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Erdocia Zabala, Ioseba

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Erdocia Zabala

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Ioseba

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Ingeniería Eléctrica, Electrónica y de Comunicación

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811458

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Now showing 1 - 7 of 7
  • PublicationOpen Access
    Conductance-frequency droop control to ensure transient stability of inverter-based stand-alone microgrids
    (Elsevier, 2023) 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
    Currently, inverter-based stand-alone microgrids are gaining interest due to the advantages of obtaining energy from renewable sources. To manage the operation, these microgrids include storage systems connected in par- allel to the PCC through electronic inverters that are controlled as voltage sources in order to support the fre- quency and voltage at the PCC. For the purpose of ensuring P and Q sharing among inverters and also the synchronization stability of the microgrid, droop control is widely used, achieving a satisfactory performance in normal operation. Nevertheless, in the presence of overloads or short-circuits, the inverters must limit the current for self-protection, thereby modifying the performance of the system that then becomes prone to suffer transient stability problems. In this paper, first the performance of the inverter-based stand-alone microgrids with the conventional P-f and Iact-f droops is analyzed, obtaining the stability boundaries during current limitation. In order to always ensure the synchronization stability of the system, this paper then proposes the G-f droop that consists in employing the equivalent conductance seen by each inverter for its frequency droop control. Furthermore, as this variable always correctly represents the inverter power angle, the system dynamics are not affected by the operating conditions. The theoretical results have been validated by means of simulation and Hardware-In-the-Loop results, showing the superior performance of the proposed G-f droop
  • PublicationOpen 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.
  • PublicationOpen 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.
  • PublicationOpen Access
    Estrategias de operación de centrales eléctricas termosolares con almacenamiento
    (2015) Erdocia Zabala, Ioseba; Sanchis Gúrpide, Pablo; García-Barberena Labiano, Javier; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa
    The increase of electric power demand and the wish to protect the environment are leading to a change in the energy sources. Conventional energy plants are losing strength against the renewable energy plants and, in particular, solar energy plants have a huge potential to provide clean energy supply for the increasing world’s energy demand. Among the existing solar technologies, Concentrating Solar Power (CSP) is one of the most promising technologies. One of the major advantages of CSP plants is the technically feasible and cost-effective integration of Thermal Energy Storage (TES) systems. To increase the plant dispatchability, it is possible to create different operational strategies defining how such TES system is used. In this work, different strategies with different overall goals have been simulated over a complete year and the results are presented and compared here to demonstrate the capabilities of the operational strategies towards an increased dispatchability and plant economic effectiveness. The analysis shows that different strategies may lead to significant differences in the plant annual production, expected economic incomes, number of power block stops, mean efficiency, etc. Specifically, it has been found that the economic incomes of a plant can be increased (+1.3%) even with a decreased total energy production (-1.5%) if the production is scheduled to follow a demand/price curve. Also, dramatic reduction in the number of turbine stops (-67%) can be achieved if the plant is operated towards this objective. The strategies presented in this study have not been optimized towards any specific objective, but only created to show the potential of well designed operational strategies in CSP plants. Therefore, many other strategies as well as optimized versions of the strategies explained below are possible and will be analyzed in future works.
  • PublicationOpen 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.
  • PublicationOpen Access
    Grid-forming control for high-power inverters
    (2022) 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
    La crisis medioambiental actual está potenciando el aumento de la demanda de fuentes renovables y sistemas de almacenamiento. La conexión de estas unidades de generación, que se realiza a través de inversores de alta potencia para minimizar costes, está causando el reemplazo completo de los generadores síncronos, dando lugar a que aparezcan más frecuentemente microrredes basadas en inversores de alta potencia que pueden operar conectadas a red, aisladas o en ambos modos. En este escenario, los inversores electrónicos ya no pueden ser controlados en modo grid-following, ya que su funcionamiento como fuentes de corriente podría comprometer la estabilidad del sistema de potencia. Para evitar esto, se ha propuesto controlar los inversores en modo grid-forming, de forma que se comporten como fuentes de tensión, contribuyendo siempre al mantenimiento de la frecuencia y la tensión y siendo capaces de operar de forma aislada. Esta tesis se centra en el desarrollo de estrategias de control grid-forming para inversores de alta potencia. El principal objetivo es diseñar e implementar técnicas que permitan garantizar la operación fiable de los inversores grid-forming en cualquier condición. Por ello, se han abordado los siguientes aspectos: • Modelado del amortiguamiento intrínseco de inversores de alta potencia para diseñar los lazos de control de forma robusta. • Desarrollo de un método que proporcione al control de tensión basado en un único lazo, generalmente implementado en inversores de alta potencia, capacidad para limitar sobrecorrientes. • Análisis de estabilidad de una microrred basada en inversores cuando se utiliza el control droop como estrategia grid-forming. • Diseño de un control droop de frecuencia que garantice la estabilidad transitoria de la microgrid en presencia de sobrecargas y cortocircuitos. • Diseño de un control droop de frecuencia que mejore la estabilidad transitoria de los inversores grid-forming durante huecos de tensión.
  • PublicationOpen Access
    Single feedback regulation of the AC voltage for high-power inverters under stand-alone operation
    (IEEE, 2019) Erdocia Zabala, Ioseba; Urtasun Erburu, Andoni; Marroyo Palomo, Luis; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    Energy-storage inverters under stand-alone operation must control the output voltage. However, existing methods for instantaneous voltage regulation are not suitable for high-power inverters due to their limited sampling frequency. To avoid this problem, a single feedback voltage loop with feedforward compensation is proposed in this paper, making it possible to actively damp the LCL filter resonance and thus facilitating the controller design. Simulation results demonstrate the fast reference tracking and the high-quality voltage obtained with non-linear loads.