[EN] Having two or more interlinking converters connected in parallel in hybrid microgrids has some benefits, like modularity, flexibility, and redundancy. However, the parallelization of the inverters leads to circulating currents that can cause system malfunctions. This work uses a method for suppressing low-frequency circulating currents in interlinking converters by controlling the zero-sequence component of the phase currents, showing that the control structure is valid for interlinking converters. The proposed control scheme has been applied to two parallel interlinking inverters of 5 kW and 2.5 kW, respectively. The interlinking inverters are connected to the grid, and they control the voltage in the DC bus of the hybrid microgrid. To validate the concept, simulation and experimental results are shown., This work was supported by the Spanish "Ministerio de Ciencia e Innovacion" and the European Regional Development Fund (ERDF) under Grant RTI2018-100732-B-C21 and Grant PID2021-122835OB-C22.

[EN] Harmonics generated by non-linear loads must be avoided to increase the overall quality of the power supply of power grids and microgrids. In this context, studies have been developed to improve the performance of active power filters. This work develops a control scheme for active filters composed of two Voltage Source Inverters that share the harmonics to be controlled. One of the inverters works at low frequency and controls the reactive power and the low order harmonics. Other inverter works at a high switching frequency and controls the high frequency harmonics. This inverter handles most of the harmonics, but its Root Mean Square (RMS) current is approximately 20% of the RMS current handled by the active power filter, so switching losses are significantly reduced., This research was funded by the Spanish Ministerio de
Asuntos Económicos y Transformación Digital and the
European Regional Development Fund (ERDF) under Grant
PID2021-122835OB-C22.

[EN] This paper presents an analytical study of the dynamics of a three-phase, grid-connected photovoltaic inverter based on the B4 topology. Following a similar procedure to that used for conventional B6 inverters, the inverter has been modelled and controlled in a synchronous reference frame by introducing the concept of 'positive sequence equivalent control signals'. A stability analysis of the control loops is presented, considering parametric variations in photovoltaic field voltage and grid inductance. A control strategy incorporating PI controllers, along with decoupling terms to enhance dynamic performance, has been implemented. To further evaluate the behavior of the inverter, additional simulations are conducted under ideal and distorted grid conditions. These tests evaluate harmonic propagation, DC bus voltage ripple and overall system performance in the presence of grid disturbances., This research was funded by the Spanish Ministerio de Ciencia e Innovación and the European Regional Development Fund (ERDF) under Grant PID2021-122835OB-C22.

[EN] The DC-Bus Signaling (DBS) is a proven method
to coordinate different agents in a microgrid, using the DCvoltage of the microgrid as a communication signal. The droop
control applied in a dc-microgrid leads to an error in the voltage
regulation of the microgrid, while the power sharing among
converters in such microgrid is achieved. By using the voltage at
each node of the grid as the DBS signal, the behavior of the
different agents in a microgrid can be managed. In this paper
the DBS technique is used to coordinate conventional
generators, Energy Storage Systems and loads in a microgrid.
The control laws proposed are tested in an experimental
microgrid., This research was funded by the Spanish Ministerio de Asuntos
Económicos y Transformación Digital and the European Regional
Development Fund (ERDF) under Grants RTI2018-100732-B-C21 and
PID2021-122835OB-C22.

[EN] The parallel operation of inverters has many benefits, such as modularity and redundancy. However, the parallel connection of inverters produces circulating currents that may result in malfunctions of the system. In this work, a control technique for the elimination of the low-frequency components of the circulating currents in grid-connected inverters is presented. The proposed control structure contains n - 1 zero-sequence control loops, with n being the number of inverters connected in parallel. Simulation and experimental results have been carried out on a prototype composed of two 5 kW inverters connected in parallel. The results have been obtained by considering the following mismatches between both inverters: inductance values of the grid filters, unbalance of the delivered power, and the use of different modulation techniques., This research was funded by the Spanish "Ministerio de Asuntos Economicos y Transformacion Digital" and the European Regional Development Fund (ERDF), under grants RTI2018100732-B-C21 and PID2021-122835OB-C22.

[EN] DC-Bus Signaling (DBS) is a proven method to coordinate different microgrid agents, using the DC voltage of the microgrid as a communication signal. The droop control applied in a DC microgrid achieves accurate power-sharing among converters while leading to a certain voltage regulation error in the microgrid bus. The behaviour of the different agents in a microgrid is managed by using the voltage at each node of the microgrid as the DBS signal. The technique proposed in this paper uses an improved DBS technique to coordinate interlinking converters, photovoltaic generators, Energy Storage Systems and loads in a microgrid. The operation of the renewable power sources of a microgrid at the full generated power is desired due to economic and environmental reasons. The DBS technique proposed in this paper is adapted to integrate renewable power sources in the microgrid. The DBS-controlled Energy Storage Systems (ESS) will store the surplus energy if the generated power exceeds consumption. In the case of fully charged ESS, the renewable generators will limit their output power to those demanded by the loads. The proposed control laws have been tested in an experimental microgrid., This research was funded by the Spanish Ministerio de Asuntos
Económicos y Transformación Digital and the European Regional
Development Fund (ERDF) under Grants RTI2018-100732-B-C21 and
PID2021-122835OB-C22.

This dataset is about the experimental results obtained and published in the article "A Control Scheme to Suppress Circulating Currents in Parallel-Connected Three-Phase Inverters": Liberos, M.; Gonzalez-Medina, R.; Patrao, I.; Garcera , G.; Figueres, E. Electronics 2022, 11, 3720.
DOI: 10.3390/electronics11223720

The parallel operation of inverters has many benefits, such as modularity and redundancy. However, the parallel connection of inverters produces circulating currents that may result in malfunctions of the system. In this work, a control technique for the elimination of the low-frequency components of the circulating currents in grid-connected inverters is presented. The proposed control structure contains n - 1 zero-sequence control loops, with n being the number of inverters connected in parallel. Simulation and experimental results have been carried out on a prototype composed of two 5 kW inverters connected in parallel. The results have been obtained by considering the following mismatches between both inverters: inductance values of the grid filters, unbalance of the delivered power, and the use of different modulation techniques.

[EN] When converters are connected in parallel, a system with some benefits, including modularity and redundancy, is obtained. However, in these circumstances, circulating currents can appear that produce some adverse effects. In this work, a study of the low-frequency circulating currents that appear in three-phase inverters connected in parallel is performed. The study is focused on the effects produced by the parameter mismatch, namely inductance mismatches, power imbalance, and the use of different pulse with modulation (PWM) techniques. The nature of the circulating current produced by each of these factors were analyzed separately. Both simulation and experimental results are shown, which were obtained using a three-phase 10-kW prototype composed of two 5-kW inverters connected in parallel., This work was supported by the Spanish Ministerio de Asuntos Económicos y Transformación Digital and the European Regional Development Fund (ERDF) under Grants RTI2018-
100732-B-C21 and PID2021-122835OB-C22.

[EN] Currently in three-phase distribution networks, especially low-voltage networks, there are some inefficient powers. These are defined as reactive power, unbalanced power owing to linear loads, power owing to supply unbalanced voltage, and harmonic power. This has given rise to the concept of power quality. To improve power quality, devices called active filters have been developed. These devices eliminate all the inefficient power. However, for most processes, the elimination of reactive power needs to be from a price/performance perspective because the use of active filters is very expensive. Therefore, the use of capacitor banks in any of their versions (single-phase, three-phase, scalable battery, SVC, etc.) is the most economical and sufficient solution. In this study, a calculation algorithm is proposed to obtain compensators for the inductive reactive power of the load, consisting only of single-phase capacitor banks. These capacitors are designed to minimise losses in the supply line, which are lower than those obtained using the minimum loss line (MLL) strategy. The resulting compensator consists of three, two, or one capacitor, depending on the load characteristics., This work is supported by the Spanish Ministry of Science, Innovation, and Universities (MICINN) and the European Regional Development Fund (ERDF) under Grant PID2021-122835OB-C22.

A theoretical analysis of a three-phase grid-connected B4 photovoltaic inverter was carried out, including modeling, control design, and stability assessment of the current and voltage control loops.
The influence of photovoltaic voltage and grid inductance variations was analyzed through a parametric stability study.
Finally, simulation-based evaluations were performed under ideal and distorted grid conditions to assess harmonic behavior, DC bus voltage ripple, and overall system performance., Funded by the Ministerio de Ciencia e Innovacion of Spain and the European Regional Development Fund (ERDF) under Grant PID2021-122835OB-C22

[EN] This dataset comprises the experimental measurements acquired using a versatile 7 kW inverter prototype configurable as B4 and B6, tested under grid-connected operation in a laboratory microgrid setup. The data support the comparative evaluation of both topologies in terms of efficiency, line-current total harmonic distortion (THD), and current unbalance, among other performance indicators reported in the associated publication.
Associated publication: Torán, E.; Liberos, M.; Patrao, I.; González-Medina, R.; Garcerá, G.; Figueres, E. Performance Evaluation of the B4 Topology for Implementing Grid-Connected Inverters in Microgrids. Electronics 2024, 13(9), 1755. DOI: 10.3390/electronics13091755., Project REMOTEWEAK, Mejora de la calidad de potencia en sistemas de potencia remotos con conexión a red débil y elevada penetración de convertidores electrónicos de potencia, funded by the Spanish Ministerio de Ciencia e Innovación and the European Regional Development Fund (ERDF) under Grant PID2021-122835OB-C22.

[EN] The B4 topology is an interesting alternative to the conventional B6 inverter due to its reduced number of parts and lower cost. Although it has been widely used in the past, especially in low-power motor drive applications, its application as a grid-connected inverter is an open area of research. In this regard, this paper analyses the feasibility of the B4 inverter topology for grid-connected applications. A versatile 7 kW inverter prototype, which may be configured as B4 and B6, was built, allowing for a comprehensive evaluation of the performance of both topologies. Through an analytical study and experimental tests, the performance of the B4 and B6 topologies was comparatively evaluated in terms of efficiency, total harmonic distortion of line currents, current unbalance, cost, and mean time between failures. The study was carried out in the context of microgrid systems, highlighting their role in the integration of renewable energy and distributed generation., This research was funded by the Spanish Ministerio de Ciencia e Innovación and the European Regional Development Fund (ERDF) under Grant PID2021-122835OB-C22.

This dataset is about the experimental results obtained and published in the article "Experimental Study of the Parameter Mismatch Effects on the Low Frequency Circulating Currents of Parallel Three Phase Inverters":Liberos, M.; González-Medina, R.; Patrao, I.; Torán, E.; Garcerá, G.; Figueres, E. Eng 2023, 4, 1356-1376.
DOI: 10.3390/eng4020079

When converters are connected in parallel, a system with some benefits, including modularity and redundancy, is obtained. However, in these circumstances, circulating currents can appear that produce some adverse effects. In this work, a study of the low-frequency circulating currents that appear in three-phase inverters connected in parallel is performed. The study is focused on the effects produced by the parameter mismatch, namely inductance mismatches, power imbalance, and the use of different pulse with modulation (PWM) techniques. The nature of the circulating current produced by each of these factors were analyzed separately. Both simulation and experimental results are shown, which were obtained using a three-phase 10-kW prototype composed of two 5-kW inverters connected in parallel

[EN] Active Power Filters (APF) for reducing current harmonic distortion have been widely used in both grids and microgrids. This work proposes a topology for an APF consisting of two Voltage Source Inverters (VSIs) connected in parallel to the same DC-link, which saves space and reduces cost compared to independent APFs. One inverter operates at a low switching frequency and compensates for low-order harmonics. The second inverter operates at a high switching frequency to target high-frequency harmonics. As the high-frequency inverter handles only around 25% of the total RMS current managed by the overall APF, switching losses are significantly reduced. However, connecting inverters in parallel produces circulating currents that can have an adverse effect on the system. In this work, circulating currents are cancelled by controlling the zero-sequence component of the currents in the two inverters., This research was funded by the Spanish Ministerio de Asuntos
Económicos y Transformación Digital and the European Regional
Development Fund (ERDF) under Grant PID2021-122835OB-C22.

[EN] Electronic converters connected to a microgrid must
contribute to its stability while sharing the load proportionally of
their nominal power. This contribution presents the Universal
Control technique in a Stationary Reference Frame (UCStRf). The
UCStRf is a control technique that implements the power-tofrequency droop law for inverters connected to a microgrid while
implementing an output virtual impedance loop to ensure the
stability of the converter in spite of variations of the microgrid
parameters. Section II presents the UCStRf control technique;
section III details the virtual output impedance design criteria;
section IV develops the small-signal model of the Active Power Loop
(APL); section V details the design of the control loops to ensure the
stability criteria; and section VI validates the proposed control
scheme by means of simulations., This work was supported by the Spanish "Ministerio de
Ciencia e Innovación" and the European Regional Development Fund (ERDF) under Grant PID2021-
122835OB-C22.

Active Power Filters (APF) for reducing current harmonic distortion have been widely used in both grids and microgrids. This work proposes a topology for an APF consisting of two Voltage Source Inverters (VSIs) connected in parallel to the same DC-link, which saves space and reduces cost compared to independent APFs. One inverter operates at a low switching frequency and compensates for low-order harmonics. The second inverter operates at a high switching frequency to target high-frequency harmonics. As the high-frequency inverter handles only around 25% of the total RMS current managed by the overall APF, switching losses are significantly reduced. However, connecting inverters in parallel produces circulating currents that can have an adverse effect on the system. In this work, circulating currents are cancelled by controlling the zero-sequence component of the currents in the two inverters.

A theoretical analysis of a three-phase grid-connected B4 photovoltaic inverter was carried out, including modeling, control design, and stability assessment of the current and voltage control loops.
The influence of photovoltaic voltage and grid inductance variations was analyzed through a parametric stability study.
Finally, simulation-based evaluations were performed under ideal and distorted grid conditions to assess harmonic behavior, DC bus voltage ripple, and overall system performance., Funded by the Ministerio de Ciencia e Innovacion of Spain and the European Regional Development Fund (ERDF) under Grant RTI2018-100732-B-C21-AR.
Funded by the Ministerio de Ciencia e Innovacion of Spain and the European Regional Development Fund (ERDF) under Grant PID2021-122835OB-C22.

Remote power systems require the operation of local generation resources, energy storage systems and loads in a harsh environment in which either there is no connection to the public electric grid (off-grid systems) or the grid is extremely weak and full of abnormalities. The general goal of this project is to improve the characteristics of remote power systems by means of power electronics converters. The data are organized in 9 main folders, each folder corresponding to a publication derived from the REMOTEWEAK project. The publications are journal papers or papers published in proceedings of international conferences, This project was funded by the Ministerio de Ciencia e Innovación of Spain and the European Regional Development Fund (ERDF) under Grant PID2021-122835OB-C22.

[EN] This paper analyzes the performance of several
topologies of grid-connected inverters. For that purpose, a
comparative analysis has been carried out among a classical sixswitch three-phase inverter (B6) and several alternatives of the
four-switch three-phase inverter topology (B4). As figures of
merit to carry out the comparative study, the efficiency, the total
harmonic distortion of the current in the grid, the unbalance of
the grid currents and the cost of each alternative have been
considered. The performance of the inverters has been
evaluated by means of realistic simulations, which have been
carried out with PSIMTM software., This research was funded by the Spanish Ministerio de Asuntos
Económicos y Transformación Digital and the European Regional
Development Fund (ERDF) under Grants RTI2018-100732-B-C21 and
PID2021-122835OB-C22.

[EN] The parallel connection of inverters has some advantages like modularity and redundancy. Nevertheless, the connection in parallel of inverters produces circulating currents that cause adverse effects in the system. In this work, it is presented a control technique for the elimination of the circulating currents. In parallel inverters, the circulating currents agree with the zero-sequence component of the phase currents, so they are suppressed by controlling the zerosequence component of the phase currents of the inverters. Simulation results have been presented considering the connection in parallel of two 5 kW inverters connected in parallel in islanded mode. The results have been obtained by considering linear and non-linear AC loads., This research was funded by the Spanish Ministerio de
Asuntos Económicos y Transformación Digital and the
European Regional Development Fund (ERDF) under Grants
RTI2018-100732-B-C21 and PID2021-122835OB-C22.

This dataset is about the experimental results obtained and published in the article by the authors I. Patrao, E. Tor n, R. Gonz lez-Medina, M. Liberos, E. Figueres and G. Garcer , "DC-Bus Signaling Control Laws for the Operation of DC-Microgrids With Renewable Power Sources," in IEEE Journal of Emerging and Selected Topics in Industrial Electronics, vol. 5, no. 3, pp. 1120-1131, July 2024, doi: 10.1109/JESTIE.2023.3345797.

The behaviour of the different agents in a microgrid is managed by using the voltage at each node of the microgrid as the DBS signal. The technique proposed in this paper uses an improved DBS technique to coordinate interlinking converters, photovoltaic generators, Energy Storage Systems and loads in a microgrid. The DBS technique proposed in this paper is adapted to integrate renewable power sources in the microgrid. The DBS-controlled Energy Storage Systems (ESS) will store the surplus energy if the generated power exceeds consumption. In the case of fully charged ESS, the renewable generators will limit their output power to those demanded by the loads. The proposed control laws have been tested in an experimental microgrid.

[EN] Photovoltaic transformerless inverters are very efficient and economical options for solar-power generation. The absence of the isolation transformer improves the converters' efficiency, but high-frequency voltage to ground can appear in the photovoltaic string poles. The high capacitance to ground of the photovoltaic generator leads to undesirable high-leakage currents. Using half-bridge topologies dramatically reduces the leakage to ground, and using a multilevel half-bridge inverters improves the output quality compared with classical inverters. The neutral point clamped + generation control circuit (NPC + GCC) topology is a multilevel single-phase transformerless inverter capable of tracking the maximum power point of two photovoltaic sources at the same time. This paper presents the control structure and the dynamic modeling of the NPC + GCC inverter. The pulse-width modulated (PWM) switch model in continuous conduction mode (CCM) was used to obtain the small-signal model of the two switching converters that make up the inverter. The resulting dynamic model was used to quantify the stability margins of both converters' current and voltage loops., This research was funded by the Spanish "Ministerio de Asuntos Economicos y Transformacion Digital" and the European Regional Development Fund (ERDF), under grant PID2021-122835OB-C22.

Having two or more interlinking converters connected in parallel in hybrid microgrids with AC and DC buses has some benefits, like modularity, flexibility, and redundancy. However, the parallelization of the inverters leads to circulating currents that can cause system malfunctions. This work uses a method for suppressing low-frequency circulating currents in interlinking converters by controlling the zero-sequence component of the phase currents, showing that the control structure is valid for interlinking converters. The proposed control scheme has been applied to two parallel interlinking inverters of 5 kW and 2.5 kW, respectively. The interlinking inverters are connected to the grid, and they control the voltage in the DC bus of the hybrid microgrid. To validate the concept, simulation and experimental results are shown.

[EN] Experimental results about the control structure and the dynamic modelling of the NPC+GCC transformerless inverter used in single phase Photovoltaic power systems. The high capacitance to ground of the photovoltaic generator leads to undesirable high-leakage currents. Using half-bridge topologies dramatically reduces the leakage to ground, and using a multilevel half-bridge inverters improves the output quality compared with classical inverters. The neutral point clamped + generation control circuit (NPC + GCC) topology is a multilevel single-phase transformerless inverter capable of tracking the maximum power point of two photovoltaic sources at the same time. The Pulse-Width Modulated (PWM) switch model in continuous conduction mode (CCM) has been used to obtain the small-signal model of the two switching converters that make up the inverter. The resulting dynamic model is used to quantify the stability margins of both converters' current and voltage loops., Project REMOTEWEAK, Mejora de la calidad de potencia en sistemas de potencia remotos con conexión a red débil y elevada penetración de convertidores electrónicos de potencia. Funded by the Ministerio de Ciencia e Innovación of Spain and the European Regional Development Fund (ERDF) under Grant PID2021-122835OB-C22