http://hdl.handle.net/11531/4153 WorkingPaper, ponencias invitadas y contribuciones en congresos no publicadas 2026-04-26T17:15:10Z http://hdl.handle.net/11531/109708 Título : Dynamic Analysis of Grid-Forming Control Strategies under High RoCoF Conditions Autor : Wagh, Chinmayi Mukund; Avila Martinez, Regulo Enrique; Rouco Rodríguez, Luis; Guillaud, Xavier; García Cerrada, Aurelio Resumen : ; The increasing penetration of inverter-based resources reduces system inertia, increasing the sensitivity of system frequency to power imbalances and potentially leading to higher rates of change of frequency (RoCoF) during disturbances. Nowadays, grid-forming (GFM) converter control strategies are being required to provide inertial support in low-inertia networks. Very often these strategies imitate the behaviour of a synchronous machine (virtual synchronous machines, or VSMs). This paper compares the dynamic behaviour of three approaches to a VSM using electromagnetic transient simulations of a converter connected to an infinite bus: (a) a virtual synchronous machine with a phase-locked loop (VSM-PLL), (b) an integral–proportional (IP) control, and (c) a virtual synchronous machine with a washout filter (VSM-washout). The inertial active-power response of these strategies is evaluated under severe frequency ramp conditions within the operational capability limits of the generation unit. The results show that IP and VSM-PLL provide effective inertial support without compromising stability, whereas VSM-washout exhibits higher sensitivity to parameter tuning, leading to a less favorable trade-off between inertial power injection and damping. http://hdl.handle.net/11531/109707 Título : Beyond Carbon Pricing: Policy-Driven Willingness to Pay for e-Fuels in EU Shipping Autor : Serna Zuluaga, Santiago; Gerres, Timo; Cossent Arín, Rafael Resumen : The decarbonization of maritime transport requires alternative fuels that are not only technically viable but also economically competitive. We quantify economic competitiveness through the willingness-to-pay (WTP), defined as the maximum e-fuel price at which ship operators remain cost-neutral relative to fossil alternatives. Using this framework, we assess how two EU regulations — the EU Emissions Trading System (EU ETS) and FuelEU Maritime— shape the economic case for e-fuel adoption.Our results show that FuelEU Maritime is the dominant regulatory driver, accounting for 70–80% of total WTP, while the EU ETS contribution is comparatively modest. Beyond this, the non-linear structure of the FuelEU Maritime non-compliance penalty causes WTP to vary with the vessel’s compliance level—defined as the share of low-emission fuel required to meet the GHG emission intensity target in a given year. Consequently, the marginal value of e-fuel is not constant: early units yield smaller penalty reductions than later ones. For instance, in 2050, a compliance level of 50% reduces the non-compliance penalty by only 16%. This structure inherently favors full compliance in individual vessels over partial compliance across fleets, even when aggregate emission reductions are equivalent.When benchmarking the obtained WTP against current production costs, our results suggest that existing regulation largely bridges the cost gap for most e-fuels, with ammonia emerging as the most cost-competitive option. Although biofuels and fossil fuels with carbon capture may offer lower production costs at comparable WTP levels, but their large-scale deployment faces binding supply-side constraints. E-fuels are therefore expected to play a complementary yet critical role in achieving long-term decarbonization targets as lower-cost alternatives become increasingly scarce.; The decarbonization of maritime transport requires alternative fuels that are not only technically viable but also economically competitive. We quantify economic competitiveness through the willingness-to-pay (WTP), defined as the maximum e-fuel price at which ship operators remain cost-neutral relative to fossil alternatives. Using this framework, we assess how two EU regulations — the EU Emissions Trading System (EU ETS) and FuelEU Maritime— shape the economic case for e-fuel adoption.Our results show that FuelEU Maritime is the dominant regulatory driver, accounting for 70–80% of total WTP, while the EU ETS contribution is comparatively modest. Beyond this, the non-linear structure of the FuelEU Maritime non-compliance penalty causes WTP to vary with the vessel’s compliance level—defined as the share of low-emission fuel required to meet the GHG emission intensity target in a given year. Consequently, the marginal value of e-fuel is not constant: early units yield smaller penalty reductions than later ones. For instance, in 2050, a compliance level of 50% reduces the non-compliance penalty by only 16%. This structure inherently favors full compliance in individual vessels over partial compliance across fleets, even when aggregate emission reductions are equivalent.When benchmarking the obtained WTP against current production costs, our results suggest that existing regulation largely bridges the cost gap for most e-fuels, with ammonia emerging as the most cost-competitive option. Although biofuels and fossil fuels with carbon capture may offer lower production costs at comparable WTP levels, but their large-scale deployment faces binding supply-side constraints. E-fuels are therefore expected to play a complementary yet critical role in achieving long-term decarbonization targets as lower-cost alternatives become increasingly scarce. http://hdl.handle.net/11531/109694 Título : Mejora del Comportamiento de Convertidores Grid-Following mediante Compensadores Síncronos: Validación Experimental en el LIDER Lab Autor : Suárez Porras, Jorge; Fernández Bernal, Fidel; Rouco Rodríguez, Luis; Tomás Martín, Andrés; García Cerrada, Aurelio; Bueno Peña, Emilio José Resumen : Los sistemas de potencia modernos enfrentan una reducción drástica de inercia y rigidez de red debido a la masiva integración de Recursos Basados en Inversores (IBRs). En este contexto, los convertidores con seguimiento de red (grid-following, GFL) que utilizan lazos de seguimiento de fase (PLL) son propensos a inestabilidad y bajo amortiguamiento ante condiciones de red débil o cambios súbitos de carga. Este artículo presenta la validación experimental de la interacción entre generación síncrona, convertidores GFL y compensadores síncronos (SC) en el entorno del laboratorio LIDER Lab (Laboratorio de Innovación y Desarrollo de Energías Renovables). Se combina el análisis de estabilidad de pequeña señal (autovalores y factores de participación) con pruebas experimentales de gran señal. Los resultados confirman que la conexión de un compensador síncrono no solo reduce el nadir de frecuencia ante escalones de carga, sino que mejora significativamente el amortiguamiento de la frecuencia medida por el PLL, mitigando el riesgo de pérdida de sincronismo.; http://hdl.handle.net/11531/109672 Título : Too many or too few? Evaluating AFIR’s distance rule against demand-driven hydrogen refuelling networks Autor : Pérez Bravo, Manuel; Serna Zuluaga, Santiago; Cossent Arín, Rafael; Linares Llamas, Pedro Resumen : ; The economic viability of hydrogen fuel-cell trucks (FCETs) depends critically on the levelised cost of hydrogen supply (LCOSH), which falls sharply with station utilization rate. Yet the Alternative Fuels Infrastructure Regulation (AFIR) mandates one refuelling station every 200 km along the TEN-T Core network irrespective of local demand density, risking systematic under-utilisation and inflated hydrogen costs in low-demand corridors. This paper develops a Mixed-Integer Programme (MIP) on the Spanish road network that jointly minimises station investment, hydrogen procurement, and operator detour costs, explicitly capturing real network routing, non-linear economies of scale, and the operating cost of truck operators (OPEX). The model yields optimal networks ranging from 15 large, high-throughput stations at low NFOC to 76 smaller, dispersed ones at high OPEX, with mean LCOSH spanning 8–12 EUR/kg accordingly. Comparing the unconstrained optimum against a greedy AFIR-compliant network (32 stations) and a hybrid scenario that fixes urban TEN-T nodes while optimising the remainder, we find that the pure distance rule imposes a social-cost premium of 5–25% depending on operator running costs, whereas the hybrid scenario consistently recovers most of this loss, holding the premium to 5–12%. Looking ahead, the ongoing transition toward vehicle automation is expected to reduce non-fuel running costs substantially, shifting the efficient network toward fewer, larger, and more concentrated stations, which reinforces the case for demand-driven siting over uniform distance rules. Supplementing AFIR with a minimum-throughput criterion and demand-aggregation instruments would align infrastructure deployment with both current economic realities and the trajectory of an increasingly automated freight sector.