Pub Date : 2010-07-25DOI: 10.1109/PES.2010.5589727
D. Xiao, M. F. Rahman
This paper presents a speed and position estimation method for the sensorless direct torque and flux control scheme for matrix converter driven interior permanent-magnet synchronous motor. The adaptive sliding mode observer simultaneously estimates the stator flux, speed and rotor position. A permanent magnet flux estimator is integrated with the observer to compensate the effect of inaccurate PM flux on the estimation error. The direct closed-loop control of both torque and stator flux are achieved using two proportional-integral controllers and indirect space vector modulation with a new overmodulation strategy. The system is characterized by low torque and flux ripples, unity input power factor, sinusoidal input/output currents, inherent bidirectional power-flow capability and good speed sensorless control performance over wide speed range, while maintaining constant switching frequency and fast dynamics. Experimental results are shown to illustrate the effectiveness of the proposed sensorless DTFC-ISVM matrix converter IPM motor drives.
{"title":"Sensorless direct torque and flux control for matrix converter-fed interior permanent magnet synchronous motor using adaptive sliding mode observer","authors":"D. Xiao, M. F. Rahman","doi":"10.1109/PES.2010.5589727","DOIUrl":"https://doi.org/10.1109/PES.2010.5589727","url":null,"abstract":"This paper presents a speed and position estimation method for the sensorless direct torque and flux control scheme for matrix converter driven interior permanent-magnet synchronous motor. The adaptive sliding mode observer simultaneously estimates the stator flux, speed and rotor position. A permanent magnet flux estimator is integrated with the observer to compensate the effect of inaccurate PM flux on the estimation error. The direct closed-loop control of both torque and stator flux are achieved using two proportional-integral controllers and indirect space vector modulation with a new overmodulation strategy. The system is characterized by low torque and flux ripples, unity input power factor, sinusoidal input/output currents, inherent bidirectional power-flow capability and good speed sensorless control performance over wide speed range, while maintaining constant switching frequency and fast dynamics. Experimental results are shown to illustrate the effectiveness of the proposed sensorless DTFC-ISVM matrix converter IPM motor drives.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130652823","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 : 2010-07-25DOI: 10.1109/PES.2010.5589470
D. Brooks, P. Pourbeik
State and potential federal policies are expected to increase renewable generation in North America in the immediate future. Much of this growth will be from variable resources such as wind generation and solar photovoltaic (PV). As the amount of variable generation increases, the reliability of the bulk power system can be negatively impacted if provisions are not made to accommodate the additional variability and uncertainty. As such, in December 2007, NERC created the Integration of Variable Generation Task Force (IVGTF) to prepare a report to identify technical considerations associated with integrating high penetrations of variable generation and specific mitigating actions needed to ensure bulk system reliability. The special report, released in April 2009, identified several follow-on tasks to further investigate measures to ensure reliability. This paper summarizes the efforts of one of four IVGTF work groups tasked with system planning related activities.
{"title":"NERC's integration of Variable Generation Task Force: Status report — Planning work group update","authors":"D. Brooks, P. Pourbeik","doi":"10.1109/PES.2010.5589470","DOIUrl":"https://doi.org/10.1109/PES.2010.5589470","url":null,"abstract":"State and potential federal policies are expected to increase renewable generation in North America in the immediate future. Much of this growth will be from variable resources such as wind generation and solar photovoltaic (PV). As the amount of variable generation increases, the reliability of the bulk power system can be negatively impacted if provisions are not made to accommodate the additional variability and uncertainty. As such, in December 2007, NERC created the Integration of Variable Generation Task Force (IVGTF) to prepare a report to identify technical considerations associated with integrating high penetrations of variable generation and specific mitigating actions needed to ensure bulk system reliability. The special report, released in April 2009, identified several follow-on tasks to further investigate measures to ensure reliability. This paper summarizes the efforts of one of four IVGTF work groups tasked with system planning related activities.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123931330","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 : 2010-07-25DOI: 10.1109/PES.2010.5589755
R. Moreno, D. Pudjianto, G. Strbac
Increased connections of wind power in the Great Britain (GB) transmission system had triggered the need to review the fundamental principles behind the deterministic Great Britain Supply Quality and Security Standards (SQSS) that has been used for more than 5 decades. This review analyses the necessary upgrades to improve the efficiency of transmission system operation and capacity required to accommodate the present and future generation system. This paper in particular addresses a number of issues raised from the applications of deterministic SQSS and its operation and design efficiency concerning the best usage of N-k policy type. With respect to the United Kingdom (UK) transmission system operation, deterministic standards have been used to determine secure maximum levels of power transfers across a particular boundary. Our studies indicate that the deterministic standards are too conservative. This leads to over requirement of transmission capacity in planning timescales or significant constraints to access remote wind power in operational timescales. As an alternative, the use of an integrated reliability and cost-benefit framework to optimize the level of transmission system security has been developed. A wide range of studies have been carried out to analyze the benefits of this approach in the UK. The results indicate the need to move towards this integrated approach in order to maximize the value of transmission and to speed up the connections of wind power.
{"title":"Future transmission network operation and design standards to support a low carbon electricity system","authors":"R. Moreno, D. Pudjianto, G. Strbac","doi":"10.1109/PES.2010.5589755","DOIUrl":"https://doi.org/10.1109/PES.2010.5589755","url":null,"abstract":"Increased connections of wind power in the Great Britain (GB) transmission system had triggered the need to review the fundamental principles behind the deterministic Great Britain Supply Quality and Security Standards (SQSS) that has been used for more than 5 decades. This review analyses the necessary upgrades to improve the efficiency of transmission system operation and capacity required to accommodate the present and future generation system. This paper in particular addresses a number of issues raised from the applications of deterministic SQSS and its operation and design efficiency concerning the best usage of N-k policy type. With respect to the United Kingdom (UK) transmission system operation, deterministic standards have been used to determine secure maximum levels of power transfers across a particular boundary. Our studies indicate that the deterministic standards are too conservative. This leads to over requirement of transmission capacity in planning timescales or significant constraints to access remote wind power in operational timescales. As an alternative, the use of an integrated reliability and cost-benefit framework to optimize the level of transmission system security has been developed. A wide range of studies have been carried out to analyze the benefits of this approach in the UK. The results indicate the need to move towards this integrated approach in order to maximize the value of transmission and to speed up the connections of wind power.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123991451","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 : 2010-07-25DOI: 10.1109/PES.2010.5590213
F. Delfino, G. Denegri, M. Invernizzi, R. Procopio
This paper deals with the use of large-size Photovoltaic (PV) units as providers of the reactive power compensation ancillary service. To do this, a suitable control scheme has been developed, which is based on an advanced control theory, called FeedBack Linearization (FBL), widely employed in the robotics field but still not so popular in power systems engineering. This allows to regulate both the injection of reactive power and the PV voltage, which is fixed to the value corresponding to the maximum power extraction from the PV unit, thanks to the implementation of an efficient MPPT algorithm, whose main features are described in detail. Several simulations are performed in the PSCAD-EMTDC electromagnetic environment to validate the proposed approach.
{"title":"A control algorithm for the maximum power point tracking and the reactive power injection from grid-connected PV systems","authors":"F. Delfino, G. Denegri, M. Invernizzi, R. Procopio","doi":"10.1109/PES.2010.5590213","DOIUrl":"https://doi.org/10.1109/PES.2010.5590213","url":null,"abstract":"This paper deals with the use of large-size Photovoltaic (PV) units as providers of the reactive power compensation ancillary service. To do this, a suitable control scheme has been developed, which is based on an advanced control theory, called FeedBack Linearization (FBL), widely employed in the robotics field but still not so popular in power systems engineering. This allows to regulate both the injection of reactive power and the PV voltage, which is fixed to the value corresponding to the maximum power extraction from the PV unit, thanks to the implementation of an efficient MPPT algorithm, whose main features are described in detail. Several simulations are performed in the PSCAD-EMTDC electromagnetic environment to validate the proposed approach.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124177324","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 : 2010-07-25DOI: 10.1109/PES.2010.5590020
Li Yang, Zhao Xu, J. Ostergaard, Z. Dong, Xianhao Ma
This paper first presents the Hopf bifurcation analysis for a vector-controlled doubly fed induction generator (DFIG) which is widely used in wind power conversion systems. Using three-phase back-to-back pulse-width-modulated (PWM) converters, DFIG can keep stator frequency constant under variable rotor speed and provide independent control of active and reactive power output. The oscillatory instability of the DFIG has been observed by simulation study. The detailed mathematical model of the DFIG closed-loop system is derived and used to analyze the observed bifurcation phenomena. The loci of the Jacobian's eigenvalues are computed and the analysis shows that the system loses stability via a Hopf bifurcation. The eigenvalue sensitivity analysis with respect to machine and control parameters are performed to assess the impact of parameters upon system stability. Moreover, the Hopf bifurcation boundaries of the key parameters are also given that can facilitate the tuning of those parameters to ensure stable operation.
{"title":"Hopf bifurcation and eigenvalue sensitivity analysis of doubly fed induction generator wind turbine system","authors":"Li Yang, Zhao Xu, J. Ostergaard, Z. Dong, Xianhao Ma","doi":"10.1109/PES.2010.5590020","DOIUrl":"https://doi.org/10.1109/PES.2010.5590020","url":null,"abstract":"This paper first presents the Hopf bifurcation analysis for a vector-controlled doubly fed induction generator (DFIG) which is widely used in wind power conversion systems. Using three-phase back-to-back pulse-width-modulated (PWM) converters, DFIG can keep stator frequency constant under variable rotor speed and provide independent control of active and reactive power output. The oscillatory instability of the DFIG has been observed by simulation study. The detailed mathematical model of the DFIG closed-loop system is derived and used to analyze the observed bifurcation phenomena. The loci of the Jacobian's eigenvalues are computed and the analysis shows that the system loses stability via a Hopf bifurcation. The eigenvalue sensitivity analysis with respect to machine and control parameters are performed to assess the impact of parameters upon system stability. Moreover, the Hopf bifurcation boundaries of the key parameters are also given that can facilitate the tuning of those parameters to ensure stable operation.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123638810","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 : 2010-07-25DOI: 10.1109/PES.2010.5590179
A. Orths, K. Rudion
THE European Union has enacted ambitious targets concerning the implementation of renewable energy sources into the present energy systems. These targets are binding and have stepwise to be fulfilled until the year 2020.
{"title":"Europe: Offshore wind power - European visions and projects","authors":"A. Orths, K. Rudion","doi":"10.1109/PES.2010.5590179","DOIUrl":"https://doi.org/10.1109/PES.2010.5590179","url":null,"abstract":"THE European Union has enacted ambitious targets concerning the implementation of renewable energy sources into the present energy systems. These targets are binding and have stepwise to be fulfilled until the year 2020.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121409334","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 : 2010-07-25DOI: 10.1109/PES.2010.5590122
Martin Troschel, Ontje Lunsdorf
An active matching of supply and demand of electric power contributes to an optimised utilisation of power grids. In this paper, we will outline the potential of conjoint power generation management and load adaption measures especially regarding system load balancing in low voltage power grids.
{"title":"Conjoint generation management and load adaption for an optimised power grid utilisation","authors":"Martin Troschel, Ontje Lunsdorf","doi":"10.1109/PES.2010.5590122","DOIUrl":"https://doi.org/10.1109/PES.2010.5590122","url":null,"abstract":"An active matching of supply and demand of electric power contributes to an optimised utilisation of power grids. In this paper, we will outline the potential of conjoint power generation management and load adaption measures especially regarding system load balancing in low voltage power grids.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114064884","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 : 2010-07-25DOI: 10.1109/PES.2010.5589339
A. Alarcón-Rodríguez, G. Ault
Distributed Energy Resources (DER) are recognized as one of the possible solutions for sustainable economic development. The optimal integration of DER is a multi-objective problem in which different technical and economical objectives must be achieved simultaneously, and where a compromise solution for different perspectives needs to be found. The stochastic nature of DER and demand increases the complexity of the problem. Advanced multi-objective planning methods with appropriate probabilistic models of DER are required. This paper presents a multi-objective analysis of the optimal integration of wind turbines. The analysis is based on the Strength Pareto Evolutionary Algorithm 2 (SPEA2) and considers technical and economical planning objectives. The unpredictable nature of DER production and demand is evaluated by means of stochastic simulation. Practical aspects of the framework's implementation are discussed, including the formulation of probabilistic constraints. Results demonstrate that the multi-objective approach proposed produces valuable information for different stakeholders involved in DER planning and development.
{"title":"Multi-objective planning of Distributed Energy Resources with probabilistic constraints","authors":"A. Alarcón-Rodríguez, G. Ault","doi":"10.1109/PES.2010.5589339","DOIUrl":"https://doi.org/10.1109/PES.2010.5589339","url":null,"abstract":"Distributed Energy Resources (DER) are recognized as one of the possible solutions for sustainable economic development. The optimal integration of DER is a multi-objective problem in which different technical and economical objectives must be achieved simultaneously, and where a compromise solution for different perspectives needs to be found. The stochastic nature of DER and demand increases the complexity of the problem. Advanced multi-objective planning methods with appropriate probabilistic models of DER are required. This paper presents a multi-objective analysis of the optimal integration of wind turbines. The analysis is based on the Strength Pareto Evolutionary Algorithm 2 (SPEA2) and considers technical and economical planning objectives. The unpredictable nature of DER production and demand is evaluated by means of stochastic simulation. Practical aspects of the framework's implementation are discussed, including the formulation of probabilistic constraints. Results demonstrate that the multi-objective approach proposed produces valuable information for different stakeholders involved in DER planning and development.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"35 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114117793","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 : 2010-07-25DOI: 10.1109/PES.2010.5590019
F. Alhasawi, J. Milanović, A. A. Alabduljabbar
the multifunctional capabilities of Flexible AC Transmission System (FACTS) devices paved new paths for controlling and enhancing the power transfer and usable capacity of transmission lines. The ability to enhance power transfers lead to their applications in a multi machine power system for the purpose of an overall reduction in power generation cost, among the others. The study presented in this paper deals with evaluation of economic viability of application of FACTS devices for generation cost reduction. It starts with optimal placement of four types of FACTS devices, namely Static Var compensator (SVC), Thyristor-Controlled Series Capacitor (TCSC), Thyristor-Controlled Voltage Regulator (TCVR), and Thyristor-Controlled Phase Shifting Transformer (TCPST) in a multi machine power system. The allocation methodology accounts for the cost of generated active and reactive powers, load growth, and cost of selected FACTS devices over a wide range of operating conditions. The allocation task is handled by the Optimal Power Flow (OPF) and Genetic Algorithm (GA) based optimization procedures. The economic viability of the solution is assessed using Net Present Value (NPV) calculation. Finally, Tornado diagram is used to assess sensitivity of the solution to various parameters involved in the optimization procedure.
{"title":"Economic viability of application of FACTS devices for reducing generating costs","authors":"F. Alhasawi, J. Milanović, A. A. Alabduljabbar","doi":"10.1109/PES.2010.5590019","DOIUrl":"https://doi.org/10.1109/PES.2010.5590019","url":null,"abstract":"the multifunctional capabilities of Flexible AC Transmission System (FACTS) devices paved new paths for controlling and enhancing the power transfer and usable capacity of transmission lines. The ability to enhance power transfers lead to their applications in a multi machine power system for the purpose of an overall reduction in power generation cost, among the others. The study presented in this paper deals with evaluation of economic viability of application of FACTS devices for generation cost reduction. It starts with optimal placement of four types of FACTS devices, namely Static Var compensator (SVC), Thyristor-Controlled Series Capacitor (TCSC), Thyristor-Controlled Voltage Regulator (TCVR), and Thyristor-Controlled Phase Shifting Transformer (TCPST) in a multi machine power system. The allocation methodology accounts for the cost of generated active and reactive powers, load growth, and cost of selected FACTS devices over a wide range of operating conditions. The allocation task is handled by the Optimal Power Flow (OPF) and Genetic Algorithm (GA) based optimization procedures. The economic viability of the solution is assessed using Net Present Value (NPV) calculation. Finally, Tornado diagram is used to assess sensitivity of the solution to various parameters involved in the optimization procedure.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116469190","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 : 2010-07-25DOI: 10.1109/PES.2010.5589857
Chao Cai, Yuping Lu, T. Ding, Guo-fang Zhu
The application of IEC61850 and non-conventional instrument transformers (NCIT) brings a new era in the development of substation. The protection intelligent electronic device (IED) in digital substation receives sampled data from different digital data sources (DDS) with digital interface based on IEC 61850-9-2 process bus. The mismatch in sampling rate between protection IED algorithms and different DDSs requires resampling in the protection IED to make sure the protection and other algorithms can run correctly. In this paper, a smart digital resampling scheme based on oversampling interpolator and quasi-continuous interpolator for fully digital relay protection is proposed. A computationally optimal poly-phase implementation structure and nyquist filter for the oversampling interpolator is designed and the Lagrange interpolation algorithm is chosen to approximate the impulse response of the quasi-continuous interpolator considering the reduction in error. Simulation results based on ATP/EMTD and MATLAB demonstrated the effectiveness of the proposed approach.
{"title":"A smart resampling scheme for digital substation relay protection","authors":"Chao Cai, Yuping Lu, T. Ding, Guo-fang Zhu","doi":"10.1109/PES.2010.5589857","DOIUrl":"https://doi.org/10.1109/PES.2010.5589857","url":null,"abstract":"The application of IEC61850 and non-conventional instrument transformers (NCIT) brings a new era in the development of substation. The protection intelligent electronic device (IED) in digital substation receives sampled data from different digital data sources (DDS) with digital interface based on IEC 61850-9-2 process bus. The mismatch in sampling rate between protection IED algorithms and different DDSs requires resampling in the protection IED to make sure the protection and other algorithms can run correctly. In this paper, a smart digital resampling scheme based on oversampling interpolator and quasi-continuous interpolator for fully digital relay protection is proposed. A computationally optimal poly-phase implementation structure and nyquist filter for the oversampling interpolator is designed and the Lagrange interpolation algorithm is chosen to approximate the impulse response of the quasi-continuous interpolator considering the reduction in error. Simulation results based on ATP/EMTD and MATLAB demonstrated the effectiveness of the proposed approach.","PeriodicalId":177545,"journal":{"name":"IEEE PES General Meeting","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116485745","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：