Pub Date : 2018-05-01DOI: 10.1109/ICHQP.2018.8378831
A. Serov, A. Shatokhin, A. Novitskiy, D. Westermann
At the present time the most popular method to measure the root-mean-square value (RMS) is based on the summation of squares of samples over a time proportional to its period. The disadvantage of this method is associated with the presence of an additional error caused by the frequency deviation of the input signal and by the presence of additional harmonics. In this article we propose an approach based on the digital filtering of the square of samples. The analytical expressions for the estimating of the RMS measurement error of the proposed measurement method are obtained. The analysis of the error resulting from the frequency deviation of the input signal and the presence of harmonics is realized. Requirements for applied digital filter are defined. Various types of digital filters including moving average filters and cascade-integrator- comb filters are considered. The estimates of RMS measurement error with respect to the signals of real power networks are defined by simulation in programs Matlab and Simulink.
{"title":"Investigation of the method of RMS measuring based on the digital filtration of the square of samples","authors":"A. Serov, A. Shatokhin, A. Novitskiy, D. Westermann","doi":"10.1109/ICHQP.2018.8378831","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378831","url":null,"abstract":"At the present time the most popular method to measure the root-mean-square value (RMS) is based on the summation of squares of samples over a time proportional to its period. The disadvantage of this method is associated with the presence of an additional error caused by the frequency deviation of the input signal and by the presence of additional harmonics. In this article we propose an approach based on the digital filtering of the square of samples. The analytical expressions for the estimating of the RMS measurement error of the proposed measurement method are obtained. The analysis of the error resulting from the frequency deviation of the input signal and the presence of harmonics is realized. Requirements for applied digital filter are defined. Various types of digital filters including moving average filters and cascade-integrator- comb filters are considered. The estimates of RMS measurement error with respect to the signals of real power networks are defined by simulation in programs Matlab and Simulink.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"113 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79320411","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378941
Andrés Mauricio Oviedo Pinzón, P. M. Silveira, Y. Baghzouz
Microgrid (MG) is a key component of the smart grid and, at the same time, is a small scale of it. The MG system has the potential to enhance the electric grid efficiency, power quality and reliability, and offer to the consumers a possible energy independence. The lack of MG compatible control systems is one of the main barriers for wide spread deployment of these kind of systems. In this paper, a hierarchical classification of the control levels and techniques applied to MG is presented. This concept is simulated on a grid-tied MG that consists of a photovoltaic array, a battery system and a diesel generator. The principal focus of the simulation relies on the primary control which shows how the lower level of control responds to modifications in the operational state of the MG.
{"title":"Simulation of microgrid hierarchical control","authors":"Andrés Mauricio Oviedo Pinzón, P. M. Silveira, Y. Baghzouz","doi":"10.1109/ICHQP.2018.8378941","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378941","url":null,"abstract":"Microgrid (MG) is a key component of the smart grid and, at the same time, is a small scale of it. The MG system has the potential to enhance the electric grid efficiency, power quality and reliability, and offer to the consumers a possible energy independence. The lack of MG compatible control systems is one of the main barriers for wide spread deployment of these kind of systems. In this paper, a hierarchical classification of the control levels and techniques applied to MG is presented. This concept is simulated on a grid-tied MG that consists of a photovoltaic array, a battery system and a diesel generator. The principal focus of the simulation relies on the primary control which shows how the lower level of control responds to modifications in the operational state of the MG.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"35 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84537503","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378860
M. Brenna, F. Foiadelli, M. Longo, D. Zaninelli
The aim of this work is to study the actual behavior of grounding systems using the Finite Element Method (FEM) in the Ansys Maxwell environment. Given the importance of grounding resistance to ensuring the proper functioning of all electrical systems and even more so for people's safety, it is nevertheless advisable to verify and validate this method for its application during the design stage. The validation of the model has been carried out through the hemispheric electrode, whose mathematical expression for the grounding resistance is well known. However, for other type of electrodes, as grounding rods, the equations usually adopted to design grounding systems provide only approximated values for their grounding resistance. Besides, these equations are able to estimate the grounding resistance only for homogeneous resistivity of the earth. Consequently, traditional methods can give values for the grounding resistance that can differ from the actual behavior due to these uncertainties. In this paper, the use of finite element analysis has been investigated to determine a better estimation of the grounding resistance in different scenarios and to find the distribution of the grounding potential for step and touch voltages calculation on particular critical conditions.
{"title":"Particular grounding systems analysis using FEM models","authors":"M. Brenna, F. Foiadelli, M. Longo, D. Zaninelli","doi":"10.1109/ICHQP.2018.8378860","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378860","url":null,"abstract":"The aim of this work is to study the actual behavior of grounding systems using the Finite Element Method (FEM) in the Ansys Maxwell environment. Given the importance of grounding resistance to ensuring the proper functioning of all electrical systems and even more so for people's safety, it is nevertheless advisable to verify and validate this method for its application during the design stage. The validation of the model has been carried out through the hemispheric electrode, whose mathematical expression for the grounding resistance is well known. However, for other type of electrodes, as grounding rods, the equations usually adopted to design grounding systems provide only approximated values for their grounding resistance. Besides, these equations are able to estimate the grounding resistance only for homogeneous resistivity of the earth. Consequently, traditional methods can give values for the grounding resistance that can differ from the actual behavior due to these uncertainties. In this paper, the use of finite element analysis has been investigated to determine a better estimation of the grounding resistance in different scenarios and to find the distribution of the grounding potential for step and touch voltages calculation on particular critical conditions.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"717 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78734398","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378874
F. Arrabal-Campos, F. G. Montoya, R. Baños, J. Martínez-Lao, A. Alcayde
Most of the related PQ disturbances studies are addressed exclusively through standing advanced mathematical concepts without possibility to test these techniques over synthetic signals. This paper presents a new application implemented in MATLAB that has been developed to set up different synthetic signals, PQ disturbances and white noise. Afterwards, FT, STFT, CWT, DWT and denoised signals are calculated. Moreover, the application can connect to any device via RESTful web service and query for data stored in smart sensors. The novelty of this application lies in the fact that it allows to monitor FT, STFT, CWT, DWT and the denoised signals continuously.
{"title":"Simulation of power quality disturbances through the wavelet transform","authors":"F. Arrabal-Campos, F. G. Montoya, R. Baños, J. Martínez-Lao, A. Alcayde","doi":"10.1109/ICHQP.2018.8378874","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378874","url":null,"abstract":"Most of the related PQ disturbances studies are addressed exclusively through standing advanced mathematical concepts without possibility to test these techniques over synthetic signals. This paper presents a new application implemented in MATLAB that has been developed to set up different synthetic signals, PQ disturbances and white noise. Afterwards, FT, STFT, CWT, DWT and denoised signals are calculated. Moreover, the application can connect to any device via RESTful web service and query for data stored in smart sensors. The novelty of this application lies in the fact that it allows to monitor FT, STFT, CWT, DWT and the denoised signals continuously.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"13 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88014071","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378940
M. Michalski, G. Wiczyński
A set of power quality measures includes Pst indicator and voltage fluctuation indices. Both of the measures describe voltage variation. They however differ in their properties. This results, among others, in different diagnostic capabilities. Because of that the power quality assessment should make use of both of the measures. One of the consequences of taking such an approach is the matter of possible recalculation of voltage fluctuation indices into Pst indicator. This paper presents an example of such recalculation. During the process a results of measurements recorded in LV power grid were used. The chosen example presents the case where the quality of Pst indicator restoration is only moderate. It is shown that the results of calculations are basically similar to real Pst indicator values. To give wider insight into the example, also maximal and minimal rms voltage values were used along voltage fluctuation indices and Pst indicator.
{"title":"An example of converting voltage fluctuation indices into Pst indicator","authors":"M. Michalski, G. Wiczyński","doi":"10.1109/ICHQP.2018.8378940","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378940","url":null,"abstract":"A set of power quality measures includes Pst indicator and voltage fluctuation indices. Both of the measures describe voltage variation. They however differ in their properties. This results, among others, in different diagnostic capabilities. Because of that the power quality assessment should make use of both of the measures. One of the consequences of taking such an approach is the matter of possible recalculation of voltage fluctuation indices into Pst indicator. This paper presents an example of such recalculation. During the process a results of measurements recorded in LV power grid were used. The chosen example presents the case where the quality of Pst indicator restoration is only moderate. It is shown that the results of calculations are basically similar to real Pst indicator values. To give wider insight into the example, also maximal and minimal rms voltage values were used along voltage fluctuation indices and Pst indicator.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"112 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82775582","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378878
Thomas A. Cooke, W. Howe
Statistical process control (SPC) is a well-known method to monitor behavior and control of process parameters through statistical analysis. In power quality (PQ), we can apply this method to PQ parameters such as harmonics, imbalance, and flicker to analyze when values are outside a normal range. However, the normal range for these PQ parameters can vary depending on known conditions relating to time of day, day of the week, or even time of year. To have a tighter set of continuous control during these periods, a dynamic set of limits would be preferred over one static limit to highlight unknown abnormalities. This paper analyzes methods to create dynamic statistical process control limits for PQ data.
{"title":"Dynamic statistical process control limits for power quality trend data","authors":"Thomas A. Cooke, W. Howe","doi":"10.1109/ICHQP.2018.8378878","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378878","url":null,"abstract":"Statistical process control (SPC) is a well-known method to monitor behavior and control of process parameters through statistical analysis. In power quality (PQ), we can apply this method to PQ parameters such as harmonics, imbalance, and flicker to analyze when values are outside a normal range. However, the normal range for these PQ parameters can vary depending on known conditions relating to time of day, day of the week, or even time of year. To have a tighter set of continuous control during these periods, a dynamic set of limits would be preferred over one static limit to highlight unknown abnormalities. This paper analyzes methods to create dynamic statistical process control limits for PQ data.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"16 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88937011","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378904
Daniel R. Pinto, V. Arioli, Glaucio R. T. Hax, Fábio K. Taniguchi, R. Torquato, W. Teixeira, P. L. Eduardo
Electric vehicle (EV) charging sites in Brazil are still scarce. However, due to the large number of homes with their own garages in the country, it is believed that the growth of the technology will stimulate the use of residential charging stations (CSs). Because the EV is a load with significant power consumption and remains connected to the grid for several hours during its slow recharge, this article aims to analyze and identify the possible impacts associated with this condition from the point of view of the power grid and the electricity utility company and its influence on the power quality of low voltage urban networks. Therefore, real field measurements are used and analyzed according to Brazilian and international recommendations and standards.
{"title":"Field investigation of the power quality impact of electric vehicles in secondary residential systems","authors":"Daniel R. Pinto, V. Arioli, Glaucio R. T. Hax, Fábio K. Taniguchi, R. Torquato, W. Teixeira, P. L. Eduardo","doi":"10.1109/ICHQP.2018.8378904","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378904","url":null,"abstract":"Electric vehicle (EV) charging sites in Brazil are still scarce. However, due to the large number of homes with their own garages in the country, it is believed that the growth of the technology will stimulate the use of residential charging stations (CSs). Because the EV is a load with significant power consumption and remains connected to the grid for several hours during its slow recharge, this article aims to analyze and identify the possible impacts associated with this condition from the point of view of the power grid and the electricity utility company and its influence on the power quality of low voltage urban networks. Therefore, real field measurements are used and analyzed according to Brazilian and international recommendations and standards.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"1 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83016918","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378858
R. K. Subroto, K. Lian
Power system harmonics can increase system loses, excite resonant frequency, and cause equipment damage. It is therefore essential to develop accurate harmonic models for harmonic sources such as power converters. During last decades, renewable energy sources have become an important part of the worldwide concern with clean power generation. In response to the growing demand for medium and high power trends, multilevel converters (MCs) have been attracting growing considerations. As they become more spread-out, their harmonic impact on the system could be significant. In this paper, a fast time-domain method (FTDM) suitable for modeling a MC is proposed. The FTDM essentially model the harmonic of interest as a harmonic state and solve it together with the system differential equations. Since the solution is analytical, the FTDM is very accurate. Nevertheless, to model a MC, the FTDM requires to solve a very large exponential matrix. Hence, a Krylov subspace method is proposed to solve for the exponential matrix, resulted from the FTDM. Two case studies on two different modulations (in-phase disposition and phase-shifted modulations) are performed to validate the proposed method. As demonstrated in the paper, the computation time of the proposed method is much shorter compared to the brute-force time-domain simulators such as PSCAD/EMTDC. Moreover, when compared to other solvers, the proposed Krylov-based method yields the best in terms of calculation time.
{"title":"Modeling of a multilevel voltage source converter using the fast time-domain method","authors":"R. K. Subroto, K. Lian","doi":"10.1109/ICHQP.2018.8378858","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378858","url":null,"abstract":"Power system harmonics can increase system loses, excite resonant frequency, and cause equipment damage. It is therefore essential to develop accurate harmonic models for harmonic sources such as power converters. During last decades, renewable energy sources have become an important part of the worldwide concern with clean power generation. In response to the growing demand for medium and high power trends, multilevel converters (MCs) have been attracting growing considerations. As they become more spread-out, their harmonic impact on the system could be significant. In this paper, a fast time-domain method (FTDM) suitable for modeling a MC is proposed. The FTDM essentially model the harmonic of interest as a harmonic state and solve it together with the system differential equations. Since the solution is analytical, the FTDM is very accurate. Nevertheless, to model a MC, the FTDM requires to solve a very large exponential matrix. Hence, a Krylov subspace method is proposed to solve for the exponential matrix, resulted from the FTDM. Two case studies on two different modulations (in-phase disposition and phase-shifted modulations) are performed to validate the proposed method. As demonstrated in the paper, the computation time of the proposed method is much shorter compared to the brute-force time-domain simulators such as PSCAD/EMTDC. Moreover, when compared to other solvers, the proposed Krylov-based method yields the best in terms of calculation time.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"1 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83153475","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378887
V. Ravindran, S. Rönnberg, T. Busatto, M. Bollen
The main objective of the paper is to investigate the existence of interharmonic emissions from an MPPT driven grid-connected PV inverter, identify their severity and persistence. The presence of interharmonics in the measured current from a PV installation is linked to direct and diffused solar irradiation as well as a high ramping rate of the irradiation causing variations in both active and reactive power. The paper sets forth a set of observations and inferences, which is an appendage to the ongoing research on the power quality aspects of solar power. Three different case studies are evaluated in detail using signal processing tools like STFT and FFT.
{"title":"Inspection of interharmonic emissions from a grid-tied PV inverter in North Sweden","authors":"V. Ravindran, S. Rönnberg, T. Busatto, M. Bollen","doi":"10.1109/ICHQP.2018.8378887","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378887","url":null,"abstract":"The main objective of the paper is to investigate the existence of interharmonic emissions from an MPPT driven grid-connected PV inverter, identify their severity and persistence. The presence of interharmonics in the measured current from a PV installation is linked to direct and diffused solar irradiation as well as a high ramping rate of the irradiation causing variations in both active and reactive power. The paper sets forth a set of observations and inferences, which is an appendage to the ongoing research on the power quality aspects of solar power. Three different case studies are evaluated in detail using signal processing tools like STFT and FFT.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"1 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80597416","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 : 2018-05-01DOI: 10.1109/ICHQP.2018.8378918
A. Gil-de-Castro, R. Medina-Gracia, S. Ronnberg, A. Blanco, J. Meyer
Measurements have shown that the harmonic currents emitted by lamps with electronic ballast depend on the circuit topology and the existing supply voltage distortion. This paper quantifies the impact of supply voltage distortion on the harmonic and supraharmonic current emission of individual Light Emitting Diode (LED) lamps and compact fluorescent lamps (CFL). It also characterizes several Power Quality (PQ) parameters when those lamps are connected to pure sinusoidal waveform.
{"title":"Differences in the performance between CFL and LED lamps under different voltage distortions","authors":"A. Gil-de-Castro, R. Medina-Gracia, S. Ronnberg, A. Blanco, J. Meyer","doi":"10.1109/ICHQP.2018.8378918","DOIUrl":"https://doi.org/10.1109/ICHQP.2018.8378918","url":null,"abstract":"Measurements have shown that the harmonic currents emitted by lamps with electronic ballast depend on the circuit topology and the existing supply voltage distortion. This paper quantifies the impact of supply voltage distortion on the harmonic and supraharmonic current emission of individual Light Emitting Diode (LED) lamps and compact fluorescent lamps (CFL). It also characterizes several Power Quality (PQ) parameters when those lamps are connected to pure sinusoidal waveform.","PeriodicalId":6506,"journal":{"name":"2018 18th International Conference on Harmonics and Quality of Power (ICHQP)","volume":"183 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72655484","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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