Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6253974
Ling Gu, K. Jin
A novel isolated switching capacitor regulator is proposed in this paper. The converter is the combination of a switching capacitor converter and a PWM regulator. The proposed converter has the following advantages: 1) Fast transient response and the output voltage can be regulated as well. 2) The main switches achieve zero-voltage-switching and the rectifier diode realizes zero-current-switching. 3) Self-driven synchronous rectifier can be employed to improve efficiency; 4) Achievement of electrical isolation and multiple-output. A 200W hardware was built to verify the analysis.
{"title":"An isolated switching capacitor regulator","authors":"Ling Gu, K. Jin","doi":"10.1109/PEDG.2012.6253974","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6253974","url":null,"abstract":"A novel isolated switching capacitor regulator is proposed in this paper. The converter is the combination of a switching capacitor converter and a PWM regulator. The proposed converter has the following advantages: 1) Fast transient response and the output voltage can be regulated as well. 2) The main switches achieve zero-voltage-switching and the rectifier diode realizes zero-current-switching. 3) Self-driven synchronous rectifier can be employed to improve efficiency; 4) Achievement of electrical isolation and multiple-output. A 200W hardware was built to verify the analysis.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134064112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6254088
M. Reza, M. Ciobotaru, V. Agelidis
This paper proposes the application of frequency locked loop (FLL) based on the second order generalized integrator (SOGI) and a Kalman filter (KF) for frequency adaptive instantaneous power quality (PQ) analysis. The FLL tracks the time-varying grid voltage fundamental frequency adaptively. The orthogonal waveforms of fundamental and harmonic components of grid voltage waveform are extracted using the quadrature signal generator (QSG)-SOGI and a linear Kalman filter (LKF), respectively. The fundamental voltage amplitude is obtained from the orthogonal voltage waveforms as provided by the QSG-SOGI and is fed to an extended Kalman filter (EKF) to extract the instantaneous flicker level (IFL). The proposed SOGI-FLL-KF technique provides accurate instantaneous results for PQ analysis based on the measurement of phasor quantities. Synthetically generated grid voltage waveforms are used in MATLAB/Simulink for instantaneous PQ analysis by the proposed SOGI-FLL-KF technique. The simulation results show that the proposed technique can be used as an effective technique for frequency adaptive instantaneous PQ assessment.
{"title":"Frequency adaptive instantaneous power quality analysis using frequency locked loop based Kalman filter technique","authors":"M. Reza, M. Ciobotaru, V. Agelidis","doi":"10.1109/PEDG.2012.6254088","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6254088","url":null,"abstract":"This paper proposes the application of frequency locked loop (FLL) based on the second order generalized integrator (SOGI) and a Kalman filter (KF) for frequency adaptive instantaneous power quality (PQ) analysis. The FLL tracks the time-varying grid voltage fundamental frequency adaptively. The orthogonal waveforms of fundamental and harmonic components of grid voltage waveform are extracted using the quadrature signal generator (QSG)-SOGI and a linear Kalman filter (LKF), respectively. The fundamental voltage amplitude is obtained from the orthogonal voltage waveforms as provided by the QSG-SOGI and is fed to an extended Kalman filter (EKF) to extract the instantaneous flicker level (IFL). The proposed SOGI-FLL-KF technique provides accurate instantaneous results for PQ analysis based on the measurement of phasor quantities. Synthetically generated grid voltage waveforms are used in MATLAB/Simulink for instantaneous PQ analysis by the proposed SOGI-FLL-KF technique. The simulation results show that the proposed technique can be used as an effective technique for frequency adaptive instantaneous PQ assessment.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134243727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6254074
M. Mao, Yongchao Zhao, Shujuan Sun, Liuchen Chang, Yu Cao, Jianhui Su, Minghe Sun, Guorong Zhang
Economic performances of a microgrid with multi-energy are effected by many factors such as the configuration of microgrid systems for the specific installation sites and cluster of loads, operation modes and dispatching schedules of the microgrid, the electricity market, energy policy and alike. And the configuration of the microgrid is the premise of all factors. This paper presents an optimization model to quantitatively evaluate the economic impacts of different installation sites on microgrids with multi-energy. In this model, optimal configuration schemes for microgrids installed at typical sites are designed by particle swarm optimization method. The economic performances of optimal configuration schemes are evaluated by the operation simulation with the proposed indexes. Those typical installation sites mentioned above belong to different regions which are divided into the five-level classifications in terms of the richness of wind and solar resource and the distributions of loads in China. The calculation results may be used for the decision-making references by the decision-makers.
{"title":"Quantitative analysis on economic impacts of installation at different sites on microgrids with multi-energy","authors":"M. Mao, Yongchao Zhao, Shujuan Sun, Liuchen Chang, Yu Cao, Jianhui Su, Minghe Sun, Guorong Zhang","doi":"10.1109/PEDG.2012.6254074","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6254074","url":null,"abstract":"Economic performances of a microgrid with multi-energy are effected by many factors such as the configuration of microgrid systems for the specific installation sites and cluster of loads, operation modes and dispatching schedules of the microgrid, the electricity market, energy policy and alike. And the configuration of the microgrid is the premise of all factors. This paper presents an optimization model to quantitatively evaluate the economic impacts of different installation sites on microgrids with multi-energy. In this model, optimal configuration schemes for microgrids installed at typical sites are designed by particle swarm optimization method. The economic performances of optimal configuration schemes are evaluated by the operation simulation with the proposed indexes. Those typical installation sites mentioned above belong to different regions which are divided into the five-level classifications in terms of the richness of wind and solar resource and the distributions of loads in China. The calculation results may be used for the decision-making references by the decision-makers.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134273232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6253981
R. Petrichenko, V. Chuvychin
This paper describes a methodology of application of smart grid technology for improvement of existing emergency automation system. Existing and new developed automation systems are considered in the paper. Authors approved advantage of suggested automation system using mathematical simulation of emergency processes in the power system. The paper describes the developed mathematical model of intellectual load shedding system and its operational algorithms.
{"title":"Smart load shedding system","authors":"R. Petrichenko, V. Chuvychin","doi":"10.1109/PEDG.2012.6253981","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6253981","url":null,"abstract":"This paper describes a methodology of application of smart grid technology for improvement of existing emergency automation system. Existing and new developed automation systems are considered in the paper. Authors approved advantage of suggested automation system using mathematical simulation of emergency processes in the power system. The paper describes the developed mathematical model of intellectual load shedding system and its operational algorithms.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133588685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6254103
W. Chae, Hakju Lee, Jungsung Park, Won-Wook Jung
The grid-interconnected Microgrid must be able to operate without the utility's grid to supply electricity in case of outage. To operate in standalone mode, the Microgrid must control electricity demand or supply to maintain the frequency. The Microgrid EMS (Energy Management System) could control supply and demand with the AGC (Auto Generation Control) function using a communication line. Note, however, that the period of AGC is too slow to maintain the frequency if there is rapid variation in loads or generation. Moreover, the transition of operation mode could fail if there is too much power flow at PCC (Point of Common Coupling). In this paper, we propose a method of improving the stability of the grid-interconnected Microgrid using BESS (Battery Energy Storage System) and super capacitor. The cooperative control method between BESS and super capacitor uses droop, which is used at the generator. BESS could operate as UPC (Unit Power Control) or FFC (Feeder Flow Control) depending on Microgrid's operation strategy. We simulate the cooperative control method using PSCAD/EMTDC to verify the validity of the method. As a result, Microgrid's stability is improved using the cooperative control method, and the life span of BESS could be prolonged.
{"title":"Cooperative operation method of two battery systems at Microgrid system","authors":"W. Chae, Hakju Lee, Jungsung Park, Won-Wook Jung","doi":"10.1109/PEDG.2012.6254103","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6254103","url":null,"abstract":"The grid-interconnected Microgrid must be able to operate without the utility's grid to supply electricity in case of outage. To operate in standalone mode, the Microgrid must control electricity demand or supply to maintain the frequency. The Microgrid EMS (Energy Management System) could control supply and demand with the AGC (Auto Generation Control) function using a communication line. Note, however, that the period of AGC is too slow to maintain the frequency if there is rapid variation in loads or generation. Moreover, the transition of operation mode could fail if there is too much power flow at PCC (Point of Common Coupling). In this paper, we propose a method of improving the stability of the grid-interconnected Microgrid using BESS (Battery Energy Storage System) and super capacitor. The cooperative control method between BESS and super capacitor uses droop, which is used at the generator. BESS could operate as UPC (Unit Power Control) or FFC (Feeder Flow Control) depending on Microgrid's operation strategy. We simulate the cooperative control method using PSCAD/EMTDC to verify the validity of the method. As a result, Microgrid's stability is improved using the cooperative control method, and the life span of BESS could be prolonged.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132695357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6254043
M. Dicorato, G. Forte, M. Trovato
The fast growth of wind generation leads to concern about its effects on electric grid. The wind power integration needs to be ruled by specific voltage and frequency requirements. As concerns voltage support, wind farm are called to guarantee a reactive power regulation range at point of common coupling (PCC). Moreover, in the presence of voltage dips or fault conditions, wind generators should be able to respect low-voltage ride-through curves to contribute to grid regulation and avoid sudden unbalances. In this paper, different control strategies of wind farm are evaluated, in order to comply with grid code requirements for voltage support. In particular, reactive power and voltage regulation is carried out through generator power factor variation and by static compensation devices as SVCs. Simulations are performed on a wind farm connected to IEEE 14-Buses test system in the presence of grid fault condition.
{"title":"Voltage compensation for wind integration in power systems","authors":"M. Dicorato, G. Forte, M. Trovato","doi":"10.1109/PEDG.2012.6254043","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6254043","url":null,"abstract":"The fast growth of wind generation leads to concern about its effects on electric grid. The wind power integration needs to be ruled by specific voltage and frequency requirements. As concerns voltage support, wind farm are called to guarantee a reactive power regulation range at point of common coupling (PCC). Moreover, in the presence of voltage dips or fault conditions, wind generators should be able to respect low-voltage ride-through curves to contribute to grid regulation and avoid sudden unbalances. In this paper, different control strategies of wind farm are evaluated, in order to comply with grid code requirements for voltage support. In particular, reactive power and voltage regulation is carried out through generator power factor variation and by static compensation devices as SVCs. Simulations are performed on a wind farm connected to IEEE 14-Buses test system in the presence of grid fault condition.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133189521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6253992
Chengxi Liu, Zhe Chen, Zhou Liu
The increasing penetration of distributed generation (DG) in distribution systems has resulted in a challenge for the conventional protection methods, due to the bi-directional power flow and the variation of fault current contribution. Moreover, the operation of distribution system in islanded mode is still an issue due to the difference between the short circuit current in islanded mode and grid-connected mode. This paper proposed a novel adaptive protection method, measuring only the local information rather than using the communication, to adapt the protection settings to the states, such as the change of operation mode (grid-connected or islanded), the change of network topology (radial or meshed) as well as the disconnection of some DG. The directional overcurrent relays (DOCR) is adopted in the distributed system to shorten the tripping time in order to maintain the DG's connection. The relay settings are calculated offline and modified online according to the state detection, including the islanding detection, the power flow detection and the fault section detection. This protection method is verified by simulating a distribution system of Denmark in DIgSILENT PowerFactory.
{"title":"A communication-less overcurrent protection for distribution system with distributed generation integrated","authors":"Chengxi Liu, Zhe Chen, Zhou Liu","doi":"10.1109/PEDG.2012.6253992","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6253992","url":null,"abstract":"The increasing penetration of distributed generation (DG) in distribution systems has resulted in a challenge for the conventional protection methods, due to the bi-directional power flow and the variation of fault current contribution. Moreover, the operation of distribution system in islanded mode is still an issue due to the difference between the short circuit current in islanded mode and grid-connected mode. This paper proposed a novel adaptive protection method, measuring only the local information rather than using the communication, to adapt the protection settings to the states, such as the change of operation mode (grid-connected or islanded), the change of network topology (radial or meshed) as well as the disconnection of some DG. The directional overcurrent relays (DOCR) is adopted in the distributed system to shorten the tripping time in order to maintain the DG's connection. The relay settings are calculated offline and modified online according to the state detection, including the islanding detection, the power flow detection and the fault section detection. This protection method is verified by simulating a distribution system of Denmark in DIgSILENT PowerFactory.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133766006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6254049
Zhijun Liu, Xiaoyan Yu, K. Jin
In this paper, a novel three-level converter with an integrated magnetic self-driven current-doubler-rectifier (CDR) is proposed. The proposed converter can reduce the current ripple of filter inductors, then split the main transformer into two transformers, and then replace the filter inductors with excitations, at last integrated these two transformers into one core. Compared to traditional ZVS CDR TL-HB converter, the proposed converter have several advantages, the current ripple of filter inductors is smaller, the windings of main transformer can be directly used to drive synchronous rectifiers, and the problem of poor clamped diode reliability in traditional ZVS CDR TL-HB converter is avoided. This paper presents the principle of the converter, discussed in detail the main switches to realize ZVS range and self-driven for SR. A 28V/100A prototype is built in lab to verify the theoretical analysis.
{"title":"A novel self-driven current-doubler-rectifier three-level converter with integrated magnetics","authors":"Zhijun Liu, Xiaoyan Yu, K. Jin","doi":"10.1109/PEDG.2012.6254049","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6254049","url":null,"abstract":"In this paper, a novel three-level converter with an integrated magnetic self-driven current-doubler-rectifier (CDR) is proposed. The proposed converter can reduce the current ripple of filter inductors, then split the main transformer into two transformers, and then replace the filter inductors with excitations, at last integrated these two transformers into one core. Compared to traditional ZVS CDR TL-HB converter, the proposed converter have several advantages, the current ripple of filter inductors is smaller, the windings of main transformer can be directly used to drive synchronous rectifiers, and the problem of poor clamped diode reliability in traditional ZVS CDR TL-HB converter is avoided. This paper presents the principle of the converter, discussed in detail the main switches to realize ZVS range and self-driven for SR. A 28V/100A prototype is built in lab to verify the theoretical analysis.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115026802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6254035
Yanjun Shi, Bangyin Liu, S. Duan
This paper discusses influences of using current transformer (CT) as feedback element in a cascade multilevel converter. First, a simplified transfer function model of CT is built by small signal test and the model parameter is verified by large signal experiment. Then, a cascade multilevel STATCOM with CT feedback is modeled and analyzed. Influences of CT on controller designing are discussed, along with solutions. Finally, experiments are performed to verify proposed method.
{"title":"Non ideal effect of current transformer and its influence on controller design of cascade multilevel STATCOM","authors":"Yanjun Shi, Bangyin Liu, S. Duan","doi":"10.1109/PEDG.2012.6254035","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6254035","url":null,"abstract":"This paper discusses influences of using current transformer (CT) as feedback element in a cascade multilevel converter. First, a simplified transfer function model of CT is built by small signal test and the model parameter is verified by large signal experiment. Then, a cascade multilevel STATCOM with CT feedback is modeled and analyzed. Influences of CT on controller designing are discussed, along with solutions. Finally, experiments are performed to verify proposed method.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116975988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-25DOI: 10.1109/PEDG.2012.6253997
J. G. Garza, B. Chong, L. Zhang
Shading of even a single photovoltaic (PV) cell can significantly reduce the power of a module. This paper presents a solution by integrating Ćuk bi-directional converters with PV modules which can allow all modules to operate at their individual maximum power points. This is achieved by applying the novel control strategy which enables proper adjustment of converters' duty ratios under different shading levels. The proposed scheme was verified in SIMULINK/MATLAB simulation and in experiment.
{"title":"Control of integrated Ćuk converter and photovoltaic modules for maximum power generation","authors":"J. G. Garza, B. Chong, L. Zhang","doi":"10.1109/PEDG.2012.6253997","DOIUrl":"https://doi.org/10.1109/PEDG.2012.6253997","url":null,"abstract":"Shading of even a single photovoltaic (PV) cell can significantly reduce the power of a module. This paper presents a solution by integrating Ćuk bi-directional converters with PV modules which can allow all modules to operate at their individual maximum power points. This is achieved by applying the novel control strategy which enables proper adjustment of converters' duty ratios under different shading levels. The proposed scheme was verified in SIMULINK/MATLAB simulation and in experiment.","PeriodicalId":146438,"journal":{"name":"2012 3rd IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116976253","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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