Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808422
E. Ghiani, R. Di Gregorio
The connection of photovoltaic systems on weak electrical distribution networks can lead to unsatisfactory operating conditions for renewable energy producers due to the occurrence of overvoltages or undervoltages. In such critical situations, where electrical parameters are outside standard regulatory levels, the intervention of electrical protections can cause damage to power generation. For this purpose, the paper presents the application of an intelligent voltage regulator capable of solving voltage regulation problems in low-voltage networks. A real case study shows the results of the application of the device in electrical distribution networks with a high penetration of photovoltaic type renewable source plants. The results show the effectiveness of its application in terms of both technical and economic aspects related to the use of the proposed voltage regulator and its comparison with traditional strategies of planning expansion, highlighting the benefits for the distributor and the owners of photovoltaic plants.
{"title":"Intelligent Low Voltage Regulator for Solving PV Overvoltages Problems in Power Distribution Systems","authors":"E. Ghiani, R. Di Gregorio","doi":"10.1109/ICHQP53011.2022.9808422","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808422","url":null,"abstract":"The connection of photovoltaic systems on weak electrical distribution networks can lead to unsatisfactory operating conditions for renewable energy producers due to the occurrence of overvoltages or undervoltages. In such critical situations, where electrical parameters are outside standard regulatory levels, the intervention of electrical protections can cause damage to power generation. For this purpose, the paper presents the application of an intelligent voltage regulator capable of solving voltage regulation problems in low-voltage networks. A real case study shows the results of the application of the device in electrical distribution networks with a high penetration of photovoltaic type renewable source plants. The results show the effectiveness of its application in terms of both technical and economic aspects related to the use of the proposed voltage regulator and its comparison with traditional strategies of planning expansion, highlighting the benefits for the distributor and the owners of photovoltaic plants.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"179 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121053999","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808777
G. Carpinelli, P. Varilone, T. Sikorski, J. Rezmer, P. Kostyła, A. Bracale
The waveforms distortion assessment nowadays requires great research efforts due to the contemporaneous presence of low- and high-frequency harmonics and interharmonics (up to 150 kHz). In this paper, a new multi-method approach allowed accurate and fast analysis of such waveforms. The method profitably integrates the performances of some basic methods: the Discrete Wavelet Transform, the sliding-window modified ESPRIT method, and the sliding-window Discrete Fourier Transform which uses a Nuttal window whose length is accurately calculated thanks to the application of the Prony method or the Particle Swarm Optimization. The accurate calculation of Nuttal window length guarantees a good performance in the high-frequency spectral components assessment while reduced computational efforts are obtained parallelizing the calculation of low- and high-frequency harmonics/interharmonics. Numerical applications on synthetic and measured waveforms demonstrate that the proposed method improves the performances of high-performing methods proposed in the recent relevant literature, in the examined cases.
{"title":"Accurate and Fast Parallelized Assessment of Waveform Distortions in Presence of Low and High frequency Spectral Components","authors":"G. Carpinelli, P. Varilone, T. Sikorski, J. Rezmer, P. Kostyła, A. Bracale","doi":"10.1109/ICHQP53011.2022.9808777","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808777","url":null,"abstract":"The waveforms distortion assessment nowadays requires great research efforts due to the contemporaneous presence of low- and high-frequency harmonics and interharmonics (up to 150 kHz). In this paper, a new multi-method approach allowed accurate and fast analysis of such waveforms. The method profitably integrates the performances of some basic methods: the Discrete Wavelet Transform, the sliding-window modified ESPRIT method, and the sliding-window Discrete Fourier Transform which uses a Nuttal window whose length is accurately calculated thanks to the application of the Prony method or the Particle Swarm Optimization. The accurate calculation of Nuttal window length guarantees a good performance in the high-frequency spectral components assessment while reduced computational efforts are obtained parallelizing the calculation of low- and high-frequency harmonics/interharmonics. Numerical applications on synthetic and measured waveforms demonstrate that the proposed method improves the performances of high-performing methods proposed in the recent relevant literature, in the examined cases.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116580529","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808772
O. Lennerhag, M. Bollen
Uncertainties in power system studies are often considered using Monte Carlo methods, or by the use of deterministic methods, often based on some worst-case assumptions. With an increasing number of uncertainties, there is a need for methods that can estimate statistical parameters from a limited number of calculations. This paper utilizes a method called the Unscented Transform together with Cornish-Fisher expansion to calculate harmonic distortion at the point of connection of a wind farm under different uncertainties. The method is shown to be able to estimate the 95% value of individual harmonics accurately when considering variations in emission and impedance, using only a limited number of calculations.
{"title":"Managing Uncertainties in Wind Farm Harmonic Studies Using Unscented Transform","authors":"O. Lennerhag, M. Bollen","doi":"10.1109/ICHQP53011.2022.9808772","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808772","url":null,"abstract":"Uncertainties in power system studies are often considered using Monte Carlo methods, or by the use of deterministic methods, often based on some worst-case assumptions. With an increasing number of uncertainties, there is a need for methods that can estimate statistical parameters from a limited number of calculations. This paper utilizes a method called the Unscented Transform together with Cornish-Fisher expansion to calculate harmonic distortion at the point of connection of a wind farm under different uncertainties. The method is shown to be able to estimate the 95% value of individual harmonics accurately when considering variations in emission and impedance, using only a limited number of calculations.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122370434","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808557
Samadhi Liyanage, S. Perera, D. Robinson
Cross harmonic generation by grid-connected high power inverters take place due to the asymmetry of inverter controllers in the presence of background harmonics in the grid. Although cross harmonic generation is often neglected in harmonic studies, the investigations reported in this paper show that the grid current magnitudes at cross harmonic frequencies can become relatively significant in some situations and hence cannot be ignored in harmonic compliance studies. This is demonstrated using example studies employing a single grid connected inverter model and a large scale three-phase solar farm model. Furthermore, an inverter harmonic model is proposed that can be used to determine the harmonic currents injected by an inverter at both the background harmonic frequency in the grid and at the cross harmonic frequency. The proposed model is validated using EMT simulation results.
{"title":"A Study on Cross-Harmonic Generation by Large Three-phase Inverters in Solar Farm Environments","authors":"Samadhi Liyanage, S. Perera, D. Robinson","doi":"10.1109/ICHQP53011.2022.9808557","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808557","url":null,"abstract":"Cross harmonic generation by grid-connected high power inverters take place due to the asymmetry of inverter controllers in the presence of background harmonics in the grid. Although cross harmonic generation is often neglected in harmonic studies, the investigations reported in this paper show that the grid current magnitudes at cross harmonic frequencies can become relatively significant in some situations and hence cannot be ignored in harmonic compliance studies. This is demonstrated using example studies employing a single grid connected inverter model and a large scale three-phase solar farm model. Furthermore, an inverter harmonic model is proposed that can be used to determine the harmonic currents injected by an inverter at both the background harmonic frequency in the grid and at the cross harmonic frequency. The proposed model is validated using EMT simulation results.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130666347","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808780
Francois du Plessis, J. Beukes
Harmonic analysis of inverters in renewable power plants can be very complex and is often only based on measurement data. This paper uses the harmonic modelling technique specified by IEC 61400-21-3 to perform a harmonic analysis on a specific inverter system and analyse the effect of grid impedance and control system parameters on harmonic distortion. Harmonic grid current distortion is often used for compliance of renewable power plants. Through impedance based arguments based on the harmonic model, this paper shows how harmonic currents, produced by the interaction between background voltage distortion and the system impedance, can decrease harmonic voltage distortion at the point of connection of a renewable power plant.
{"title":"Influence of System Parameters on Harmonic Distortion Contributions of Renewable Power Plants","authors":"Francois du Plessis, J. Beukes","doi":"10.1109/ICHQP53011.2022.9808780","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808780","url":null,"abstract":"Harmonic analysis of inverters in renewable power plants can be very complex and is often only based on measurement data. This paper uses the harmonic modelling technique specified by IEC 61400-21-3 to perform a harmonic analysis on a specific inverter system and analyse the effect of grid impedance and control system parameters on harmonic distortion. Harmonic grid current distortion is often used for compliance of renewable power plants. Through impedance based arguments based on the harmonic model, this paper shows how harmonic currents, produced by the interaction between background voltage distortion and the system impedance, can decrease harmonic voltage distortion at the point of connection of a renewable power plant.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134060814","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808834
Heremans Florian, Vliegen Kristof, Van Reusel Koen
In 1983 F. D. Martzloff published a paper "The Propagation and Attenuation of Surge Voltages and Surge Currents in Low-Voltage AC Circuits". The experiment as described in the 1983 paper is experimentally revalidated with a view of its relevance for the insulation level of equipment in low-voltage residential networks.
{"title":"Propagation and Attenuation of Surge Voltages and its consequence for the insulation coordination in Low-Voltage AC Circuits","authors":"Heremans Florian, Vliegen Kristof, Van Reusel Koen","doi":"10.1109/ICHQP53011.2022.9808834","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808834","url":null,"abstract":"In 1983 F. D. Martzloff published a paper \"The Propagation and Attenuation of Surge Voltages and Surge Currents in Low-Voltage AC Circuits\". The experiment as described in the 1983 paper is experimentally revalidated with a view of its relevance for the insulation level of equipment in low-voltage residential networks.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"91 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134036512","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808709
N. Bulatov, A. Kryukov, K. Suslov
Operation of 6-10-35 kV power transmission lines (PTL) under a double earth fault is characterized by significant currents flowing in the ground, which increases the magnetic effect and can result in dangerous voltages on extended metal structures, for example, pipelines passing near these transmission lines. The paper presents the results of studies conducted to develop a method for computer modeling of induced voltages on an above-ground pipeline due to the electromagnetic effect of power lines during double earth faults. This problem was solved using algorithms relying on phase coordinates and implemented in the Fazonord software. Obtained results suggest that under double earth faults, the pipeline parts can be exposed to significant induced voltages, which are close to values that are limiting for emergency conditions. The proposed method and the developed computer models can be used in practice to ensure the electrical safety of personnel working on pipelines located near 6-10-35 kV high-voltage transmission lines.
{"title":"Modeling High-voltage Transmission Line Operation under Double Earth Faults for Calculating Voltage Induced on Pipeline","authors":"N. Bulatov, A. Kryukov, K. Suslov","doi":"10.1109/ICHQP53011.2022.9808709","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808709","url":null,"abstract":"Operation of 6-10-35 kV power transmission lines (PTL) under a double earth fault is characterized by significant currents flowing in the ground, which increases the magnetic effect and can result in dangerous voltages on extended metal structures, for example, pipelines passing near these transmission lines. The paper presents the results of studies conducted to develop a method for computer modeling of induced voltages on an above-ground pipeline due to the electromagnetic effect of power lines during double earth faults. This problem was solved using algorithms relying on phase coordinates and implemented in the Fazonord software. Obtained results suggest that under double earth faults, the pipeline parts can be exposed to significant induced voltages, which are close to values that are limiting for emergency conditions. The proposed method and the developed computer models can be used in practice to ensure the electrical safety of personnel working on pipelines located near 6-10-35 kV high-voltage transmission lines.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133143856","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808815
Baoling Guo, J. Pouget, Luc Bossoney, M. Carpita, Thomas Meier, Jean-Paul Maye
The DC railway electrification systems are widely used to supply the national, regional, and urban (metro and tramway) railway systems. However, the catenary line voltage is subject to high voltage variations due to the moving train loads. The catenary line voltage drops when the train accelerates, while the overvoltage occurs when the train brakes. The frequent overvoltages can increase system maintenance costs and reduce life cycles of the onboard devices. In a practical design, if the catenary voltage reaches its upper limit, the rheostat brake is performed to maintain the voltage stability. The braking energy is dissipated as heat by the onboard rheostat, such operation can reduce the global energy efficiency. Therefore, this work proposes to install Electrical Vehicle (EV) charging stations along the DC electric railway line in order to stabilize the catenary voltage. The braking energy is used by charging EV to achieve higher energy efficiency. A regional 850 V DC railway microgrid located in mountain area is considered in this work. Two cases without and with EV chargers are modeled, simulated, and compared by using Matlab/Simulink. The results highlight the performance of the EV charging solution in terms of voltage stabilization and braking energy savings, also economic aspects.
{"title":"Catenary overvoltage stabilization of DC railway electrical system by integrating EV charging stations","authors":"Baoling Guo, J. Pouget, Luc Bossoney, M. Carpita, Thomas Meier, Jean-Paul Maye","doi":"10.1109/ICHQP53011.2022.9808815","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808815","url":null,"abstract":"The DC railway electrification systems are widely used to supply the national, regional, and urban (metro and tramway) railway systems. However, the catenary line voltage is subject to high voltage variations due to the moving train loads. The catenary line voltage drops when the train accelerates, while the overvoltage occurs when the train brakes. The frequent overvoltages can increase system maintenance costs and reduce life cycles of the onboard devices. In a practical design, if the catenary voltage reaches its upper limit, the rheostat brake is performed to maintain the voltage stability. The braking energy is dissipated as heat by the onboard rheostat, such operation can reduce the global energy efficiency. Therefore, this work proposes to install Electrical Vehicle (EV) charging stations along the DC electric railway line in order to stabilize the catenary voltage. The braking energy is used by charging EV to achieve higher energy efficiency. A regional 850 V DC railway microgrid located in mountain area is considered in this work. Two cases without and with EV chargers are modeled, simulated, and compared by using Matlab/Simulink. The results highlight the performance of the EV charging solution in terms of voltage stabilization and braking energy savings, also economic aspects.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133305704","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808423
P. Schachinger, Dennis Albert, H. Renner
Low frequency currents (LFC) in transformer neutral points can lead to disturbances in high voltage grids. Half-cycle saturation of transformers, caused by LFCs, results in increased audible sound, voltage distortions and led in the past even to blackouts. The main source of LFCs are changes in the Earth’s geomagnetic field, caused by solar storms. However, LFC measurements reveal additional man-made causes as well. In this paper, two known sources of LFCs are discussed briefly and a new source is introduced and documented by combining neutral point measurements and phasor measurements in the Austrian power grid.
{"title":"Low Frequency Currents Source Identification","authors":"P. Schachinger, Dennis Albert, H. Renner","doi":"10.1109/ICHQP53011.2022.9808423","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808423","url":null,"abstract":"Low frequency currents (LFC) in transformer neutral points can lead to disturbances in high voltage grids. Half-cycle saturation of transformers, caused by LFCs, results in increased audible sound, voltage distortions and led in the past even to blackouts. The main source of LFCs are changes in the Earth’s geomagnetic field, caused by solar storms. However, LFC measurements reveal additional man-made causes as well. In this paper, two known sources of LFCs are discussed briefly and a new source is introduced and documented by combining neutral point measurements and phasor measurements in the Austrian power grid.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115654480","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 : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808635
M. Brenna, H. J. Kaleybar, F. Foiadelli, D. Zaninelli
Electric railway supplying systems (ERSSs) as one of the foremost and critical loads of the grid have been faced with power quality (PQ) issues all around the world. Due to the various PQ distortion types, and planned priorities, different mitigation methods have been introduced by experts over years and they have been updated based on the emergence of new power electronic-based technologies. These methods mainly deal with harmonic issues, low power factor, imbalance situations, transients, and variation phenomena. The main purpose of this paper is to classify and explain these mitigation technologies including their structure, application and features in detail, which can provide a useful perspective to researchers working in this area.
{"title":"Modern Power Quality Improvement Devices Applied to Electric Railway Systems","authors":"M. Brenna, H. J. Kaleybar, F. Foiadelli, D. Zaninelli","doi":"10.1109/ICHQP53011.2022.9808635","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808635","url":null,"abstract":"Electric railway supplying systems (ERSSs) as one of the foremost and critical loads of the grid have been faced with power quality (PQ) issues all around the world. Due to the various PQ distortion types, and planned priorities, different mitigation methods have been introduced by experts over years and they have been updated based on the emergence of new power electronic-based technologies. These methods mainly deal with harmonic issues, low power factor, imbalance situations, transients, and variation phenomena. The main purpose of this paper is to classify and explain these mitigation technologies including their structure, application and features in detail, which can provide a useful perspective to researchers working in this area.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"435 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122804973","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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