Person:
Marroyo Palomo, Luis

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Marroyo Palomo

First Name

Luis

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Ingeniería Eléctrica y Electrónica

ORCID

0000-0002-8344-8374

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495

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Now showing 1 - 10 of 53

Open Access
Power angle-frequency droop control to enhance transient stability of grid-forming inverters under voltage dips
(IEEE, 2022) Erdocia Zabala, Ioseba; Urtasun Erburu, Andoni; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Due to the replacement of synchronous generators, grid operators are currently demanding to control grid-connected inverters in grid–forming mode to make them participate in the maintenance of the grid. To carry this out, the traditional droop controls based on the active and reactive powers are usually adopted, achieving a satisfactory performance in normal operation. Nevertheless, the power-frequency (P-ω) droop may become transiently unstable under voltage dips. This is because of the modification of the active power response caused by the inverter current limitation together with the voltage reduction. To enhance this, the power angle-frequency (δinv-ω) droop is proposed, consisting in employing an estimation of the inverter power angle as input to obtain the inverter frequency. The proposed method provides the inverter with the same performance as the P-ω droop in normal operation, while enhancing considerably the transient stability margins under current limitation. This is thanks to the higher variation of the inverter power angle with the phase difference between the inverter and the grid. Simulation results show the transient stability problems of the P-ω droop as well as the superior performance of the proposed δinv-ω droop control, which has also been verified by means of HIL results.
Open Access
Control strategy for an integrated photovoltaic-battery system
(IEEE, 2017) Urtasun Erburu, Andoni; Sanchis Gúrpide, Pablo; Marroyo Palomo, Luis; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
In photovoltaic-battery systems, more attention is usually paid to the MPPT control while the battery management is put aside. This paper proposes two control strategies for an integrated PV-battery system, both of them making it possible to perform MPPT or regulate the battery voltage to its maximum value in order to prevent it from overcharging. Simulation results prove the feasibility of both controls.
Open Access
High frequency power transformers with foil windings: maximum interleaving and optimal design
(IEEE, 2015) Barrios Rípodas, Ernesto; Urtasun Erburu, Andoni; Ursúa Rubio, Alfredo; Marroyo Palomo, Luis; Sanchis Gúrpide, Pablo; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Foil conductors and primary and secondary interleaving are normally used to minimize winding losses in high frequency transformers used for high-current power applications. However, winding interleaving complicates the transformer assembly, since taps are required to connect the winding sections, and also complicates the transformer design, since it introduces a new tradeoff between minimizing losses and reducing the construction difficulty. This paper presents a novel interleaving technique, named maximum interleaving, that makes it possible to minimize the winding losses as well as the construction difficulty. An analytical design methodology is also proposed in order to obtain free cooled transformers with a high efficiency, low volume and, therefore, a high power density. For the purpose of evaluating the advantages of the proposed maximum interleaving technique, the methodology is applied to design a transformer positioned in the 5 kW 50 kHz intermediate high frequency resonant stage of a commercial PV inverter. The proposed design achieves a transformer power density of 28 W/cm3 with an efficiency of 99.8%. Finally, a prototype of the maximum-interleaved transformer is assembled and validated satisfactorily through experimental tests.
Open Access
A PV ramp-rate control strategy to extend battery lifespan using forecasting
(Elsevier, 2022) González Moreno, Alejandro; Marcos Álvarez, Javier; Parra Laita, Íñigo de la; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This study analyses and presents a new ramp-rate control algorithm for smoothing PV power fluctuations, designed to address three fundamental objectives: to reduce battery cycling, to meet minimum storage requirements and to be able to operate, without ramp-rate violations, with real publicly-available forecasting. The algorithm was compared to three benchmark methods and, as a performance limit, also to a hypothetical perfect prediction. Different performance variables were analyzed for all the strategies within a restricted ramp-rate constraint (2%/min): minimum storage requirement, battery power distributions, throughput energy, state of charge (SOC) distributions, degradation (calendar and cycling), expected battery lifespan and levelized cost of energy (LCOE). The proposal proves to be the most cost-effective smoothing technique and the simulation results show that its performance is comparable to the obtained with the use of an assumed perfect prediction.
Open Access
Energy management for an electro-thermal renewable based residential microgrid with energy balance forecasting and demand side management
(Elsevier, 2021) Pascual Miqueleiz, Julio María; Arcos Avilés, Diego; Ursúa Rubio, Alfredo; Sanchis Gúrpide, Pablo; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper proposes an energy management strategy for a residential microgrid comprising photovoltaic (PV) panels, a small wind turbine and solar thermal collectors. The microgrid can control the power exchanged with the grid thanks to a battery and a controllable electric water heater, which provide two degrees of freedom to the control strategy. As input data, the proposed control strategy uses the battery state of charge (SOC), the temperature of the hot water tank, the power of each microgrid element as well as the demand and renewable generation forecasts. By using forecasted data and by controlling the electric water heater, the strategy is able to achieve a better grid power profile while using a smaller battery than previous works, hence reducing the overall cost of the system. The strategy is tested by means of simulation with real data for one year and it is also experimentally validated in the microgrid built at the Renewable Energy Laboratory at the UPNA.
Open Access
State-of-charge-based droop control for stand-alone AC supply systems with distributed energy storage
(Elsevier, 2015) Urtasun Erburu, Andoni; Sanchis Gúrpide, Pablo; Marroyo Palomo, Luis; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The droop method is an advantageous technique for stand-alone AC supply systems, allowing for power sharing among various inverters with no need for communication cables. However, in stand-alone systems with multiple distributed energy storage units, the conventional droop methods are unable to control the storage unit state-of-charge (SOC) in order to change simultaneously. Existing techniques endeavor to solve this problem by changing the slope of the P – f curve however this solution compromises the power response performance. As an alternative, this paper proposes a new SOC-based droop control, whereby the P – f curve is shifted either upwards or downwards according to the battery SOC. The proposed technique makes it possible to select the time constant for the battery SOC convergence and, at the same time, to optimize the power response performance. The paper also shows how the SOC changes when the ratios between the battery capacity and the inverter rated power are different and how the proposed technique can limit the SOC imbalance. Simulation and experimental results corroborate the theoretical analysis.
Open Access
On the testing, characterization, and evaluation of PV inverters and dynamic MPPT performance under real varying operating conditions
(Wiley, 2007) Sanchis Gúrpide, Pablo; López Taberna, Jesús; Ursúa Rubio, Alfredo; Gubía Villabona, Eugenio; Marroyo Palomo, Luis; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
The increasing number of photovoltaic inverters that are coming on to the PV marketstresses the need to carry out a dynamic characterization of these elements and theirmaximum power point tracking (MPPT) algorithms under real operating conditions.In order to make these conditions repeatable at the laboratory, PV array simulatorsare used. However, actual simulators, including the commercial simulators, recreateonly a single or small set of PV array characteristic curves in which quite commonlytheoretical calculations are included in order to simulate irradiance and temperatureartificial variations. This is far from being a recreation of the real and long dynamicbehavior of a PVarray or generator. The testing and evaluation of the performance ofPV inverters and MPPT algorithms has to be carried out when the PV system movesdynamically according to real operating conditions, including processes such asrapidly changing atmospheric conditions, partial shadows, dawn, and nightfall. Thispaper tries to contribute to the analysis of this problem by means of an electronicsystem that both measures the real evolution of the characteristic curves of PVarraysat outdoor operation and then recreates them at the laboratory to test PV inverters.This way the equipment can highlight the different performances of PV inverters andMPPT techniques when they operate under real operating conditions. As an example,two commercial inverters are tested and analyzed under the recreated behavior of aPV generator during 2 singular days that include processes of partial shading and fastirradiance variations.
Open Access
Influence of control in cycling degradation when batteries perform PV ramp-rate control
(IEEE, 2023) González Moreno, Alejandro; Marcos Álvarez, Javier; Parra Laita, Íñigo de la; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This work studies the importance of the correct selection of control parameters in order to avoid unnecessary cycling in batteries when they perform PV smoothing. The classic ramp-rate control method (CRRC) is studied as smoothing technique and the key role of the state of charge (SOC) control is analyzed for a real 38.5 MW PV plant, particularly the influence of proportional gain (K). Depending on K, battery cycling degradation (CyD), power requirements, SOC limits and throughout energy performance were discussed. According to the results, the correct tuning could prolong battery lifespan by reducing cycling degradation up to 80% (depending on the fluctuation restrictions and K) and avoiding unnecessary energy losses, power requirements and undesirable SOC operation levels. Finally, a simple general rule is proposed to set K value when CRRC is used and its applicability is tested by simulating two additional PV plants with rated power of 1.1 and 75.6 MW.
Open Access
The potential of forecasting in reducing the LCOE in PV plants under ramp-rate restrictions
(Elsevier, 2019) Cirés Buey, Eulalia; Marcos Álvarez, Javier; Parra Laita, Íñigo de la; García Solano, Miguel; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
An increasing number of grid codes are requiring the limitation of the PV output power fluctuation over a given time scale. Batteries represent the most obvious solution to smooth power fluctuations, with the corresponding negative impact on the PV energy cost. However, short-term forecasting is currently being proposed as a tool to reduce battery capacity requirements or even completely remove it. Although these solutions decrease or avoid the battery cost, it also entails some energy curtailment losses which obviously raise the final cost of PV energy. This energy losses, currently unknown, are independent of the forecasting accuracy and represent the minimal additional cost in the hypothetical case of a perfect prediction. Thus, this paper compares Levelized Cost of Energy (LCOE) of three ramp-rate control strategies in order to determine which would give the lowest cost: battery-based, ideal short-term forecasting, or a combination of both. Results show that curtailment losses would be small enough to make battery-less strategy an appropriate choice, so it is worthwhile improving short-term forecasting in view of the potential LCOE savings. Database is taken from high resolution measurements recorded for over a year at 8 PV plants ranging from 1 to 46 MWp.
Open Access
Boost DC-AC inverter: a new control strategy
(IEEE, 2005) Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Gubía Villabona, Eugenio; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Boost dc–ac inverter naturally generates in a single stage an ac voltage whose peak value can be lower or greater than the dc input voltage. The main drawback of this structure deals with its control. Boost inverter consists of Boost dc–dc converters that have to be controlled in a variable-operation point condition. The sliding mode control has been proposed as an option. However, it does not directly control the inductance averaged-current. This paper proposes a control strategy for the Boost inverter in which each Boost is controlled by means of a double-loop regulation scheme that consists of a new inductor current control inner loop and an also new output voltage control outer loop. These loops include compensations in order to cope with the Boost variable operation point condition and to achieve a high robustness to both input voltage and output current disturbances. As shown by simulation and prototype experimental results, the proposed control strategy achieves a very high reliable performance, even in difficult transient situations such as nonlinear loads, abrupt load changes, short circuits, etc., which sliding mode control cannot cope with.