Grid-supplied load is the traditional load minus new energy generation,so grid-supplied load forecasting is challenged by uncertainties associated with the total energy demand and the energy generated off-grid.In addi...Grid-supplied load is the traditional load minus new energy generation,so grid-supplied load forecasting is challenged by uncertainties associated with the total energy demand and the energy generated off-grid.In addition,with the expansion of the power system and the increase in the frequency of extreme weather events,the difficulty of grid-supplied load forecasting is further exacerbated.Traditional statistical methods struggle to capture the dynamic characteristics of grid-supplied load,especially under extreme weather conditions.This paper proposes a novel gridsupplied load prediction model based on Convolutional Neural Network-Bidirectional LSTM-Attention mechanism(CNN-BiLSTM-Attention).The model utilizes transfer learning by pre-training on regular weather data and fine-tuning on extreme weather samples,aiming to improve prediction accuracy and robustness.Experimental results demonstrate that the proposed model outperforms traditional statistical methods and existing machine learning models.Through comprehensive experimental validation,the attention mechanism demonstrates exceptional capability in identifying and weighting critical temporal features across different timescales,which significantly contributes to enhanced prediction performance and stability under diverse weather conditions.Moreover,the proposed approach consistently exhibits strong generalization capabilities across multiple test cases when applied to different regional power grids with distinct operational patterns and varying load characteristics,showcasing its practical adaptability to real-world scenarios.This study provides a practical solution for enhancing grid-supplied load forecasting capabilities in the face of increasingly complex and unpredictable weather patterns.展开更多
Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloy...Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloying/dealloying processes and low electronic conductivity of Si anodes restrict their electrochemical performance.Thus,carbon(C)materials with special physical and chemical properties are applied in Si anodes to effectively solve these problems.This review focuses on current status in the exploration of Si/C anodes,including the lithiation mechanism and solid electrolyte interface formation,various carbon sources in Si/C anodes,such as traditional carbon sources(graphite,pitch,biomass),and novel carbon sources(MXene,graphene,MOFs-derived carbon,graphdiyne,etc.),as well as interfacial bonding modes of Si and C in the Si/C anodes.Finally,we summarize and prospect the selection of carbonaceous materials,structural design and interface control of Si/C anodes,and application of Si/C anodes in all-solid-state lithium-ion batteries and sodium-ion batteries et al.This review will help researchers in the design of novel Si/C anodes for rechargeable batteries.展开更多
In the present scenario,modular multilevel converters(MMCs)are considered to be one of the most promising and effective topologies in the family of high-power converters because of their modular design and good scalab...In the present scenario,modular multilevel converters(MMCs)are considered to be one of the most promising and effective topologies in the family of high-power converters because of their modular design and good scalability;MMCs are extensively used in high-voltage and high-power applications.Based on their unique advantages,MMCs have attracted increasing attention from academic circles over the past years.Several studies have focused on different aspects of MMCs,including submodule topologies,modeling schemes,modulation strategies,control schemes for voltage balancing and circulating currents,fault diagnoses,and fault-tolerant control strategies.To summarize the current research status of MMCs,all the aforementioned research issues with representative research approaches,results and characteristics are systematically overviewed.In the final section,the current research status of MMCs and their future trends are emphasized.展开更多
The modular multilevel converter(MMC)has been a highly promising topology in the high-voltage direct-current(HVDC)transmission area,where each arm of the MMC may consist of hundreds of series-connected submodules and ...The modular multilevel converter(MMC)has been a highly promising topology in the high-voltage direct-current(HVDC)transmission area,where each arm of the MMC may consist of hundreds of series-connected submodules and an inductor.Due to its parameter inaccuracy,component aging,and so on,the component parameter in different arms of the MMC may be different,which may cause circulating current in the MMC-HVDC transmission system,and result in current deterioration,power losses,and electromagnetic interference,etc.In this paper,the circulating current suppressing(CCS)in the MMC-HVDC system,due to asymmetric arm impedance,is analyzed.Based on the mathematical analysis,a method of using an auxiliary circuit is proposed for the MMC to realize the CCS and improve the performance of the MMC-HVDC system.Simulation studies are conducted with PSCAD/EMTDC in the HVDC system,which confirms the feasibility of the proposed method.展开更多
Power loss management is one of the most significant challenges for reliability improvement of modular multilevel converters(MMCs).In the MMC,the bottom switch/diode in each submodule(SM)normally takes the maximum pow...Power loss management is one of the most significant challenges for reliability improvement of modular multilevel converters(MMCs).In the MMC,the bottom switch/diode in each submodule(SM)normally takes the maximum power loss.In this paper,a power loss optimization control(PLOC)for MMCs is proposed,where the maximum power losses in the bottom switch/diode of each SM can be effectively reduced through injecting optimum second-order harmonic current into the circulating current of MMCs,and accordingly the reliability of MMCs can be improved by the proposed PLOC.Simulation results with PSCAD software and experimental results with a 1 kW MMC platform are provided to confirm the validity of the proposed PLOC for MMCs.展开更多
基金the Science and Technology Project of State Grid Fujian Electric Power Co.,Ltd.(Project No.B31300240001)with the project title“Research on Key Technologies for Load Forecasting and Regulation Capability Evaluation of Regional Power Grid Taking into AccountWide Area Distributed New Energy Access”.
文摘Grid-supplied load is the traditional load minus new energy generation,so grid-supplied load forecasting is challenged by uncertainties associated with the total energy demand and the energy generated off-grid.In addition,with the expansion of the power system and the increase in the frequency of extreme weather events,the difficulty of grid-supplied load forecasting is further exacerbated.Traditional statistical methods struggle to capture the dynamic characteristics of grid-supplied load,especially under extreme weather conditions.This paper proposes a novel gridsupplied load prediction model based on Convolutional Neural Network-Bidirectional LSTM-Attention mechanism(CNN-BiLSTM-Attention).The model utilizes transfer learning by pre-training on regular weather data and fine-tuning on extreme weather samples,aiming to improve prediction accuracy and robustness.Experimental results demonstrate that the proposed model outperforms traditional statistical methods and existing machine learning models.Through comprehensive experimental validation,the attention mechanism demonstrates exceptional capability in identifying and weighting critical temporal features across different timescales,which significantly contributes to enhanced prediction performance and stability under diverse weather conditions.Moreover,the proposed approach consistently exhibits strong generalization capabilities across multiple test cases when applied to different regional power grids with distinct operational patterns and varying load characteristics,showcasing its practical adaptability to real-world scenarios.This study provides a practical solution for enhancing grid-supplied load forecasting capabilities in the face of increasingly complex and unpredictable weather patterns.
基金supported by the National Natural Science Foundation of China(5197219862133007)the Taishan Scholars Program of Shandong Province(tsqn201812002,ts20190908)+1 种基金the Shenzhen Fundamental Research Program(JCYJ20190807093405503)The Natural Science Foundation of Shandong Province(No.ZR2020JQ19)。
文摘Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloying/dealloying processes and low electronic conductivity of Si anodes restrict their electrochemical performance.Thus,carbon(C)materials with special physical and chemical properties are applied in Si anodes to effectively solve these problems.This review focuses on current status in the exploration of Si/C anodes,including the lithiation mechanism and solid electrolyte interface formation,various carbon sources in Si/C anodes,such as traditional carbon sources(graphite,pitch,biomass),and novel carbon sources(MXene,graphene,MOFs-derived carbon,graphdiyne,etc.),as well as interfacial bonding modes of Si and C in the Si/C anodes.Finally,we summarize and prospect the selection of carbonaceous materials,structural design and interface control of Si/C anodes,and application of Si/C anodes in all-solid-state lithium-ion batteries and sodium-ion batteries et al.This review will help researchers in the design of novel Si/C anodes for rechargeable batteries.
基金Supported by the Science and Technology Program of State Grid Corporation of China(5100-201999330A-0-0-00)。
文摘In the present scenario,modular multilevel converters(MMCs)are considered to be one of the most promising and effective topologies in the family of high-power converters because of their modular design and good scalability;MMCs are extensively used in high-voltage and high-power applications.Based on their unique advantages,MMCs have attracted increasing attention from academic circles over the past years.Several studies have focused on different aspects of MMCs,including submodule topologies,modeling schemes,modulation strategies,control schemes for voltage balancing and circulating currents,fault diagnoses,and fault-tolerant control strategies.To summarize the current research status of MMCs,all the aforementioned research issues with representative research approaches,results and characteristics are systematically overviewed.In the final section,the current research status of MMCs and their future trends are emphasized.
基金This work was supported by the Science and Technology Program of the State Grid Corporation of China(Grant No.5100-201999330A-0-0-00).
文摘The modular multilevel converter(MMC)has been a highly promising topology in the high-voltage direct-current(HVDC)transmission area,where each arm of the MMC may consist of hundreds of series-connected submodules and an inductor.Due to its parameter inaccuracy,component aging,and so on,the component parameter in different arms of the MMC may be different,which may cause circulating current in the MMC-HVDC transmission system,and result in current deterioration,power losses,and electromagnetic interference,etc.In this paper,the circulating current suppressing(CCS)in the MMC-HVDC system,due to asymmetric arm impedance,is analyzed.Based on the mathematical analysis,a method of using an auxiliary circuit is proposed for the MMC to realize the CCS and improve the performance of the MMC-HVDC system.Simulation studies are conducted with PSCAD/EMTDC in the HVDC system,which confirms the feasibility of the proposed method.
基金supported in part by the National Natural Science Foundation of China under Grant No.61873062in part by the Natural Science Foundation of Jiangsu Province under Grant No.BK20180395in part by the Six Talent Peaks Project of Jiangsu Province under Grant No.GDZB-002.
文摘Power loss management is one of the most significant challenges for reliability improvement of modular multilevel converters(MMCs).In the MMC,the bottom switch/diode in each submodule(SM)normally takes the maximum power loss.In this paper,a power loss optimization control(PLOC)for MMCs is proposed,where the maximum power losses in the bottom switch/diode of each SM can be effectively reduced through injecting optimum second-order harmonic current into the circulating current of MMCs,and accordingly the reliability of MMCs can be improved by the proposed PLOC.Simulation results with PSCAD software and experimental results with a 1 kW MMC platform are provided to confirm the validity of the proposed PLOC for MMCs.
