Pub Date : 2014-11-24DOI: 10.1109/NAPS.2014.6965447
B. Abegaz, S. Mahajan
This paper presents an optimal, real-time integration control mechanism for interconnecting hybrid energy sources into a virtual power plant. The implemented virtual power plant consists of distributed energy sources including ten solar panels providing 1 MW aggregate power, six wind turbines generating 9 MW aggregate power, and ten grid connected battery energy storage systems which support the overall grid. Importantly, the capacity, the availability and the uninterrupted operation of the virtual power plant were identified as metrics to evaluate the real-time integration of distributed energy sources into the virtual power plant. Furthermore, optimization techniques were developed using mixed integer linear programming in CPLEX (IBM ILOG optimization studio) to identify the optimal real-time operating margins for the aggregate virtual power plant. Using the optimal real-time integration control mechanism, the capacity factor of the virtual power plant was improved by 45 %, the system unavailability was reduced by 5.3 %, and the system interruption was reduced by 65.47 %, while the duration of the interruption decreased by 13 minutes per day as compared to non-optimal integration control strategies. The obtained results demonstrate that the optimal real-time integration control mechanism yields a more functional and reliable integration control of the virtual power plant, and thus increases the economic feasibility of distributed energy resources in the energy market.
{"title":"Optimal real-time integration control of a virtual power plant","authors":"B. Abegaz, S. Mahajan","doi":"10.1109/NAPS.2014.6965447","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965447","url":null,"abstract":"This paper presents an optimal, real-time integration control mechanism for interconnecting hybrid energy sources into a virtual power plant. The implemented virtual power plant consists of distributed energy sources including ten solar panels providing 1 MW aggregate power, six wind turbines generating 9 MW aggregate power, and ten grid connected battery energy storage systems which support the overall grid. Importantly, the capacity, the availability and the uninterrupted operation of the virtual power plant were identified as metrics to evaluate the real-time integration of distributed energy sources into the virtual power plant. Furthermore, optimization techniques were developed using mixed integer linear programming in CPLEX (IBM ILOG optimization studio) to identify the optimal real-time operating margins for the aggregate virtual power plant. Using the optimal real-time integration control mechanism, the capacity factor of the virtual power plant was improved by 45 %, the system unavailability was reduced by 5.3 %, and the system interruption was reduced by 65.47 %, while the duration of the interruption decreased by 13 minutes per day as compared to non-optimal integration control strategies. The obtained results demonstrate that the optimal real-time integration control mechanism yields a more functional and reliable integration control of the virtual power plant, and thus increases the economic feasibility of distributed energy resources in the energy market.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131814601","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965450
Anushree S. Pethe, V. Vittal, G. Heydt
An important operating aspect of all transmission systems is power system stability and satisfactory dynamic performance. A particularly problematic operating scenario occurs when conventional generation is operated at a low level but photovoltaic solar generation is at a high level. This paper addresses the impact of high solar penetration that results in potentially problematic low system damping operating conditions. An actual case study is reported in which real operating system data are used. Solutions to low damping cases are discussed and a solution based on the retuning of a conventional power system stabilizer is reported. The Larsen Swann method is used.
{"title":"Evaluation and mitigation of power system oscillations arising from high solar penetration with low conventional generation","authors":"Anushree S. Pethe, V. Vittal, G. Heydt","doi":"10.1109/NAPS.2014.6965450","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965450","url":null,"abstract":"An important operating aspect of all transmission systems is power system stability and satisfactory dynamic performance. A particularly problematic operating scenario occurs when conventional generation is operated at a low level but photovoltaic solar generation is at a high level. This paper addresses the impact of high solar penetration that results in potentially problematic low system damping operating conditions. An actual case study is reported in which real operating system data are used. Solutions to low damping cases are discussed and a solution based on the retuning of a conventional power system stabilizer is reported. The Larsen Swann method is used.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127856996","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965360
H. Shaker, H. Chitsaz, H. Zareipour, D. Wood
In this paper, direct and indirect net demand forecasting approaches are compared. Net demand is defined as the total system load minus total wind power generation of the system. Since volatility of wind power is added to the net demand, it is more volatile and uncertain than the load alone. This could make the results of direct and indirect net demand forecasting approaches different. Wavelet Neural Network (WNN) with Morlet Wavelet activation function is selected to be the forecasting engine for wind power, load, and net demand in this paper. For training the WNN, Levenberg-Marquardt algorithm is used. Simulations are performed using Alberta's and Ireland's wind and load data. The WNN forecasting engine is compared to MLP and RBF neural networks along with the persistence. Results showed the superiority of the WNN over other models for net demand forecasting application.
{"title":"On comparison of two strategies in net demand forecasting using Wavelet Neural Network","authors":"H. Shaker, H. Chitsaz, H. Zareipour, D. Wood","doi":"10.1109/NAPS.2014.6965360","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965360","url":null,"abstract":"In this paper, direct and indirect net demand forecasting approaches are compared. Net demand is defined as the total system load minus total wind power generation of the system. Since volatility of wind power is added to the net demand, it is more volatile and uncertain than the load alone. This could make the results of direct and indirect net demand forecasting approaches different. Wavelet Neural Network (WNN) with Morlet Wavelet activation function is selected to be the forecasting engine for wind power, load, and net demand in this paper. For training the WNN, Levenberg-Marquardt algorithm is used. Simulations are performed using Alberta's and Ireland's wind and load data. The WNN forecasting engine is compared to MLP and RBF neural networks along with the persistence. Results showed the superiority of the WNN over other models for net demand forecasting application.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"152 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116096440","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965431
B. Eidson, M. Halpin
Amplitude modulation is a well-known cause of voltage fluctuations resulting in light flicker. Amplitude modulation can be more generally quanlified in terms of interharmonics. As the use of 60 W incandescent lamps declines, the need increases to broaden voltage fluctuation quantification beyond light flicker. If interharmonic measurements could be correlated to currently accepted flicker severity measurements, the effort to make inter-harmonic measurements the grounds of general voltage fluctuation measurement could be justified. This relationship between interharmonics and classic light flicker has been explored in this paper. The recommendations in IEC 61000-4-7 and 61000-4-15 for measuring interharmonics and short-term flicker severity, respectively, were followed. Interharmonic measurements were accumulated over 10 minutes in order for them to be easily compared to the short-term flicker measurements.
{"title":"Evaluating correlations between interharmonics and voltage fluctuations","authors":"B. Eidson, M. Halpin","doi":"10.1109/NAPS.2014.6965431","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965431","url":null,"abstract":"Amplitude modulation is a well-known cause of voltage fluctuations resulting in light flicker. Amplitude modulation can be more generally quanlified in terms of interharmonics. As the use of 60 W incandescent lamps declines, the need increases to broaden voltage fluctuation quantification beyond light flicker. If interharmonic measurements could be correlated to currently accepted flicker severity measurements, the effort to make inter-harmonic measurements the grounds of general voltage fluctuation measurement could be justified. This relationship between interharmonics and classic light flicker has been explored in this paper. The recommendations in IEC 61000-4-7 and 61000-4-15 for measuring interharmonics and short-term flicker severity, respectively, were followed. Interharmonic measurements were accumulated over 10 minutes in order for them to be easily compared to the short-term flicker measurements.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"7 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116739767","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965423
A. Shrestha, V. Cecchi, R. Cox
This paper describes a dynamic Remedial Action Scheme (RAS) which incorporates Wide-Area Monitoring Systems (WAMS) and online Transient Stability Analysis (TSA) for emergency control. The proposed scheme updates RAS control actions online based on the system operating condition and system configuration. The Single Machine Equivalent (SIME) method is used to compute stability margins for credible contingencies. A real-time test platform consisting of a Real Time Digital Simulator (RTDS), PMUs, a protocol gateway, a RAS logic controller, and the MATLAB-based TSA and RAS determination tool is developed to test the proposed approach. Test cases demonstrating effectiveness of the proposed dynamic RAS are presented.
{"title":"Dynamic Remedial Action Scheme using online transient stability analysis","authors":"A. Shrestha, V. Cecchi, R. Cox","doi":"10.1109/NAPS.2014.6965423","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965423","url":null,"abstract":"This paper describes a dynamic Remedial Action Scheme (RAS) which incorporates Wide-Area Monitoring Systems (WAMS) and online Transient Stability Analysis (TSA) for emergency control. The proposed scheme updates RAS control actions online based on the system operating condition and system configuration. The Single Machine Equivalent (SIME) method is used to compute stability margins for credible contingencies. A real-time test platform consisting of a Real Time Digital Simulator (RTDS), PMUs, a protocol gateway, a RAS logic controller, and the MATLAB-based TSA and RAS determination tool is developed to test the proposed approach. Test cases demonstrating effectiveness of the proposed dynamic RAS are presented.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"13 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114100845","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965367
Feng Dong, Xiatian Xu, Xu Zhang
Contingency analysis solution is a basic function to evaluate the security of power systems in steady state. During a contingency analysis a power flow solution is solved for each credible contingency. Due to the number of contingencies to evaluate, such analysis is very time consuming. Since the contingencies are independent of one another, the analysis is inherently a parallelizable process. This paper presents the parallel contingency analysis solution using OpenMP (Open Multi Processing) standards. The solution distributes contingency solutions among multiple processors evenly. It has been implemented in one of the most established commercial planning software tools. Two real, large scale systems are used to demonstrate the efficiency of parallel contingency analysis solutions.
应急分析解是评估电力系统稳态安全性的基本功能。在权变分析过程中，对每个可信权变求解潮流解。由于要评估的偶发事件的数量，这种分析非常耗时。由于偶然性是相互独立的，因此分析本质上是一个可并行化的过程。本文提出了基于OpenMP (Open Multi Processing)标准的并行应急分析方案。该方案在多个处理器之间均匀地分配偶然性解决方案。它已在最成熟的商业规划软件工具之一中实现。两个真实的大型系统被用来证明并行偶然性分析解决方案的有效性。
{"title":"Parallel contingency analysis solution based on OpenMP","authors":"Feng Dong, Xiatian Xu, Xu Zhang","doi":"10.1109/NAPS.2014.6965367","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965367","url":null,"abstract":"Contingency analysis solution is a basic function to evaluate the security of power systems in steady state. During a contingency analysis a power flow solution is solved for each credible contingency. Due to the number of contingencies to evaluate, such analysis is very time consuming. Since the contingencies are independent of one another, the analysis is inherently a parallelizable process. This paper presents the parallel contingency analysis solution using OpenMP (Open Multi Processing) standards. The solution distributes contingency solutions among multiple processors evenly. It has been implemented in one of the most established commercial planning software tools. Two real, large scale systems are used to demonstrate the efficiency of parallel contingency analysis solutions.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124335624","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965461
Rehan Fazal, M. Choudhry
Electro-mechanical oscillations of very small magnitude exist in power system and often persist for long periods of time and restrict the power transfer capacity. These oscillations can further increase with the variation in load if the controller is not properly designed. Robust decentralized controllers are used to enhance the transient stability of non-linear power systems. This paper discusses the methodology for designing non-linear controller for power system using Synergetic Control Theory. The controller is tested on a Single Machine Infinite Bus (SMIB) system with Static Var Compensator (SVC). The performance of the controller is tested with static non-linear load connected. The controller is robust for variation in load and damps the oscillation in the power system. Also, the effect of disturbance is observed on the system with the non-linear controller.
{"title":"Decentralized synergetic controller using static var compensator","authors":"Rehan Fazal, M. Choudhry","doi":"10.1109/NAPS.2014.6965461","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965461","url":null,"abstract":"Electro-mechanical oscillations of very small magnitude exist in power system and often persist for long periods of time and restrict the power transfer capacity. These oscillations can further increase with the variation in load if the controller is not properly designed. Robust decentralized controllers are used to enhance the transient stability of non-linear power systems. This paper discusses the methodology for designing non-linear controller for power system using Synergetic Control Theory. The controller is tested on a Single Machine Infinite Bus (SMIB) system with Static Var Compensator (SVC). The performance of the controller is tested with static non-linear load connected. The controller is robust for variation in load and damps the oscillation in the power system. Also, the effect of disturbance is observed on the system with the non-linear controller.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123634497","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965444
Y. Sangsefidi, S. Ziaeinejad, A. Mehrizi‐Sani, A. Shoulaie
This paper proposes a novel control method for two-phase induction motors using a two-leg voltage-sourced converter (VSC) in high speed applications and field-weakening regions. The proposed Approximate Stator Flux Control (ASFC) method is based on the dynamic model of two-phase induction motors and provides good dynamic behavior of the drive system. The switching strategy of ASFC method is proposed and the speed of the rotating field and the average switching frequency of the VSC are derived. ASFC method controls the speed of the rotating field by adjusting the stator flux modulus. No need to use current transducers and mechanical sensors makes implementation cost of ASFC comparable with that of the conventional scalar control system. Through simulations, the performance of the proposed two-phase ASFC method is evaluated and compared with the scalar control method. In addition, the correctness of the presented theories of ASFC method is validated by dynamic simulations.
{"title":"A simple algorithm to control two-phase induction motors using a two-leg VSC","authors":"Y. Sangsefidi, S. Ziaeinejad, A. Mehrizi‐Sani, A. Shoulaie","doi":"10.1109/NAPS.2014.6965444","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965444","url":null,"abstract":"This paper proposes a novel control method for two-phase induction motors using a two-leg voltage-sourced converter (VSC) in high speed applications and field-weakening regions. The proposed Approximate Stator Flux Control (ASFC) method is based on the dynamic model of two-phase induction motors and provides good dynamic behavior of the drive system. The switching strategy of ASFC method is proposed and the speed of the rotating field and the average switching frequency of the VSC are derived. ASFC method controls the speed of the rotating field by adjusting the stator flux modulus. No need to use current transducers and mechanical sensors makes implementation cost of ASFC comparable with that of the conventional scalar control system. Through simulations, the performance of the proposed two-phase ASFC method is evaluated and compared with the scalar control method. In addition, the correctness of the presented theories of ASFC method is validated by dynamic simulations.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122457242","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965398
Haosen Guo, Chen-Ching Liu, Guanqun Wang
A PMU-based method using Maximal Lyapunov Exponent (MLE) to determine the stability of a system following a disturbance has been established in previous research. This paper proposes a new method to determine the proper time window of MLE in an on-line environment. Spectral analysis is applied to the oscillation waveforms to calculate the variable window size of MLE. Two MLEs are calculated using the same window size but at different initial times. The consistency of the two MLEs indicates that sufficient information has been included in the first time window to characterize the system dynamics. Otherwise, the window size needs to be adapted for the operating condition. This method increases the accuracy of prediction given by MLE. A case study using a 200-bus system is presented to validate the feasibility of the proposed method.
{"title":"Lyapunov exponents over variable window sizes for prediction of rotor angle stability","authors":"Haosen Guo, Chen-Ching Liu, Guanqun Wang","doi":"10.1109/NAPS.2014.6965398","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965398","url":null,"abstract":"A PMU-based method using Maximal Lyapunov Exponent (MLE) to determine the stability of a system following a disturbance has been established in previous research. This paper proposes a new method to determine the proper time window of MLE in an on-line environment. Spectral analysis is applied to the oscillation waveforms to calculate the variable window size of MLE. Two MLEs are calculated using the same window size but at different initial times. The consistency of the two MLEs indicates that sufficient information has been included in the first time window to characterize the system dynamics. Otherwise, the window size needs to be adapted for the operating condition. This method increases the accuracy of prediction given by MLE. A case study using a 200-bus system is presented to validate the feasibility of the proposed method.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131413877","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965448
B. Poudel, V. Cecchi
A novel approach for modeling frequency-dependent impedance of a power transmission line is introduced and an analytical equation is derived. This paper focuses on the real part of this frequency-dependent impedance, which is referred to as apparent resistance; the imaginary part can then be treated in a similar manner. The apparent resistance is expressed in terms of frequency and line length, assuming all other influencing variables to be constant. Various numerical approximation techniques, which implement least square methods are applied to obtain a final approximated expression for this apparent resistance. Computational time and error between the analytical equation and the simplified approximated equation are compared. Results have shown that during the run of the digital simulation, the proposed equation is executed much faster than the analytical equations.
{"title":"An approach for modeling frequency-dependent apparent resistance of power transmission lines","authors":"B. Poudel, V. Cecchi","doi":"10.1109/NAPS.2014.6965448","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965448","url":null,"abstract":"A novel approach for modeling frequency-dependent impedance of a power transmission line is introduced and an analytical equation is derived. This paper focuses on the real part of this frequency-dependent impedance, which is referred to as apparent resistance; the imaginary part can then be treated in a similar manner. The apparent resistance is expressed in terms of frequency and line length, assuming all other influencing variables to be constant. Various numerical approximation techniques, which implement least square methods are applied to obtain a final approximated expression for this apparent resistance. Computational time and error between the analytical equation and the simplified approximated equation are compared. Results have shown that during the run of the digital simulation, the proposed equation is executed much faster than the analytical equations.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124656849","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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