Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398656
A. Bonfiglio, F. Delfino, F. Pampararo, R. Procopio, M. Rossi, L. Barillari
The aim of this paper is to describe the Smart Polygeneration Microgrid (SPM), which is going to be constructed at the Savona Campus of the Genoa University, also thanks to funding from the Italian Ministry of Education, University and Research. Besides producing renewable and high efficiency energy for the University Campus, the SPM will constitute a test-bed facility for research, development and testing of management strategies, devices and components for smart grid applications. The main features of this infrastructure will be outlined, pointing out its peculiarities, such as the use of the IEC 61850 protocol and a close integration between electric and heating networks. Furthermore, the activities which will be carried out thanks to the SPM and the challenges in its operation and optimal management will be discussed, in the context of the current research on microgrid and smart grid technologies.
{"title":"The Smart Polygeneration Microgrid test-bed facility of Genoa University","authors":"A. Bonfiglio, F. Delfino, F. Pampararo, R. Procopio, M. Rossi, L. Barillari","doi":"10.1109/UPEC.2012.6398656","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398656","url":null,"abstract":"The aim of this paper is to describe the Smart Polygeneration Microgrid (SPM), which is going to be constructed at the Savona Campus of the Genoa University, also thanks to funding from the Italian Ministry of Education, University and Research. Besides producing renewable and high efficiency energy for the University Campus, the SPM will constitute a test-bed facility for research, development and testing of management strategies, devices and components for smart grid applications. The main features of this infrastructure will be outlined, pointing out its peculiarities, such as the use of the IEC 61850 protocol and a close integration between electric and heating networks. Furthermore, the activities which will be carried out thanks to the SPM and the challenges in its operation and optimal management will be discussed, in the context of the current research on microgrid and smart grid technologies.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122168290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398628
M. Ramos, D. Bernardon, L. Comassetto, M. Resener, E. Daza
This work focuses on the study of electromagnetic transients existing in power systems in the occurrence of phase to ground and three phase faults, aiming to evaluate the dynamic capability of circuit breakers, switch disconnectors and current transformers. The substation equipments such as circuit breakers, current transformers and switch disconnectors are usually specified according to symmetrical short circuit currents. In this sense, this paper presents an analysis of the impact of short-circuit currents during the transient period, through simulations using data from a real system in the ATPDraw software. Through the results obtained from the simulations it was possible to evaluate the dynamic stress submitted to the equipment of the substations in the occurrence of faults. The study shows the importance of the analysis of asymmetrical short-circuit currents during the specification of the equipments rating, which should support these currents, or yet evaluation of existing equipments in the case of a system expansion that can significantly influence the short-circuit level.
{"title":"Analysis of short-circuit asymmetrical currents in power distribution systems","authors":"M. Ramos, D. Bernardon, L. Comassetto, M. Resener, E. Daza","doi":"10.1109/UPEC.2012.6398628","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398628","url":null,"abstract":"This work focuses on the study of electromagnetic transients existing in power systems in the occurrence of phase to ground and three phase faults, aiming to evaluate the dynamic capability of circuit breakers, switch disconnectors and current transformers. The substation equipments such as circuit breakers, current transformers and switch disconnectors are usually specified according to symmetrical short circuit currents. In this sense, this paper presents an analysis of the impact of short-circuit currents during the transient period, through simulations using data from a real system in the ATPDraw software. Through the results obtained from the simulations it was possible to evaluate the dynamic stress submitted to the equipment of the substations in the occurrence of faults. The study shows the importance of the analysis of asymmetrical short-circuit currents during the specification of the equipments rating, which should support these currents, or yet evaluation of existing equipments in the case of a system expansion that can significantly influence the short-circuit level.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126683379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398457
D. Banham-Hall, C. Smith, G. Taylor, M. Irving
Wind power represents a growing share of electricity supply on many power systems around the world. The UK has plans for over 33GW of offshore wind power to be developed before 2020, which would substantially alter the generation mix. The GB electric grid has traditionally depended on fossil fuel fired synchronous plant to control power output and maintain the balance between supply and demand through system frequency regulation. Modern wind turbines are equipped with advanced power electronic converters which provide flexible, controllable, interfaces to the power system, but are inherently driven by an intermittent resource. This paper addresses the control of large offshore wind farms, in order to contribute to the frequency stability of the GB electric grid. It shows that wind farms can be controlled to provide frequency response, within the limitations of the available wind power. The paper then addresses the possibility of using Vanadium Redox Flow Batteries to provide reserve capacity for the wind farm. The paper highlights the many benefits of these batteries in conjunction with wind farms and demonstrates that they can contribute to providing reliable frequency regulation from offshore wind farms.
{"title":"Active power control from large offshore wind farms","authors":"D. Banham-Hall, C. Smith, G. Taylor, M. Irving","doi":"10.1109/UPEC.2012.6398457","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398457","url":null,"abstract":"Wind power represents a growing share of electricity supply on many power systems around the world. The UK has plans for over 33GW of offshore wind power to be developed before 2020, which would substantially alter the generation mix. The GB electric grid has traditionally depended on fossil fuel fired synchronous plant to control power output and maintain the balance between supply and demand through system frequency regulation. Modern wind turbines are equipped with advanced power electronic converters which provide flexible, controllable, interfaces to the power system, but are inherently driven by an intermittent resource. This paper addresses the control of large offshore wind farms, in order to contribute to the frequency stability of the GB electric grid. It shows that wind farms can be controlled to provide frequency response, within the limitations of the available wind power. The paper then addresses the possibility of using Vanadium Redox Flow Batteries to provide reserve capacity for the wind farm. The paper highlights the many benefits of these batteries in conjunction with wind farms and demonstrates that they can contribute to providing reliable frequency regulation from offshore wind farms.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114239827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398435
A. H. Najarkolaei, J. Lota, W. Hosny
Broadband power line (BPL) data transmission deals with transfer of data via the existing power line systems and is a fast emerging technology. The main advantage of BPL is being able to use the existing power line infrastructure, thereby reducing the cost. However, power line systems were not designed for high-speed data transmission as they consist of various branches and power line elements such as bridges, taps, transformers and capacitor banks. Therefore, the power line transmission medium not only introduces noise but is also adverse to high-speed data transfer in terms of the channel bandwidth. In this paper a power line channel has been modelled using Matlab and the effects of variations in the direct length, branch length and branch load on the channel frequency response are investigated. Simulations indicate suitability of multi-carrier transmission over the power line channels.
{"title":"Data transfer over low-voltage European power distribution networks","authors":"A. H. Najarkolaei, J. Lota, W. Hosny","doi":"10.1109/UPEC.2012.6398435","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398435","url":null,"abstract":"Broadband power line (BPL) data transmission deals with transfer of data via the existing power line systems and is a fast emerging technology. The main advantage of BPL is being able to use the existing power line infrastructure, thereby reducing the cost. However, power line systems were not designed for high-speed data transmission as they consist of various branches and power line elements such as bridges, taps, transformers and capacitor banks. Therefore, the power line transmission medium not only introduces noise but is also adverse to high-speed data transfer in terms of the channel bandwidth. In this paper a power line channel has been modelled using Matlab and the effects of variations in the direct length, branch length and branch load on the channel frequency response are investigated. Simulations indicate suitability of multi-carrier transmission over the power line channels.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123845299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398569
K. Sunderland, Michael Conlon
The effect of increased connections of micro generation technologies can only be truly analysed if accurate distribution network models are used. Such models must be 4-wire, capable of load unbalance consideration and cognisant of the effects associated with multiple grounding on the network. This paper describes such a model. Through a multi-phase load flow algorithm based on the backward/forward load flow technique, a 4-wire suburban distribution network in Dublin, Ireland which explicitly incorporates representation of the earth will be analysed. In conjunction with representative consumer load and commercially available micro wind generators, issues including voltage unbalance, voltage rise (associated with varying penetration of micro/small generation technologies) and neutral earth voltage (NEV) effects associated with such technologies are investigated.
{"title":"4-Wire load flow analysis of a representative urban network incoprating SSEG","authors":"K. Sunderland, Michael Conlon","doi":"10.1109/UPEC.2012.6398569","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398569","url":null,"abstract":"The effect of increased connections of micro generation technologies can only be truly analysed if accurate distribution network models are used. Such models must be 4-wire, capable of load unbalance consideration and cognisant of the effects associated with multiple grounding on the network. This paper describes such a model. Through a multi-phase load flow algorithm based on the backward/forward load flow technique, a 4-wire suburban distribution network in Dublin, Ireland which explicitly incorporates representation of the earth will be analysed. In conjunction with representative consumer load and commercially available micro wind generators, issues including voltage unbalance, voltage rise (associated with varying penetration of micro/small generation technologies) and neutral earth voltage (NEV) effects associated with such technologies are investigated.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124911896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398612
F. Aashoor, F. V. P. Robinson
Photovoltaic (PV) panels are devices that convert sun light into electrical energy and are considered to be one of the major ways of producing clean and inexhaustible renewable energy. However, these devices do not always naturally operate at maximum efficiency due to the nonlinearity of their output current-voltage characteristic which is affected by the panel temperature and irradiance. Hence, the addition of a high performance maximum-power-point tracking, MPPT, power converter interface is the key to keeping the PV system operating at the optimum power point which then gives maximum efficiency. Many MPPT power-converters and different types of control techniques have been considered in the past. This paper primarily considers the MPPT power-converter control method or algorithm. A so called perturb and observe (P&O) technique is considered in this work. This technique is widely used due to its low cost and ease of implementation. With conventional P&O algorithms using fixed iteration step-size, it is impossible to satisfy both performance requirements of fast dynamic response and good accuracy during the steady state at the same time. This is because, if the step-size is set to be big enough for a fast dynamic response, the oscillation around the maximum-power operating point will increase during the steady state leading to lost power generation, and if the step size is too small optimum generation is not quickly restored during changing operating conditions. To overcome these limitations a new adaptive P&O method with variable step size has been investigated which has been implemented using fuzzy logic control. The proposed method has been evaluated by simulation using MATLAB and compared with the conventional P&O under different insolation, or sun-light intensity, levels. The obtained results illustrate the effectiveness of the proposed technique and its ability for practical and efficient tracking of maximum power.
{"title":"A variable step size perturb and observe algorithm for photovoltaic maximum power point tracking","authors":"F. Aashoor, F. V. P. Robinson","doi":"10.1109/UPEC.2012.6398612","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398612","url":null,"abstract":"Photovoltaic (PV) panels are devices that convert sun light into electrical energy and are considered to be one of the major ways of producing clean and inexhaustible renewable energy. However, these devices do not always naturally operate at maximum efficiency due to the nonlinearity of their output current-voltage characteristic which is affected by the panel temperature and irradiance. Hence, the addition of a high performance maximum-power-point tracking, MPPT, power converter interface is the key to keeping the PV system operating at the optimum power point which then gives maximum efficiency. Many MPPT power-converters and different types of control techniques have been considered in the past. This paper primarily considers the MPPT power-converter control method or algorithm. A so called perturb and observe (P&O) technique is considered in this work. This technique is widely used due to its low cost and ease of implementation. With conventional P&O algorithms using fixed iteration step-size, it is impossible to satisfy both performance requirements of fast dynamic response and good accuracy during the steady state at the same time. This is because, if the step-size is set to be big enough for a fast dynamic response, the oscillation around the maximum-power operating point will increase during the steady state leading to lost power generation, and if the step size is too small optimum generation is not quickly restored during changing operating conditions. To overcome these limitations a new adaptive P&O method with variable step size has been investigated which has been implemented using fuzzy logic control. The proposed method has been evaluated by simulation using MATLAB and compared with the conventional P&O under different insolation, or sun-light intensity, levels. The obtained results illustrate the effectiveness of the proposed technique and its ability for practical and efficient tracking of maximum power.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122708135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398613
M. Moghadam, M. Darwish
This paper is to present a new model of multilevel DC to AC inverter. The Multilevel inverter topology is based on buck/boost converter circuit. The output voltage of the inverter is shaped by selecting the appropriate duty cycle of the buck/boost switching pattern. This new topology offers almost step-less output voltage without the need for multi DC sources or several capacitor banks.
{"title":"A buck/boost based Multilevel inverter topology for UPEC2012 conference proceeding","authors":"M. Moghadam, M. Darwish","doi":"10.1109/UPEC.2012.6398613","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398613","url":null,"abstract":"This paper is to present a new model of multilevel DC to AC inverter. The Multilevel inverter topology is based on buck/boost converter circuit. The output voltage of the inverter is shaped by selecting the appropriate duty cycle of the buck/boost switching pattern. This new topology offers almost step-less output voltage without the need for multi DC sources or several capacitor banks.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121884656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398608
F. Solomonesc, R. Teslovan, C. Barbulescu, S. Kilyeni, Petru Dan Cristian
There is a growing interest in finding new ways to solve power systems related problems. Heuristic search methods are considered a good alternative to conventional ones. The present work focuses on genetic algorithms (GA). A GA adapted for power flow solving is detailed. Some practical issues are presented.
{"title":"Genetic algorithm power flow computing approach","authors":"F. Solomonesc, R. Teslovan, C. Barbulescu, S. Kilyeni, Petru Dan Cristian","doi":"10.1109/UPEC.2012.6398608","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398608","url":null,"abstract":"There is a growing interest in finding new ways to solve power systems related problems. Heuristic search methods are considered a good alternative to conventional ones. The present work focuses on genetic algorithms (GA). A GA adapted for power flow solving is detailed. Some practical issues are presented.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115787595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398611
P. L. Mantock, M. Moghadam, M. Darwish
This paper presents a new concept of an ultra-low loss cable which can be used in transmission and distribution systems. The cable has been developed by the reconfiguring of a capacitor which has a “theoretically” zero loss and practically ultra- low losses. The main idea behind this new concept is to present the cable as a linear capacitor where the power can be transmitted without any significant losses.
{"title":"A Charge Transfer Cable (CTC) ‘an ultra-low loss cable’","authors":"P. L. Mantock, M. Moghadam, M. Darwish","doi":"10.1109/UPEC.2012.6398611","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398611","url":null,"abstract":"This paper presents a new concept of an ultra-low loss cable which can be used in transmission and distribution systems. The cable has been developed by the reconfiguring of a capacitor which has a “theoretically” zero loss and practically ultra- low losses. The main idea behind this new concept is to present the cable as a linear capacitor where the power can be transmitted without any significant losses.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124881866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398598
Ahmad Abdel-Majeed, M. Braun
Accurate and reliable state estimation for low voltage networks is the core stone for flexible operation and control in the current transaction from passive conventional to active smart grids. The development in the energy supply has revealed a rapid increase of controllable distributed generators, consumer's installation, stationary storage systems and electric vehicles. This development leads to a significantly different kind of system behavior which must be understood first, and then to make suggestions for operational network improvements in order to increase the security and efficiency of the distribution system operation. For this, a high chronological and topological resolution of information for the system state estimation in the low voltage level is necessary. However, measurement data are necessary for state estimation, these measurements can be obtained either from the distribution system measurement infrastructure or from the smart meters at the connection points of the customer. The focus of this paper is to obtain the technical feasibility of using smart meter and their measurements for low voltage network observability and controllability through state estimation techniques. Also to analyse the impact of high accuracy measurement data provided from smart meters on the state estimation output accuracy for both voltage and it's phase angle.
{"title":"Low voltage system state estimation using smart meters","authors":"Ahmad Abdel-Majeed, M. Braun","doi":"10.1109/UPEC.2012.6398598","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398598","url":null,"abstract":"Accurate and reliable state estimation for low voltage networks is the core stone for flexible operation and control in the current transaction from passive conventional to active smart grids. The development in the energy supply has revealed a rapid increase of controllable distributed generators, consumer's installation, stationary storage systems and electric vehicles. This development leads to a significantly different kind of system behavior which must be understood first, and then to make suggestions for operational network improvements in order to increase the security and efficiency of the distribution system operation. For this, a high chronological and topological resolution of information for the system state estimation in the low voltage level is necessary. However, measurement data are necessary for state estimation, these measurements can be obtained either from the distribution system measurement infrastructure or from the smart meters at the connection points of the customer. The focus of this paper is to obtain the technical feasibility of using smart meter and their measurements for low voltage network observability and controllability through state estimation techniques. Also to analyse the impact of high accuracy measurement data provided from smart meters on the state estimation output accuracy for both voltage and it's phase angle.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125257041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：