The ability to predict or confirm ferroresonance depends primarily on the correctness of the tran... more The ability to predict or confirm ferroresonance depends primarily on the correctness of the transformer model used by the computer simulation. Ferroresonance is introduced and a general modeling approach is given. An overview of available literature and contributors to this area is provided. A simple case of ferroresonance in a single phase transformer is used to illustrate this "phenomenon." Three phase transformer core structures are discussed. Ferroresonance in three phase grounded-wye distribution systems is described and illustrated with waveform data obtained from laboratory simulations. Representation of the study zone is discussed, modeling techniques are presented, and implementation suggestions are made. Three case studies are presented. Transformer representation is critical to performing a valid simulation. The direction of ongoing research is discussed, and the reader is advised to monitor the literature for ongoing rapid improvements in transformer modeling techniques.
In this paper we present an efficient method to generate realistic simulations of extracellular r... more In this paper we present an efficient method to generate realistic simulations of extracellular recordings. The method uses a hybrid and computationally simple approach, where the features of the background noise arise naturally from its biophysical process of generation. The generated data resemble the characteristics of real recordings, as quantified by the amplitude and frequency distributions. Moreover, we reproduce real features that are specially challenging for the analysis of extracellular data, such as the presence of sparse firing neurons and multi-unit activity. We compare our simulations with real recordings from the human medial temporal lobe and exemplify their use for testing spike detection and sorting algorithms. These results show that this technique provides an optimal scenario for generating realistic simulations of extracellular recordings.
This paper presents a brief review of techniques available for reducing large systems to smaller ... more This paper presents a brief review of techniques available for reducing large systems to smaller equivalents. This paper is divided into high frequency equivalents, low frequency equivalents, and wideband equivalents. Numerical examples are presented to demonstrate selected methods of high frequency equivalencing.
This paper describes the challenges and lessons learned when developing industrial-grade data tra... more This paper describes the challenges and lessons learned when developing industrial-grade data translators aimed for the interfacing of power-flow programs with Electromagnetic Transients Program-type programs. It has been found that the greatest challenges to overcome include: 1) the lack, in the databases used in power-flow programs, of vital pieces of information necessary to perform transient studies; 2) inconsistency in the format of data files; 3) the presence of data entry mistakes in very large databases; 4) the validation of the translated data; and 5) the analysis of the large amount of data that transient simulations provide. Several examples are presented to show the implemented Manuscript
This paper presents a procedure for the calculation of lightning flashover rates of transmission ... more This paper presents a procedure for the calculation of lightning flashover rates of transmission lines using a Monte Carlo method. The procedure has been implemented in the Alternative Transients Program version of the Electromagnetic Transients Program. Parametric studies using this procedure can also be performed to determine the sensitivity of the flashover rate with respect to some parameters of the transmission line and the return stroke. Some refinements are proposed to decrease the computer time while preserving the accuracy of calculations.
This work presents an experimental study of the gasification of a wood biomass in a moving bed do... more This work presents an experimental study of the gasification of a wood biomass in a moving bed downdraft reactor with two-air supply stages. This configuration is considered as primary method to improve the quality of the producer gas, regarding its tar reduction. By varying the air flow fed to the gasifier and the distribution of gasification air between stages (AR), being the controllable and measurable variables for this type of gasifiers, measuring the CO, CH 4 and H 2 gas concentrations and through a mass and energy balance, the gas yield and its power, the cold efficiency of the process and the equivalence ratio (ER), as well as other performance variables were calculated. The gasifier produces a combustible gas with a CO, CH 4 and H 2 concentrations of 19.04, 0.89 and 16.78% v respectively, at a total flow of air of 20 Nm 3 h À1 and an AR of 80%. For these conditions, the low heating value of the gas was 4539 kJ Nm À3. Results from the calculation model show a useful gas power and cold efficiency around 40 kW and 68%, respectively. The resulting ER under the referred operation condition is around 0.40. The results suggested a considerable effect of the secondary stage over the reduction of the CH 4 concentration which is associated with the decreases of the tar content in the produced gas. Under these conditions the biomass devolatilization in the pyrolysis zone gives much lighter compounds which are more easily cracked when the gas stream passes through the combustion zone.
This task force paper presents multi-domain tools and their interfacing issues to perform simulat... more This task force paper presents multi-domain tools and their interfacing issues to perform simulations that require expertise in multiple areas of physics, such as electrothermal, electromechanical, electrochemical, and electromagnetic simulations, etc. Features of single multi-domain simulation tools, which are capable of simulating more than one system such as electrical chemical, mechanical, etc., are discussed. In addition, programs that are not capable of performing multi-domain simulation independently but can be interfaced with other programs to perform multi-domain simulation are also covered. Two case studies are reported where multi-domain simulations are performed in offline and realtime environments through the interfacing of more than one simulation tool.
This paper describes methods and issues related to interfacing electromagnetic transient simulati... more This paper describes methods and issues related to interfacing electromagnetic transient simulation programs with general mathematical algorithms, which are either custom-developed by the user or are available through other mathematical analysis platforms. Various interfacing types and techniques are described along with potential areas of application. Implementation methods are detailed for each type of interface as well. This paper presents several interfacing examples from a wide variety of applications, including advanced switching schemes for power converters and controller implementation.
Distribution software packages were primarily designed for analyzing radial systems with very lim... more Distribution software packages were primarily designed for analyzing radial systems with very limited capabilities for representing distributed resources (DR). Software manufacturers are presently updating and expanding the capabilities of their tools. The challenges, however, are many, since the new tools should be able to represent a wide range of power component models, efficiently compute steady-state and transient unbalanced operating conditions, or cope with DR interconnections whose design cannot be anticipated yet. This paper summarizes the main types of studies related to planning, analysis, and design of distribution networks, analyzes the models required for representing distributed resources, and discusses the future capabilities of distribution software packages. This paper includes test cases that illustrate some of the studies related to planning, analysis, and design of distribution networks with penetration of DR.
The ability to predict or confirm ferroresonance depends primarily on the correctness of the tran... more The ability to predict or confirm ferroresonance depends primarily on the correctness of the transformer model used by the computer simulation. Ferroresonance is introduced and a general modeling approach is given. An overview of available literature and contributors to this area is provided. A simple case of ferroresonance in a single phase transformer is used to illustrate this "phenomenon." Three phase transformer core structures are discussed. Ferroresonance in three phase grounded-wye distribution systems is described and illustrated with waveform data obtained from laboratory simulations. Representation of the study zone is discussed, modeling techniques are presented, and implementation suggestions are made. Three case studies are presented. Transformer representation is critical to performing a valid simulation. The direction of ongoing research is discussed, and the reader is advised to monitor the literature for ongoing rapid improvements in transformer modeling techniques.
In this paper we present an efficient method to generate realistic simulations of extracellular r... more In this paper we present an efficient method to generate realistic simulations of extracellular recordings. The method uses a hybrid and computationally simple approach, where the features of the background noise arise naturally from its biophysical process of generation. The generated data resemble the characteristics of real recordings, as quantified by the amplitude and frequency distributions. Moreover, we reproduce real features that are specially challenging for the analysis of extracellular data, such as the presence of sparse firing neurons and multi-unit activity. We compare our simulations with real recordings from the human medial temporal lobe and exemplify their use for testing spike detection and sorting algorithms. These results show that this technique provides an optimal scenario for generating realistic simulations of extracellular recordings.
This paper presents a brief review of techniques available for reducing large systems to smaller ... more This paper presents a brief review of techniques available for reducing large systems to smaller equivalents. This paper is divided into high frequency equivalents, low frequency equivalents, and wideband equivalents. Numerical examples are presented to demonstrate selected methods of high frequency equivalencing.
This paper describes the challenges and lessons learned when developing industrial-grade data tra... more This paper describes the challenges and lessons learned when developing industrial-grade data translators aimed for the interfacing of power-flow programs with Electromagnetic Transients Program-type programs. It has been found that the greatest challenges to overcome include: 1) the lack, in the databases used in power-flow programs, of vital pieces of information necessary to perform transient studies; 2) inconsistency in the format of data files; 3) the presence of data entry mistakes in very large databases; 4) the validation of the translated data; and 5) the analysis of the large amount of data that transient simulations provide. Several examples are presented to show the implemented Manuscript
This paper presents a procedure for the calculation of lightning flashover rates of transmission ... more This paper presents a procedure for the calculation of lightning flashover rates of transmission lines using a Monte Carlo method. The procedure has been implemented in the Alternative Transients Program version of the Electromagnetic Transients Program. Parametric studies using this procedure can also be performed to determine the sensitivity of the flashover rate with respect to some parameters of the transmission line and the return stroke. Some refinements are proposed to decrease the computer time while preserving the accuracy of calculations.
This work presents an experimental study of the gasification of a wood biomass in a moving bed do... more This work presents an experimental study of the gasification of a wood biomass in a moving bed downdraft reactor with two-air supply stages. This configuration is considered as primary method to improve the quality of the producer gas, regarding its tar reduction. By varying the air flow fed to the gasifier and the distribution of gasification air between stages (AR), being the controllable and measurable variables for this type of gasifiers, measuring the CO, CH 4 and H 2 gas concentrations and through a mass and energy balance, the gas yield and its power, the cold efficiency of the process and the equivalence ratio (ER), as well as other performance variables were calculated. The gasifier produces a combustible gas with a CO, CH 4 and H 2 concentrations of 19.04, 0.89 and 16.78% v respectively, at a total flow of air of 20 Nm 3 h À1 and an AR of 80%. For these conditions, the low heating value of the gas was 4539 kJ Nm À3. Results from the calculation model show a useful gas power and cold efficiency around 40 kW and 68%, respectively. The resulting ER under the referred operation condition is around 0.40. The results suggested a considerable effect of the secondary stage over the reduction of the CH 4 concentration which is associated with the decreases of the tar content in the produced gas. Under these conditions the biomass devolatilization in the pyrolysis zone gives much lighter compounds which are more easily cracked when the gas stream passes through the combustion zone.
This task force paper presents multi-domain tools and their interfacing issues to perform simulat... more This task force paper presents multi-domain tools and their interfacing issues to perform simulations that require expertise in multiple areas of physics, such as electrothermal, electromechanical, electrochemical, and electromagnetic simulations, etc. Features of single multi-domain simulation tools, which are capable of simulating more than one system such as electrical chemical, mechanical, etc., are discussed. In addition, programs that are not capable of performing multi-domain simulation independently but can be interfaced with other programs to perform multi-domain simulation are also covered. Two case studies are reported where multi-domain simulations are performed in offline and realtime environments through the interfacing of more than one simulation tool.
This paper describes methods and issues related to interfacing electromagnetic transient simulati... more This paper describes methods and issues related to interfacing electromagnetic transient simulation programs with general mathematical algorithms, which are either custom-developed by the user or are available through other mathematical analysis platforms. Various interfacing types and techniques are described along with potential areas of application. Implementation methods are detailed for each type of interface as well. This paper presents several interfacing examples from a wide variety of applications, including advanced switching schemes for power converters and controller implementation.
Distribution software packages were primarily designed for analyzing radial systems with very lim... more Distribution software packages were primarily designed for analyzing radial systems with very limited capabilities for representing distributed resources (DR). Software manufacturers are presently updating and expanding the capabilities of their tools. The challenges, however, are many, since the new tools should be able to represent a wide range of power component models, efficiently compute steady-state and transient unbalanced operating conditions, or cope with DR interconnections whose design cannot be anticipated yet. This paper summarizes the main types of studies related to planning, analysis, and design of distribution networks, analyzes the models required for representing distributed resources, and discusses the future capabilities of distribution software packages. This paper includes test cases that illustrate some of the studies related to planning, analysis, and design of distribution networks with penetration of DR.
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