novel interactive flexibility engagement scheme that can take into account building users'willingness and optimize the building flexibility provision.The chance-constrained programming method was applied to manage the supply-demand balance of the resource aggregator and ensure risk-aware decision-making in power dispatch.The case study results show the strong economic and environmental performance of the proposed strategy.The proposed strategy leads to a win-win situation in which profit increases through a load reduction of 13% and a carbon emission reduction of 3% is achieved for different stakeholders,which also shows a trade-off between the economic benefits and the risk of supply shortage.展开更多
The penetration rate of new wind and photovoltaic energy in the power system has increased significantly,and the dramatic fluctuation of the net load of the grid has led to a severe lack of flexibility in the regional...The penetration rate of new wind and photovoltaic energy in the power system has increased significantly,and the dramatic fluctuation of the net load of the grid has led to a severe lack of flexibility in the regional grid.This paper proposes a hierarchical optimal dispatch strategy for a high proportion of new energy power systems that considers the balanced response of grid flexibility.Firstly,various flexibility resource regulation capabilities on the source-load side are analyzed,and then flexibility demand and flexibility response are matched,and flexibility demand response assessment is proposed;then,a hierarchical optimal dispatch model of the grid taking flexibility adjustment capability into account is established,and the upper model optimizes the net load curve with the objectives of minimizing the fluctuation of the net load,maximizing the benefits of energy storage and controllable loads,and optimizing the flexibility adjustment capability.The upper layer model optimizes the net load curve by minimizing net load fluctuation,maximizing energy storage and controllable load revenue,and optimizing flexibility adjustment capability.In contrast,the lower layer model optimizes the power allocation of thermal power units and regulates the lost load of wind and solar power generation by minimizing the total system operating cost.The results show that the proposed strategy improves the flexibility of the grid by 15.2%,gives full play to the regulation capability of each flexibility resource,and reduces the fluctuation of the net load by 15.6%to achieve optimal coordination between different types of flexibility resources.展开更多
The increasing use of renewable energy sources,combined with the increase in electricity demand,has highlighted the importance of energy flexibility management in electrical grids.Energy flexibility is the capacity th...The increasing use of renewable energy sources,combined with the increase in electricity demand,has highlighted the importance of energy flexibility management in electrical grids.Energy flexibility is the capacity that generators and consumers have to change production and/or consumption to support grid operation,ensuring the stability and efficiency of the grid.Thus,Local Flexibility Markets(LFMs)are market-oriented mechanisms operated at different time horizons that support flexibility provision and trading at the distribution level,where the Distribution System Operators(DSOs)are the flexibility-demanding actors,and prosumers are the flexibility providers.This paper investigates the requirements and constraints of forecasting algorithms required to participate in LFMs.The paper analyses the adequacy of current load forecasting algorithms to fulfill the requirements of LFMs.The work extracts the forecasting requirements for data granularity,forecasting horizon,participants aggregation,and their relevance for market operation;highlighting the implications of data availability at both training and forecasting stages related to the different localmarket actors(i.e.,DSO,aggregator,prosumer)and market operation timing.The analysis evidences the relevance of load aggregation and forecasting horizon in the performance of forecasting algorithms and their impact on the accuracy,depending on the actors and stages duringmarket operation.It evaluates howdata volume,forecasting horizon,and participant aggregation affect the performance of forecasting models.Key findings show that aggregating participants and reducing the forecasting horizon considerably improve forecasting accuracy.The accuracy of DSO forecasting is usually better due to the availability and completeness of aggregated data at the system level(i.e.,feeder,transformer,substation).Main findings show that increasing training data further than half a year does not keep improving forecasting accuracy,using a next-hour time horizon achieves around 29%better accuracy than a nextday time horizon,aggregating LFM participants can increase forecasting up to 100%depending on the aggregation number.The findings are discussed in the context of LFM operated with current data infrastructures and provide recommendations for improving the integration of forecasting algorithms to enhance flexibility management.展开更多
Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force ...Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force distribution are not well understood.In this study,fluid-structure interaction models are developed for numerical analyses.This modeling technique is verified with an experimental test in the literature using both circular and rectangular cross-sections.A series of material elasticities that present structural properties ranging from rigid to flexible is then used to conduct analyses.This finding indicates that an increase in structural flexibility can decrease the impact force to some extent,but this effect is limited.A concrete bridge pier with fluid flow impact can be considered rigid when it is fixed at the bottom.After that,the effects of the initial downstream water height and the width of water tank on the hydrodynamic force are thoroughly investigated.The results demonstrate that the increase in the downstream water height with a constant upstream water height corresponds to a decreased force.Moreover,the vertical column results in a blockage effect on the fluid flow.The greater the blockage effect,the higher the hydrodynamic force.The blockage effect from the vertical column can be neglected when the tank width is greater than eight times the structural cross-section diameter.展开更多
Objective:To analyze the mediating effect of psychological flexibility between death anxiety and quality of life in cancer patients.Methods:A convenience sampling method was used to select cancer patients who received...Objective:To analyze the mediating effect of psychological flexibility between death anxiety and quality of life in cancer patients.Methods:A convenience sampling method was used to select cancer patients who received treatment at our hospital from January 2022 to January 2024,by the inclusion and exclusion criteria.General information,psychological flexibility,death anxiety,and quality of life scores were collected for analysis.Result:The psychological flexibility and quality of life scores of cancer patients with an annual family income≤100,000 RMB were significantly lower than those of cancer patients with an annual family income>100,000 RMB(P<0.05),while the death anxiety scores were significantly lower for the former group as well(P<0.05).Cancer patients staged as Ⅰ-Ⅱ had significantly higher psychological flexibility and quality of life scores than those staged as Ⅲ-Ⅳ(P<0.05),while their death anxiety scores were significantly lower(P<0.05).Psychological flexibility in cancer patients was negatively correlated with death anxiety(r=-0.614,P<0.05)and positively correlated with quality of life(r=0.628,P<0.05),while death anxiety was negatively correlated with quality of life(r=-0.112,P<0.05).The direct effect of death anxiety on quality of life was-0.232,accounting for 58.32%of the total effect.The mediating effect of psychological flexibility between death anxiety and quality of life was-0.218,accounting for 41.83%of the total effect.Conclusion:Death anxiety can directly affect the quality of life of cancer patients,and it can also indirectly affect the quality of life through psychological flexibility.Clinicians should promptly address patients’death anxiety and provide interventions to enhance psychological flexibility,thereby improving the quality of life.展开更多
输电网灵活性受到节点灵活性与网络传输灵活性耦合影响且灵活性供需平衡关系随源荷波动动态变化,所以有必要开展输电网多元灵活性资源协调规划研究。该文针对输电网潮流动态变化的特点,构建一种反应灵活性资源传输需求和网络传输能力动...输电网灵活性受到节点灵活性与网络传输灵活性耦合影响且灵活性供需平衡关系随源荷波动动态变化,所以有必要开展输电网多元灵活性资源协调规划研究。该文针对输电网潮流动态变化的特点,构建一种反应灵活性资源传输需求和网络传输能力动态匹配程度的网络传输灵活性指标;然后,建立包含储能装置与统一潮流控制器(unified power flow controller,UPFC)的输电网多元灵活性资源两阶段协调优化规划模型;最后,通过算例分析验证所提的网络传输灵活性指标能够定量地反应网络传输灵活性随源荷波动的动态变化,基于网络传输灵活性最优的两阶段规划模型,有利于更好地挖掘原网络的传输能力,规划方案对更高的源-荷波动水平具有更好的适应性,提出的灵活性重要度指标可为灵活性资源初步选址提供指导。展开更多
机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,...机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,本文提出一种变频可调式调谐质量阻尼器(Tuned mass damper,TMD)的结构设计与参数优化方法,建立了集成调谐质量阻尼器与机器人加工系统的动力学模型。该方法基于偏心曲柄滑块机构实现频率可调,根据电涡流阻尼原理完成阻尼参数调控。进一步开展机器人加工系统动柔度控制试验,结果表明,本文所提方法可使末端动柔度峰值降低67.8%,显著提升加工稳定性边界。展开更多
基金National Key R&D Program of China of the 13th Five-Year Plan(No.2018YFD1100704)。
文摘To meet the challenge of mismatches between power supply and demand,modern buildings must schedule flexible energy loads in order to improve the efficiency of power grids.Furthermore,it is essential to understand the effectiveness of flexibility management strategies under different climate conditions and extreme weather events.Using both typical and extreme weather data from cities in five major climate zones of China,this study investigates the energy flexibility potential of an office building under three short-term HVAC management strategies in the context of different climates.The results show that the peak load flexibility and overall energy performance of the three short-term strategies were affected by the surrounding climate conditions.The peak load reduction rate of the pre-cooling and zone temperature reset strategies declined linearly as outdoor temperature increased.Under extreme climate conditions,the daily peak-load time was found to be over two hours earlier than under typical conditions,and the intensive solar radiation found in the extreme conditions can weaken the correlation between peak load reduction and outdoor temperature,risking the ability of a building’s HVAC system to maintain a comfortable indoor environment.
基金financially supported by the National Natu-ral Science Foundation of China(Nos.22375047,22378068,and 22075046)the Natural Science Foundation of Fujian Province(No.2022J01568)+2 种基金the National Key Research and Development Program of China(Nos.2022YFB3804905 and 2022YFB3804900)China Postdoctoral Science Foundation(No.2023M743437)start-up funding from Wenzhou Institute,University of Chinese Academy of Sciences(No.WIUCASQD2019002).
文摘Highly transparent,durable,and flexible liquid-repellent coatings are urgently needed in the realm of transparent materials,such as car windows,optical lenses,solar panels,and flexible screen materials.However,it has been difficult to strike a balance between the robustness and flexibility of coatings constructed by a single cross-linked network design.To overcome the conundrum,this innovative approach effectively combines two distinct cross-linked networks with unique functions,thus overcoming the challenge.Through a tightly interwoven structure comprised of added crosslinking sites,the coating achieves improved liquid repellency(WCA>100°,OSA<10°),increased durability(withstands 2,000 cycles of cotton wear),enhanced flexibility(endures 5,000 cycles of bending with a bending radius of 1 mm),and maintains high transparency(over 98%in the range of 410 nm to 760 nm).Additionally,the coating with remarkable adhesion can be applied to multiple substrates,enabling large-scale preparation and easy cycling coating,thus expanding its potential applications.The architecture of this fluoride-free dual cross-linked network not only advances liquid-repellent surfaces but also provides valuable insights for the development of eco-friendly materials in the future.
基金supported by the Spanish Ministry of Science and Innovation under Projects PID2022-137680OB-C32 and PID2022-139187OB-I00.
文摘Customer segmentation according to load-shape profiles using smart meter data is an increasingly important application to vital the planning and operation of energy systems and to enable citizens’participation in the energy transition.This study proposes an innovative multi-step clustering procedure to segment customers based on load-shape patterns at the daily and intra-daily time horizons.Smart meter data is split between daily and hourly normalized time series to assess monthly,weekly,daily,and hourly seasonality patterns separately.The dimensionality reduction implicit in the splitting allows a direct approach to clustering raw daily energy time series data.The intraday clustering procedure sequentially identifies representative hourly day-unit profiles for each customer and the entire population.For the first time,a step function approach is applied to reduce time series dimensionality.Customer attributes embedded in surveys are employed to build external clustering validation metrics using Cramer’s V correlation factors and to identify statistically significant determinants of load-shape in energy usage.In addition,a time series features engineering approach is used to extract 16 relevant demand flexibility indicators that characterize customers and corresponding clusters along four different axes:available Energy(E),Temporal patterns(T),Consistency(C),and Variability(V).The methodology is implemented on a real-world electricity consumption dataset of 325 Small and Medium-sized Enterprise(SME)customers,identifying 4 daily and 6 hourly easy-to-interpret,well-defined clusters.The application of the methodology includes selecting key parameters via grid search and a thorough comparison of clustering distances and methods to ensure the robustness of the results.Further research can test the scalability of the methodology to larger datasets from various customer segments(households and large commercial)and locations with different weather and socioeconomic conditions.
基金financially supported by the Collaborative Research Fund(C5018-20GF)of the Research Grant Council(RGC)of Hong Kong Special Administrative Regionthe Shenzhen Science and Technology Innovation Commission Grant(KCXST20221021111203007)。
文摘Pressure has been introduced into power systems owing to the intermittent and uncertain nature of renewable energy.As a result,energy resource aggregators are emerging in the electricity market to realize sustainable and economic advantages through distributed generation,energy storage,and demand response resources.However,resource aggregators face the challenge of dealing with the uncertainty of renewable energy generation and setting appropriate incentives to exploit substantial energy flexibility in the building sector.In this study,a risk-aware optimal dispatch strategy that integrates probabilistic renewable energy prediction and bi-level building flexibility engagements is proposed.A natural gradient boosting algorithm(NGBoost),which requires no prior knowledge of uncertain variables,was adopted to develop a probabilistic photovoltaic(PV)forecasting model.The lack of suitable flexibility incentives is addressed by a novel interactive flexibility engagement scheme that can take into account building users'willingness and optimize the building flexibility provision.The chance-constrained programming method was applied to manage the supply-demand balance of the resource aggregator and ensure risk-aware decision-making in power dispatch.The case study results show the strong economic and environmental performance of the proposed strategy.The proposed strategy leads to a win-win situation in which profit increases through a load reduction of 13% and a carbon emission reduction of 3% is achieved for different stakeholders,which also shows a trade-off between the economic benefits and the risk of supply shortage.
文摘The penetration rate of new wind and photovoltaic energy in the power system has increased significantly,and the dramatic fluctuation of the net load of the grid has led to a severe lack of flexibility in the regional grid.This paper proposes a hierarchical optimal dispatch strategy for a high proportion of new energy power systems that considers the balanced response of grid flexibility.Firstly,various flexibility resource regulation capabilities on the source-load side are analyzed,and then flexibility demand and flexibility response are matched,and flexibility demand response assessment is proposed;then,a hierarchical optimal dispatch model of the grid taking flexibility adjustment capability into account is established,and the upper model optimizes the net load curve with the objectives of minimizing the fluctuation of the net load,maximizing the benefits of energy storage and controllable loads,and optimizing the flexibility adjustment capability.The upper layer model optimizes the net load curve by minimizing net load fluctuation,maximizing energy storage and controllable load revenue,and optimizing flexibility adjustment capability.In contrast,the lower layer model optimizes the power allocation of thermal power units and regulates the lost load of wind and solar power generation by minimizing the total system operating cost.The results show that the proposed strategy improves the flexibility of the grid by 15.2%,gives full play to the regulation capability of each flexibility resource,and reduces the fluctuation of the net load by 15.6%to achieve optimal coordination between different types of flexibility resources.
基金funded by RESCHOOL,grant agreement No.101096490.
文摘The increasing use of renewable energy sources,combined with the increase in electricity demand,has highlighted the importance of energy flexibility management in electrical grids.Energy flexibility is the capacity that generators and consumers have to change production and/or consumption to support grid operation,ensuring the stability and efficiency of the grid.Thus,Local Flexibility Markets(LFMs)are market-oriented mechanisms operated at different time horizons that support flexibility provision and trading at the distribution level,where the Distribution System Operators(DSOs)are the flexibility-demanding actors,and prosumers are the flexibility providers.This paper investigates the requirements and constraints of forecasting algorithms required to participate in LFMs.The paper analyses the adequacy of current load forecasting algorithms to fulfill the requirements of LFMs.The work extracts the forecasting requirements for data granularity,forecasting horizon,participants aggregation,and their relevance for market operation;highlighting the implications of data availability at both training and forecasting stages related to the different localmarket actors(i.e.,DSO,aggregator,prosumer)and market operation timing.The analysis evidences the relevance of load aggregation and forecasting horizon in the performance of forecasting algorithms and their impact on the accuracy,depending on the actors and stages duringmarket operation.It evaluates howdata volume,forecasting horizon,and participant aggregation affect the performance of forecasting models.Key findings show that aggregating participants and reducing the forecasting horizon considerably improve forecasting accuracy.The accuracy of DSO forecasting is usually better due to the availability and completeness of aggregated data at the system level(i.e.,feeder,transformer,substation).Main findings show that increasing training data further than half a year does not keep improving forecasting accuracy,using a next-hour time horizon achieves around 29%better accuracy than a nextday time horizon,aggregating LFM participants can increase forecasting up to 100%depending on the aggregation number.The findings are discussed in the context of LFM operated with current data infrastructures and provide recommendations for improving the integration of forecasting algorithms to enhance flexibility management.
基金The National Natural Science Foundation of China(No.52222804,U21A20154).
文摘Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force distribution are not well understood.In this study,fluid-structure interaction models are developed for numerical analyses.This modeling technique is verified with an experimental test in the literature using both circular and rectangular cross-sections.A series of material elasticities that present structural properties ranging from rigid to flexible is then used to conduct analyses.This finding indicates that an increase in structural flexibility can decrease the impact force to some extent,but this effect is limited.A concrete bridge pier with fluid flow impact can be considered rigid when it is fixed at the bottom.After that,the effects of the initial downstream water height and the width of water tank on the hydrodynamic force are thoroughly investigated.The results demonstrate that the increase in the downstream water height with a constant upstream water height corresponds to a decreased force.Moreover,the vertical column results in a blockage effect on the fluid flow.The greater the blockage effect,the higher the hydrodynamic force.The blockage effect from the vertical column can be neglected when the tank width is greater than eight times the structural cross-section diameter.
文摘Objective:To analyze the mediating effect of psychological flexibility between death anxiety and quality of life in cancer patients.Methods:A convenience sampling method was used to select cancer patients who received treatment at our hospital from January 2022 to January 2024,by the inclusion and exclusion criteria.General information,psychological flexibility,death anxiety,and quality of life scores were collected for analysis.Result:The psychological flexibility and quality of life scores of cancer patients with an annual family income≤100,000 RMB were significantly lower than those of cancer patients with an annual family income>100,000 RMB(P<0.05),while the death anxiety scores were significantly lower for the former group as well(P<0.05).Cancer patients staged as Ⅰ-Ⅱ had significantly higher psychological flexibility and quality of life scores than those staged as Ⅲ-Ⅳ(P<0.05),while their death anxiety scores were significantly lower(P<0.05).Psychological flexibility in cancer patients was negatively correlated with death anxiety(r=-0.614,P<0.05)and positively correlated with quality of life(r=0.628,P<0.05),while death anxiety was negatively correlated with quality of life(r=-0.112,P<0.05).The direct effect of death anxiety on quality of life was-0.232,accounting for 58.32%of the total effect.The mediating effect of psychological flexibility between death anxiety and quality of life was-0.218,accounting for 41.83%of the total effect.Conclusion:Death anxiety can directly affect the quality of life of cancer patients,and it can also indirectly affect the quality of life through psychological flexibility.Clinicians should promptly address patients’death anxiety and provide interventions to enhance psychological flexibility,thereby improving the quality of life.
文摘输电网灵活性受到节点灵活性与网络传输灵活性耦合影响且灵活性供需平衡关系随源荷波动动态变化,所以有必要开展输电网多元灵活性资源协调规划研究。该文针对输电网潮流动态变化的特点,构建一种反应灵活性资源传输需求和网络传输能力动态匹配程度的网络传输灵活性指标;然后,建立包含储能装置与统一潮流控制器(unified power flow controller,UPFC)的输电网多元灵活性资源两阶段协调优化规划模型;最后,通过算例分析验证所提的网络传输灵活性指标能够定量地反应网络传输灵活性随源荷波动的动态变化,基于网络传输灵活性最优的两阶段规划模型,有利于更好地挖掘原网络的传输能力,规划方案对更高的源-荷波动水平具有更好的适应性,提出的灵活性重要度指标可为灵活性资源初步选址提供指导。
文摘机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,本文提出一种变频可调式调谐质量阻尼器(Tuned mass damper,TMD)的结构设计与参数优化方法,建立了集成调谐质量阻尼器与机器人加工系统的动力学模型。该方法基于偏心曲柄滑块机构实现频率可调,根据电涡流阻尼原理完成阻尼参数调控。进一步开展机器人加工系统动柔度控制试验,结果表明,本文所提方法可使末端动柔度峰值降低67.8%,显著提升加工稳定性边界。
