Power electronics group

The power electronics group uses the power electronics facilities in order to work with industry and offer educational activities such as the power electronics and smart grids courses. In addition, researchers from the power electronics group perform their studies using the modern equipment.

Main activities are

Latest projects in collaboration with industry:

Design of power electronic testbench for Vanadium Redox Flow Batteries (in the frame of HyFlow 2020-2023)

In the frame of an European project H2020, HyFlow, the team in the power electronics laboratory is developing a test bench for testing and cycling a Vanadium Redox Flow Battery. https://hyflow-h2020.eu/. The test bench consists of a bidirectional DC/DC converter which can deliver and absorb more than 120A. The main idea is to perform the polarization curves and  other dynamic tests.

Main participants: Mr. Adrien Rosselet, Mr. Yaroslav Vlasor, MSc. Ildar Idrisov and Prof. Ibanez.

Development of open-source inverters in collaboration with Prof. P. Vorobev for industrial project with Rossetti (2020-2021)

photo_2021-09-29_18-09-24 Design, development and test of three fully-controlled inverters for working in grid-forming and grid-following modes.Main participants:  Mr. Yaroslav Vlasov, MSc. Ildar Idrisov,  Prof. Ibanez, Prof. Vorovev.yaroslav1

 

Design of advanced control algorithms for Watts battery company (2020)

Advanced control systems were developed for the home uniterruptible power supply which Watts battery produces, in the frame of single-phase grid-inverter. Advanced digital signal processors were using for that purpose.Main participants: MSc. Ildar Idrisov and Prof. Ibanez. main_img-1522x1080-1-e1582761634532

 

 

Research activities

The research activities are divided in;

– Master thesis

– PhD and researchers activities

The master theses can be found here. There you can find a short description of the activities and links to further information including articles and conference papers. The research activities of PhD students and researchers can be found below.

 

 – “Multi modular converters”, from 2019 and ongoing, Mr. Fernando Davalos

foto2a Mr. Davalos has been working in low voltage multi-modular converters for supercapacitors. He was researching and developing an efficient low-voltage cell that can be connected in series or in parallel in order to create an energy storage system for AC grids or DC grids. The module is totally independent, it includes the storage device, the balancing system and the power conversion.

- “Flexibility quantification of thermostatically controlled loads for demand response applications”, 2019-2021, Mrs. Victoria Gasca, Prof. Ibanez

vicky vick1 Mrs. Victoria Gasca has been exploring the flexibility of the thermal heaters in a distributed system in order to provide services to the grid. Particularly, she focused her attention in grid frequency regulation.  Her research has been recently published in:María Victoria Gasca, Federico Ibáñez, David Pozo, “Flexibility quantification of thermostatically controlled loads for demand response applications,” Electric Power Systems Research, Volume 202, 2022, 107592,
ISSN 0378-7796, https://doi.org/10.1016/j.epsr.2021.107592.

 

Abstract

The need for flexible networks is an emerging challenge for power system operators (SO). The use of additional support, such as demand response (DR), must be quantified in order to offer a reliable service, given that this information is vital for demand aggregators. Thermostatically controlled loads (TCLs) are one of the most promising options among DR solutions; due to TCLs’ thermal characteristics their power may be increased or reduced accounting as ancillary services. However, TCLs tend to synchronize their behavior, which may affect their capacity to provide flexibility.

This paper proposes a method for quantifying TCLs’ power flexibility, taking into account different scenarios, types of controllers and loads. Two control methods are compared, and a modified control algorithm is applied to the controllers under analysis to avoid TCL synchronization. The analysis was validated by simultaneously using real demand data from the UK National Grid and temperature data for the same region and time frame.

 

 

- “Asymmetric Cascaded Multilevel Converter”, 2019-2021, Mr. Rahim Samanbahksh, Prof. Ibanez

z-1 Mr. Rahim Samanbahksh is currently working in a new type of Z-source converter for energy storage. Z-source converters has many advanteges in comparison with traditional converters. They can work as step-up or step-down converters, can tolerate short circuits and can deliver AC or DC signals. Rahim is focused on minimizing the in-rush current and the harmonic distortion when the Z-source converter works as an inverter.

 

 

- “Asymmetric Cascaded Multilevel Converter”, 2019-2021, Mr. Rahim Samanbahksh, Prof. Ibanez

Mr. Rahim Samanbahksh has been studied a new type of multilevel converter that can reach up to 15 leves using a single module and if cascaded, it can reack 127 levels, minimizing the signal distortion and allowing to work at very low switching frequencies, even grid frequencies. His work was recently published in IEEE Access:R. Samanbakhsh, F. M. Ibanez, P. Koohi and F. Martin, “A New Asymmetric Cascaded Multilevel Converter Topology With Reduced Voltage Stress and Number of Switches,” in IEEE Access, vol. 9, pp. 92276-92287, 2021, doi: 10.1109/ACCESS.2021.3092691. rahim2

Abstract:

This paper presents a new structure of a multilevel inverter with fewer components, which is suitable for renewable energy sources and industrial loads applications. The structure has three unequal input sources and ten switches that can generate a 15-level output voltage. Furthermore, it can be connected in cascade for increasing, even more, the number of levels and output voltage. The main feature of the proposed inverter is its very low harmonic distortion at the output voltage and current due to the control method, which is based on the nearest level control method for generating a high-quality output voltage. A typical application of this inverter is in solar cells and wind turbines. Both simulations in Matlab/Simulink and experimental results in a scaled-down prototype validate the proposed theoretical analysis.

- “Design Balancing Systems for Supercapacitors Based on Their Stochastic Model”, 2019-2020, Prof. Ibanez

balancings Prof. Ibanez has been working in the design of balacing systems for supercapacitors considering the manufacturer’s tolerances. He analyzed two types of balancing methods: passive and active systems. Details are given in:F. Martin Ibanez, I. Idrisov, F. Martin and A. Rujas, “Design Balancing Systems for Supercapacitors Based on Their Stochastic Model,” in IEEE Transactions on Energy Conversion, vol. 35, no. 2, pp. 733-745, June 2020, doi: 10.1109/TEC.2020.2968364.

Abstract:

This article analyzes a stochastic supercapacitor model and uses the model to estimate the losses for different balancing methods. In addition, it proposes guidelines for designing a supercapacitor bank that includes balancing networks. Supercapacitors (SCs) can be used as the main part of an energy storage system (ESS) that transfers high power to a DC or AC grid. This is needed in grids with a high penetration of renewable energies in order to balance generation and consumption. The design method is based on a supercapacitor model which uses stochastic variables: capacitance, series resistance and self-discharge current. As the balancing network affects the overall efficiency of the SC bank, dissipative and non-dissipative balancing networks are studied. Then different strategies are compared taking into account the complexity, cost and efficiency of the balancing network in the bank.

 

 – “Improvements on signal-to-noise ratio in feedback measurement in DC/DC converters”, 2020, Mr. Fernando Davalos, Prof. Ibanez

Mr. Davalos and Prof. Ibanez have been researching on measurements units at high voltage. A method to increase the signal-to-noise ratio is performed by developing a HV reference. Details can be found in:F. D. Hernandez, F. Ibanez, S. Gutierrez and W. Martinez, “Improvements on signal-to-noise ratio in feedback measurement in DC/DC converters,” 2020 22nd European Conference on Power Electronics and Applications (EPE’20 ECCE Europe), 2020, pp. 1-10, doi: 10.23919/EPE20ECCEEurope43536.2020.9215774. img_20200316_180809

Abstract:

This paper presents different techniques for sensing the feedback signals of isolated DC/DC converters. The paper compares the traditional measuring chain with two other options that improve the signal-to-noise (SNR) significantly. A theoretical analysis and experimental tests are presented. The results indicate that, with this SNR improvement.

- “Hybrid energy storage systems”, 2018-2020, Prof. Ibanez

Prof. Ibanez has been working in hybrid storage systems by combining supercapacitors and batteries using DC/DC converters. The selected topology is called semi-active hybrid storage system where only one energy storage device is under control. Prof. Ibanez has focused his studies in the control of the battery current in order to improve the performance of the storage system, while the supercapacitors deliver high power pulses. Details of his research can be found in:F. M. Ibanez, A. M. Beizama Florez, S. Gutiérrez and J. M. Echeverrría, “Extending the Autonomy of a Battery for Electric Motorcycles,” in IEEE Transactions on Vehicular Technology, vol. 68, no. 4, pp. 3294-3305, April 2019, doi: 10.1109/TVT.2019.2896901. dav

- “Bidirectional Series Resonant DC/AC Converter for Energy Storage Systems”, 2017-2018, Prof. Ibanez

picture2 Prof. Ibanez has beed developing a bidirectional inverter using resonant techniques. It combines a resonant dual active bridge with a single phase inverter in order to avoid the inverter stage in an energy storage system.The results and details are published in:F. M. Ibanez, “Bidirectional Series Resonant DC/AC Converter for Energy Storage Systems,” in IEEE Transactions on Power Electronics, vol. 34, no. 4, pp. 3429-3444, April 2019, doi: 10.1109/TPEL.2018.2854924.

 

Abstract:

This paper presents a novel bidirectional series resonant converter for energy storage systems (ESS). Conversion between a dc energy storage device and an ac grid has grown in importance because of the renewable energy generators and ESS used in microgrids, which usually use batteries or supercapacitors as storage devices in order to provide different services and improve the quality and reliability of the grid. This novel converter avoids the need to have two converting stages: one for converting the energy from the storage device to a regulated dc value, and the other for converting the regulated dc to the ac output. Conversion occurs via a modified dc/dc dual-bridge series resonant converter. The output bridge of the converter is attached to the input bridge through a resonant branch and a high frequency (HF) transformer, and it is also attached to the ac link through an output filter. Therefore, two ac power signals are mixed in the output bridge: a HF signal, which maintains the dc link capacitor voltage, and a low frequency power signal, which transfers energy to the grid. This paper details the different working modes of the converter and presents a 3000 W prototype that validates the design.