Pub Date : 2019-05-09DOI: 10.1109/AEIT-HVDC.2019.8740430
M. J. Pérez-Molina, D. M. Larruskain, P. López, O. Abarrategi, M. Santos-Mugica
From a prospect where High Voltage Direct Current systems are the most promising alternative for new grid expansion as well as for integration of renewable energies at worldwide level, this paper analyses DC protection systems and their challenges on detecting and clearing faults. The focus of this paper is a comparison between non-unit and unit protection systems. It is also presented a study case with a simple non-unit algorithm, which is enhanced with a communication system.
{"title":"A comparison of non-unit and unit protection algorithms for HVDC grids","authors":"M. J. Pérez-Molina, D. M. Larruskain, P. López, O. Abarrategi, M. Santos-Mugica","doi":"10.1109/AEIT-HVDC.2019.8740430","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740430","url":null,"abstract":"From a prospect where High Voltage Direct Current systems are the most promising alternative for new grid expansion as well as for integration of renewable energies at worldwide level, this paper analyses DC protection systems and their challenges on detecting and clearing faults. The focus of this paper is a comparison between non-unit and unit protection systems. It is also presented a study case with a simple non-unit algorithm, which is enhanced with a communication system.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131853461","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740645
Giuseppe Lagrotteria, Davide Pietribiasi, Marco Marelli
Increased use of HVDC for transmission of bulk power for long distances is now associated with the availability of insulated cables of different technologies and up to 600 kV and more. The evolution for extruded cables has been extremely fast, and seems not to stop. Paper is presenting some of the newer developments in this field.
{"title":"HVDC Cables - The technology boost","authors":"Giuseppe Lagrotteria, Davide Pietribiasi, Marco Marelli","doi":"10.1109/AEIT-HVDC.2019.8740645","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740645","url":null,"abstract":"Increased use of HVDC for transmission of bulk power for long distances is now associated with the availability of insulated cables of different technologies and up to 600 kV and more. The evolution for extruded cables has been extremely fast, and seems not to stop. Paper is presenting some of the newer developments in this field.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"123 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127060705","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740612
Alberto Persico, Massimo Spiranelli, M. Hyttinen, D. Barron
The paper deals with the development of IFA2 project, a new HVDC link between United Kingdom and France, being constructed by ABB. The major constraints (electrical, environmental, planning and landscaping) and the advantageous solution adopted to minimize the size of the AC yard of the converter station in UK are described within this document. The innovative ABB Hybrid module PASS420, together with a Gas Insulated Busbar solution, is being used in order to be compliant with the severe specification of the contract and to achieve an excellent degree of compactness and building encompassed solution.
{"title":"IFA2 - HVDC goes compact with Hybrid PASS420 modules and GIB connections","authors":"Alberto Persico, Massimo Spiranelli, M. Hyttinen, D. Barron","doi":"10.1109/AEIT-HVDC.2019.8740612","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740612","url":null,"abstract":"The paper deals with the development of IFA2 project, a new HVDC link between United Kingdom and France, being constructed by ABB. The major constraints (electrical, environmental, planning and landscaping) and the advantageous solution adopted to minimize the size of the AC yard of the converter station in UK are described within this document. The innovative ABB Hybrid module PASS420, together with a Gas Insulated Busbar solution, is being used in order to be compliant with the severe specification of the contract and to achieve an excellent degree of compactness and building encompassed solution.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134367168","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740551
G. Macchia, M. Trovato, M. Dicorato, G. Forte
In order to enhance the control ability of HVDC systems, more and more attention is devoted to Voltage Source Converters (VSCs), enabling instantaneous control of large amounts of power with improved stability features and providing ancillary services to the AC system. A crucial issue in VSC control is represented by their synchronization with the AC grid usually obtained by phase locked loop techniques. In this paper, the Virtual Synchronous Machine concept is exploited through Power-Synchronization Method (PSM), aiming to mimic the behavior of synchronous generators with VSCs. Therefore, a full and detailed dynamic model of a PSM-controlled VSC is developed, tuned and tested by means of time domain simulations.
{"title":"Modelling of VSC-HVDC with power synchronization method including frequency support","authors":"G. Macchia, M. Trovato, M. Dicorato, G. Forte","doi":"10.1109/AEIT-HVDC.2019.8740551","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740551","url":null,"abstract":"In order to enhance the control ability of HVDC systems, more and more attention is devoted to Voltage Source Converters (VSCs), enabling instantaneous control of large amounts of power with improved stability features and providing ancillary services to the AC system. A crucial issue in VSC control is represented by their synchronization with the AC grid usually obtained by phase locked loop techniques. In this paper, the Virtual Synchronous Machine concept is exploited through Power-Synchronization Method (PSM), aiming to mimic the behavior of synchronous generators with VSCs. Therefore, a full and detailed dynamic model of a PSM-controlled VSC is developed, tuned and tested by means of time domain simulations.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133882633","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740460
L. Michi, G. Donnini, P. Capurso, A. C. Bugliari, F. Falorni, M. Quadrio, D. Canever, L. Giorgi
New challenges in power system planning, such as integration of massive amount of Renewable Energy Resources (RES), global decarbonization and efficiency targets, must be addressed by the Transmission System Operator (TSO) to guarantee optimal management, reliability and power grid flexibility. In this context, High Voltage Direct Current (HVDC) may play a key role, providing additional benefits compared to HVAC transmission line. Therefore, a valid and detailed model of different HVDC technologies and configurations is needed for grid planning and middle-long term studies. The aim of this paper is reporting the Italian experience in HVDC transmission system models for steady state studies, with special reference to LCC or CSC (line-commutated converter or current-source converter) and VSC (voltage-source converter) HVDC, analyzing their impact in load-flow solution techniques. The HVDC implementation in Common Grid Model Exchange Data (CGMES), the data exchange standard defined in ENTSO-E framework, used to improve Pan-European grid modelling and information exchange among TSOs for TYNDP studies are also presented.
{"title":"An overview of the HVDC transmission system models in planning tools: the Italian experience","authors":"L. Michi, G. Donnini, P. Capurso, A. C. Bugliari, F. Falorni, M. Quadrio, D. Canever, L. Giorgi","doi":"10.1109/AEIT-HVDC.2019.8740460","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740460","url":null,"abstract":"New challenges in power system planning, such as integration of massive amount of Renewable Energy Resources (RES), global decarbonization and efficiency targets, must be addressed by the Transmission System Operator (TSO) to guarantee optimal management, reliability and power grid flexibility. In this context, High Voltage Direct Current (HVDC) may play a key role, providing additional benefits compared to HVAC transmission line. Therefore, a valid and detailed model of different HVDC technologies and configurations is needed for grid planning and middle-long term studies. The aim of this paper is reporting the Italian experience in HVDC transmission system models for steady state studies, with special reference to LCC or CSC (line-commutated converter or current-source converter) and VSC (voltage-source converter) HVDC, analyzing their impact in load-flow solution techniques. The HVDC implementation in Common Grid Model Exchange Data (CGMES), the data exchange standard defined in ENTSO-E framework, used to improve Pan-European grid modelling and information exchange among TSOs for TYNDP studies are also presented.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"01 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127255709","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740356
L. Michi, E. Carlini, T. B. Scirocco, G. Bruno, R. Gnudi, G. Pecoraro, C. Pisani
AC Transmission Emulation Control Strategy is a promising way to control the ordered active power flow in a VSC-HVDC system as a function of the phase angle over the parallel AC interconnection. The main advantage of this strategy is that no direct operator active power set-point dispatch is needed: HVDC interconnection basically behaves like an alternating current (AC) transmission line characterized by a proper impedance. Despite the high-level control strategy seems relatively simple the choice of an appropriate set of parameters is essential in order to preserve system stability on wide and appropriate grid support in N-1 condition. In light of this need, the paper introduces general criteria to follow for optimal tuning of VSC-HVDC control system in AC Transmission Emulation Control mode. It can be considered as a general methodology that can assist TSO in selecting those parameters of VSC-HVDC control system in AC Transmission Emulation Control mode which mainly affect the HVDCs behaviour in the interconnected power systems.
{"title":"AC Transmission Emulation Control Strategy in VSC-HVDC systems: general criteria for optimal tuning of control system","authors":"L. Michi, E. Carlini, T. B. Scirocco, G. Bruno, R. Gnudi, G. Pecoraro, C. Pisani","doi":"10.1109/AEIT-HVDC.2019.8740356","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740356","url":null,"abstract":"AC Transmission Emulation Control Strategy is a promising way to control the ordered active power flow in a VSC-HVDC system as a function of the phase angle over the parallel AC interconnection. The main advantage of this strategy is that no direct operator active power set-point dispatch is needed: HVDC interconnection basically behaves like an alternating current (AC) transmission line characterized by a proper impedance. Despite the high-level control strategy seems relatively simple the choice of an appropriate set of parameters is essential in order to preserve system stability on wide and appropriate grid support in N-1 condition. In light of this need, the paper introduces general criteria to follow for optimal tuning of VSC-HVDC control system in AC Transmission Emulation Control mode. It can be considered as a general methodology that can assist TSO in selecting those parameters of VSC-HVDC control system in AC Transmission Emulation Control mode which mainly affect the HVDCs behaviour in the interconnected power systems.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130822635","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740513
O. Vestergaard, P. Lundberg
The Maritime Link (ML) is the first bipolar VSC HVDC in the world with DC overhead line and DC cable. The paper addresses some interesting studies which are performed during design phase. First, it is demonstrated the capabilities of VSC HVDC including sharing spinning reserve between two AC grids interconnected with HVDC link and avoiding load shedding under critical network conditions and contingency. Also, considering the evolution of VSC HVDC technology, the cost-effective DC fault clearing capability becomes more robust due to less switches operating involved when clearing a DC fault, and excellent performance is demonstrated by the site recording.
Maritime Link (ML)是世界上第一个具有直流架空线路和直流电缆的双极VSC HVDC。本文介绍了在设计阶段进行的一些有趣的研究。首先，论证了VSC高压直流在关键网络条件和突发事件下，在与高压直流链路互联的两个交流电网之间共享旋转储备和避免减载的能力。此外，考虑到VSC高压直流技术的发展，由于在清除直流故障时涉及的开关操作较少，因此经济高效的直流故障清除能力变得更加强大，并且通过现场记录证明了出色的性能。
{"title":"Maritime Link The First Bipolar VSC HVDC with Overhead Line","authors":"O. Vestergaard, P. Lundberg","doi":"10.1109/AEIT-HVDC.2019.8740513","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740513","url":null,"abstract":"The Maritime Link (ML) is the first bipolar VSC HVDC in the world with DC overhead line and DC cable. The paper addresses some interesting studies which are performed during design phase. First, it is demonstrated the capabilities of VSC HVDC including sharing spinning reserve between two AC grids interconnected with HVDC link and avoiding load shedding under critical network conditions and contingency. Also, considering the evolution of VSC HVDC technology, the cost-effective DC fault clearing capability becomes more robust due to less switches operating involved when clearing a DC fault, and excellent performance is demonstrated by the site recording.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123780321","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740630
P. Molfino, M. Nervi, S. Malgarotti
In the preliminary design of a HVDC link one of the most peculiar and complex phases is the correct choice and configuration of main return electrodes. The choice may be strongly dependent on a large number of technical, local and environmental constraints; therefore, there may be situations leading to an obvious choice, and other where the designer has significantly larger freedom of choice. To clarify the subject, this paper gives an overview of the main arising issues and of the procedures that can be followed.
{"title":"On the choice of the right HVDC Electrode type","authors":"P. Molfino, M. Nervi, S. Malgarotti","doi":"10.1109/AEIT-HVDC.2019.8740630","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740630","url":null,"abstract":"In the preliminary design of a HVDC link one of the most peculiar and complex phases is the correct choice and configuration of main return electrodes. The choice may be strongly dependent on a large number of technical, local and environmental constraints; therefore, there may be situations leading to an obvious choice, and other where the designer has significantly larger freedom of choice. To clarify the subject, this paper gives an overview of the main arising issues and of the procedures that can be followed.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"159 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130995256","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740529
J. Przybilla, U. Kellner-Werdehausen, Sebastian P. Sommer
During the 1970s thyristors were used for the first time to realize a Line Commutated Converter (LCC) for High Voltage Direct Current (HVDC) transmission lines which decreased power losses and increased reliability. At that time thyristors with a blocking capability of 1.65 kV and a silicon diameter of 35 mm had been specially developed for this application. Nearly 43,000 thyristors were installed in this first transmission line using thyristors, Cahora Bassa, to transfer 1920 MW at ± 533 kV over 1420 km from Mozambique to South Africa. Currently there is a trend to realize HVDC transmission lines increasingly with Voltage Source Converters (VSC). This was further stimulated by the introduction of the Modular Multilevel Converter technology (MMC) which decreased system complexity greatly. Today's installations are built up to ±500 kV and 2 GW and for future projects ±800 kV with 5 GW are under discussion. Although the main semiconductor device in VSCs is the IGBT, classical bipolar devices are critical for VSC operation, too. Special developed diodes with extreme soft switching behavior are used as Free Wheeling Diodes (FWD) and antiparallel thyristors protect the IGBTs in case of surge current events. Recently Press Pack IGBT (PPI) has come into focus as an alternative realization for VSC architectures.
{"title":"Realizing Bipolar Power Semiconductor for Highest Reliable Applications","authors":"J. Przybilla, U. Kellner-Werdehausen, Sebastian P. Sommer","doi":"10.1109/AEIT-HVDC.2019.8740529","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740529","url":null,"abstract":"During the 1970s thyristors were used for the first time to realize a Line Commutated Converter (LCC) for High Voltage Direct Current (HVDC) transmission lines which decreased power losses and increased reliability. At that time thyristors with a blocking capability of 1.65 kV and a silicon diameter of 35 mm had been specially developed for this application. Nearly 43,000 thyristors were installed in this first transmission line using thyristors, Cahora Bassa, to transfer 1920 MW at ± 533 kV over 1420 km from Mozambique to South Africa. Currently there is a trend to realize HVDC transmission lines increasingly with Voltage Source Converters (VSC). This was further stimulated by the introduction of the Modular Multilevel Converter technology (MMC) which decreased system complexity greatly. Today's installations are built up to ±500 kV and 2 GW and for future projects ±800 kV with 5 GW are under discussion. Although the main semiconductor device in VSCs is the IGBT, classical bipolar devices are critical for VSC operation, too. Special developed diodes with extreme soft switching behavior are used as Free Wheeling Diodes (FWD) and antiparallel thyristors protect the IGBTs in case of surge current events. Recently Press Pack IGBT (PPI) has come into focus as an alternative realization for VSC architectures.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134321387","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 : 2019-05-01DOI: 10.1109/AEIT-HVDC.2019.8740653
M. Marzinotto, A. Battaglia, G. Mazzanti
HVDC cables connected to Current Source Converters are subjected to polarity reversal when the HVDC intertie changes the power flow. Mass Impregnated Non-Draining cables had been using since the dawn of HVDC transmission with Current Source Converters and over the years they have shown their own ability to withstand the overstressing electric field values that arise during a polarity reversal. Cable manufacturers give restrictions on the number of polarity reversal that a cable can sustain and furthermore they give procedures to pursue in order to preserve cable life under such conditions. A phenomenological ageing model under fast polarity reversal is illustrated in this paper giving some information about its parameters. Besides, a space charge measurement test method to be applied during laboratory tests on full sized cables is illustrated in line with the IEEE 1732 standard. Aim of this paper is to merge the two approaches since the outcomes of space charge measurements on full sized cables can help in the parameters inference of the polarity reversal ageing model.
{"title":"Space charges and life models for lifetime inference of HVDC cables under voltage polarity reversal","authors":"M. Marzinotto, A. Battaglia, G. Mazzanti","doi":"10.1109/AEIT-HVDC.2019.8740653","DOIUrl":"https://doi.org/10.1109/AEIT-HVDC.2019.8740653","url":null,"abstract":"HVDC cables connected to Current Source Converters are subjected to polarity reversal when the HVDC intertie changes the power flow. Mass Impregnated Non-Draining cables had been using since the dawn of HVDC transmission with Current Source Converters and over the years they have shown their own ability to withstand the overstressing electric field values that arise during a polarity reversal. Cable manufacturers give restrictions on the number of polarity reversal that a cable can sustain and furthermore they give procedures to pursue in order to preserve cable life under such conditions. A phenomenological ageing model under fast polarity reversal is illustrated in this paper giving some information about its parameters. Besides, a space charge measurement test method to be applied during laboratory tests on full sized cables is illustrated in line with the IEEE 1732 standard. Aim of this paper is to merge the two approaches since the outcomes of space charge measurements on full sized cables can help in the parameters inference of the polarity reversal ageing model.","PeriodicalId":186931,"journal":{"name":"2019 AEIT HVDC International Conference (AEIT HVDC)","volume":"146 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124696737","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：