DC grid interface converter based on Three-phase isolated matrix topology with phase-shift modulationPietro Emiliani (ESR10)Conference paper presented at PEDG2022 |
Reactive Power Control for Bidirectional Isolated High-Frequency Link ConverterPietro Emiliani (ESR10)Conference paper presented at SPEEDAM2022 |
Comparative Evaluation of Isolated dc-dc Converters for Low Power ApplicationsMohammadreza Azizi (ESR05)Isolated dc-dc converters are particularly important for utilizing renewable energy. These converters are used for direct connection to the dc microgrid or as voltage boosters for on/off-grid ac applications. This article examines and evaluates five popular types of isolated dc-dc converters for low-power applications. In this study, by examining the performance of converters, the general equations governing these converters have been extracted. The converter components are then designed for a low-power application. Using simulations in Simulink/MATLAB, these converters have been evaluated and compared from different perspectives. Published in: 2022 IEEE 20th International Power Electronics and Motion Control Conference (PEMC) held at Transilvania University in Brasov, Romania. DOI: 10.1109/PEMC51159.2022.9962944 |
Feature of Solar Radiation Forecast Services Use for Solar PlantsMykola Lukianov (ESR06)The main purpose of the study is the review common cloudiness forecast services, uncertainty interval calculation of solar radiation for these services based on comparing with real solar radiation, estimating the opportunity of combining forecast data from several sources to minimize error and analysing the profit from the power plant using forecast services. I. Verbytskyi, M. Lukianov and R. Strzelecki, "Feature of Solar Radiation Forecast Services Use for Solar Plants," 2022 IEEE 8th International Conference on Energy Smart Systems (ESS), Kyiv, Ukraine, 2022, pp. 108-111, doi: 10.1109/ESS57819.2022.9969258. |
Black Start and Fault Tolerant Operation of Isolated Matrix Converter for dc MicrogridsPietro Emiliani (ESR10)Conference Paper presented at IECON2022 |
Digital Control of PFC Rectifier with Combined Feedforward and PI RegulatorPietro Emiliani (ESR10)Conference paper presented at IECON2022 |
Comparison of Four-Switch Buck-Boost and Dual Active Bridge Converter for DC Microgrid ApplicationsGabriele Arena (ESR08)Abstract: Attention to DC Microgrids is recently increasing, due to the expansion of DC components, such as renewable energy sources (RESs), energy storage systems (ESSs), and DC loads. There is a large number of scientific publications on different converter topologies, but only a few of them addresses a direct comparison of different DC/DC converter solution for Microgrid applications. This work presents a comparison between Four-Switch Buck-Boost and Dual Active Bridge Converters in terms of applicability to DC Microgrids, considering efficiency and short circuit behavior. |
Accuracy Analysis of Dual Active Bridge Simulations under Different Integration MethodsGabriele Arena (ESR08)Abstract: One of the biggest challenge in the power electronics field is the simulation of power converters. Computer simulations and real-time simulations are really important in this field because they allow to save money during the prototyping stage and to make the entire process more efficient by predicting possible malfunctions already in the design stage. This paper introduces the impact of using different integration methods for solving the differential equations of power converters on the accuracy of the simulation. In particular, the paper focus on one of the most adopted DC-DC converter topology for automotive and microgrid applications, which is the Dual Active Bridge. |
Performance Evaluation of a Three-Phase PV Power Plant under Unbalanced Conditions with Islanding Detection Reliability TestAnas Abdullah Alvi (ESR03)The use of renewable energy is increasing ever so highly during this modern age of technology. The use of wind, solar and hydro energy is rising rapidly in the world due to the less emissions of harmful gases in the atmosphere. Since the energy produced from these sources like wind and solar energy is increasing a lot, the use of grid connected inverters is also expanding. Deep analysis of these inverters’ operation is important when working in non-ideal situations. The main aim of this paper is to analyze the operation of a three-phase photovoltaic power plant (rated at 250 kW) supplying power to both three-phase and single-phase loads. The analysis covers both, connected and disconnected modes and also includes the performance of a basic islanding detection method considering voltage and frequency deviation of the phase locked loop (PLL) at the Point of Common Coupling (PCC) and the effect on the whole system considering unbalanced situations with different values of irradiances is observed. The novelty of this paper is to identify a case in which the islanding detection fails due to the connection of a single-phase load in the point of low voltage. |
Identification of static and dynamic parameters of PV models through multi-objective optimizationLuis Enrique Garcia Marrero (ESR11)The accuracy of photovoltaic models used to describe the characteristics of photovoltaic panels is crucial to evaluate the performance and to ensure safety, cost-effectiveness and compliance of photovoltaic systems. In particular, when the parameters for static and dynamic models are optimized independently, it has been shown that they might be not consistent across different environmental conditions. By exploiting the dependency of common parameters between the two models, the fitting problem is transformed into a multi-objective optimization problem, which is solved using evolutionary algorithms. The results showed that selecting a tradeoff solution from the Pareto front obtained, leads to a more consistent set of parameters for each environmental condition analyzed. |
Bidirectional EV Charger Integration into LV DC Traction GridMykola Lukianov (ESR06)Conference paper presented at IEEE CPE-POWERENG 2023 |
Back-to-Back Energy Router Based on Common-Ground InvertersMohammadreza Azizi (ESR05)This paper proposes an energy router based on a back-to-back structure with common-ground inverters. Connecting the neutral wire of the ac system to the negative port of the dc link eliminates leakage currents and ensures safety. The proposed energy router uses two common-ground inverters. Each inverter has five switches and has the ability to increase/decrease the voltage and operate in both directions. The operation mode of the common-ground inverter has been investigated and the simulation results using PLECS confirm the accuracy of the overall structure and benefits compared to classical H-bridge inverter. |
Challenges in photovoltaic parameter identification under mismatching conditionsLuis Enrique Garcia Marrero (ESR11)When connecting a few solar cells in series to create a photovoltaic (PV) module, even the smallest discrepancies between them are enough to create mismatch losses. Sometimes this mismatch is mainly due to the non–uniformity of the operating conditions associated with variations in irradiance or cell temperature. However, even under uniform conditions, the unavoidable dispersion of the intrinsic parameters of the cells, due to degradation and aging effects, could be a cause of mismatch because each cell, sharing the same value of current, will be polarized at a slightly different voltage. For accounting for the presence of mismatch in a series of PV cells a Double - Single Diode Model (D-SDM) is introduced in this paper. The parameters between the resulting two SDMs circuits were related to obtaining reliable and coherent characterization for different operating conditions. A robust procedure is developed for estimating its parameters and evolutionary algorithms are employed to solve the optimization problem. The proposed methodology was also validated using experimental data from a single cell of the same type as the module. |
Dynamic Modeling of Si-based Photovoltaic Modules using Impedance Spectroscopy TechniqueLuis Enrique Garcia Marrero (ESR11)In a scenario where the deployment of photovoltaic (PV) systems is increasing, the characterization and the monitoring of the state of health are pivotal. To this aim, Impedance Spectroscopy (IS) provides useful information about the dynamics of PV generators. In this work, an equivalent electric ac model for the characterization of PV modules is discussed. The model is applied to experimental spectra measured on a 52Wp c-Si based PV module in outdoor conditions. The fitting problem is solved by means of two different approaches, one based on the analytic solution of the model equations which employs few points of the experimental spectrum and the other based on an optimization algorithm, requiring the whole set of frequency points. The parameters’ values obtained from both approaches are commented, providing useful information on the behavior of the PV module under test. |
DC Fast Charging of Electric Vehicles: a Review on Architecture and Power Conversion TechnologyGabriele Arena (ESR08)Abstract: Increasing efforts have been made over the years in order to make a green energy transition possible and widespread of electric vehicles (EVs) is expected to play a key role in this regard. However, EVs require a distributed and reliable infrastructure of charging stations in order to get popularity among customers. Moreover, charging time of EVs is a crucial point that companies and researchers need to face in order to guarantee the same reliability of internal combustion engine vehicles (ICEVs). For these reasons, this paper aims to review architectures and power converters typically adopted in DC fast charging stations. |
Predictive Control for Isolated Matrix Rectifier Without Current Distortion at Sector BoundaryGabriele Arena (ESR08)Abstract: Three phase active rectifiers are needed to supply dc loads from the ac distribution grid without introducing large distortions on the ac grid. Galvanic isolation is a requirement for many applications due to safety concerns. High frequency link power conversion topologies, based on indirect matrix converters, are an emerging solution for such applications. In this paper a predictive digital control is developed for an isolated three phase ac/dc matrix converter by combining a deadbeat controller and space vector modulation. This approach simplifies the controller design and allows for full-range soft-switching with sinusoidal input currents. Due to the discrete operating sectors of high frequency link topologies, an additional modulation mode is introduced near sector boundaries, reducing the distortion caused by sector changes. The proposed deadbeat controller is validated with PSIM simulations. |
Three-Phase Four Wire High-Frequency Link Converter for Residential DC GridsGabriele Arena (ESR08)Abstract: There is increasing penetration of dc native renewable technologies, such as batteries and photovoltaics in the distribution grid. These renewable technologies can be interconnected with dc microgrids, which in turn often have a bidirectional connection with the ac distribution grid to enable energy exchange. For safety reasons, this connection is often galvanically isolated with a transformer. This paper presents a single stage high frequency link converter, based on an indirect matrix converter. A three leg four wire configuration is proposed to be able to operate in unbalanced conditions and provide various ancillary grid services. A digital controller is developed to control the grid currents and eliminate distortion at the zero crossing of the matrix converter. The results are verified with a PSIM model. |
Converter Averaging Approach for Modeling a Residential Supply SubsystemLuis Ignacio Martínez Caballero (ESR02)Conference paper presented at CPE-POWERENG 2023 |
Control Strategy of Hybrid Energy Storage System for High-Dynamic Load ChangesLuis Ignacio Martínez Caballero (ESR02)Paper submitted at CPE-POWERENG 2023 |
An Improved Three-Phase Transformerless Neutral Point Clamped Inverter Topology for Common Mode Voltage ReductionJamil Hassan (ESR01)Transformerless photovoltaic (PV) inverters are more effective, lighter in weight, and less expensive than transformer-based topologies. However, a leakage current (iLeakage) is produced when transformers are removed due to the direct connection between the PV panel and the grid. This current reduces the life of the insulation, causes safety problems, and increases the harmonic distortion in the grid current. To overcome these issues, an improved three-phase transformerless neutral point clamped (NPC) topology is proposed by employing two additional switches on the primary side of a traditional NPC inverter. This arrangement reduces the i Leakage significantly and improves the harmonic behavior of the grid current by operating the additional switches in zero switching states. Furthermore, when compared to a conventional H8 inverter, its multilevel capability reduces voltage stress on semiconductor devices. Finally, the proposed topology is validated with the help of the Simulink model in MATLAB by comparing it to a traditional three-phase H8 inverter, considering iLeakage, common-mode voltage (CMV), and the grid current total harmonic distortions (THD). |
Modular Multilevel Converters Enabling Multibus DC DistributionMahyar Hassanifar (ESR07)The modular multilevel converter (MMC) is a promising topology for enabling hybrid grids, which includes different medium- and low-voltage (MV and LV) ac and dc grids. Owing to its capability to break dc current and work in buck mode, especially, MMCs have been widely studied for MVdc applications in ac-dc hybrid grids. It has been adopted as a frontend bidirectional ac-dc converter or a dc-dc converter employing medium frequency transformers to enable ultra-fast charging stations. Furthermore, MMC can provide different levels of LVdc by expanding the topology with an additional converter, which can help to realize a multibus dc distribution grid. Finally, this property can be used to realize a solid-state transformer (SST) for hybrid grids. However, it is required to identify and characterize the merits and demerits of various MMC structures available to form multibus dc distribution systems. Therefore, in this paper, MMC-based converters proposed in the literature are classified according to the ac-dc and dc-dc conversions. In addition, expected challenges and further possibilities in using them as a multibus dc enabler are also discussed in this paper. |
A Comparative Study of Three-Phase Inverter Topologies for Common Mode Voltage Reduction in Photovoltaic ApplicationsJamil Hassan (ESR01)The popularity of photovoltaic (PV) systems has increased as the demand for renewable energy sources has risen in recent years. The inverter is an important component and has a significant impact on the overall performance of a PV system. Therefore, its topology must be chosen carefully based on the application. This paper presents a study and comparison of different inverter topologies for PV applications. The paper begins by discussing the traditional three-phase H6 inverter topology for PV systems and then reviews various inverter topologies derived from this structure for leakage current reduction. Three topologies are chosen and compared their potential for PV applications considering leakage currents and total harmonic distortions using the MATLAB/Simulink simulation model. |
Semiconductor Devices Condition Monitoring Using Harmonics in Inverter Control VariablesShuyu Ou (ESR04)The health status of power semiconductor devices in power converters is important but difficult to monitor. This paper analyzes the relationship between harmonics in inverter control variables and a health precursor (the on-state voltage V on of power semiconductor devices). Based on the analysis, harmonics can estimate V on without adding extra sensing circuits. The method is validated through simulations. |
A Data-Driven Condition Monitoring Method for Capacitor in Modular Multilevel Converter (MMC)Shuyu Ou (ESR04)Abstract The modular multilevel converter (MMC) is a topology that consists of a high number of capacitors, and degradation of capacitors can lead to converter malfunction, limiting the overall system lifetime. Condition monitoring methods can be applied to assess the health status of capacitors and realize predictive maintenance to improve reliability. Current research works for condition monitoring of capacitors in an MMC mainly monitor either capacitance or equivalent series resistance (ESR), while these two health indicators can shift at different speeds and lead to different end-of-life times. Hence, monitoring only one of these parameters may lead to unreliable health status evaluation. This paper proposes a data-driven method to estimate capacitance and ESR at the same time, in which particle swarm optimization (PSO) is leveraged to update the obtained estimations. Then, the results of the estimations are used to predict the sub-module voltage, which is based on a capacitor voltage equation. Furthermore, minimizing the mean square error between the predicted and actual measured voltage makes the estimations closer to the actual values. The effectiveness and feasibility of the proposed method are validated through simulations and experiments. |
Advancements in Photovoltaic Research: Electro-Impedance Spectroscopy for PV Cell CharacterizationLuis Enrique Garcia Marrero (ESR11)This article presents a method for characterizing the dynamic behavior of photovoltaic (PV) cells using the Electro-Impedance Spectroscopy (EIS) technique. High-precision laboratory equipment has been used to measure a single PV cell, capturing impedance (Z LB) and voltage-current (I - V ) curve characteristics. We propose a model incorporating variable capacitance and conductance behavior for describing diode impedance dynamics. The experimental IV curve and impedance measurements are used as the reference for model parameters fitting through an evolutionary algorithm. Exploiting data from a single spectral measurement at a specific operating point, the methodology enables the prediction of the IV curve and spectral impedance plot at any operating point, as long as the irradiance conditions remain constant. The experimentation in a PV cell demonstrates a strong match between the obtained real data and the mathematical model. However, it is important to note that these findings are based on controlled simulated environmental conditions in a single cell. Further testing on PV panels is required to reproduce conditions such as mismatch or partial shadowing in order to stress and test the proposed model. |
Impedance Spectroscopy for partial shading detection on series-connected PV panelsLuis Enrique Garcia Marrero (ESR11)This work investigates an improved method for detecting and simulating the effect of partial shading on photovoltaic (PV) panels by combining experimental and simulation procedures. The method entails measuring current-voltage (IV) curves and impedance spectra for two Photovoltaic (PV) panels under outdoor conditions. The shade is then recreated in one panel, and measurements are repeated to generate a dataset for adjusting a Constant Phase Element (CPE). In addition, the single-diode model (SDM) is tested using the SPICE environment for further validation. Experiments are repeated at different irradiances and operation points to fully understand PV panel performance in diverse environments. The paper focuses on the experimental outcomes. This study examines tuning a CPE model based on experimental data and using the single-diode model in SPICE simulations. The study's comprehensiveness is demonstrated by presenting data for various irradiances and operating points. The improved CPE model's reliability and precision, as well as validation of the single diode model in SPICE, are emphasized. The findings from the experiments contribute to better comprehension of PV panel dynamics in non-uniform scenarios. The importance of reproducing these results in simulation for engineering applications is emphasized, providing the path for future advances in PV panel design and optimization based on spectrum measurements. |
Dc Leakage Current in Isolated Grid-Connected dc Nanogrid-Origins and Elimination MethodsMohammadreza Azizi (ESR05)The LVdc system is a relatively new trend in the distribution sector, which seems to grow widely in the near future due to its promising advantages. In this context, LVdc protection and grounding are challenging issues. Although the galvanically isolated connection mode of dc nanogrid to the ac grid has high reliability, the leakage current can still be injected into the ac grid through the interwinding capacitors and the insulation resistance between the primary and secondary windings of the transformer. The way of grounding the dc nanogrid can also be a determining factor in the leakage current and its dc components. This study deals with the leakage current in the galvanically isolated dc nanogrid. Then, it examines the dc leakage current and its relationship with the dc nanogrid grounding and finally provides solutions to remove the dc components in the leakage current. |
Multi-Objective Energy Management of Smart Buildings Through a Bilevel Optimization ApproachSaeed Akbari (ESR12)This paper introduces an optimization-based model developed to manage energy flow within smart buildings while facilitating energy exchange with the grid through a bi-level framework. The primary objective of this model is to minimize electricity bills while improving the peak-to-valley ratio of power exchange profiles with the grid, concerning system constraints and users' comfort. To achieve this, an energy storage system is incorporated to handle peak-shaving and valley-filling applications. Notably, the energy storage system operates as the follower of the building energy management system, focusing on improving the energy exchange profile. Simulation results demonstrate the effectiveness of this energy management strategy in enhancing techno-economic metrics simultaneously. |
An Economical Optimization for the Participation of a Residential Microgrid in Flexibility Markets Providing Ancillary ServicesAnas Abdullah Alvi (ESR03)The growing number of renewable energies based distributed energy resources and new loads such as electric vehicles are creating uncertainty and instability in the grid and thus increasing the need to provide ancillary services and other flexibility resources. This paper deals with an economical optimization of power reservation of energy storage systems in a residential microgrid to provide ancillary services and thus participating in flexibility markets by receiving economic incentives. The study proposes an energy management system for a residential microgrid that includes household loads, photovoltaic generation, energy storage systems and electric vehicles. The economic objective of reducing electricity bill and the technical goal of providing ancillary services by reserving a fixed power capacity of the energy storage systems along with including grid congestion constraint are achieved by designing and testing a genetic algorithm with suitable parameters to define new set-points of operation for the energy storage systems and the charging/discharging of electric vehicles. |
Energy Communities in the EU: Analysis of ownership models and funding mechanismsKonstantinos Pantazis (ESR15)Energy Communities (ECs) have gained much attention in academia and policy as they embody the active participation of citizens in the energy transition. However, different actors can participate in ECs, and various ownership models and legal forms can emerge based on their relationships. For instance, some are limited liability companies, or cooperatives, or free associations with various private and public actors as members or initiators of the EC. The ownership model has an impact on the ways that ECs can raise capital and fund their activities. For example, some communities are based on equity capital, whereas others have better access to debt capital. However, there is no academic literature that examines the relationship between the ownership model of ECs and the funding mechanisms they use. Therefore, the current study aims to categorize the ECs that exist in the EU based on their ownership model and to examine the relationship, between ownership models and the funding mechanisms used to finance energy generation plants. Finally, this study explores the barriers ECs face in order to raise capital and finance their activities. The ownership model consists of five elements, (a) the membership, (b) the governance structure, (c) the purpose of the organization, (d) the local distribution of benefits (e) the initiators of ECs. To achieve the above research objective, a survey, using a self-completion questionnaire, was conducted and distributed to ECs in the EU. No differences were found between the ECs in terms of governance, local distribution of benefits, and the purpose of the organization. However, the ECs differ significantly from each other in terms of the members and initiators of the ECs. Based on these two dimensions, eight (8) different categories were identified. Furthermore, each of these categories uses different funding mechanisms to raise funds and finance their projects. Finally, it appears that the size of the investment and the size of the EC, in terms of the number of members, affect the financing mechanism used by ECs. |
Study of Battery Energy Storage Operation in Droop-Controlled Residential DC NanogridSayeed Hasan (ESR10)Abstract: Conventional AC systems offer a straightforward, adaptable, and reliable electrification solution for residential buildings. However, this simplicity has several drawbacks when utilizing renewables, such as decreased efficiency due to additional conversion stages, load imbalance in multiphase systems, harmonics, and improper energy balance. A DC-based approach could be used instead of the AC in residential nanogrids (NGs). For a residential NG, DC systems can eliminate those DC-AC conversion stages by only relying on one grid-side active front-end converter. Additionally, using DC droop control, the stable operation of a DC NG can be achieved without extra communication between converters sharing the DC bus. The paper focuses on simulating the operation of a droop-controlled residential DC NG for the case of maximum self-consumption and the resulting battery degradation. The simulation used a J-minute temporal average, actual generation, and consumption data from an Estonian dwelling. In addition, the simulation considers the economic aspects of the system and battery reliability assessment using simulated data. |
A Current Control Method for an Interleaved Boost Converter Under CCM/DCM Operation in a PV SystemLuis Ignacio Martínez Caballero (ESR02)DC-DC boost converters are widely adopted in power conditioning systems for renewable energy sources (RESs) and, due to unidirectional power transfer, are subject to operation in either continuous conduction mode (CCM) or discontinuous conduction mode (DCM). Current controllers that ensure operation in both modes have been developed, however, most of the solutions presented in the literature are developed for power-factor (PFC) correction rectifiers, limiting their application to other systems. In a two-stage photovoltaic (PV) generation system, the boost converter operates in a wide range of input voltages, resulting in DCM under low irradiance conditions or during system startup. This work presents an average current estimation method that provides similar performance to the current reference tracking regardless of the operation mode. The current controller has been designed based on the large signal averaged model which accounts for both operation modes. Moreover, a correction factor is derived to generate the correct duty cycle based on the average voltage of the switching leg. Simulation studies are conducted to evaluate the performance of the proposed method, the operation for the switching and averaged model is shown, and the transition between the two modes is demonstrated. |
Fault Tolerant Control for Medium Voltage Hybrid MMC With Cold Reserve SubmodulesMahyar Hassanifar (ESR07)The hybrid modular multilevel converter (HMMC), which consists of half-and full-bridge sub modules (SMs), offers critical advantages in handling overmodulation conditions and blocking dc fault current compared to half-bridge MMC. The high number of SMs poses a threat to the proper operation of the HMMC after an SM failure. To ensure the reliability of HMMC, the use of redundant SMs is pivotal, particularly in medium-voltage applications where the number of SMs is comparatively lower than in high-voltage ones. The redundant SM can be used as a cold reserve SM, referring to the condition that the redundant SM is not being used in the normal condition and inserted after SM failure, which prevents an increase in MMC losses and components thermal stress. This work proposes a sorting method for the seamless and smooth insertion of the cold reserve SM in the event of SM failure, as a replacement for faulty SM. The main goal is to avoid the inrush current and high stress on the capacitor during the insertion of cold reserve SM and achieve a controlled charging process of the capacitor in the inserted SM. Finally, the feasibility and effectiveness of the suggested method are validated through comprehensive simulation studies. |
Modified Sorting Algorithm for Fault- Tolerant Operation of Hybrid MMC With Hot Reserve SubmodulesMahyar Hassanifar (ESR07)The hybrid modular multilevel converter (HMMC) is formed of a combination of half- and full-bridge submodules. HMMC offers advantages in working under overmodulation conditions and effectively blocking the dc fault current with a reduced number of semiconductor switches compared to FB-based MMC, which makes it a fitting option for high and medium-voltage applications. While the modular nature of the MMC is considered a key strength, a high number of power switches raises a potential reliability concern in the event of sub-module (SM) failure. Hence, the implementation of fault-tolerant strategies is critical to ensure the uninterrupted operation of the HMMC. This study aims to develop a fault-tolerant technique through hot reserve redundant SMs by using a modified sorting algorithm. The sorting algorithm is adopted to ensure the correct operation of HMMC during fault occurrence. Also, this work introduces a new control on the insertion index to operate in overmodulation operating mode with reduced dc-link voltage. Finally, the feasibility and availability of the modified sorting method for using hot reserve SMs in HMMC are verified through the EMT simulations in MATLAB\Simulink environment. |
Soft-Start Method for Boost Converter Under Rapid Irradiance ChangesLuis Ignacio Martínez Caballero (ESR02)The modern power system is facing a high penetration of distributed energy resources such as photovoltaic (PV) powered installations. These systems are subject to intermittent operation due to the changing environmental conditions. The systems can face rapid changes in irradiance that lead to the reinitialization of the converter. In this sense, it is necessary to provide safe procedures that enable the operation of the converter under any condition. In this work, a soft-start method is presented for the boost converter that is part of a two-stage PV system configuration. The open circuit voltage of the PV system is used as an indicator of the estimated available power and to detect rapid irradiance changes. Besides, the implementation consists of simple timers and comparisons that can be carried out in available microcontrollers that are used to implement the control routines. Simulation results confirm the operation of the converter under step changes of irradiance for both flexible and maximum power point operation modes. |
An Intentional Islanded Mode of Operation for a Four-Leg Converter Under Rapid and Asymmetrical Load ChangesLuis Ignacio Martínez Caballero (ESR02)The intentional islanded mode of operation is becoming critical for power electronics converters since small energy storages are developed for residential applications. It provides an uninterruptable power supply for the local loads and creates an opportunity to disconnect from the grid if needed. In order to provide the full functionality of the islanding mode, the four-leg power electronics converters are required to work with unpredictable, asymmetrical loads. Maintaining desired voltage levels at the point of common coupling during high power demand is challenging. Moreover, rapid load changes, mainly resistive in residential solutions, can cause a voltage stability problem. The load change study must also focus on the converter’s start of operation without load or total load disconnection, which are crucial for voltage stability. This paper presents control enhancements for the islanded mode of operation. It identifies the issue of rapid asymmetrical load changes and presents a solution based on simulation research. |
Assessment of Mixed Energy Storage System Considering High Spatial Resolution Data from a Real PV InstallationSayeed Hasan (ESR10)Abstract: This paper focuses on improving instability issues in typical residential PV micro installation operation. Based on the high-resolution long-term recording of the power fluctuation in residential photovoltaic installations located in Tallinn, Estonia, different instability problems are identified and addressed. A mixed energy storage system (ESS) was considered for rapid and effective compensation of the detected fluctuations. A hybrid supercapacitor and battery based system was proposed to mitigate the actual problems in PV generation and balance the system operation. A 32 Wh supercapacitor bank coupled to the DC link of the PV inverter was proposed to mitigate the short-term and long-term power fluctuations on the generation side. Peaks and dips in the consumption and generation were identified using the Z-score-based peak detection method. The experimental results from different ESS sizes were compared and discussed. Moreover, several instances of generation fluctuations were mitigated by utilizing the supercapacitor bank. |
Implementation Issues of Droop Controlled DC Nanogrids: State of Charge Management of Battery Energy Storage and Impact of Sensor Gain ToleranceSayeed Hasan (ESR10)Abstract: DC nanogrids are becoming more prevalent for efficient residential electrification in both rural and urban areas. Droop-controlled DC nanogrids are a viable substitute for conventional AC nanogrids owing to their advantages, such as no need for synchronization, reduced material usage, higher efficiency, and flexible operation. However, adopting fixed droop curves in a DC nanogrid has some limitations related to the practical implementation of measurements. This paper shows how these issues affect the state of charge management and energy flow control of a battery energy storage system (BESS). A framework for energy flow and BESS state of charge (SOC) management by means of online modification of droop curves is implemented based on the measured DC bus voltage and estimated SOC values. Moreover, the paper analyzes how tolerance of the embedded measurement system influences DC nanogrid operation and provides recommendations for its design. |
APEC 2025, Atlanta, US. Paper: A Sensor-less IGBT On-State Voltage Estimation Method Using Inverter Control VariablesShuyu Ou (ESR04)Proposed a new sensorless IGBT health monitoring method based on the deviation in control variables. DOI: 10.1109/APEC48143.2025.10977401 |
ECCE Asia 2025Shuyu Ou (ESR04)Physics-Informed Neural Network for Parameter Identification: a Buck Converter Case Study |
Fast and Robust Energy Router Control in Dynamic Conditions Using Flatness-Based Control TheoryMohammadreza Azizi (ESR05)Flatness-based control theory is developed to enhance the dynamic performance of a multiport energy router. The energy router integrates multiple power sources and sinks, including photovoltaic systems, battery storage, the grid, and various loads. Consequently, any sudden change in a subsystem can induce dynamic conditions across the entire system. The presented method controls the grid-side inverter and regulates the dc link voltage. To implement this control approach, the system equations have been established, and it has been demonstrated that the system is differentially flat. Afterward, the controller design has been addressed. The simulation results confirm the proper performance of this method, and the comparisons made validate the high speed and accuracy of the system responses compared to conventional solutions. |
Power Quality Analysis for Selective Harmonic Compensation in Islanded AC NanogridAyesha Aslam (ESR01)A comprehensive power quality analysis is conducted on an AC nanogrid system comprising of a 2-level voltage source inverter (2L VSI) and a 3-level T-type inverter (3L T-type). The research investigates voltage and current stability, harmonic distortion, and power quality performance under diverse load conditions, including linear, nonlinear, and unbalanced load scenarios. Employing the PLECS simulation environment, the study evaluates power quality indicators against European electric grid standards, specifically focusing on total harmonic distortion (THD), and voltage imbalance. The investigation uses an integrated control scheme incorporating multiple second-order generalized integrators (MSOGI), droop control, virtual impedance loops, and discretized proportional-resonant (PR) controllers. Fourier analysis techniques are applied to comprehensively assess harmonic characteristics and power quality metrics. The research contributes critical insights into nanogrid system performance, addressing emerging challenges in distributed energy infrastructure and providing a methodological framework for power quality evaluation in advanced electrical systems. |
Energy Community Business Models ArchetypesKonstantinos Pantazis (ESR15)Energy Communities (ECs) constitute innovative organizational forms that promote energy market democratization by enabling multiple stakeholders to produce, manage, and control energy assets. Despite the emergence of diverse EC business models (BMs), a systematic categorization is lacking. Prior literature offers heterogeneous analyses due to varied analytical frameworks. This paper identifies and categorizes key dimensions from the literature and develops a tailored analytical framework for evaluating EC BMs. Through a systematic review of academic papers and reports, we identified five of the most recurrent and significant dimensions: value proposition, value capture, main functions, governance, and membership. These dimensions form the foundation of our newly developed comprehensive framework. Using this framework, we delineate four archetypal EC business models: self-consumption, third-party, aggregator, and integrated energy services and e-mobility. The proposed framework enhances the analysis of EC BMs and provides practical guidance for researchers and practitioners in designing, assessing, and optimizing these models. |
Detection of Series Resistance Degradation in PV Modules Using Measured Current-Voltage and Frequency-Domain ImpedanceLuis Enrique Garcia Marrero (ESR11)Model-based parameter identification methods are widely used to monitor the condition of photovoltaic (PV) modules. Series resistance is a key parameter for detecting PV module aging, as it typically increases with degradation. This paper compares three parameter identification approaches for tracking changes in series resistance: the Single Diode Model (SDM), the recently proposed Double Single Diode Model (D-SDM), and a dynamic model based on the Constant Phase Element (CPE). Measured current-voltage and frequency-domain impedance data from a commercial PV module under uniform irradiance conditions are used to fit the corresponding models. The series resistance of the PV module is estimated in both its nominal state and with an additional series resistor to simulate degradation. The results indicate that while the standard SDM captures resistance changes, it exhibits greater fluctuations across varying irradiance levels. In contrast, the D-SDM and CPE-based approaches provide more stable and reliable resistance estimates, making them better suited for accurate degradation detection. |
Techno-Economic Optimization of Electric Vehicle Charging Station with Virtual Power Plant – a University Campus Use CaseS.M. Masum Ahmed (ESR14)Electric Vehicles (EVs) are crucial for decarbonizing the transport sector, which accounts for about one-quarter of the EU’s total Greenhouse Gas (GHG) emissions. However, most EV Charging Stations (EVCS) still rely on fossil fuel-based energy generation, contributing to grid-related emissions. Integrating Renewable Energy Sources (RES) with EVCS is a key strategy to lower the emissions intensity of the EV supply chain, though its techno-economic benefits remain largely underexplored. This study addresses this gap by conducting a techno-economic feasibility analysis of RESpowered EVCS at NOVA University Lisbon, either through onsite RES integration or via a Virtual Power Plant (VPP). Two datasets were combined—including parking hours, building energy demand, and economic variables—to evaluate three scenarios using HOMER and a genetic algorithm: (i) Grid-to-Vehicle (base), (ii) EVCS with on-site RES, and (iii) EVCS with VPP. The VPP scenario is most optimal, achieving the lowest cost of energy (0.111 €/kWh), the highest RES fraction (34.6%), and a 16.15% reduction in energy bills relative to the base scenario. |
Tuning and Assessment of Inner Control Loops in an Islanded Nanogrid with Harmonic and Unbalanced LoadsAyesha Aslam (ESR01)This paper presents the design and tuning of proportional-resonant (PR) controllers in discrete domain using SISOTOOL feature in MATLAB. The controllers are applied to an AC nanogrid system that comprises of a 2-level voltage source inverter (2L VSI) and 3-level T-type (3L T-type) inverter system. The system is tested with various types of loads, including linear, non-linear and unbalanced loads, within the PLECS environment. The response of the controller system is visualized in SISOTOOL and validated through stability analysis, which includes Bode and Nyquist plots. Additionally, control system requirements such as rising time and settling time are assessed. The PLECS simulation results using discrete PR controllers are analyzed in terms of stability and harmonic mitigation. |