柔性交流输电系统(flexible AC transmission system,FACTS)的并网位置对电力系统的安全运行具有重要影响。本文综合考虑故障发生后的暂态与稳态过程,提出兼顾暂稳态判据的选址打分方法,在单机等面积定则基础上,推导出FACTS元件等值系...柔性交流输电系统(flexible AC transmission system,FACTS)的并网位置对电力系统的安全运行具有重要影响。本文综合考虑故障发生后的暂态与稳态过程,提出兼顾暂稳态判据的选址打分方法,在单机等面积定则基础上,推导出FACTS元件等值系统的暂态裕度量化积分,将暂态稳定裕度近似灵敏度和稳态母线电压越限危险度作为选址依据。基于FACTS元件与储能相结合技术,将有功死区控制、电池荷电状态限制和逆变器容量限制考虑进FACTS元件建模中,利用PSASP/UD自定义模块搭建具有储能作用的FACTS模型。通过电力系统分析软件PSASP中CEPRI-36节点系统进行仿真,在得分高的母线处采取FACTS元件以注入电流源形式并网参与系统紧急控制,验证本文所提选址方法的准确性及FACTS元件对抑制电力系统连锁故障扩散的影响。展开更多
基于现代智能电网中电压质量问题的严重性,提出了一种基于动态电压恢复器(dynamic voltage restorer,DVR)的配电网电压质量改善策略。通过在MATLAB/Simulink中建立含DVR的配电网模型,分别在供电电压中加入3次和5次谐波进行仿真分析。结...基于现代智能电网中电压质量问题的严重性,提出了一种基于动态电压恢复器(dynamic voltage restorer,DVR)的配电网电压质量改善策略。通过在MATLAB/Simulink中建立含DVR的配电网模型,分别在供电电压中加入3次和5次谐波进行仿真分析。结果表明,在未采用DVR时,配电网负载电压总谐波畸变率(total harmonic distortion,THD)分别高达18%和23%。采用所提DVR控制策略后,负载电压THD均降至4%以下,有效抑制了电压畸变,实现了平滑补偿。研究结果验证了该DVR控制策略在改善配电网电压质量方面的有效性,为智能电网建设提供了技术支持。展开更多
Knowledge graph(KG)fact prediction aims to complete a KG by determining the truthfulness of predicted triples.Reinforcement learning(RL)-based approaches have been widely used for fact prediction.However,the existing ...Knowledge graph(KG)fact prediction aims to complete a KG by determining the truthfulness of predicted triples.Reinforcement learning(RL)-based approaches have been widely used for fact prediction.However,the existing approaches largely suffer from unreliable calculations on rule confidences owing to a limited number of obtained reasoning paths,thereby resulting in unreliable decisions on prediction triples.Hence,we propose a new RL-based approach named EvoPath in this study.EvoPath features a new reward mechanism based on entity heterogeneity,facilitating an agent to obtain effective reasoning paths during random walks.EvoPath also incorporates a new postwalking mechanism to leverage easily overlooked but valuable reasoning paths during RL.Both mechanisms provide sufficient reasoning paths to facilitate the reliable calculations of rule confidences,enabling EvoPath to make precise judgments about the truthfulness of prediction triples.Experiments demonstrate that EvoPath can achieve more accurate fact predictions than existing approaches.展开更多
With the daily expansion of global energy consumption,developing the power grids is of uttermost importance.However,building a new trans-mission line is costly and time-consuming,so utilizing the same lines with possi...With the daily expansion of global energy consumption,developing the power grids is of uttermost importance.However,building a new trans-mission line is costly and time-consuming,so utilizing the same lines with possible higher transmission capacity is very cost-effective.In this regard,to increase the capacity of the transmission lines,the flexible alternating current transmission system(FACTS)has been widely used in power grids in recent years by industrialized countries.One of the essential topics in electrical power systems is the reactive power compensation,and the FACTS plays a significant role in controlling the reactive power current in the power grid and the system voltage oscillations and stability.When a static synchronous compensator(STATCOM)is embedded in a power system to increase the bus voltage,a supplementary damping controller can be designed to enhance the system oscillation damping.Given the expansion of the grids in the power system,the complexity of their optimization and the extraordinary ability of the imperialist competitive algorithm(ICA)for solving such problems,in this paper,the ICA has been used to determine the optimal position and size of the FACTS devices.展开更多
This work is part of the resolution of problems encountered on a 225 KV MANGOMBE-OYOMABANG line. This line is characterized by important technical losses, so that the voltage injected in the busbar is always lower tha...This work is part of the resolution of problems encountered on a 225 KV MANGOMBE-OYOMABANG line. This line is characterized by important technical losses, so that the voltage injected in the busbar is always lower than 200kV. The main objective of this work is to show the new solutions that can provide a combined FACTS-STATCOM and IPC 240 dual system on this line. Then to show the limitation of STATCOM compared to RPI 240. The results obtained allowed us to observe that in symmetrical operation the STATCOM improves the voltage profile on the busbar and in asymmetrical operation we found that it continues to regulate the voltage of each phase despite the unbalance. But the system remains too unbalanced because of the sequence current flow. The IPC 240 corrects this limitation, allowing asymmetrical operation of the line in an emergency while providing continuous service to the load.展开更多
With the development of modern society,the demand for nutrition,health,and food safety among people is also increasing.More and more consumers are connecting their diet to a healthy lifestyle in order to reduce the oc...With the development of modern society,the demand for nutrition,health,and food safety among people is also increasing.More and more consumers are connecting their diet to a healthy lifestyle in order to reduce the occurrence of chronic diseases.Spirulina,known as green ginseng,is one of the most productive microalgae with high output value.It is considered as one of the most ideal dietary supplements due to its unique nutritional and health benefits.The main components of spirulina include protein,fat,vitamins,chlorophyll,and minerals.The protein content is particularly high,ranging from 60-70%.Spirulina can be used as a natural nutritional supplement,providing various essential nutrients needed by the body.Apart from being a nutritional supplement,spirulina is also widely utilized in the food,medicine,and cosmetics industries.Spirulina powder can be added to various foods such as bread,cakes,and biscuits to enhance their nutritional value.Spirulina extract can also be used in the production of healthcare and beauty products.Furthermore,the antioxidant and immune-boosting effects of spirulina make it a promising natural medicine for research in the treatment of cancer and liver disease.This paper aims to provide comprehensive information on the nutritional composition,secondary metabolites,and biological activities of spirulina,thereby contributing to the spirulina industry.展开更多
研究多变量系统等效开环过程(effective open-loop process,EOP)理论在电力系统多柔性交流输电装置(flexible AC transmission system,FACTS)协调控制量化分析中的应用,并提出基于EOP的多FCATS阻尼控制器交互作用分析方法及量化指标。...研究多变量系统等效开环过程(effective open-loop process,EOP)理论在电力系统多柔性交流输电装置(flexible AC transmission system,FACTS)协调控制量化分析中的应用,并提出基于EOP的多FCATS阻尼控制器交互作用分析方法及量化指标。推导电力系统阻尼控制框架下的EOP,在此基础上建立用于多FACTS阻尼控制器分析的阻尼控制等效开环过程(damping control effective open-loop process,DCEOP)。提出基于DCEOP谱半径和多变量Nyquist推广定理的多FACTS阻尼控制器交互影响分析方法,可以判断系统中是否存在多FACTS阻尼控制器的负交互作用。进一步推导并提出基于DCEOP的多FACTS交互风险因子和交互作用因子,实现了多FACTS阻尼控制器协调控制及交互作用的量化分析。最后,通过算例分析验证了所提方法的正确性以及在实际电网中应用的可行性。展开更多
文摘柔性交流输电系统(flexible AC transmission system,FACTS)的并网位置对电力系统的安全运行具有重要影响。本文综合考虑故障发生后的暂态与稳态过程,提出兼顾暂稳态判据的选址打分方法,在单机等面积定则基础上,推导出FACTS元件等值系统的暂态裕度量化积分,将暂态稳定裕度近似灵敏度和稳态母线电压越限危险度作为选址依据。基于FACTS元件与储能相结合技术,将有功死区控制、电池荷电状态限制和逆变器容量限制考虑进FACTS元件建模中,利用PSASP/UD自定义模块搭建具有储能作用的FACTS模型。通过电力系统分析软件PSASP中CEPRI-36节点系统进行仿真,在得分高的母线处采取FACTS元件以注入电流源形式并网参与系统紧急控制,验证本文所提选址方法的准确性及FACTS元件对抑制电力系统连锁故障扩散的影响。
文摘基于现代智能电网中电压质量问题的严重性,提出了一种基于动态电压恢复器(dynamic voltage restorer,DVR)的配电网电压质量改善策略。通过在MATLAB/Simulink中建立含DVR的配电网模型,分别在供电电压中加入3次和5次谐波进行仿真分析。结果表明,在未采用DVR时,配电网负载电压总谐波畸变率(total harmonic distortion,THD)分别高达18%和23%。采用所提DVR控制策略后,负载电压THD均降至4%以下,有效抑制了电压畸变,实现了平滑补偿。研究结果验证了该DVR控制策略在改善配电网电压质量方面的有效性,为智能电网建设提供了技术支持。
基金the National Natural Science Foundation of China,Nos.62272480 and 62072470and the National Science Foundation of Hunan Province,Nos.2021JJ30881 and 2020JJ4758.
文摘Knowledge graph(KG)fact prediction aims to complete a KG by determining the truthfulness of predicted triples.Reinforcement learning(RL)-based approaches have been widely used for fact prediction.However,the existing approaches largely suffer from unreliable calculations on rule confidences owing to a limited number of obtained reasoning paths,thereby resulting in unreliable decisions on prediction triples.Hence,we propose a new RL-based approach named EvoPath in this study.EvoPath features a new reward mechanism based on entity heterogeneity,facilitating an agent to obtain effective reasoning paths during random walks.EvoPath also incorporates a new postwalking mechanism to leverage easily overlooked but valuable reasoning paths during RL.Both mechanisms provide sufficient reasoning paths to facilitate the reliable calculations of rule confidences,enabling EvoPath to make precise judgments about the truthfulness of prediction triples.Experiments demonstrate that EvoPath can achieve more accurate fact predictions than existing approaches.
基金This work was supported in part by an International Research Partnership“Electrical Engineering-Thai French Research Center(EE-TFRC)”under the project framework of the Lorraine Universited’Excellence(LUE)in cooperation between Universitede Lorraine and King Mongkut’s University of Technology North Bangkok and in part by the National Research Council of Thailand(NRCT)under Senior Research Scholar Program under Grant No.N42A640328.
文摘With the daily expansion of global energy consumption,developing the power grids is of uttermost importance.However,building a new trans-mission line is costly and time-consuming,so utilizing the same lines with possible higher transmission capacity is very cost-effective.In this regard,to increase the capacity of the transmission lines,the flexible alternating current transmission system(FACTS)has been widely used in power grids in recent years by industrialized countries.One of the essential topics in electrical power systems is the reactive power compensation,and the FACTS plays a significant role in controlling the reactive power current in the power grid and the system voltage oscillations and stability.When a static synchronous compensator(STATCOM)is embedded in a power system to increase the bus voltage,a supplementary damping controller can be designed to enhance the system oscillation damping.Given the expansion of the grids in the power system,the complexity of their optimization and the extraordinary ability of the imperialist competitive algorithm(ICA)for solving such problems,in this paper,the ICA has been used to determine the optimal position and size of the FACTS devices.
文摘This work is part of the resolution of problems encountered on a 225 KV MANGOMBE-OYOMABANG line. This line is characterized by important technical losses, so that the voltage injected in the busbar is always lower than 200kV. The main objective of this work is to show the new solutions that can provide a combined FACTS-STATCOM and IPC 240 dual system on this line. Then to show the limitation of STATCOM compared to RPI 240. The results obtained allowed us to observe that in symmetrical operation the STATCOM improves the voltage profile on the busbar and in asymmetrical operation we found that it continues to regulate the voltage of each phase despite the unbalance. But the system remains too unbalanced because of the sequence current flow. The IPC 240 corrects this limitation, allowing asymmetrical operation of the line in an emergency while providing continuous service to the load.
文摘With the development of modern society,the demand for nutrition,health,and food safety among people is also increasing.More and more consumers are connecting their diet to a healthy lifestyle in order to reduce the occurrence of chronic diseases.Spirulina,known as green ginseng,is one of the most productive microalgae with high output value.It is considered as one of the most ideal dietary supplements due to its unique nutritional and health benefits.The main components of spirulina include protein,fat,vitamins,chlorophyll,and minerals.The protein content is particularly high,ranging from 60-70%.Spirulina can be used as a natural nutritional supplement,providing various essential nutrients needed by the body.Apart from being a nutritional supplement,spirulina is also widely utilized in the food,medicine,and cosmetics industries.Spirulina powder can be added to various foods such as bread,cakes,and biscuits to enhance their nutritional value.Spirulina extract can also be used in the production of healthcare and beauty products.Furthermore,the antioxidant and immune-boosting effects of spirulina make it a promising natural medicine for research in the treatment of cancer and liver disease.This paper aims to provide comprehensive information on the nutritional composition,secondary metabolites,and biological activities of spirulina,thereby contributing to the spirulina industry.
文摘研究多变量系统等效开环过程(effective open-loop process,EOP)理论在电力系统多柔性交流输电装置(flexible AC transmission system,FACTS)协调控制量化分析中的应用,并提出基于EOP的多FCATS阻尼控制器交互作用分析方法及量化指标。推导电力系统阻尼控制框架下的EOP,在此基础上建立用于多FACTS阻尼控制器分析的阻尼控制等效开环过程(damping control effective open-loop process,DCEOP)。提出基于DCEOP谱半径和多变量Nyquist推广定理的多FACTS阻尼控制器交互影响分析方法,可以判断系统中是否存在多FACTS阻尼控制器的负交互作用。进一步推导并提出基于DCEOP的多FACTS交互风险因子和交互作用因子,实现了多FACTS阻尼控制器协调控制及交互作用的量化分析。最后,通过算例分析验证了所提方法的正确性以及在实际电网中应用的可行性。
