Person:
Marroyo Palomo, Luis

person.page.identifierURI

https://academica-e.unavarra.es/handle/2454/49511

Last Name

Marroyo Palomo

First Name

Luis

person.page.departamento

Ingeniería Eléctrica, Electrónica y de Comunicación

person.page.instituteName

ISC. Institute of Smart Cities

ORCID

0000-0002-8344-8374

person.page.upna

495

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Now showing 1 - 10 of 18

Open Access
Analysis of polyamide and fluoropolymer backsheets: Degradation and insulation failure in field-aged photovoltaic modules
(John Wiley & Sons, 2022) Pascual Miqueleiz, Julio María; García Solano, Miguel; Marcos Álvarez, Javier; 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
Durability of photovoltaic (PV) modules is of great concern not only from the point of view of cost-effectiveness but also from the point of view of safety and sustainability. The backsheet of a PV module is one of the most critical parts of the PV module from the point of view of protection and also one of the most important sources of PV modules' failure; hence, it is of great importance to understand its different forms of failure. In this paper we analyze the case of an 8-MW PV plant, which had suffered a rapid degradation of their PV modules' backsheets. The case is especially relevant as all the PV modules are from the same model and manufacturer but with different backsheet materials (polyamide and fluoropolymer) and different times of exposure: on one hand, all PV modules originally installed in the plant (i.e., 6 years under operation when tested), and also, extra modules that had been stored indoors for replacement and had been mounted in the plant for less than 1 year when tested, serving as reference modules. In this paper we present the signs of degradation of these PV modules after different times of exposure under real operation using different on-field and laboratory tests. We propose different techniques for rapid diagnosis of backsheet degradation so that the problem can be detected at a very early stage, before it results in major energy losses or in safety issues.
Open Access
Modeling the inherent damping of high-power inverters
(IEEE, 2020) Erdocia Zabala, Ioseba; Urtasun Erburu, Andoni; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In order to decide whether passive or active damping is required in a three-phase inverter, a previous step is to assess the intrinsic damping of the system. However, few works focus on modeling this damping for DC/AC operation. This paper proposes two models to reproduce the damping sources: the simulation model, used to validate the system in large-signal, and the small-signal model, which can be employed for the controller design. Both models have been validated by means of experimental results for a 1.64 MVA inverter.
Open Access
Outdoor performance of a CdTe based PV generator during 5 years of operation
(IEEE, 2022) Guerra Menjívar, Moisés Roberto; Parra Laita, Íñigo de la; Marcos Álvarez, Javier; García Solano, Miguel; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Together with the huge growth of the traditional crystalline silicon (Si-x) PV manufacturers, other thin-film solar cells have also emerged such as cadmium telluride (CdTe) manufacturers. They are characterized by the fact that they were created to reduce costs and by the scarcity of silicon, from which the rest of the modules are made. Despite they need more space to generate the same amount of energy as crystalline modules, their price is supposed to be much lower, and argue that they have a better performance at high temperatures. However, real comparisons between the outdoor performance of CdTe and Si-x modules have been scarcely addressed in the literature. This paper provides a comparison under real operating conditions of a CdTe photovoltaic generator versus a conventional silicon generator during 5 years of operation in a mid-latitude area, identifying the causes of the differences observed.
Open Access
Long-term degradation rate of crystalline silicon PV modules at commercial PV plants: an 82-MWp assessment over 10 years
(Wiley, 2021) Pascual Miqueleiz, Julio María; Martínez Moreno, Francisco; García Solano, Miguel; Marcos Álvarez, Javier; Marroyo Palomo, Luis; Lorenzo Pigueiras, Eduardo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Due to high competitiveness in the PV sector, despite the low degradation rate of crystalline silicon PV modules (below 0.5%/year), it is still important for utilities to know its actual value due to its impact on energy yield and hence, profitability, over the lifetime of a PV plant. However, uncertainties related to both the influence of downtime periods due to problems that may appear under normal operation of a commercial PV plant and to the measurement of degradation rates at PV plant level make this a challenging task. In order to obtain a significant value, in this paper, three measuring methods with different uncertainty sources are used for 82 MWp of PV modules on different locations in Spain and Portugal over 10 years. According to the different methods used and PV plants analyzed, excluding PV plants with problems, a range of degradation rates between 0.01 and 0.47%/year has been found. The overall average value observed is 0.27%/year. The findings of this work have also revealed the great importance of good operation and maintenance practices in order to keep overall low degradation rates.
Open Access
Inverter-based PV ramp-rate limitation strategies: minimizing energy losses
(IEEE, 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 work analyzes the reduction of power generation in strategies that regulate the PV ramp-rate by using inverter limitation. Although the operating principle implies some energy production losses, not all these losses are necessary. Three different strategies were simulated using experimental 5-second data collected throughout a year at a 38.6 MW PV plant, and their energy losses were obtained for different ramprate levels. An improvement in one of these strategies is proposed and evaluated. The main findings suggest that the proposed modification has the potential to drastically reduce annual production losses to insignificant levels. Regardless of the ramp-rate constrain, simulation results evidenced energy losses bellow 1%.
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
Effect of the inner current loop on the voltage regulation for three-phase photovoltaic inverters
(IEEE, 2020) Urtasun Erburu, Andoni; Sanchis Gúrpide, Pablo; Marroyo Palomo, Luis; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In three-phase grid-connected PV inverters, regulating the input voltage is a fundamental requirement. In order to reduce the influence of the PV non-linear behavior and ensure stability in the whole operating range, the input capacitance is currently oversized. This paper reveals the important effect of the inner current loop in the voltage stability and proposes to use a Proportional (P) controller instead of a PI controller. If tuned following the guidelines provided in this paper, the P controller makes it possible to design a stable voltage loop without increasing the input capacitance, thus reducing the converter cost.
Open Access
Control method to coordinate inverters and batteries for power ramp-rate control in large PV plants: minimizing energy losses and battery charging stress
(Elsevier, 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 presents a novel control method for multi-megawatt photovoltaic (PV) plants that is able to regulate each plant inverter and the battery system to mitigate PV power fluctuations. The proposed control method makes it possible to implement different PV ramp-rate control strategies based on the use of batteries and the limitation of inverters during positive fluctuations, which have been conceptually proposed in the specialized bibliography, but have omitted how to perform the coordination between PV generators. The dynamic model and the tuning of the control parameters are presented and the method is used to correctly implement different inverter-limitation strategies using 5-second data from a real 45 MWp PV plant. Furthermore, a new control strategy is proposed. This strategy reduces curtailment losses to negligible values and takes into account and addresses the intrinsic asymmetry in the battery charging and discharging capability, an issue that has been overlooked in the specialized bibliography. The results show that the proposed control method can effectively control each of the multiple inverters in order to obtain the desired PV plant operation to regulate the battery charging power, even during highly fluctuating scenarios.
Open Access
Enhancement of the voltage control response in three-phase photovoltaic inverters with small dc capacitors
(IEEE, 2023) Urtasun Erburu, Andoni; Sanchis Gúrpide, Pablo; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In the case of photovoltaic (PV) inverters, an adequate dc voltage regulation is fundamental to maximize or limit the power injected into the grid. However, the traditional control requires a large dc capacitance to ensure stability in the whole operating range while the existing alternatives, despite achieving a stable control with a small capacitance, become too slow in the open-circuit area. This paper proposes two control methods to improve this performance. Firstly, a new voltage control with virtual impedance emulation is presented, showing that the response becomes faster in all operating points. Secondly, the control with impedance emulation is combined with a feed-forward compensation, further improving the dynamic response. Both methods are very simple to implement and their superior performance when using a small dc capacitance is verified by means of simulation results.
Open Access
Dual voltage-current control to provide grid-forming inverters with current limiting capability
(IEEE, 2021) Erdocia Zabala, Ioseba; Urtasun Erburu, Andoni; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The rapid uptake of renewable energy sources is causing synchronous generators (SG) to be replaced by power electronic inverters meaning these inverters need to offer the characteristics traditionally associated with SG. As a result, it has been proposed that the inverters should be controlled in grid-forming mode in order to support the voltage of the microgrids. Given that these inverters are controlled as a voltage source, temporary events such as short-circuits or overloads could cause currents that are far higher than the rated current. As the semiconductors used in power electronics are highly sensitive to overcurrents, this paper proposes a dual voltage-current control that provides the grid-forming inverters with the capability to quickly limit the current under any overload or short-circuit condition. The proposed method has been validated through experimental tests in stand-alone mode.