Pub Date : 2018-09-01DOI: 10.1109/TDC-LA.2018.8511761
J. Acosta, M. Tavares
Most human activities depend on electrical systems. Thereby, energy that flows toward the electrical systems has to be conducted through transmission lines. However, conventional lines are limited by their natural power capacity. Thus, this paper proposes a mathematical model to be used with evolutionary computing in order to optimize the overhead transmission line power capacity. This enhancement is achieved by modifying the position of phase conductors in overhead transmission lines. Electrical and mechanical aspects are analyzed during the optimization process. Depending on the voltage level, different tower configurations with higher power capacity and lesser right of way are obtained, being more friendly with the environment. In $500~mathrm {k}mathrm {V}$ were obtained geometries with 20.89% to 105.13% higher power capacity than conventional lines. Compared with previous approaches the model shows good results obtaining solutions with similar or higher power capacity. Thus, the obtained geometries can be used in new transmission line projects when a higher transmission capacity and lesser right of way is desired.
{"title":"Enhancement of overhead transmission line capacity through evolutionary computing","authors":"J. Acosta, M. Tavares","doi":"10.1109/TDC-LA.2018.8511761","DOIUrl":"https://doi.org/10.1109/TDC-LA.2018.8511761","url":null,"abstract":"Most human activities depend on electrical systems. Thereby, energy that flows toward the electrical systems has to be conducted through transmission lines. However, conventional lines are limited by their natural power capacity. Thus, this paper proposes a mathematical model to be used with evolutionary computing in order to optimize the overhead transmission line power capacity. This enhancement is achieved by modifying the position of phase conductors in overhead transmission lines. Electrical and mechanical aspects are analyzed during the optimization process. Depending on the voltage level, different tower configurations with higher power capacity and lesser right of way are obtained, being more friendly with the environment. In $500~mathrm {k}mathrm {V}$ were obtained geometries with 20.89% to 105.13% higher power capacity than conventional lines. Compared with previous approaches the model shows good results obtaining solutions with similar or higher power capacity. Thus, the obtained geometries can be used in new transmission line projects when a higher transmission capacity and lesser right of way is desired.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114672649","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 : 2018-09-01DOI: 10.1109/TDC-LA.2018.8511777
Claudia Zanabria, F. Andrén, T. Strasser
The upcoming large-scale integration of distributed energy resources into power distribution grids motivates the implementation of advanced control applications to ensure security of supply and power quality. The realization of such increasingly complex applications is also characterized by higher engineering efforts, even resulting in increased total life-cycle costs. However, by using proper method and corresponding tools there is a huge optimization potential for the engineering process. Various approaches and tools with different characteristics have been developed so far in order to provide support along the engineering and validation process of power system applications. However, it is not always clear which tools are the best choice for the different development steps. In order to overcome this issue this work provides a comparison of specification and design approaches which are being commonly used in the domain of power and energy systems.
{"title":"Comparing Specification and Design Approaches for Power Systems Applications","authors":"Claudia Zanabria, F. Andrén, T. Strasser","doi":"10.1109/TDC-LA.2018.8511777","DOIUrl":"https://doi.org/10.1109/TDC-LA.2018.8511777","url":null,"abstract":"The upcoming large-scale integration of distributed energy resources into power distribution grids motivates the implementation of advanced control applications to ensure security of supply and power quality. The realization of such increasingly complex applications is also characterized by higher engineering efforts, even resulting in increased total life-cycle costs. However, by using proper method and corresponding tools there is a huge optimization potential for the engineering process. Various approaches and tools with different characteristics have been developed so far in order to provide support along the engineering and validation process of power system applications. However, it is not always clear which tools are the best choice for the different development steps. In order to overcome this issue this work provides a comparison of specification and design approaches which are being commonly used in the domain of power and energy systems.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115901358","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 : 2018-09-01DOI: 10.1109/TDC-LA.2018.8511735
O. C. Zevallos, R. Prada
The increase in electricity generation from wind and solar sources brings important changes in the operational and dynamic characteristics of the power system when it is subjected to major disturbances. One important technical problem is the risk of losing transient stability by progressively replacing of conventional generation with energy sources connected to the system through electronic converters, reducing the overall system inertia. However, the converters could potentially bring new opportunities of fast control to give support to synchronous generators connected to the power system in response to a disturbance. In this paper, a control strategy for the inverter is proposed based on the injection of the current identified as having the major participation in the variation of the synchronous machine rotor angle. The identification is based on the eigenvalue sensitivity analysis with respect to the rotor angle. The proposed method is tested in a hybrid system with a synchronous generator connected in parallel with an inverter, both connected to an infinite bus through two transmission lines. The dynamic response of the rotor angle is assessed simulating a two phase to ground fault. The results show that the inverter must absorb active power, releasing the kinetic energy stored in the rotational masses of the synchronous machine, and effectively reducing the rotor angle excursions.
{"title":"Inverter Control Strategy to Reduce the Synchronous Machine Rotor Angle Excursions","authors":"O. C. Zevallos, R. Prada","doi":"10.1109/TDC-LA.2018.8511735","DOIUrl":"https://doi.org/10.1109/TDC-LA.2018.8511735","url":null,"abstract":"The increase in electricity generation from wind and solar sources brings important changes in the operational and dynamic characteristics of the power system when it is subjected to major disturbances. One important technical problem is the risk of losing transient stability by progressively replacing of conventional generation with energy sources connected to the system through electronic converters, reducing the overall system inertia. However, the converters could potentially bring new opportunities of fast control to give support to synchronous generators connected to the power system in response to a disturbance. In this paper, a control strategy for the inverter is proposed based on the injection of the current identified as having the major participation in the variation of the synchronous machine rotor angle. The identification is based on the eigenvalue sensitivity analysis with respect to the rotor angle. The proposed method is tested in a hybrid system with a synchronous generator connected in parallel with an inverter, both connected to an infinite bus through two transmission lines. The dynamic response of the rotor angle is assessed simulating a two phase to ground fault. The results show that the inverter must absorb active power, releasing the kinetic energy stored in the rotational masses of the synchronous machine, and effectively reducing the rotor angle excursions.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123320200","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 : 2018-09-01DOI: 10.1109/tdc-la.2018.8511671
{"title":"T&D-LA 2018 Breaker Page","authors":"","doi":"10.1109/tdc-la.2018.8511671","DOIUrl":"https://doi.org/10.1109/tdc-la.2018.8511671","url":null,"abstract":"","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129713538","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 : 2018-09-01DOI: 10.1109/TDC-LA.2018.8511760
M. S. Ortiz, D. Bernardon, M. Wolter, Émerson Rafael da Silva, L. L. Pfitscher, W. Hokama
Electricity suppliers have increasingly invested in technology solutions, especially in the automation area, to improve the electricity supply to their consumers. In contingency situations, the process of restoring the electric energy consists of identifying and isolating the fault, quickly restoring the power supply to unaffected areas, according to the reconfiguration of the network through the opening or closing of the maneuver equipment. After fault correction, new maneuvers are performed to return to the normal state of the networks. Hence, the reactive characteristics of network elements such as line inductances and the loads of capacitor banks, can originate undesirable electromagnetic transients during the switching maneuvers. Therefore, this paper aims to present the development of a methodology for the analysis of the technical viability of parallelism in the distribution networks with capacitor banks for the reestablishment of electric energy, considering the cascade of loads between the network feeders. The proposed study is, therefore, a particularity of the distribution systems and the validation of the operational feasibility of the maneuvers will be verified from computational simulations performed with the ATPDraw software.
{"title":"Analysis of the Technical Feasibility of Network Parallelism for Load Transfers in Contingency Situations","authors":"M. S. Ortiz, D. Bernardon, M. Wolter, Émerson Rafael da Silva, L. L. Pfitscher, W. Hokama","doi":"10.1109/TDC-LA.2018.8511760","DOIUrl":"https://doi.org/10.1109/TDC-LA.2018.8511760","url":null,"abstract":"Electricity suppliers have increasingly invested in technology solutions, especially in the automation area, to improve the electricity supply to their consumers. In contingency situations, the process of restoring the electric energy consists of identifying and isolating the fault, quickly restoring the power supply to unaffected areas, according to the reconfiguration of the network through the opening or closing of the maneuver equipment. After fault correction, new maneuvers are performed to return to the normal state of the networks. Hence, the reactive characteristics of network elements such as line inductances and the loads of capacitor banks, can originate undesirable electromagnetic transients during the switching maneuvers. Therefore, this paper aims to present the development of a methodology for the analysis of the technical viability of parallelism in the distribution networks with capacitor banks for the reestablishment of electric energy, considering the cascade of loads between the network feeders. The proposed study is, therefore, a particularity of the distribution systems and the validation of the operational feasibility of the maneuvers will be verified from computational simulations performed with the ATPDraw software.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121688000","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 : 2018-09-01DOI: 10.1109/TDC-LA.2018.8511707
O. Montoya, W. Gil-González, A. Garcés
This paper presents an integration of three-phase supercapacitor energy storage (SCES) in power grids via passivity- based control (PBC) theory under different reference frames. The SCES systems have the possibility to interchange active and reactive power between the supercapacitor and converter to the electrical power network. The active power is directly related to the energy stored on the supercapacitor, while the reactive power is redistributed by the forced commutated switches present in the voltage source converter (VSC) used to integrate the SCES system to the power grid. PBC theory allows designing Lyapunov stable controllers for autonomous and non-autonomous dynamical sys- tems via port-Hamiltonian (pH) representations. The averaging modeling theory employs to develop the controllers under abc, $alphabeta$ and $dq$ reference frames. Simulation results show the possibility of using the SCES devices to compensate active and reactive power in power grids dynamically in all operating quadrants. All simulations are conducted via MATLAB/SIMULINK software.
{"title":"SCES Integration in Power Grids: a PBC Approach under abc, αβ0 and dq0 Reference Frames","authors":"O. Montoya, W. Gil-González, A. Garcés","doi":"10.1109/TDC-LA.2018.8511707","DOIUrl":"https://doi.org/10.1109/TDC-LA.2018.8511707","url":null,"abstract":"This paper presents an integration of three-phase supercapacitor energy storage (SCES) in power grids via passivity- based control (PBC) theory under different reference frames. The SCES systems have the possibility to interchange active and reactive power between the supercapacitor and converter to the electrical power network. The active power is directly related to the energy stored on the supercapacitor, while the reactive power is redistributed by the forced commutated switches present in the voltage source converter (VSC) used to integrate the SCES system to the power grid. PBC theory allows designing Lyapunov stable controllers for autonomous and non-autonomous dynamical sys- tems via port-Hamiltonian (pH) representations. The averaging modeling theory employs to develop the controllers under abc, $alphabeta$ and $dq$ reference frames. Simulation results show the possibility of using the SCES devices to compensate active and reactive power in power grids dynamically in all operating quadrants. All simulations are conducted via MATLAB/SIMULINK software.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123819145","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 : 2018-09-01DOI: 10.1109/TDC-LA.2018.8511716
J. Hermoza, R. Reta
After the liberalization of the electricity sector, electricity wholesale markets computed market prices based on audited costs or based on free prices. The first one has been implemented in many Latin American countries, while free prices have been implemented in more liberalized and competitive markets. The aim of this work is to develop a hydrothermal market simulator to evaluate the impact of migrating an electricity market based on audited costs to one based on free prices. The simulator considers different generating firms and includes the transmission network by means of a methodology of analytical derivation to find equilibria of pure strategies. The strategic behavior of the firms has been modeled through the Nash-Cournot Equilibrium.
{"title":"Electricity Market Simulator to Assess the Implementation of Free Prices considering the Transmission Network","authors":"J. Hermoza, R. Reta","doi":"10.1109/TDC-LA.2018.8511716","DOIUrl":"https://doi.org/10.1109/TDC-LA.2018.8511716","url":null,"abstract":"After the liberalization of the electricity sector, electricity wholesale markets computed market prices based on audited costs or based on free prices. The first one has been implemented in many Latin American countries, while free prices have been implemented in more liberalized and competitive markets. The aim of this work is to develop a hydrothermal market simulator to evaluate the impact of migrating an electricity market based on audited costs to one based on free prices. The simulator considers different generating firms and includes the transmission network by means of a methodology of analytical derivation to find equilibria of pure strategies. The strategic behavior of the firms has been modeled through the Nash-Cournot Equilibrium.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126709809","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 : 2018-09-01DOI: 10.1109/tdc-la.2018.8511788
J. Leite, J. Mantovani, M. Kezunovic
In this paper, local automatic switching plans, considering distribution network topology and hourly loading, are used to implement a self-healing strategy, which minimizes the switching operations to restore the interrupted customers within the shortest time interval. This self-healing implementation is done using decentralized multi-agent system (MAS) where all local switching agents have awareness about the current network state and work cooperatively to reach the global purpose of the distribution network automatic restoration. We are proposing the utilization of intelligent electronic devices (IEDs) as the hosts of the local switching agents. The embedded code for the agent’s autonomy, as well as the information exchange among agents are described, implemented and tested.
{"title":"Distribution System Self-Healing Implementation using Decentralized IED-based Multi-Agent System","authors":"J. Leite, J. Mantovani, M. Kezunovic","doi":"10.1109/tdc-la.2018.8511788","DOIUrl":"https://doi.org/10.1109/tdc-la.2018.8511788","url":null,"abstract":"In this paper, local automatic switching plans, considering distribution network topology and hourly loading, are used to implement a self-healing strategy, which minimizes the switching operations to restore the interrupted customers within the shortest time interval. This self-healing implementation is done using decentralized multi-agent system (MAS) where all local switching agents have awareness about the current network state and work cooperatively to reach the global purpose of the distribution network automatic restoration. We are proposing the utilization of intelligent electronic devices (IEDs) as the hosts of the local switching agents. The embedded code for the agent’s autonomy, as well as the information exchange among agents are described, implemented and tested.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115193271","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 : 2018-09-01DOI: 10.1109/TDC-LA.2018.8511648
J. Villavicencio, A. Padilha-Feltrin, J. Melo
In order to develop studies such as the impact of residential photovoltaic (PV) system installation in low-voltage networks, the number of PV systems by transformer must be known. The number of residential PV systems can be estimated using socioeconomics information obtained in census data. This information is aggregated by census tract or subarea. In this paper, a technique to allocate estimated PV systems from the PV market potential in subareas to distribution transformers is presented. The proposed methodology is applied to a residential area in Brazil and, then, a voltage impact study in the low-voltage network is performed. The obtained results are hence useful on the planning and operation studies performed by utilities.
{"title":"Allocation of PV Systems from Residential Subareas to Distribution Transformers","authors":"J. Villavicencio, A. Padilha-Feltrin, J. Melo","doi":"10.1109/TDC-LA.2018.8511648","DOIUrl":"https://doi.org/10.1109/TDC-LA.2018.8511648","url":null,"abstract":"In order to develop studies such as the impact of residential photovoltaic (PV) system installation in low-voltage networks, the number of PV systems by transformer must be known. The number of residential PV systems can be estimated using socioeconomics information obtained in census data. This information is aggregated by census tract or subarea. In this paper, a technique to allocate estimated PV systems from the PV market potential in subareas to distribution transformers is presented. The proposed methodology is applied to a residential area in Brazil and, then, a voltage impact study in the low-voltage network is performed. The obtained results are hence useful on the planning and operation studies performed by utilities.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115563246","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 : 2018-09-01DOI: 10.1109/TDC-LA.2018.8511775
Jose Galarza, Bartolomé Sáenz
The modular multilevel converter (MMC) in high voltage direct current (HVDC) is equipped with hundreds of sub-modules (SMs), so the detailed model consist of hundreds of switching devices and consequently large computational effort but mathematical converter model with Arm Level Averaged (ALA) allows to know the dynamic and converter control decreasing simulation time. This paper presents a control strategy decou- pling the modulation index implemented in MMC-ALA model, it allows MMC operation with variable DC bus voltage but keeping constant the capacitor voltage in upper and lower arms, the evaluations consider the next operations: boost mode reducing DC bus voltage to 0.5.p.u., DC fault and SM voltage increased. The upper and lower capacitor voltages in all cases follow the reference independently to DC bus voltage value, the strategy is simulated in 150 MW converter using Matlab/Simulink.
{"title":"Control Strategy Implemented in Modular Multilevel Converter to Improve the Operation During Variable DC Bus Voltage","authors":"Jose Galarza, Bartolomé Sáenz","doi":"10.1109/TDC-LA.2018.8511775","DOIUrl":"https://doi.org/10.1109/TDC-LA.2018.8511775","url":null,"abstract":"The modular multilevel converter (MMC) in high voltage direct current (HVDC) is equipped with hundreds of sub-modules (SMs), so the detailed model consist of hundreds of switching devices and consequently large computational effort but mathematical converter model with Arm Level Averaged (ALA) allows to know the dynamic and converter control decreasing simulation time. This paper presents a control strategy decou- pling the modulation index implemented in MMC-ALA model, it allows MMC operation with variable DC bus voltage but keeping constant the capacitor voltage in upper and lower arms, the evaluations consider the next operations: boost mode reducing DC bus voltage to 0.5.p.u., DC fault and SM voltage increased. The upper and lower capacitor voltages in all cases follow the reference independently to DC bus voltage value, the strategy is simulated in 150 MW converter using Matlab/Simulink.","PeriodicalId":267301,"journal":{"name":"2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115676786","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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