Articles de revista
http://hdl.handle.net/2117/3651
2024-03-28T21:52:33Z
2024-03-28T21:52:33Z
An appropriate index to assess the global cancellation level of the harmonic currents consumed by a set of single-phase uncontrolled rectifiers and a set of fluorescent lamps
Mesas García, Juan José
Sainz Sapera, Luis
Monjo Mur, Lluís
Pedra Durán, Joaquim
http://hdl.handle.net/2117/370845
2022-07-24T15:54:08Z
2022-07-21T13:12:32Z
An appropriate index to assess the global cancellation level of the harmonic currents consumed by a set of single-phase uncontrolled rectifiers and a set of fluorescent lamps
Mesas García, Juan José; Sainz Sapera, Luis; Monjo Mur, Lluís; Pedra Durán, Joaquim
An in-depth study of harmonic current reduction in European commercial buildings due to the harmonic cancellation effect when a set of single-phase uncontrolled rectifiers and a set of fluorescent lamps are connected at the same voltage level is essential, since both types of non-linear loads are very present in commercial and residential sectors. This paper provides an appropriate index to assess the global cancellation level of the harmonic currents for this study. The equivalent circuit per phase of the typical three-phase power system of European commercial installations is presented and simplified for the cancellation analysis of the harmonic currents consumed by a set of multiple identical single-phase uncontrolled rectifiers and a set of multiple identical fluorescent lamps connected at the same voltage level. The suitability and usefulness of the proposed index are shown by applying it to that analysis, which leads to some results of practical interest. This index can be generalized to any number of sets of multiple identical non-linear loads and can be applied in graphical and optimization studies that will allow a greater benefit from the harmonic cancellation effect to be obtained given the global nature of the index.
2022-07-21T13:12:32Z
Mesas García, Juan José
Sainz Sapera, Luis
Monjo Mur, Lluís
Pedra Durán, Joaquim
An in-depth study of harmonic current reduction in European commercial buildings due to the harmonic cancellation effect when a set of single-phase uncontrolled rectifiers and a set of fluorescent lamps are connected at the same voltage level is essential, since both types of non-linear loads are very present in commercial and residential sectors. This paper provides an appropriate index to assess the global cancellation level of the harmonic currents for this study. The equivalent circuit per phase of the typical three-phase power system of European commercial installations is presented and simplified for the cancellation analysis of the harmonic currents consumed by a set of multiple identical single-phase uncontrolled rectifiers and a set of multiple identical fluorescent lamps connected at the same voltage level. The suitability and usefulness of the proposed index are shown by applying it to that analysis, which leads to some results of practical interest. This index can be generalized to any number of sets of multiple identical non-linear loads and can be applied in graphical and optimization studies that will allow a greater benefit from the harmonic cancellation effect to be obtained given the global nature of the index.
Artificial intelligence-based protection for smart grids
Bakkar, Mostafa
Bogarra Rodríguez, Santiago
Córcoles López, Felipe
Aboelhassan, Ahmed
Wang, Shuo
Iglesias, Javier
http://hdl.handle.net/2117/369973
2022-07-12T09:00:29Z
2022-07-12T08:59:59Z
Artificial intelligence-based protection for smart grids
Bakkar, Mostafa; Bogarra Rodríguez, Santiago; Córcoles López, Felipe; Aboelhassan, Ahmed; Wang, Shuo; Iglesias, Javier
Lately, adequate protection strategies need to be developed when Microgrids (MGs) are connected to smart grids to prevent undesirable tripping. Conventional relay settings need to be adapted to changes in Distributed Generator (DG) penetrations or grid reconfigurations, which is a complicated task that can be solved efficiently using Artificial Intelligence (AI)-based protection. This paper compares and validates the difference between conventional protection (overcurrent and differential) strategies and a new strategy based on Artificial Neural Networks (ANNs), which have been shown as adequate protection, especially with reconfigurable smart grids. In addition, the limitations of the conventional protections are discussed. The AI protection is employed through the communication between all Protective Devices (PDs) in the grid, and a backup strategy that employs the communication among the PDs in the same line. This paper goes a step further to validate the protection strategies based on simulations using the MATLABTM platform and experimental results using a scaled grid. The AI-based protection method gave the best solution as it can be adapted for different grids with high accuracy and faster response than conventional protection, and without the need to change the protection settings. The scaled grid was designed for the smart grid to advocate the behavior of the protection strategies experimentally for both conventional and AI-based protections.
2022-07-12T08:59:59Z
Bakkar, Mostafa
Bogarra Rodríguez, Santiago
Córcoles López, Felipe
Aboelhassan, Ahmed
Wang, Shuo
Iglesias, Javier
Lately, adequate protection strategies need to be developed when Microgrids (MGs) are connected to smart grids to prevent undesirable tripping. Conventional relay settings need to be adapted to changes in Distributed Generator (DG) penetrations or grid reconfigurations, which is a complicated task that can be solved efficiently using Artificial Intelligence (AI)-based protection. This paper compares and validates the difference between conventional protection (overcurrent and differential) strategies and a new strategy based on Artificial Neural Networks (ANNs), which have been shown as adequate protection, especially with reconfigurable smart grids. In addition, the limitations of the conventional protections are discussed. The AI protection is employed through the communication between all Protective Devices (PDs) in the grid, and a backup strategy that employs the communication among the PDs in the same line. This paper goes a step further to validate the protection strategies based on simulations using the MATLABTM platform and experimental results using a scaled grid. The AI-based protection method gave the best solution as it can be adapted for different grids with high accuracy and faster response than conventional protection, and without the need to change the protection settings. The scaled grid was designed for the smart grid to advocate the behavior of the protection strategies experimentally for both conventional and AI-based protections.
Methodology for obtaining simplified models for the long-term energy management of renewable assets under a high degree of uncertainty
Coronas Herrero, Sergio
Hoz Casas, Jordi de la
Martín Cañadas, María Elena
Mesas García, Juan José
Matas Alcalá, José
http://hdl.handle.net/2117/369062
2023-02-19T09:48:05Z
2022-06-23T10:56:40Z
Methodology for obtaining simplified models for the long-term energy management of renewable assets under a high degree of uncertainty
Coronas Herrero, Sergio; Hoz Casas, Jordi de la; Martín Cañadas, María Elena; Mesas García, Juan José; Matas Alcalá, José
This paper addresses the attainment of a methodology aimed at obtaining simplified models embedding the regulatory constraints imposed by the country-specific remuneration mechanisms in the energy management system of long operating life renewable assets under a high degree of uncertainty. This methodology, composed of different steps in which sensitivity analysis as well as Monte Carlo simulation play a key role, is focused on a significant case study that has implemented two of the most widely used worldwide remuneration mechanisms in the promotion of renewable energies, i.e., feed-in tariffs and auctions. The earnings before interest, tax, depreciation and amortization have been used as the output variable of the energy management model, as it is essential to take into account both revenues and operating costs of these renewable assets to manage them optimally. Some valid simplified models have been achieved by applying the proposed methodology to the case study with generalized errors below 5%. Specifically, one simplified energy management system model has been obtained under the feed-in tariff scheme, which involves acting on almost 40% of the equations of the original model and reducing the initial input parameters by 22%. Meanwhile, two simplified energy management system models have been obtained under the auction scheme. The most conservative simplified model involves acting on almost 50% of the equations of the original model and reducing the initial input parameters by 35%, while in the less conservative case it involves acting on more than 50% of the equations of the original model and reducing the initial input parameters by 42%. In short, although the uncertainty on the energy assets cannot be completely eliminated, it can be considerably reduced by facilitating the assessment of its prospective financial results. The validity of the achieved simplified models demonstrates the suitability and usefulness of the proposed simplifying methodology, providing a touch of quality in the long-term judgement and decision-making of the stakeholders when optimally managing renewable energy facilities under any type of remuneration scheme.
2022-06-23T10:56:40Z
Coronas Herrero, Sergio
Hoz Casas, Jordi de la
Martín Cañadas, María Elena
Mesas García, Juan José
Matas Alcalá, José
This paper addresses the attainment of a methodology aimed at obtaining simplified models embedding the regulatory constraints imposed by the country-specific remuneration mechanisms in the energy management system of long operating life renewable assets under a high degree of uncertainty. This methodology, composed of different steps in which sensitivity analysis as well as Monte Carlo simulation play a key role, is focused on a significant case study that has implemented two of the most widely used worldwide remuneration mechanisms in the promotion of renewable energies, i.e., feed-in tariffs and auctions. The earnings before interest, tax, depreciation and amortization have been used as the output variable of the energy management model, as it is essential to take into account both revenues and operating costs of these renewable assets to manage them optimally. Some valid simplified models have been achieved by applying the proposed methodology to the case study with generalized errors below 5%. Specifically, one simplified energy management system model has been obtained under the feed-in tariff scheme, which involves acting on almost 40% of the equations of the original model and reducing the initial input parameters by 22%. Meanwhile, two simplified energy management system models have been obtained under the auction scheme. The most conservative simplified model involves acting on almost 50% of the equations of the original model and reducing the initial input parameters by 35%, while in the less conservative case it involves acting on more than 50% of the equations of the original model and reducing the initial input parameters by 42%. In short, although the uncertainty on the energy assets cannot be completely eliminated, it can be considerably reduced by facilitating the assessment of its prospective financial results. The validity of the achieved simplified models demonstrates the suitability and usefulness of the proposed simplifying methodology, providing a touch of quality in the long-term judgement and decision-making of the stakeholders when optimally managing renewable energy facilities under any type of remuneration scheme.
New methodology to calculate DC voltage signature in n-phases TRUs under supply voltage sags
Saura Perisé, Jaime
Bakkar, Mostafa
Bogarra Rodríguez, Santiago
http://hdl.handle.net/2117/363543
2022-05-17T10:56:41Z
2022-03-08T10:36:51Z
New methodology to calculate DC voltage signature in n-phases TRUs under supply voltage sags
Saura Perisé, Jaime; Bakkar, Mostafa; Bogarra Rodríguez, Santiago
A new methodology based on the shadow projection has been developed to study any multipulse rectifier's dynamic behavior under balanced and unbalanced conditions. The proposed methodology calculates the DC average voltage and instantaneous values under balanced and unbalanced supply voltage conditions for multiphase Transformer Rectifier Units (TRUs). The calculation of the developed algorithms is more practical than the classical methods and other approaches based on Fourier series or symmetrical components that are difficult to apply under unbalanced conditions. Furthermore, classical methods are not simple to determine the limits of the integrals and calculate them to obtain the average value, so a more friendly and practical methodology has been developed to analyze rectifiers operating under supply voltage sags. This new methodology has been validated by simulation for a 12-pulse TRU in series and parallel connections, and it has also been validated for a 36-pulse TRU in parallel connection using interphase inductors. The accuracy of the calculations is validated by the experimental results for 12-pulse TRUs, series, and parallel connection, and 18-pulse TRU in series connection.
2022-03-08T10:36:51Z
Saura Perisé, Jaime
Bakkar, Mostafa
Bogarra Rodríguez, Santiago
A new methodology based on the shadow projection has been developed to study any multipulse rectifier's dynamic behavior under balanced and unbalanced conditions. The proposed methodology calculates the DC average voltage and instantaneous values under balanced and unbalanced supply voltage conditions for multiphase Transformer Rectifier Units (TRUs). The calculation of the developed algorithms is more practical than the classical methods and other approaches based on Fourier series or symmetrical components that are difficult to apply under unbalanced conditions. Furthermore, classical methods are not simple to determine the limits of the integrals and calculate them to obtain the average value, so a more friendly and practical methodology has been developed to analyze rectifiers operating under supply voltage sags. This new methodology has been validated by simulation for a 12-pulse TRU in series and parallel connections, and it has also been validated for a 36-pulse TRU in parallel connection using interphase inductors. The accuracy of the calculations is validated by the experimental results for 12-pulse TRUs, series, and parallel connection, and 18-pulse TRU in series connection.
Three-port small signal admittance-based model of VSCs for studies of multi-Terminal HVDC hybrid AC/DC yransmission grids
Pedra Durán, Joaquim
Sainz Sapera, Luis
Monjo Mur, Lluís
http://hdl.handle.net/2117/361944
2022-02-14T02:09:46Z
2022-02-08T10:39:48Z
Three-port small signal admittance-based model of VSCs for studies of multi-Terminal HVDC hybrid AC/DC yransmission grids
Pedra Durán, Joaquim; Sainz Sapera, Luis; Monjo Mur, Lluís
Multi-terminal high voltage direct current (HVDC) systems, together with AC transmission systems and voltage source converters (VSCs), form hybrid AC/DC grids with complex dynamic and transient interactions. VSCs characterization taking into account DC- and AC-side dynamics in order to study these interactions is not yet well solved. This paper presents a three-port transfer admittance-based matrix model of VSCs that can be applied for such purpose. It is derived from dq-complex space vectors and characterizes both AC- and DC-side dynamics by relating AC- and DC-side current and voltages in a three-dimensional admittance transfer matrix which considers the VSC outer control loops. The paper also proposes a systematical procedure for studying multi-terminal HVDC hybrid AC/DC transmission grids by the Norton admittance method, where the proposed VSC model can be easily included in the Norton admittance matrix. This procedure allows the study of grid dynamics using impedance-based stability criteria. The proposed model and procedure are applied to a stability study in a multi-terminal HVDC hybrid AC/DC transmission grid. PSCAD/EMTDC simulations are used to validate the application.
© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
2022-02-08T10:39:48Z
Pedra Durán, Joaquim
Sainz Sapera, Luis
Monjo Mur, Lluís
Multi-terminal high voltage direct current (HVDC) systems, together with AC transmission systems and voltage source converters (VSCs), form hybrid AC/DC grids with complex dynamic and transient interactions. VSCs characterization taking into account DC- and AC-side dynamics in order to study these interactions is not yet well solved. This paper presents a three-port transfer admittance-based matrix model of VSCs that can be applied for such purpose. It is derived from dq-complex space vectors and characterizes both AC- and DC-side dynamics by relating AC- and DC-side current and voltages in a three-dimensional admittance transfer matrix which considers the VSC outer control loops. The paper also proposes a systematical procedure for studying multi-terminal HVDC hybrid AC/DC transmission grids by the Norton admittance method, where the proposed VSC model can be easily included in the Norton admittance matrix. This procedure allows the study of grid dynamics using impedance-based stability criteria. The proposed model and procedure are applied to a stability study in a multi-terminal HVDC hybrid AC/DC transmission grid. PSCAD/EMTDC simulations are used to validate the application.
Integration of Distributed Energy Resources to Unbalanced Grids under Voltage Sags with Grid Code Compliance
Rolán Blanco, Alejandro
Bogarra Rodríguez, Santiago
Bakkar, Mostafa
http://hdl.handle.net/2117/361578
2024-01-01T01:29:41Z
2022-02-03T13:09:12Z
Integration of Distributed Energy Resources to Unbalanced Grids under Voltage Sags with Grid Code Compliance
Rolán Blanco, Alejandro; Bogarra Rodríguez, Santiago; Bakkar, Mostafa
The aim of this paper is to analyze the situations in which distributed power generation systems (DPGSs) based on renewable energy sources (RESs) can be controlled when operating under voltage sags. Analytical models for both solar photovoltaic (PV) system and doubly-fed induction generator (DFIG)-based wind turbine (WT) written in the complex form of the Park variables are given. Three kinds of control for the grid-side converter (GSC) of a PV system are compared: constant forward voltage control (CFVC), balanced positive -sequence control (BPSC) and the proposed BPSC with grid code requirements (BPSC-GCR). Regarding the rotor-side converter (RSC) of a DFIG-based WT, its controllability is studied considering three different-sized DFIG-based WT units: 6 MW (offshore), 2 MW (onshore) and 7.5 kW (setup). The converter limits are also considered. Simulations carried out in MATLAB reveal that a RES-based DPGS can achieve fault ride-through (FRT) when subject to a certain fault (i.e., with a specific duration and depth), but it may be uncontrollable for different-sized units operating under different faults without considering the grid code requirements. Finally, experimental results prove the robustness of the BPSC-GCR method to let GSCs of PV systems achieve FRT under sags.
2022-02-03T13:09:12Z
Rolán Blanco, Alejandro
Bogarra Rodríguez, Santiago
Bakkar, Mostafa
The aim of this paper is to analyze the situations in which distributed power generation systems (DPGSs) based on renewable energy sources (RESs) can be controlled when operating under voltage sags. Analytical models for both solar photovoltaic (PV) system and doubly-fed induction generator (DFIG)-based wind turbine (WT) written in the complex form of the Park variables are given. Three kinds of control for the grid-side converter (GSC) of a PV system are compared: constant forward voltage control (CFVC), balanced positive -sequence control (BPSC) and the proposed BPSC with grid code requirements (BPSC-GCR). Regarding the rotor-side converter (RSC) of a DFIG-based WT, its controllability is studied considering three different-sized DFIG-based WT units: 6 MW (offshore), 2 MW (onshore) and 7.5 kW (setup). The converter limits are also considered. Simulations carried out in MATLAB reveal that a RES-based DPGS can achieve fault ride-through (FRT) when subject to a certain fault (i.e., with a specific duration and depth), but it may be uncontrollable for different-sized units operating under different faults without considering the grid code requirements. Finally, experimental results prove the robustness of the BPSC-GCR method to let GSCs of PV systems achieve FRT under sags.
Frequency domain stability assessment of photovoltaic power generation systems with quasi-z-source inverters
Sainz Sapera, Luis
Monjo Mur, Lluís
http://hdl.handle.net/2117/359862
2022-05-19T11:04:37Z
2022-01-18T08:31:29Z
Frequency domain stability assessment of photovoltaic power generation systems with quasi-z-source inverters
Sainz Sapera, Luis; Monjo Mur, Lluís
Photovoltaic power generation systems are one of the main renewable power sources, and quasi-Z-source inverters are becoming powerful devices to integrate these systems in AC grids. However, stability issues due to the damping behaviour of converters must be considered. There are several studies in this direction but instability concerns are not completely solved yet. This paper contributes with a procedure for the stability assessment of photovoltaic power generation systems with quasiZ-source inverters in the frequency domain. The study is based on the small-signal averaged model of the system expressed in the s-domain and the stability criterion derived from the frequency characteristics of the state-space matrix. The influence of the photovoltaic power generation system operating point on stability is studied by the proposed procedure. Eigenvalue analysis and PSCAD/EMTDC simulations are also performed to validate the obtained results.
2022-01-18T08:31:29Z
Sainz Sapera, Luis
Monjo Mur, Lluís
Photovoltaic power generation systems are one of the main renewable power sources, and quasi-Z-source inverters are becoming powerful devices to integrate these systems in AC grids. However, stability issues due to the damping behaviour of converters must be considered. There are several studies in this direction but instability concerns are not completely solved yet. This paper contributes with a procedure for the stability assessment of photovoltaic power generation systems with quasiZ-source inverters in the frequency domain. The study is based on the small-signal averaged model of the system expressed in the s-domain and the stability criterion derived from the frequency characteristics of the state-space matrix. The influence of the photovoltaic power generation system operating point on stability is studied by the proposed procedure. Eigenvalue analysis and PSCAD/EMTDC simulations are also performed to validate the obtained results.
Stability assessment for multi-infeed grid-connected VSCs modeled in the admittance matrix form
Orellana Montaño, Luis Carlos
Sainz Sapera, Luis
Prieto Araujo, Eduardo
Gomis Bellmunt, Oriol
http://hdl.handle.net/2117/359830
2023-10-22T04:41:16Z
2022-01-17T10:51:08Z
Stability assessment for multi-infeed grid-connected VSCs modeled in the admittance matrix form
Orellana Montaño, Luis Carlos; Sainz Sapera, Luis; Prieto Araujo, Eduardo; Gomis Bellmunt, Oriol
The increasing use of power electronics converters to integrate renewable energy sources has been a subject of concern due to the resonance oscillatory phenomena caused by their interaction with poorly damped AC networks. Early studies are focused on assessing the controller influence of a single converter connected to simple networks, and they are no longer representative for existing systems. Lately, studies of multi-infeed grid-connected converters are of particular interest, and their main aim is to apply traditional criteria and identify their difficulties in the stability assessment. An extension of traditional criteria is commonly proposed as a result of these analysis, but they can be burdensome for large and complex power systems. The present work addresses this issue by proposing a simple criterion to assess the stability of large power systems with high-penetration of power converters. The criterion has its origin in the mode analysis and positive-net damping stability criteria, and it addresses the stability in the frequency domain by studying the eigenvalues magnitude and real component of dynamic models in the admittance matrix form. Its effectiveness is tested in two case studies developed in Matlab/Simulink which compare it with traditional criteria, proving its simplicity.
© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
2022-01-17T10:51:08Z
Orellana Montaño, Luis Carlos
Sainz Sapera, Luis
Prieto Araujo, Eduardo
Gomis Bellmunt, Oriol
The increasing use of power electronics converters to integrate renewable energy sources has been a subject of concern due to the resonance oscillatory phenomena caused by their interaction with poorly damped AC networks. Early studies are focused on assessing the controller influence of a single converter connected to simple networks, and they are no longer representative for existing systems. Lately, studies of multi-infeed grid-connected converters are of particular interest, and their main aim is to apply traditional criteria and identify their difficulties in the stability assessment. An extension of traditional criteria is commonly proposed as a result of these analysis, but they can be burdensome for large and complex power systems. The present work addresses this issue by proposing a simple criterion to assess the stability of large power systems with high-penetration of power converters. The criterion has its origin in the mode analysis and positive-net damping stability criteria, and it addresses the stability in the frequency domain by studying the eigenvalues magnitude and real component of dynamic models in the admittance matrix form. Its effectiveness is tested in two case studies developed in Matlab/Simulink which compare it with traditional criteria, proving its simplicity.
State-space model of quasi-z-source inverter-PV systems for transient dynamics studies and network stability assessment
Monjo Mur, Lluís
Sainz Sapera, Luis
Mesas García, Juan José
Pedra Durán, Joaquim
http://hdl.handle.net/2117/359827
2022-05-19T10:35:01Z
2022-01-17T10:12:55Z
State-space model of quasi-z-source inverter-PV systems for transient dynamics studies and network stability assessment
Monjo Mur, Lluís; Sainz Sapera, Luis; Mesas García, Juan José; Pedra Durán, Joaquim
Photovoltaic (PV) power systems are increasingly being used as renewable power generation sources. Quasi-Z-source inverters (qZSI) are a recent, high-potential technology that can be used to integrate PV power systems into AC networks. Simultaneously, concerns regarding the stability of PV power systems are increasing. Converters reduce the damping of grid-connected converter systems, leading to instability. Several studies have analyzed the stability and dynamics of qZSI, although the characterization of qZSI-PV system dynamics in order to study transient interactions and stability has not yet been properly completed. This paper contributes a small-signal, state-space-averaged model of qZSI-PV systems in order to study these issues. The model is also applied to investigate the stability of PV power systems by analyzing the influence of system parameters. Moreover, solutions to mitigate the instabilities are proposed and the stability is verified using PSCAD time domain simulations.
2022-01-17T10:12:55Z
Monjo Mur, Lluís
Sainz Sapera, Luis
Mesas García, Juan José
Pedra Durán, Joaquim
Photovoltaic (PV) power systems are increasingly being used as renewable power generation sources. Quasi-Z-source inverters (qZSI) are a recent, high-potential technology that can be used to integrate PV power systems into AC networks. Simultaneously, concerns regarding the stability of PV power systems are increasing. Converters reduce the damping of grid-connected converter systems, leading to instability. Several studies have analyzed the stability and dynamics of qZSI, although the characterization of qZSI-PV system dynamics in order to study transient interactions and stability has not yet been properly completed. This paper contributes a small-signal, state-space-averaged model of qZSI-PV systems in order to study these issues. The model is also applied to investigate the stability of PV power systems by analyzing the influence of system parameters. Moreover, solutions to mitigate the instabilities are proposed and the stability is verified using PSCAD time domain simulations.
Quasi-z-source inverter-based photovoltaic power system modeling for grid stability studies
Monjo Mur, Lluís
Sainz Sapera, Luis
Mesas García, Juan José
Pedra Durán, Joaquim
http://hdl.handle.net/2117/359422
2022-01-18T07:31:09Z
2022-01-12T12:18:51Z
Quasi-z-source inverter-based photovoltaic power system modeling for grid stability studies
Monjo Mur, Lluís; Sainz Sapera, Luis; Mesas García, Juan José; Pedra Durán, Joaquim
Quasi-Z-source inverters (qZSIs) are becoming a powerful power conversion technology in photovoltaic (PV) power systems because they allow energy power conversion in a single stage operation. However, they can cause system resonances and reduce system damping, which may lead to instabilities. These stability problems are well known in grid-connected voltage source converter systems but not in quasi-Z-source inverter (qZSI)-based PV power systems. This paper contributes with Matlab/Simulink and PSCAD/EMTDC models of qZSI-based PV power systems to analyze transient interactions and stability problems. These models consider all power circuits and control blocks of qZSI-based PV power systems and can be used in sensitivity studies on the influence of system parameters on stability. PV power system stability is assessed from the proposed models. The causes of instabilities are analyzed from numerical simulations and possible solutions are proposed.
2022-01-12T12:18:51Z
Monjo Mur, Lluís
Sainz Sapera, Luis
Mesas García, Juan José
Pedra Durán, Joaquim
Quasi-Z-source inverters (qZSIs) are becoming a powerful power conversion technology in photovoltaic (PV) power systems because they allow energy power conversion in a single stage operation. However, they can cause system resonances and reduce system damping, which may lead to instabilities. These stability problems are well known in grid-connected voltage source converter systems but not in quasi-Z-source inverter (qZSI)-based PV power systems. This paper contributes with Matlab/Simulink and PSCAD/EMTDC models of qZSI-based PV power systems to analyze transient interactions and stability problems. These models consider all power circuits and control blocks of qZSI-based PV power systems and can be used in sensitivity studies on the influence of system parameters on stability. PV power system stability is assessed from the proposed models. The causes of instabilities are analyzed from numerical simulations and possible solutions are proposed.