Pub Date : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980670
R. Melício, V. Mendes, H. Pousinho, M. Seixas
A new integrated mathematical model for the simulation of offshore wind energy conversion system performance is presented in this paper. The mathematical model considers an offshore variable-speed turbine in deep water equipped with a permanent magnet synchronous generator using full-power two-level converter, converting the energy of a variable frequency source in injected energy into the electric network with constant frequency, through a high voltage DC transmission submarine cable. The mathematical model for the drive train is a concentrate two mass model which incorporates the dynamic for the structure and tower due to the need to emulate the effects of the moving surface. Controller strategy considered is a proportional integral one. Also, pulse width modulation using space vector modulation supplemented with sliding mode is used for trigger the transistor of the converter. Finally, a case study is presented to access the system performance.
{"title":"Simulation of offshore wind system with two-level converters: HVDC power transmission","authors":"R. Melício, V. Mendes, H. Pousinho, M. Seixas","doi":"10.1109/EPEPEMC.2014.6980670","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980670","url":null,"abstract":"A new integrated mathematical model for the simulation of offshore wind energy conversion system performance is presented in this paper. The mathematical model considers an offshore variable-speed turbine in deep water equipped with a permanent magnet synchronous generator using full-power two-level converter, converting the energy of a variable frequency source in injected energy into the electric network with constant frequency, through a high voltage DC transmission submarine cable. The mathematical model for the drive train is a concentrate two mass model which incorporates the dynamic for the structure and tower due to the need to emulate the effects of the moving surface. Controller strategy considered is a proportional integral one. Also, pulse width modulation using space vector modulation supplemented with sliding mode is used for trigger the transistor of the converter. Finally, a case study is presented to access the system performance.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123277905","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980512
L. Tutelea, S. Deaconu, G. Popa
This paper analyses two running regimes of low speed twin stator windings induction generator (TSWIG), directly coupled to the shaft of the wind turbine. A single low cost (reduced power) active rectifier is used to deliver the energy to the dc grid for a large shaft speed variation. At the rated speed, the capacitor battery supplies the induction generator with entire reactive power reducing this way the apparent power of the active rectifier. When the turbine speed decreases, the capacitor battery capability also decreases but the active rectifier (inverter) could assist the generator magnetization because the turbine power reduction relieves the active power of the active rectifier. The paper also investigates the self excitation of the stand alone TSWIG in an emergency regime. Digital simulation proves the self excitation at rated wind speed as well at low wind speed with power limitation.
{"title":"Reduced cost low speed wind or hydro energy conversion system with twin stator windings induction generator","authors":"L. Tutelea, S. Deaconu, G. Popa","doi":"10.1109/EPEPEMC.2014.6980512","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980512","url":null,"abstract":"This paper analyses two running regimes of low speed twin stator windings induction generator (TSWIG), directly coupled to the shaft of the wind turbine. A single low cost (reduced power) active rectifier is used to deliver the energy to the dc grid for a large shaft speed variation. At the rated speed, the capacitor battery supplies the induction generator with entire reactive power reducing this way the apparent power of the active rectifier. When the turbine speed decreases, the capacitor battery capability also decreases but the active rectifier (inverter) could assist the generator magnetization because the turbine power reduction relieves the active power of the active rectifier. The paper also investigates the self excitation of the stand alone TSWIG in an emergency regime. Digital simulation proves the self excitation at rated wind speed as well at low wind speed with power limitation.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"294 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120923735","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980529
S. Ohashi, M. Yoshida, T. Yokoyama
Variable carrier frequency control of PWM inverter based on deadbeat control using SoC-FPGA based hardware controller was proposed. To adopt to the fault ride through (FRT) conditions, deadbeat control was introduced to control the output current, and variable carrier method was applied to achieve high efficiency without the deterioration of controllability of the output current. The disturbance compensator was also implemented to achieve the superior tracking accuracy to the reference current. Design concept of SoC-FPGA based hardware controller was described and the verifications of the proposed method were carried out through simulations and experiments.
{"title":"Verification of variable carrier deadbeat control with digital hysteresis method using SoC-FPGA for utility interactive inverter for FRT conditions","authors":"S. Ohashi, M. Yoshida, T. Yokoyama","doi":"10.1109/EPEPEMC.2014.6980529","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980529","url":null,"abstract":"Variable carrier frequency control of PWM inverter based on deadbeat control using SoC-FPGA based hardware controller was proposed. To adopt to the fault ride through (FRT) conditions, deadbeat control was introduced to control the output current, and variable carrier method was applied to achieve high efficiency without the deterioration of controllability of the output current. The disturbance compensator was also implemented to achieve the superior tracking accuracy to the reference current. Design concept of SoC-FPGA based hardware controller was described and the verifications of the proposed method were carried out through simulations and experiments.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121356521","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980558
S. D'arco, J. Suul, M. Molinas
This paper proposes a simple method for damping of oscillations in dc grids based on Voltage Source Converters (VSCs). The damping effect is achieved by a control loop for counteracting measured dc voltage oscillations by acting on the active current reference of the ac-side VSC controller. The design of the damping method is supported by participation factor analysis and parametric sensitivities of a small-signal model representing an investigated test case. This investigated system is consisting of a single HVDC converter station connected to a dc cable equivalent and an ac grid. The validity of the developed small-signal model is verified by comparison to a simulation model including nonlinear effects of the investigated converter configuration. The small-signal model is then used to analyze the stability and dynamic characteristics of the system with and without the proposed active damping and to identify a suitable tuning of the damping controller.
{"title":"Implementation and analysis of a control scheme for damping of oscillations in VSC-based HVDC grids","authors":"S. D'arco, J. Suul, M. Molinas","doi":"10.1109/EPEPEMC.2014.6980558","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980558","url":null,"abstract":"This paper proposes a simple method for damping of oscillations in dc grids based on Voltage Source Converters (VSCs). The damping effect is achieved by a control loop for counteracting measured dc voltage oscillations by acting on the active current reference of the ac-side VSC controller. The design of the damping method is supported by participation factor analysis and parametric sensitivities of a small-signal model representing an investigated test case. This investigated system is consisting of a single HVDC converter station connected to a dc cable equivalent and an ac grid. The validity of the developed small-signal model is verified by comparison to a simulation model including nonlinear effects of the investigated converter configuration. The small-signal model is then used to analyze the stability and dynamic characteristics of the system with and without the proposed active damping and to identify a suitable tuning of the damping controller.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121766577","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980518
K. Boulaam, A. Boukhelifa
In this paper, a fuzzy sliding mode control algorithm is proposed to improve performances of a variable speed wind energy conversion system (WECS) connected to the grid. To reduce the converter size, a doubly fed induction generator (DFIG) is used. Using a DFIG offers also the possibility to its stator active and reactive powers to be controlled independently. The active power reference is obtained by applying the maximum power point tracking (MPPT) strategy based on speed control technique. The combination of sliding mode and fuzzy logic permits to enjoy the benefits of these two methods. The proposed approach is tested in Simulink/Matlab environment. The simulation results show good performances of the global conversion system.
{"title":"Fuzzy sliding mode control of DFIG power for a wind conversion system","authors":"K. Boulaam, A. Boukhelifa","doi":"10.1109/EPEPEMC.2014.6980518","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980518","url":null,"abstract":"In this paper, a fuzzy sliding mode control algorithm is proposed to improve performances of a variable speed wind energy conversion system (WECS) connected to the grid. To reduce the converter size, a doubly fed induction generator (DFIG) is used. Using a DFIG offers also the possibility to its stator active and reactive powers to be controlled independently. The active power reference is obtained by applying the maximum power point tracking (MPPT) strategy based on speed control technique. The combination of sliding mode and fuzzy logic permits to enjoy the benefits of these two methods. The proposed approach is tested in Simulink/Matlab environment. The simulation results show good performances of the global conversion system.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127749375","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980686
A. Kaszewski, Andrzej Gałecki, B. Ufnalski, L. Grzesiak
This paper presents a control strategy for four-leg grid-connected PWM rectifiers that have an active power filtering function. The four-leg voltage source converter topology gives ability to control an input current in the neutral leg. That is important for the active power filtering function when there is an unbalanced load. The control strategy is based on a voltage oriented method that has a cascaded DC voltage and current controllers designed in a rotating reference frame. The DC voltage controller is a PI-type, whereas the input current is shaped by a full-state feedback controller. The novelty of the proposed solution is the control structure that has modified the DC voltage error signal by adding a discontinuity element and reduction the number of current signals by half. The discontinuity element is needed to provide a constant reference current signal during active power filtering operation. The paper describes in detail the design procedure for the voltage and current controllers. Numerical results for active rectification and active power filtering operations are presented and discussed. Numerical results have been obtained by using a discrete control model.
{"title":"State-space current control for four-leg grid-connected PWM rectifiers with active power filtering function","authors":"A. Kaszewski, Andrzej Gałecki, B. Ufnalski, L. Grzesiak","doi":"10.1109/EPEPEMC.2014.6980686","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980686","url":null,"abstract":"This paper presents a control strategy for four-leg grid-connected PWM rectifiers that have an active power filtering function. The four-leg voltage source converter topology gives ability to control an input current in the neutral leg. That is important for the active power filtering function when there is an unbalanced load. The control strategy is based on a voltage oriented method that has a cascaded DC voltage and current controllers designed in a rotating reference frame. The DC voltage controller is a PI-type, whereas the input current is shaped by a full-state feedback controller. The novelty of the proposed solution is the control structure that has modified the DC voltage error signal by adding a discontinuity element and reduction the number of current signals by half. The discontinuity element is needed to provide a constant reference current signal during active power filtering operation. The paper describes in detail the design procedure for the voltage and current controllers. Numerical results for active rectification and active power filtering operations are presented and discussed. Numerical results have been obtained by using a discrete control model.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128017504","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980586
V. V. Aban, A. Hava
In this study, the input filter design and dc-bus voltage control of ac motor drives utilizing low capacitance film capacitor are investigated. The dc-bus voltage instability problem arising due to the resonance between the dc-bus capacitor and circuit inductances is explained. A dimensioning algorithm of dc-bus filter components for stable operation is given. The simulation results of the low capacitance motor drives with and without dc-link inductor are provided to observe the stability of the dc-bus at different resonant frequencies. Voltage and current mode active stabilization methods found in literature aiming to actively damp the resonances in the dc-bus are analyzed and evaluated in the simulations for 2.2 kW and 37 kW rated induction motors driving constant torque load (CTL) and variable torque loads (VTL). Results are analyzed both in terms of input (line current) power quality and output (motor motion) quality.
{"title":"Performance analysis, filter component sizing, and controller structure selection of small capacitor diode rectifier front end inverter drives","authors":"V. V. Aban, A. Hava","doi":"10.1109/EPEPEMC.2014.6980586","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980586","url":null,"abstract":"In this study, the input filter design and dc-bus voltage control of ac motor drives utilizing low capacitance film capacitor are investigated. The dc-bus voltage instability problem arising due to the resonance between the dc-bus capacitor and circuit inductances is explained. A dimensioning algorithm of dc-bus filter components for stable operation is given. The simulation results of the low capacitance motor drives with and without dc-link inductor are provided to observe the stability of the dc-bus at different resonant frequencies. Voltage and current mode active stabilization methods found in literature aiming to actively damp the resonances in the dc-bus are analyzed and evaluated in the simulations for 2.2 kW and 37 kW rated induction motors driving constant torque load (CTL) and variable torque loads (VTL). Results are analyzed both in terms of input (line current) power quality and output (motor motion) quality.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133980645","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980693
G. Cipriani, V. Di Dio, L. Ferraris, D. La Cascia, R. Miceli, E. Pošković, G. Sauba
This paper presents detailed energy and network models for the intelligent control of a distributed system which also comprises power generation from renewables. The two models provide interactive energy monitoring, intelligent control and power demand balancing at home, block and neighbor level. Particularly, it is here described how the energy model works and also details of how it has been validated are here given. Moreover, it is shown how the energy model simulation results are transferred to the network simulation software SynerGEE, set up by GL Noble Denton Industrial Services Ltd (UK), in order to fully perform network simulations.
{"title":"Energy and network models for the intelligent control of distributed systems","authors":"G. Cipriani, V. Di Dio, L. Ferraris, D. La Cascia, R. Miceli, E. Pošković, G. Sauba","doi":"10.1109/EPEPEMC.2014.6980693","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980693","url":null,"abstract":"This paper presents detailed energy and network models for the intelligent control of a distributed system which also comprises power generation from renewables. The two models provide interactive energy monitoring, intelligent control and power demand balancing at home, block and neighbor level. Particularly, it is here described how the energy model works and also details of how it has been validated are here given. Moreover, it is shown how the energy model simulation results are transferred to the network simulation software SynerGEE, set up by GL Noble Denton Industrial Services Ltd (UK), in order to fully perform network simulations.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115032569","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980614
H. Hafezi, Eyup Akpinar, A. Balikci
In this paper single-phase instantaneous reactive power (p-q) method and non-active current method have been compared. Reactive power and reactive current calculation using these methods have been considered here under distorted voltage and current waveforms. It has been shown that these two methods have some limitations for reactive power compensation. The p-q method with hysteresis current controller and non-active current theory with sinusoidal pulse width modulation (SPWM) controller have been analyzed in Matlab/Simulink. A prototype system has been designed using TMS320F2812 EzDSP in the laboratory and assessment based on simulation and experimental results is given for these methods in this paper.
{"title":"Assessment of two different reactive power estimation methods on single phase loads","authors":"H. Hafezi, Eyup Akpinar, A. Balikci","doi":"10.1109/EPEPEMC.2014.6980614","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980614","url":null,"abstract":"In this paper single-phase instantaneous reactive power (p-q) method and non-active current method have been compared. Reactive power and reactive current calculation using these methods have been considered here under distorted voltage and current waveforms. It has been shown that these two methods have some limitations for reactive power compensation. The p-q method with hysteresis current controller and non-active current theory with sinusoidal pulse width modulation (SPWM) controller have been analyzed in Matlab/Simulink. A prototype system has been designed using TMS320F2812 EzDSP in the laboratory and assessment based on simulation and experimental results is given for these methods in this paper.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122111984","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980528
M. Gulin, M. Vašak, T. Pavlovic
Residential microgrids are mainly based on renewable energy sources (i.e., mainly on photovoltaic panels), energy storage systems (that enable time-shift between production and consumption), and on power converters representing control points that by proper operation ensure overall system stability and quality of power supply. For optimal techno-economical microgrid operation, i.e. microgrid voltage level control and power flow management, the models of microgrid components involved must be known. In this paper we verify a single-diode five-parameters equivalent electrical model of a photovoltaic array by experiments, and based on the verified model propose a new power production model suitable for microgrid power flow optimization applications. Microgrid components are connected to a common power link via an appropriate power converter in order to ensure components' maximum efficiency and the overall system stability. Simulation of DC/DC power converters on a switching level requires significant computational efforts due to high switching frequencies (10-100 kHz). However, it is shown that dynamical behaviour of a DC/DC power converter in closed control loop can be replaced by a PT2 dynamic element with good approximation accuracy. All equivalent electrical models presented in this paper are implemented in the professional simulation platform for power electronic systems Plexim PLECS.
{"title":"Model identification of a photovoltaic system for a DC microgrid simulation","authors":"M. Gulin, M. Vašak, T. Pavlovic","doi":"10.1109/EPEPEMC.2014.6980528","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980528","url":null,"abstract":"Residential microgrids are mainly based on renewable energy sources (i.e., mainly on photovoltaic panels), energy storage systems (that enable time-shift between production and consumption), and on power converters representing control points that by proper operation ensure overall system stability and quality of power supply. For optimal techno-economical microgrid operation, i.e. microgrid voltage level control and power flow management, the models of microgrid components involved must be known. In this paper we verify a single-diode five-parameters equivalent electrical model of a photovoltaic array by experiments, and based on the verified model propose a new power production model suitable for microgrid power flow optimization applications. Microgrid components are connected to a common power link via an appropriate power converter in order to ensure components' maximum efficiency and the overall system stability. Simulation of DC/DC power converters on a switching level requires significant computational efforts due to high switching frequencies (10-100 kHz). However, it is shown that dynamical behaviour of a DC/DC power converter in closed control loop can be replaced by a PT2 dynamic element with good approximation accuracy. All equivalent electrical models presented in this paper are implemented in the professional simulation platform for power electronic systems Plexim PLECS.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126314042","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}
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