NUEVAS TOPOLOGIAS DE CONVERSION, CONFIGURACIONES Y ESTRATEGIAS DE CONTROL PARA LA FUTURA RED ELECTRICA BASADA EN ENERGIAS RENOVABLES

PID2019-110956RB-I00

Nombre agencia financiadora Agencia Estatal de Investigación
Acrónimo agencia financiadora AEI
Programa Programa Estatal de Generación de Conocimiento y Fortalecimiento Científico y Tecnológico del Sistema de I+D+i
Subprograma Subprograma Estatal de Generación de Conocimiento
Convocatoria Proyectos I+D
Año convocatoria 2019
Unidad de gestión Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020
Centro beneficiario UNIVERSIDAD PUBLICA DE NAVARRA
Identificador persistente http://dx.doi.org/10.13039/501100011033

Publicaciones

Found(s) 6 result(s)
Found(s) 1 page(s)

Sub-synchronous resonance damping control strategy for DFIG wind turbines

Academica-e. Repositorio Institucional de la Universidad Pública de Navarra
  • 0000-0002-0192-3814
  • 0000-0002-0067-1715
  • 0000-0002-8940-2422
  • Burgos, Rolando
Doubly-fed induction generator (DFIG) wind turbines connected to capacitive series-compensated transmission lines are prone to exhibit oscillatory behavior. The phenomena is called sub-synchronous resonances (SSRs), as these oscillations occur at frequencies below the fundamental component. This paper first develops a modeling methodology for DFIG wind turbines, based on impedance matrices, that is applied to model a real wind farm where SSRs were reported. The stability analysis performed shows how the interaction between the grid-side converter and the rotor-side converter contribute to the instability of DFIG wind energy conversion systems connected to series compensated grids. With this model, we propose a simple sub-synchronous resonance control strategy based on an orthogonal proportional action applied to the rotor currents, and a variable gain in the PI controller adjusted as a function of the DFIG rotational speed. This control strategy depends only on the rotor currents, which are local and already measured variables in any DFIG wind turbine, and is implemented in the rotor side converter, so it does not imply an additional cost at wind farm or wind turbine level and can be applied to any DFIG wind energy conversion system (WECS). Additionally, it proves to be robust for any line impedance series compensation level, and it does not need real-time information concerning the grid at which the wind turbine is connected, or its parameters. A real case study is considered, where the sub-synchronous resonance damping strategy presented in this work is able to stabilize the system for every possible line impedance compensation level., This work was supported by the Agencia Estatal de Investigacion (AEI) (Spanish State Research Agency) under Grant PID2019-110956RB-I00/AEI/10.13039 and Grant DPI-2016-80641-R.




Grid-forming control for high-power inverters, Técnicas de controles grid-forming para inversores de alta potencia

Academica-e. Repositorio Institucional de la Universidad Pública de Navarra
  • Erdocia Zabala, Ioseba
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., The present environmental crisis is driving the increase in demand for renewable sources and energy storage systems. The connection of these generation units, made through high-power inverters to minimize costs, is leading to the total replacement of synchronous generators, giving rise to the more frequent appearance of high-power inverter-based microgrids that can work tied to the main grid, islanded or in both operating modes. In this scenario, electronics inverters can no longer be controlled in grid-following mode since their performance as current sources would compromise the stability of the power systems. To avoid this, the concept of controlling the inverters in grid-forming mode has been proposed, in such a way that they perform as voltage sources, always contributing to the maintenance of frequency and voltage and having capability of working under stand-alone mode.
This thesis aims to develop grid-forming control strategies for high-power inverters. The main objective is to design and implement techniques that permit ensuring the reliable operation of grid-forming inverters at all possible conditions. Therefore, the following issues are addressed:
• Modeling of the inherent damping of high-power inverters to robustly design the control loops.
• Development of a method that provides the single-loop voltage control, generally implemented in high-power inverters, with an overcurrent limiting capability.
• Stability analysis of inverter-based microgrids when using the conventional droop control as grid-forming strategy.
• Design of a frequency droop control that guarantees the transient stability of inverter-based microgrids in stand-alone mode in the presence of overloads or short-circuits.
• Design of a frequency droop control that enhances the transient stability of grid-forming inverters in grid-connected mode under voltage dips., This thesis has been funded by the Public University of Navarre through a PhD scholarship. The company Ingeteam Power Technology has supported economically and technically this project under OTRI contracts 20200901027 and 2018901116. Moreover, the Spanish State Research Agency (AEI) and FEDER-UE have supported the investigation under grants PID2019-110956RB-I00 and DPI2016-80641-R., Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011), Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)




Toroidal inductor design in multilevel DC-DC electric vehicle battery charger including high-frequency effects

Academica-e. Repositorio Institucional de la Universidad Pública de Navarra
  • 0000-0002-6993-0631
  • 0000-0001-7671-4032
  • 0000-0002-1201-4827
Inductor filters, such as the ones implemented in
DC-DC buck-boost converters for electric vehicle chargers,
have a major impact on the converter weight, volume and cost.
Thus, their design is key in order to obtain an optimal design of
the whole converter. This paper proposes a design methodology
for powder core toroidal inductors, which is based on a holistic
approach of the design of the inductor, where losses due to highfrequency effects are computed by means of specific loss model
for toroidal windings, and saturation, geometrical and thermal
constraints are considered. The convenience of the design tool is
shown through an analysis over a wide variation of parameters,
including converter topology, parallelization, switching
frequency and inductance. The analysis demonstrates the
relevance of high-frequency effects on the inductor design, so
certain misconceptions can be avoided, such as that the inductor
volume monotonically decreases when the inductance value is
decreased or that paralleling inductors always results in more
compact designs. A design example is presented for a 15-kW,
three-level electric vehicle battery charger. The algorithm is
used to obtain an optimal design of the converter, including the
inductors and SiC MOSFET devices. Finally, an easy method to
obtain a commercial inductor design from the theoretical one
provided by the algorithm is presented., This work was supported by the Spanish State Research Agency (AEI) under grant PID2019-110956RB-100 and by the Public University of Navarre (UPNA) under a PhD scholarship.




Deadbeat voltage control for a grid-forming power converter with LCL filter

Academica-e. Repositorio Institucional de la Universidad Pública de Navarra
  • 0000-0002-0192-3814
  • 0000-0002-5927-1388
  • 0000-0002-0067-1715
  • 0000-0002-8940-2422
  • Pérez, Marcelo A.
Grid-forming power converters are controlled as voltage sources to regulate the grid voltage and frequency. These converters can increase power system strength if they impose a voltage waveform resilient to grid transients. For this reason, in this paper, we propose a deadbeat control strategy of the capacitor voltage for high power converters with LCL filter. To damp the LCL resonant poles, an active damping strategy is developed, based on a modification of the deadbeat control law. With this purpose, a notch filter is applied to the electrical variables allowing to emulate different damping resistances for the fundamental component and the harmonics. As a result, the active damping does not introduce tracking errors of the fundamental frequency component, while it provides damping to the filter resonance. The proposed strategy does not require knowledge of the grid impedance, an interesting feature in grid-connected power converters because the grid impedance is generally unknown. Experimental results validate the proposed strategy., This work was supported in part by Spanish State
Research Agency (AEI) under Grants PID2019-110956RB-I00 /AEI/ 10.13039
and TED2021-132604B-I00, in part by the Spanish Ministry of Universities
through “Programa Estatal de Promoción del Talento y su Empleabilidad en
I+D+i, Subprograma Estatal de Movilidad, del Plan Estatal de Investigación
Científica y Técnica y de Innovación 2017-2020” Program, in part by the
Advanced Center for Electrical and Electronics Engineering (AC3E) under Grant
ANID/FB0008, in part by Solar Energy Research Center (SERC) under Grant
ANID/FONDAP/15110019, and in part by the ANID/Fondecyt under Regular
Grant 1211826.




Selective harmonic mitigation: limitations of classical control strategies and benefits of model predictive control

Academica-e. Repositorio Institucional de la Universidad Pública de Navarra
  • 0000-0002-5927-1388
  • 0000-0002-0192-3814
  • 0000-0002-0067-1715
  • 0000-0002-8940-2422
Selective harmonic mitigation pulsewidth modulation (SHMPWM) combined with model predictive control (MPC) is a promising approach for grid-connected power converters. SHMPWM can guarantee grid code compliance in steady state, e.g. grid harmonic injection, with a reduced output converter filter, while MPC improves dynamic response and allows grid code compliance in the event of grid transients. This paper presents a survey of the MPC strategies already published in the literature developed for their use with SHMPWM. The existing strategies fall into two categories: direct model predictive control with an implicit selective harmonic mitigation modulator, and direct model predictive control based on finite control set (FCS-MPC). One representative control strategy of each group is compared to each other and to the performance of classical proportional- integral (PI) controllers combined with SHMPWM. The goal is to identify the potential benefits of MPC for grid-connected power converters, and determine the main advantages and limitations of the two selected state-of-the-art control strategies. Their performance is assessed through Hardware-in-the-Loop (HIL) experimental results in terms of real-time implementation, harmonic content grid code compliance, dynamic response and performance under grid transients., This work is part of the projects PID2019-110956RB-I00 and TED2021-
132604B-I00, funded by MCIN/AEI/10.13039/501100011033 and by the European
Union NextGenerationEU/PRTR. It has also been partially supported
by Ingeteam Power Technology and the Public University of Navarre.




Asymmetrical firing angle modulation for 12-pulse thyristor rectifiers supplying high-power electrolyzers

Academica-e. Repositorio Institucional de la Universidad Pública de Navarra
  • Iribarren Zabalegui, Álvaro
  • 0000-0001-7671-4032
  • 0000-0002-6993-0631
  • 0000-0002-1201-4827
  • 0000-0001-6240-8659
This paper presents an asymmetrical firing angle modulation strategy for 12-pulse thyristor rectifiers aimed at supplying high-power electrolyzers, which allows to reduce the size of the passive filter and the static compensator (STATCOM) required to comply with grid harmonic regulations and achieve unity power factor. Usually, 12-pulse thyristor rectifiers follow a symmetric modulation strategy in which the same firing angle is applied to both 6-pulse bridges. In this case, large passive ac-side inductances are required to reduce grid current harmonics, which increase the reactive power consumption and thus the required STATCOM size. However, this paper demonstrates that by applying different firing angles to the two 6-pulse bridges it is possible to comply with the harmonic regulation limits using smaller filtering inductances and therefore reducing the STATCOM size. The methodology to find the optimal firing angle values that should be applied in order to minimize the filtering inductance and the STATCOM size for a given electrolyzer is explained. This strategy is validated by simulation, and results show that the required filtering inductance and the apparent power of the STATCOM can be effectively reduced by 62% and 31%, respectively, using this asymmetrical firing angle modulation., This work is part of the projects PID2019-110956RB-I00 and TED2021-132604B-I00, funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR. It has also been supported by Ingeteam Power Technology.