Nancy Visairo - Academia.edu (original) (raw)
Papers by Nancy Visairo
IEEE Access
Modern power grids are becoming more stressed, more complex, and beginning to have a significant ... more Modern power grids are becoming more stressed, more complex, and beginning to have a significant integration of energy sources based on power electronics devices, which significantly changes the dynamics of power grids affecting the design and operation of Remedial Action Schemes such as UVLS and UFLS, where the conventional operation philosophy of these schemes is based in operating parameters such as thresholds, amount, and location of the load shedding fixed regardless of the event. Therefore, they are not adaptable to the various conditions of the modern power grids, causing their misoperation. In recent years, a wide variety of adaptive schemes around the world have been proposed as a solid solution with good performance, since its main characteristic is its ability to consider the magnitude of the event in its load shedding, turning them into more selective and with flexibility in their operating parameters. The aim of this article is to review the development of adaptive schemes in UVLS and UFLS over the years, identifying how to approach the design of such adaptable schemes, which operating parameters tend to give them greater flexibility and which have been less explored. Then broken down the methods used to give flexibility to the operating parameters of UVLS and UFLS, and also that other devices such as FACTS and ESS can enhance its operation, with the aim of provide a broad vision of how to give them flexibility to these parameters and which of them are identified as an opportunity to improve the performance of the adaptive schemes. Finally, the review includes some RAS with adaptive approach implemented in real systems which some of them includes load shedding, to show how these schemes have reconfigured their design and operation by giving flexibility to some operating parameters, it is possible to show the need of modern power grids to have adaptive RAS. INDEX TERMS Special protection scheme, remedial action scheme, adaptive underfrequency load shedding, adaptive undervoltage load shedding, modern power grids.
Energies
Controlling a PWM rectifier can be challenging due to the bilinear nature of its averaged model. ... more Controlling a PWM rectifier can be challenging due to the bilinear nature of its averaged model. This paper introduces the use of the Butterworth approach to design and control an LCL-filter-based PWM rectifier with power quality functions. By leveraging the linear part of the system, this approach reduces the number of variables involved in the control scheme. The rectifier is designed and controlled in a concatenated manner to ensure proper performance even during demanding power-quality events. The uniqueness of this approach lies in the fact that a fourth-order model can be regulated by using solely three-state variables and linear techniques founded on Butterworth polynomial synthesis. This approach differs from previous methods in that it does not employ nonlinear controllers, dq transformations, or double control loops. Hence, this divergent approach contributes to the simplification of power converter design and control through the application of the same polynomial synthesi...
2022 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC)
Energies, 2019
This paper deals with a battery energy storage system (BESS) in only one of its multiple operatin... more This paper deals with a battery energy storage system (BESS) in only one of its multiple operating modes, that is when the BESS is charging the battery bank and with the focus on the control scheme design for the BESS input stage, which is a three-phase LCL-filter PWM rectifier. The rectifier's main requirements comprise output voltage regulation, power factor control, and low input current harmonic distortion, even in the presence of input voltage variations. Typically, these objectives are modeled by using a dq model with its corresponding two-loop controller architecture, including an outer voltage loop and a current internal loop. This paper outlines an alternative approach to tackle the problem by using not only an input–output map linearization controller, with the aim of a single-loop current control, but also by avoiding the dq modeling. In this case, the voltage is indirectly controlled by computing the current references based on the converter power balance. The mathem...
International Journal of Electrical Power & Energy Systems, 2019
This paper presents the power flow modeling of droop-controlled distributed generation units with... more This paper presents the power flow modeling of droop-controlled distributed generation units with secondary frequency and voltage restoration control for hierarchically controlled islanded microgrids. These models are incorporated in the conventional Newton-Raphson power flow method as a new bus, without the necessity of a slack bus, and include the gains of the control systems that influence the steady-state solution. Two case studies are addressed. In the first case study, comparisons of the proposed models against the steady-state solutions obtained with PSCAD and Simscape Power System of Simulink, where the closed-loop controls are explicitly modeled, are presented. In the second case study, the proposed method is contrasted against the droop-based approach. The results obtained exhibit low computing effort, reliability, and effectiveness of the proposed models since quadratic convergence behavior is maintained independently of the size and topology of the microgrid. Besides, it is demonstrated that hierarchical and droop controllers lead to different solutions, which confirms the necessity of including the hierarchical control in the power flow model.
IEEE Transactions on Smart Grid, 2016
This paper presents the application of Newton-based methods in the time-domain for the computatio... more This paper presents the application of Newton-based methods in the time-domain for the computation of the periodic steady state solutions of microgrids with multiple distributed generation units, harmonic stability and power quality analysis. Explicit representation of the commutation process of the power electronic converters and closed-loop power management strategies are fully considered. Case studies under different operating scenarios are presented: grid-connected mode, islanded mode, variations in the Thevenin equivalent of the grid and the loads. Besides, the close relation between the harmonic distortion, steady state performance of the control systems, asymptotic stability and power quality is analyzed in order to evaluate the importance and necessity of using full models in stressed and harmonic distorted scenarios.
2022 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC)
DYNA INGENIERIA E INDUSTRIA, 2012
Advances in Water Resources, 2007
This paper presents a method for the identification of two leaks in a pressurized single pipeline... more This paper presents a method for the identification of two leaks in a pressurized single pipeline where both transient and static behavior of the fluid in leaks conditions are used to identify the parameters associated to the leaks without requirements of valve perturbation. The procedure is based on a family F of lumped parameters nonlinear models with same steady state behavior in leaks condition and parameterized in terms of a known parameter z eq assuming only pressure and flow rate measurements at the extremes of the line. This model is derived discretizing only the space variable. The key of the method is the automatic selection of the specific family F of models to be identified using the steady state conditions produced by the leaks. This fact reduces the research interval and the number of unknown parameters simplifying the minimization issue of the error between model and measured data. Considering this family an algorithm combining transient and steady state measurements is presented. The potential of the technique and its robustness with respect to operation point changes after the leaks occurrence are illustrated by simulation using the parameters of a water pilot pipeline of 135 m long installed at the UNAM in which the L 2 norm of the upstream and downstream flow error is minimized.
IEEE Access
The stability issues assessment by the impedance-based method demands the computation of accurate... more The stability issues assessment by the impedance-based method demands the computation of accurate small-signal models. However, obtaining impedance models can be a time-consuming task if analytical models or the perturbation-based method are used. Especially in large-scale, poorly damped, distributed, and frequency-dependent parameter systems. A third approach, which has been less explored, is based on numerical derivative approximations, rather than analytical equations or time-domain simulations. This approach works with large-scale systems, avoiding tedious mathematical expressions and large recursive time-domain simulations. As a step-forward in this approach, this paper proposes a numericaloriented method, based on the finite-difference method, to compute impedance models of time-delay powerelectronics-based power systems. An outstanding feature of the proposal is the capability to incorporate the exact delays into the numerical models of impedance without resorting to approximations nor increasing the size of the system model. We compare the proposed method with the analytical and perturbation methods using a grid-connected microgrid with two power electronic inverters as a test system. The results confirm the correct performance of the proposal. INDEX TERMS Impedance-based method, small-signal stability, VSC-based systems, time-delay.
2021 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC), 2021
The increment of power electronics converters in the power systems has challenged the study of st... more The increment of power electronics converters in the power systems has challenged the study of stability and resonance, causing that traditional approaches must be complemented with new tools, such as the so-called impedance-based method which is a powerful alternative to investigate these issues. This work tries to be an introductory self-contained tutorial, explaining the stages involved in the derivation of the impedance model in the dq-domain of electronic converters. The method is revised with depth, showing the highlights thoroughly to obtain the analytical model. In order to validate the model, the numerical identification is also addressed, which is a second approach to compute the impedance using measurements of the system. A test system (a power converter interconnected to the grid) is used to illustrate the concepts, and simulations in the frequency domain show the match between the two approaches.
2020 15th IEEE Conference on Industrial Electronics and Applications (ICIEA), 2020
The present paper aims to analyze the Battery Energy Storage System (BESS), which is connected to... more The present paper aims to analyze the Battery Energy Storage System (BESS), which is connected to the grid in the distribution network, exclusively when it is operating as a battery charger under unbalanced grid voltage. The hypothesis establishes that it is possible to ride through an unbalanced voltage condition (typically caused by unsymmetrical loads, unsymmetrical transformer windings and transmission impedance) by using a nonlinear controller based on input-output linearization using only the current loops for each phase and generating the current references based on the balanced power. The methodology is based on the use of the mathematical model for a three-phase LCL-filter PWM rectifier (because the analysis is just for the battery charge mode of the BESS), delta connected and 100 kW. To test the closed-loop system, simulations including the battery model have been performed by using PSCAD/EMTDC.
2010 7th International Conference on Electrical Engineering Computing Science and Automatic Control, 2010
A two stages robust Generalized PI feedback controller for a single-phase active multilevel recti... more A two stages robust Generalized PI feedback controller for a single-phase active multilevel rectifier is proposed. The controller is based on the system modeled in the d-q synchronous reference frame. Based on input-output linearization theory a current controller that decouples the d-q components and compensates unknown perturbations is obtained. Performing a transformation of the system, stability of zero dynamics is
IEEE Transactions on Industrial Electronics, 2018
This paper proposes a light, flexible, and yet reliable multi-parametric estimation algorithm for... more This paper proposes a light, flexible, and yet reliable multi-parametric estimation algorithm for gridconnected VSC-based systems. This approach combines the nonlinear least squares (NLSQ) fitting algorithm and the steady-state extended harmonic domain (EHD) model to take into account the harmonic effects. The EHD model is used to take advantage of the harmonic content of the electrical signals to provide robustness and improved performance to the NLSQ estimation methodology. In addition, this harmonic formulation reduces the necessity of synchronized measurements. Details of the implementation are provided by an experimental case study in which the grid equivalent (Thevenin voltage, inductance, and resistance), the AC-side filter (inductance and resistance), and the converter switching and conduction loss resistance are accurately estimated for three different operating conditions.
Energies
This paper presents an improvement of the tuning process of the holistic control published by the... more This paper presents an improvement of the tuning process of the holistic control published by the authors in previous research to achieve a seamless transition among three operation mode changes and load transients. The proposed tuning approach reveals an improvement in the energy consumption of the Battery Energy Storage System (BESS) during all operation mode transients compared to the holistic control. For this aim, the system addressed is a BESS with the capability to ride through three operation modes of interest: the grid-connected mode as an inverter, the grid-connected mode as a rectifier, and the islanded operation mode. The LCL filter design by using the Butterworth polynomial approach is presented in more detail, and its smooth inherent transient response is preserved when the tuning of the controller gains is carried out by using the same polynomial approach but now including the integral action within the Butterworth polynomial. To reveal the reduction in energy consump...
IEEE Access
This paper is dedicated to presenting control-tuning methodologies for the rotor-side converter (... more This paper is dedicated to presenting control-tuning methodologies for the rotor-side converter (RSC) and grid-side converter (GSC) of series-compensated DFIG-based wind farms (WF) and to determining the origin of subsynchronous resonance (SSR). Unlike conventional approaches to re-tuning controller gains to achieve desirable performance, these methodologies only consider the mathematical models of the states variables to be controlled. A PI cascade topology is used to control the RSC and GSC. An inner loop is required for current control and an outer loop for voltage control. Special consideration is taken for tuning the RSC because this converter is coupled with the mechanical variables as mechanical rotor speed of the DFIG. Compared with standard tuning, a better system behavior during a resonance condition is achieved with the proposed tuning methodology. Regarding the analysis of the SSR origin, the modal impedance (MI) technique is used as a tool to study SSR issues; its advantages compared to the driving point impedance technique are highlighted. In this context, the small-signal-stability (SSS) analysis is performed to evaluate the overall system. With the combination of MI and SSS, the phenomena of induction generator effect, torque interaction, and torque amplification are analyzed. As a result, the modes involved in the SSR phenomenon are identified and a discrimination procedure is described to determine the origin of the SSR. INDEX TERMS Doubly fed induction generator (DFIG), subsynchronous resonance (SSR), eigenvalue analysis, oscillatory stability, power converter, wind farm, control tuning.
Mathematical Problems in Engineering, 2017
The requirements of PWM rectifiers for delivering power to motor drives include power factor corr... more The requirements of PWM rectifiers for delivering power to motor drives include power factor correction and output voltage regulation even when strong variations such as voltage sags and dynamic load transients occur simultaneously. To achieve these objectives, the classic approach is to use a two-loop controller with its d-q model. In this paper, the authors propose a simplified approach to address that problem by using a feedback linearization-based nonlinear controller using only a single-loop current control and avoiding d-q modeling to reduce processing stages. To demonstrate the feasibility of this approach, several simulations are presented considering a 1.5 kW PWM rectifier.
2018 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC), 2018
This paper presents the analysis of AC powerelectronic-based power systems with distributed gener... more This paper presents the analysis of AC powerelectronic-based power systems with distributed generation units, such as microgrids, for stability and resonance analysis. Two case studies are addressed, and the explicit representation of the commutation process is fully considered. In the first case, an islanded controlled microgrid is presented, the resonances in the system are analyzed and their impact on the stability are shown. In the second case, the resonances and harmonic content in an open-loop system are addressed for three different transmission line models, the results are compared between the fundamental frequency model and the commutated model, showing the varied behaviors that can appear considering different line models.
COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 2019
Purpose The purpose of this study is to present the performance evaluation of three shooting meth... more Purpose The purpose of this study is to present the performance evaluation of three shooting methods typically applied to obtain the periodic steady state of electric power systems, with the aim to check the benefits of the use of cloud computing regarding relative efficiency and computation time. Design/methodology/approach The mathematical formulation of the methods is presented, and their parallelization potential is explained. Two case studies are addressed, and the solution is computed with the shooting methods using multiple computer cores through cloud computing. Findings The results obtained show a reduction in the computation time and increase in the relative efficiency by the application of these methods with parallel cloud computing, in the problem of obtainment of the periodic steady state of electric power systems in an efficient way. Additionally, the characteristics of the methods, when parallel cloud computing is used, are shown and comparisons among them are present...
IEEE Access
Modern power grids are becoming more stressed, more complex, and beginning to have a significant ... more Modern power grids are becoming more stressed, more complex, and beginning to have a significant integration of energy sources based on power electronics devices, which significantly changes the dynamics of power grids affecting the design and operation of Remedial Action Schemes such as UVLS and UFLS, where the conventional operation philosophy of these schemes is based in operating parameters such as thresholds, amount, and location of the load shedding fixed regardless of the event. Therefore, they are not adaptable to the various conditions of the modern power grids, causing their misoperation. In recent years, a wide variety of adaptive schemes around the world have been proposed as a solid solution with good performance, since its main characteristic is its ability to consider the magnitude of the event in its load shedding, turning them into more selective and with flexibility in their operating parameters. The aim of this article is to review the development of adaptive schemes in UVLS and UFLS over the years, identifying how to approach the design of such adaptable schemes, which operating parameters tend to give them greater flexibility and which have been less explored. Then broken down the methods used to give flexibility to the operating parameters of UVLS and UFLS, and also that other devices such as FACTS and ESS can enhance its operation, with the aim of provide a broad vision of how to give them flexibility to these parameters and which of them are identified as an opportunity to improve the performance of the adaptive schemes. Finally, the review includes some RAS with adaptive approach implemented in real systems which some of them includes load shedding, to show how these schemes have reconfigured their design and operation by giving flexibility to some operating parameters, it is possible to show the need of modern power grids to have adaptive RAS. INDEX TERMS Special protection scheme, remedial action scheme, adaptive underfrequency load shedding, adaptive undervoltage load shedding, modern power grids.
Energies
Controlling a PWM rectifier can be challenging due to the bilinear nature of its averaged model. ... more Controlling a PWM rectifier can be challenging due to the bilinear nature of its averaged model. This paper introduces the use of the Butterworth approach to design and control an LCL-filter-based PWM rectifier with power quality functions. By leveraging the linear part of the system, this approach reduces the number of variables involved in the control scheme. The rectifier is designed and controlled in a concatenated manner to ensure proper performance even during demanding power-quality events. The uniqueness of this approach lies in the fact that a fourth-order model can be regulated by using solely three-state variables and linear techniques founded on Butterworth polynomial synthesis. This approach differs from previous methods in that it does not employ nonlinear controllers, dq transformations, or double control loops. Hence, this divergent approach contributes to the simplification of power converter design and control through the application of the same polynomial synthesi...
2022 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC)
Energies, 2019
This paper deals with a battery energy storage system (BESS) in only one of its multiple operatin... more This paper deals with a battery energy storage system (BESS) in only one of its multiple operating modes, that is when the BESS is charging the battery bank and with the focus on the control scheme design for the BESS input stage, which is a three-phase LCL-filter PWM rectifier. The rectifier's main requirements comprise output voltage regulation, power factor control, and low input current harmonic distortion, even in the presence of input voltage variations. Typically, these objectives are modeled by using a dq model with its corresponding two-loop controller architecture, including an outer voltage loop and a current internal loop. This paper outlines an alternative approach to tackle the problem by using not only an input–output map linearization controller, with the aim of a single-loop current control, but also by avoiding the dq modeling. In this case, the voltage is indirectly controlled by computing the current references based on the converter power balance. The mathem...
International Journal of Electrical Power & Energy Systems, 2019
This paper presents the power flow modeling of droop-controlled distributed generation units with... more This paper presents the power flow modeling of droop-controlled distributed generation units with secondary frequency and voltage restoration control for hierarchically controlled islanded microgrids. These models are incorporated in the conventional Newton-Raphson power flow method as a new bus, without the necessity of a slack bus, and include the gains of the control systems that influence the steady-state solution. Two case studies are addressed. In the first case study, comparisons of the proposed models against the steady-state solutions obtained with PSCAD and Simscape Power System of Simulink, where the closed-loop controls are explicitly modeled, are presented. In the second case study, the proposed method is contrasted against the droop-based approach. The results obtained exhibit low computing effort, reliability, and effectiveness of the proposed models since quadratic convergence behavior is maintained independently of the size and topology of the microgrid. Besides, it is demonstrated that hierarchical and droop controllers lead to different solutions, which confirms the necessity of including the hierarchical control in the power flow model.
IEEE Transactions on Smart Grid, 2016
This paper presents the application of Newton-based methods in the time-domain for the computatio... more This paper presents the application of Newton-based methods in the time-domain for the computation of the periodic steady state solutions of microgrids with multiple distributed generation units, harmonic stability and power quality analysis. Explicit representation of the commutation process of the power electronic converters and closed-loop power management strategies are fully considered. Case studies under different operating scenarios are presented: grid-connected mode, islanded mode, variations in the Thevenin equivalent of the grid and the loads. Besides, the close relation between the harmonic distortion, steady state performance of the control systems, asymptotic stability and power quality is analyzed in order to evaluate the importance and necessity of using full models in stressed and harmonic distorted scenarios.
2022 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC)
DYNA INGENIERIA E INDUSTRIA, 2012
Advances in Water Resources, 2007
This paper presents a method for the identification of two leaks in a pressurized single pipeline... more This paper presents a method for the identification of two leaks in a pressurized single pipeline where both transient and static behavior of the fluid in leaks conditions are used to identify the parameters associated to the leaks without requirements of valve perturbation. The procedure is based on a family F of lumped parameters nonlinear models with same steady state behavior in leaks condition and parameterized in terms of a known parameter z eq assuming only pressure and flow rate measurements at the extremes of the line. This model is derived discretizing only the space variable. The key of the method is the automatic selection of the specific family F of models to be identified using the steady state conditions produced by the leaks. This fact reduces the research interval and the number of unknown parameters simplifying the minimization issue of the error between model and measured data. Considering this family an algorithm combining transient and steady state measurements is presented. The potential of the technique and its robustness with respect to operation point changes after the leaks occurrence are illustrated by simulation using the parameters of a water pilot pipeline of 135 m long installed at the UNAM in which the L 2 norm of the upstream and downstream flow error is minimized.
IEEE Access
The stability issues assessment by the impedance-based method demands the computation of accurate... more The stability issues assessment by the impedance-based method demands the computation of accurate small-signal models. However, obtaining impedance models can be a time-consuming task if analytical models or the perturbation-based method are used. Especially in large-scale, poorly damped, distributed, and frequency-dependent parameter systems. A third approach, which has been less explored, is based on numerical derivative approximations, rather than analytical equations or time-domain simulations. This approach works with large-scale systems, avoiding tedious mathematical expressions and large recursive time-domain simulations. As a step-forward in this approach, this paper proposes a numericaloriented method, based on the finite-difference method, to compute impedance models of time-delay powerelectronics-based power systems. An outstanding feature of the proposal is the capability to incorporate the exact delays into the numerical models of impedance without resorting to approximations nor increasing the size of the system model. We compare the proposed method with the analytical and perturbation methods using a grid-connected microgrid with two power electronic inverters as a test system. The results confirm the correct performance of the proposal. INDEX TERMS Impedance-based method, small-signal stability, VSC-based systems, time-delay.
2021 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC), 2021
The increment of power electronics converters in the power systems has challenged the study of st... more The increment of power electronics converters in the power systems has challenged the study of stability and resonance, causing that traditional approaches must be complemented with new tools, such as the so-called impedance-based method which is a powerful alternative to investigate these issues. This work tries to be an introductory self-contained tutorial, explaining the stages involved in the derivation of the impedance model in the dq-domain of electronic converters. The method is revised with depth, showing the highlights thoroughly to obtain the analytical model. In order to validate the model, the numerical identification is also addressed, which is a second approach to compute the impedance using measurements of the system. A test system (a power converter interconnected to the grid) is used to illustrate the concepts, and simulations in the frequency domain show the match between the two approaches.
2020 15th IEEE Conference on Industrial Electronics and Applications (ICIEA), 2020
The present paper aims to analyze the Battery Energy Storage System (BESS), which is connected to... more The present paper aims to analyze the Battery Energy Storage System (BESS), which is connected to the grid in the distribution network, exclusively when it is operating as a battery charger under unbalanced grid voltage. The hypothesis establishes that it is possible to ride through an unbalanced voltage condition (typically caused by unsymmetrical loads, unsymmetrical transformer windings and transmission impedance) by using a nonlinear controller based on input-output linearization using only the current loops for each phase and generating the current references based on the balanced power. The methodology is based on the use of the mathematical model for a three-phase LCL-filter PWM rectifier (because the analysis is just for the battery charge mode of the BESS), delta connected and 100 kW. To test the closed-loop system, simulations including the battery model have been performed by using PSCAD/EMTDC.
2010 7th International Conference on Electrical Engineering Computing Science and Automatic Control, 2010
A two stages robust Generalized PI feedback controller for a single-phase active multilevel recti... more A two stages robust Generalized PI feedback controller for a single-phase active multilevel rectifier is proposed. The controller is based on the system modeled in the d-q synchronous reference frame. Based on input-output linearization theory a current controller that decouples the d-q components and compensates unknown perturbations is obtained. Performing a transformation of the system, stability of zero dynamics is
IEEE Transactions on Industrial Electronics, 2018
This paper proposes a light, flexible, and yet reliable multi-parametric estimation algorithm for... more This paper proposes a light, flexible, and yet reliable multi-parametric estimation algorithm for gridconnected VSC-based systems. This approach combines the nonlinear least squares (NLSQ) fitting algorithm and the steady-state extended harmonic domain (EHD) model to take into account the harmonic effects. The EHD model is used to take advantage of the harmonic content of the electrical signals to provide robustness and improved performance to the NLSQ estimation methodology. In addition, this harmonic formulation reduces the necessity of synchronized measurements. Details of the implementation are provided by an experimental case study in which the grid equivalent (Thevenin voltage, inductance, and resistance), the AC-side filter (inductance and resistance), and the converter switching and conduction loss resistance are accurately estimated for three different operating conditions.
Energies
This paper presents an improvement of the tuning process of the holistic control published by the... more This paper presents an improvement of the tuning process of the holistic control published by the authors in previous research to achieve a seamless transition among three operation mode changes and load transients. The proposed tuning approach reveals an improvement in the energy consumption of the Battery Energy Storage System (BESS) during all operation mode transients compared to the holistic control. For this aim, the system addressed is a BESS with the capability to ride through three operation modes of interest: the grid-connected mode as an inverter, the grid-connected mode as a rectifier, and the islanded operation mode. The LCL filter design by using the Butterworth polynomial approach is presented in more detail, and its smooth inherent transient response is preserved when the tuning of the controller gains is carried out by using the same polynomial approach but now including the integral action within the Butterworth polynomial. To reveal the reduction in energy consump...
IEEE Access
This paper is dedicated to presenting control-tuning methodologies for the rotor-side converter (... more This paper is dedicated to presenting control-tuning methodologies for the rotor-side converter (RSC) and grid-side converter (GSC) of series-compensated DFIG-based wind farms (WF) and to determining the origin of subsynchronous resonance (SSR). Unlike conventional approaches to re-tuning controller gains to achieve desirable performance, these methodologies only consider the mathematical models of the states variables to be controlled. A PI cascade topology is used to control the RSC and GSC. An inner loop is required for current control and an outer loop for voltage control. Special consideration is taken for tuning the RSC because this converter is coupled with the mechanical variables as mechanical rotor speed of the DFIG. Compared with standard tuning, a better system behavior during a resonance condition is achieved with the proposed tuning methodology. Regarding the analysis of the SSR origin, the modal impedance (MI) technique is used as a tool to study SSR issues; its advantages compared to the driving point impedance technique are highlighted. In this context, the small-signal-stability (SSS) analysis is performed to evaluate the overall system. With the combination of MI and SSS, the phenomena of induction generator effect, torque interaction, and torque amplification are analyzed. As a result, the modes involved in the SSR phenomenon are identified and a discrimination procedure is described to determine the origin of the SSR. INDEX TERMS Doubly fed induction generator (DFIG), subsynchronous resonance (SSR), eigenvalue analysis, oscillatory stability, power converter, wind farm, control tuning.
Mathematical Problems in Engineering, 2017
The requirements of PWM rectifiers for delivering power to motor drives include power factor corr... more The requirements of PWM rectifiers for delivering power to motor drives include power factor correction and output voltage regulation even when strong variations such as voltage sags and dynamic load transients occur simultaneously. To achieve these objectives, the classic approach is to use a two-loop controller with its d-q model. In this paper, the authors propose a simplified approach to address that problem by using a feedback linearization-based nonlinear controller using only a single-loop current control and avoiding d-q modeling to reduce processing stages. To demonstrate the feasibility of this approach, several simulations are presented considering a 1.5 kW PWM rectifier.
2018 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC), 2018
This paper presents the analysis of AC powerelectronic-based power systems with distributed gener... more This paper presents the analysis of AC powerelectronic-based power systems with distributed generation units, such as microgrids, for stability and resonance analysis. Two case studies are addressed, and the explicit representation of the commutation process is fully considered. In the first case, an islanded controlled microgrid is presented, the resonances in the system are analyzed and their impact on the stability are shown. In the second case, the resonances and harmonic content in an open-loop system are addressed for three different transmission line models, the results are compared between the fundamental frequency model and the commutated model, showing the varied behaviors that can appear considering different line models.
COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 2019
Purpose The purpose of this study is to present the performance evaluation of three shooting meth... more Purpose The purpose of this study is to present the performance evaluation of three shooting methods typically applied to obtain the periodic steady state of electric power systems, with the aim to check the benefits of the use of cloud computing regarding relative efficiency and computation time. Design/methodology/approach The mathematical formulation of the methods is presented, and their parallelization potential is explained. Two case studies are addressed, and the solution is computed with the shooting methods using multiple computer cores through cloud computing. Findings The results obtained show a reduction in the computation time and increase in the relative efficiency by the application of these methods with parallel cloud computing, in the problem of obtainment of the periodic steady state of electric power systems in an efficient way. Additionally, the characteristics of the methods, when parallel cloud computing is used, are shown and comparisons among them are present...