Pub Date : 2008-03-12DOI: 10.1109/MEPCON.2008.4562295
G. Alexandrov, M. Dardeer
This paper describes the configuration and main characteristics of the 500 kV grid in Egypt and presents an analysis for the problem of limitation the voltage drop along the transmission line connecting the southern and northern regions of Egypt with a length of 800 km during its loading from the maximum to the idle regime. It is shown that this problem can be solved by compensating the charging capacity of the line by utilization of controlled shunt reactors of a transformer type CSRT.
{"title":"500 kV transmission system in Egypt solving problem of voltage regulation by means of controlled shunt reactor transformer type (CSRT)","authors":"G. Alexandrov, M. Dardeer","doi":"10.1109/MEPCON.2008.4562295","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562295","url":null,"abstract":"This paper describes the configuration and main characteristics of the 500 kV grid in Egypt and presents an analysis for the problem of limitation the voltage drop along the transmission line connecting the southern and northern regions of Egypt with a length of 800 km during its loading from the maximum to the idle regime. It is shown that this problem can be solved by compensating the charging capacity of the line by utilization of controlled shunt reactors of a transformer type CSRT.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126153634","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562316
H. Okumus
Hysteresis band control is one of the simplest and most popular techniques used in direct torque control (DTC) of induction machine drives. However the conventional fixed band hysteresis control has a variable switching frequency which causes serious problems in DTC. To solve these problems a new constant switching frequency torque controller is proposed to replace the conventional hysteresis-based controller in this paper. The technique, based on the same concept, but with the hysteresis band implemented with fuzzy logic is proposed to optimize the DTC drive performance. The proposed technique is verified by simulations. The system is first simulated by MATLAB/Simulink and tested by hardware in the loop. Then, it is implemented based on a TMS320C6711, 32-bit fixed point digital signal processor. Experimental results prove the feasibility of the proposed strategy as compared with the conventional method.
{"title":"A new torque controller for Direct Torque Controlled Induction Machine drives","authors":"H. Okumus","doi":"10.1109/MEPCON.2008.4562316","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562316","url":null,"abstract":"Hysteresis band control is one of the simplest and most popular techniques used in direct torque control (DTC) of induction machine drives. However the conventional fixed band hysteresis control has a variable switching frequency which causes serious problems in DTC. To solve these problems a new constant switching frequency torque controller is proposed to replace the conventional hysteresis-based controller in this paper. The technique, based on the same concept, but with the hysteresis band implemented with fuzzy logic is proposed to optimize the DTC drive performance. The proposed technique is verified by simulations. The system is first simulated by MATLAB/Simulink and tested by hardware in the loop. Then, it is implemented based on a TMS320C6711, 32-bit fixed point digital signal processor. Experimental results prove the feasibility of the proposed strategy as compared with the conventional method.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124850292","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562345
A. Nosseir, A. Attia, F. Tahoon, N. Osman
Transformers are one of the most important elements of power systems. Most transformers are equipped with protection systems to avoid damage to the transformers [1]. As any outage of the transformer have severed technical and economical consequences for the network, so implementing fast relaying algorithms for transformer protection devices to satisfy high reliability of the whole power systems is very important. In designing high speed protection systems, the fast discrimination of magnetizing inrush current is very important to prevent the false tripping of relays. The conventional method of inrush current detection [2] for transformer protection based on the value of the second harmonic component of the differential current which requires a long time exceeding one cycle. This paper discriminates between the inrush current state and the internal fault condition based on the transformer magnetizing characteristics within one short cycle. Simulation using EMTP-ATP program on a three phase transformer are carried out. Study cases of inrush current at different switching instants and for all types of internal faults for different phases and on different percentages of transformer windings are simulated. The results obtained from EMTP-ATP package for all simulated conditions used as a training data to artificial neural network (ANN). This helps the differential relay to recognize inrush and internal fault and give the trip signal in case of internal fault only.
{"title":"A fast and reliable transformer protection system based on the transformer magnetizing characteristics and artificial neural networks","authors":"A. Nosseir, A. Attia, F. Tahoon, N. Osman","doi":"10.1109/MEPCON.2008.4562345","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562345","url":null,"abstract":"Transformers are one of the most important elements of power systems. Most transformers are equipped with protection systems to avoid damage to the transformers [1]. As any outage of the transformer have severed technical and economical consequences for the network, so implementing fast relaying algorithms for transformer protection devices to satisfy high reliability of the whole power systems is very important. In designing high speed protection systems, the fast discrimination of magnetizing inrush current is very important to prevent the false tripping of relays. The conventional method of inrush current detection [2] for transformer protection based on the value of the second harmonic component of the differential current which requires a long time exceeding one cycle. This paper discriminates between the inrush current state and the internal fault condition based on the transformer magnetizing characteristics within one short cycle. Simulation using EMTP-ATP program on a three phase transformer are carried out. Study cases of inrush current at different switching instants and for all types of internal faults for different phases and on different percentages of transformer windings are simulated. The results obtained from EMTP-ATP package for all simulated conditions used as a training data to artificial neural network (ANN). This helps the differential relay to recognize inrush and internal fault and give the trip signal in case of internal fault only.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131599827","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562368
M. Osama, Azim High
The focus of this paper is the implementation and performance analysis of an elevator three-phase induction motor drive and its comparison to the traditional dual stator winding line-supplied elevator motors. To carry-on this study, a scaled prototype elevator is designed and manufactured. The elevator system motion controller is implemented via a PLC. The elevator ASD (Adjustable Speed Drive) consists of a variable frequency converter driving the three-phase induction motor coupled to a gearbox. The implemented elevator motion control system is discussed in this paper. The per-phase equivalent circuit motor parameters and loss components are measured in case of variable frequency supply and compared to the 50-Hz sinsuoidal line supply case. The steady-state as well as dynamic performance of the elevator electric motor drive system is also evaluated.
{"title":"Implementation and performance analysis of an elevator electric motor drive system","authors":"M. Osama, Azim High","doi":"10.1109/MEPCON.2008.4562368","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562368","url":null,"abstract":"The focus of this paper is the implementation and performance analysis of an elevator three-phase induction motor drive and its comparison to the traditional dual stator winding line-supplied elevator motors. To carry-on this study, a scaled prototype elevator is designed and manufactured. The elevator system motion controller is implemented via a PLC. The elevator ASD (Adjustable Speed Drive) consists of a variable frequency converter driving the three-phase induction motor coupled to a gearbox. The implemented elevator motion control system is discussed in this paper. The per-phase equivalent circuit motor parameters and loss components are measured in case of variable frequency supply and compared to the 50-Hz sinsuoidal line supply case. The steady-state as well as dynamic performance of the elevator electric motor drive system is also evaluated.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116441049","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562337
S. M. El-Makkawy
From the standpoint of the gas insulation design, the most important factors in discharge performance is the corona starting voltage and the flashover voltage. The main problem of insulation design will be solved if the corona onset voltage and flashover voltage are calculated for given electrode arrangement. In this study a general computer program using Matlab is developed to predict the discharge inception voltage levels in sphere-to-sphere gap with the presence of floating conducting particles in air insulated DC power apparatus. Therefore, through out the computations of discharge inception voltages, streamer theory is considered. The streamer theory closely associated to the electric field distribution inside the gap, in order to compute the critical single avalanche size which is responsible for initiating the streamer channel at the discharge inception voltage. The floating metals particles treated in this work are rectangular plates, needles with hemispherical ends and spheres. As a theoretical base, a charge simulation program has been carried out to determine the effect of floating particle in electric field distribution along the gap axis between two sphere electrodes. The dependence of field enhancement and its distribution and corona inception voltage within the floating particle on the shape, size and location of floating metal and the electrode spacing are emphasized. The results concluded that the enhancement of electric field depends on the Shape but in all case the electric field is distorted. The results show that the effect of various parameters on the stress distribution within a floating metal particle is important in the design and testing of dielectric insulating materials.
{"title":"Computation of electric stress and corona onset voltage in air gaps with floating particles","authors":"S. M. El-Makkawy","doi":"10.1109/MEPCON.2008.4562337","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562337","url":null,"abstract":"From the standpoint of the gas insulation design, the most important factors in discharge performance is the corona starting voltage and the flashover voltage. The main problem of insulation design will be solved if the corona onset voltage and flashover voltage are calculated for given electrode arrangement. In this study a general computer program using Matlab is developed to predict the discharge inception voltage levels in sphere-to-sphere gap with the presence of floating conducting particles in air insulated DC power apparatus. Therefore, through out the computations of discharge inception voltages, streamer theory is considered. The streamer theory closely associated to the electric field distribution inside the gap, in order to compute the critical single avalanche size which is responsible for initiating the streamer channel at the discharge inception voltage. The floating metals particles treated in this work are rectangular plates, needles with hemispherical ends and spheres. As a theoretical base, a charge simulation program has been carried out to determine the effect of floating particle in electric field distribution along the gap axis between two sphere electrodes. The dependence of field enhancement and its distribution and corona inception voltage within the floating particle on the shape, size and location of floating metal and the electrode spacing are emphasized. The results concluded that the enhancement of electric field depends on the Shape but in all case the electric field is distorted. The results show that the effect of various parameters on the stress distribution within a floating metal particle is important in the design and testing of dielectric insulating materials.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129766407","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562404
N. Abdel-Rahim, A. Shaltout
Single-phase induction motors are widely used in many applications. Improvements in its performance means a great saving in electrical energy consumption. An inverter-fed variable frequency motor is a typical example of such improvement. In this regard, the paper presents a comprehensive analysis of the performance of the single-phase induction motor when it is fed with an inverter. Dynamic models and analysis of the motor behavior during transient and steady state phases are presented. A speed controller based on slip frequency technique is proposed. The controlled motor exhibited better performance at both staring and steady state.
{"title":"Slip frequency controlled inverter-fed single-phase induction motors","authors":"N. Abdel-Rahim, A. Shaltout","doi":"10.1109/MEPCON.2008.4562404","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562404","url":null,"abstract":"Single-phase induction motors are widely used in many applications. Improvements in its performance means a great saving in electrical energy consumption. An inverter-fed variable frequency motor is a typical example of such improvement. In this regard, the paper presents a comprehensive analysis of the performance of the single-phase induction motor when it is fed with an inverter. Dynamic models and analysis of the motor behavior during transient and steady state phases are presented. A speed controller based on slip frequency technique is proposed. The controlled motor exhibited better performance at both staring and steady state.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129979211","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562340
B. M. Hasaneen, A. Elbaset
This paper presents a design and simulation of DC/DC boost converter. This system has a nonlinear dynamic behavior, as it work in switch-mode. Moreover, it is exposed to significant variations which may take this system away from nominal conditions, due to changes on the load or on the line voltage at the input. The input usually is obtained by PV array and therefore the design and simulation in this paper covers the whole range of radiations and temperature. In this paper we analyze the equations of a boost converter and propose a design components and simulation of DC/DC boost converter. This work is applied to photovoltaic system for tracking the point of maximum power.
{"title":"Design and simulation of DC/DC boost converter","authors":"B. M. Hasaneen, A. Elbaset","doi":"10.1109/MEPCON.2008.4562340","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562340","url":null,"abstract":"This paper presents a design and simulation of DC/DC boost converter. This system has a nonlinear dynamic behavior, as it work in switch-mode. Moreover, it is exposed to significant variations which may take this system away from nominal conditions, due to changes on the load or on the line voltage at the input. The input usually is obtained by PV array and therefore the design and simulation in this paper covers the whole range of radiations and temperature. In this paper we analyze the equations of a boost converter and propose a design components and simulation of DC/DC boost converter. This work is applied to photovoltaic system for tracking the point of maximum power.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131655098","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562408
A. El Aroudi, E. Alarcón, E. Rodriguez, R. Leyva
In this paper we combine two different approaches for studying stability of DC-DC power electronic circuits. The first method is based on the Routh-Hurwitz criterion for stability of linear systems and it is suitable for detecting low frequency oscillations. The second approach uses the ripple injected in the modulator from the controller and it is suitable for predicting subharmonic oscillations. A DC-DC buck converter is used as an example to put in evidence the usefulness of the method. After showing that the system can undergo both period doubling and Neimark-Sacker bifurcation by numerical time domain simulations from the switching model, we give analytical closed form conditions for slow scale (low frequency) instability. The ripple at the PWM modulator is taken into account to predict the subharmonic oscillations.
{"title":"Stability of DC-DC converters: A ripple based index approach","authors":"A. El Aroudi, E. Alarcón, E. Rodriguez, R. Leyva","doi":"10.1109/MEPCON.2008.4562408","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562408","url":null,"abstract":"In this paper we combine two different approaches for studying stability of DC-DC power electronic circuits. The first method is based on the Routh-Hurwitz criterion for stability of linear systems and it is suitable for detecting low frequency oscillations. The second approach uses the ripple injected in the modulator from the controller and it is suitable for predicting subharmonic oscillations. A DC-DC buck converter is used as an example to put in evidence the usefulness of the method. After showing that the system can undergo both period doubling and Neimark-Sacker bifurcation by numerical time domain simulations from the switching model, we give analytical closed form conditions for slow scale (low frequency) instability. The ripple at the PWM modulator is taken into account to predict the subharmonic oscillations.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114614445","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562400
H. Ashour
The rapid development and high controllability advantages of power electronic devices lead to their application in voltage stabilizers and tap-changers as competitive options with commercially available mechanical counterparts. This paper introduces a new electronic voltage stabilizer topology utilizes four AC switches in a form that may be named as "AC H-bridge" connection, and based on pulse width modulation (PWM) AC chopper combined with a single low power compensating transformer. Such topology eliminates the need of the main input multi-tapping transformer, hence reducing the overall size, weight and cost. Depending on the selected switches and value of the chopping duty cycle, the proposed configuration is capable of stepping up or down the input voltage, hence keeping the output voltage constant with continuous flow of input current and better harmonics restraining in the output load voltage. Mathematical equations describing the function of the proposed topology have been demonstrated and simulation analysis has been presented. Practical verification to confirm the capability of the setup has been illustrated through several experimental results and analysis.
{"title":"A new electronic step-up/down voltage stabilizer topology based on H-Bridge AC chopper","authors":"H. Ashour","doi":"10.1109/MEPCON.2008.4562400","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562400","url":null,"abstract":"The rapid development and high controllability advantages of power electronic devices lead to their application in voltage stabilizers and tap-changers as competitive options with commercially available mechanical counterparts. This paper introduces a new electronic voltage stabilizer topology utilizes four AC switches in a form that may be named as \"AC H-bridge\" connection, and based on pulse width modulation (PWM) AC chopper combined with a single low power compensating transformer. Such topology eliminates the need of the main input multi-tapping transformer, hence reducing the overall size, weight and cost. Depending on the selected switches and value of the chopping duty cycle, the proposed configuration is capable of stepping up or down the input voltage, hence keeping the output voltage constant with continuous flow of input current and better harmonics restraining in the output load voltage. Mathematical equations describing the function of the proposed topology have been demonstrated and simulation analysis has been presented. Practical verification to confirm the capability of the setup has been illustrated through several experimental results and analysis.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133944445","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562378
A. Abdelaziz, S. Mekhamer, M. Kamh, M. Badr
This paper introduces a solution of the dynamic economic dispatch (DED) problem using a hybrid approach of Hopfield neural network (HNN) and quadratic programming (QP). The hybrid algorithm is based on using enhanced HNN; to solve the static part of the problem; and the QP algorithm for solving the dynamic part of the DED. This technique guarantees the global optimality of the solution due to its look-ahead capability. The new algorithm is applied and tested to an example from the literature and the solution is then compared with that obtained by some other techniques to prove the superiority and effectiveness of the proposed algorithm.
{"title":"A hybrid Hopfield neural network-quadratic programming approach for dynamic economic dispatch problem","authors":"A. Abdelaziz, S. Mekhamer, M. Kamh, M. Badr","doi":"10.1109/MEPCON.2008.4562378","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562378","url":null,"abstract":"This paper introduces a solution of the dynamic economic dispatch (DED) problem using a hybrid approach of Hopfield neural network (HNN) and quadratic programming (QP). The hybrid algorithm is based on using enhanced HNN; to solve the static part of the problem; and the QP algorithm for solving the dynamic part of the DED. This technique guarantees the global optimality of the solution due to its look-ahead capability. The new algorithm is applied and tested to an example from the literature and the solution is then compared with that obtained by some other techniques to prove the superiority and effectiveness of the proposed algorithm.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132451324","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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