1,720,965 research outputs found
Real-time temperature sensitive electrical parameters and model- based condition monitoring for PV inverter applications
No full textTo improve the reliability of power converters, condition monitoring is a useful approach as this allows
to schedule maintenance more carefully or even implement adaptive control. The current state of the
art is focused on the measurement of damage sensitive parameters which can be used directly or
complementary with a digital twin. Several papers report successful experiments where these damage
sensitive parameters of switching devices are used to evaluate wear under constant power conditions.
This approach needs to be extended for PV inverter applications as these experience complex power
profiles in varying weather conditions. This poster presentation will focus on a methodology to monitor
the damage sensitive drain to source on-resistance in concession with the internal gate resistance which
is only sensitive to the junction temperature. This allows to separate the influence of temperature and
damage which allows the use of complex mission profiles. To simplify the evaluation even further, a
second approach is proposed where the additional gate resistance measurement is replaced by a
modeling strategy. The electrical part of the electro-thermal model is build using a two dimensional
lookup table approach and the thermal model is represented by a Cauer network. The thermal
resistances in each layer are determined by a FEM simulation. This poster presents the preliminary
results which show a validation of the model with measurements on an inverter prototype and the
proposed condition monitoring circuits simulated in spice
Cost Comparison for Different PV-Battery System Architectures Including Power Converter Reliability
No full textThis paper compares the levelized energy cost of a commercial DC-coupled photovoltaic battery systems with a multiple input multiple output converter. The comparison is based on an electrothermal simulation allowing to include the actual converter efficiency and degradation in different use cases. The multiple input multiple output converter proofs to be less expensive and more reliable, however, the lower efficiency causes the final levelized energy cost to be higher.This work has been supported by Flanders Innovation & Entrepreneurship and Flux50 under project DAPPER, HBC.2020.2144. Martijn Deckers is funded by a PhD grant of the Research Foundation Flanders (FWO), 1S87522N
Cost Comparison for Different PV-Battery System Architectures Including Power Converter Reliability
No full textThis paper compares the levelized energy cost of a commercial DC-coupled photovoltaic battery systems with a multiple input multiple output converter. The comparison is based on an electrothermal simulation allowing to include the actual converter efficiency and degradation in different use cases. The multiple input multiple output converter proofs to be less expensive and more reliable, however, the lower efficiency causes the final levelized energy cost to be higher.This work has been supported by Flanders Innovation & Entrepreneurship and Flux50 under project DAPPER, HBC.2020.2144. Martijn Deckers is funded by a PhD grant of the Research Foundation Flanders (FWO), 1S87522N
Real-time temperature sensitive electrical parameters and model- based condition monitoring for PV inverter applications
No full textTo improve the reliability of power converters, condition monitoring is a useful approach as this allows
to schedule maintenance more carefully or even implement adaptive control. The current state of the
art is focused on the measurement of damage sensitive parameters which can be used directly or
complementary with a digital twin. Several papers report successful experiments where these damage
sensitive parameters of switching devices are used to evaluate wear under constant power conditions.
This approach needs to be extended for PV inverter applications as these experience complex power
profiles in varying weather conditions. This poster presentation will focus on a methodology to monitor
the damage sensitive drain to source on-resistance in concession with the internal gate resistance which
is only sensitive to the junction temperature. This allows to separate the influence of temperature and
damage which allows the use of complex mission profiles. To simplify the evaluation even further, a
second approach is proposed where the additional gate resistance measurement is replaced by a
modeling strategy. The electrical part of the electro-thermal model is build using a two dimensional
lookup table approach and the thermal model is represented by a Cauer network. The thermal
resistances in each layer are determined by a FEM simulation. This poster presents the preliminary
results which show a validation of the model with measurements on an inverter prototype and the
proposed condition monitoring circuits simulated in spice
Real-Time MOSFET Condition Monitoring for Variable Mission Profiles With a Dual Extended Kalman Filter
No full textThe article proposes a methodology to detect real-time power mosfet degradation, in variable mission profile applications, using externally measurable electrical parameters. This complements the work done for fixed operation conditions in current literature. To achieve this, the damage and temperature sensitive drain to source resistance is accompanied with a gate resistance measurement only sensitive to temperature. Together, they allow for the detection of, and the distinction between, bond wire and die attach solder layer degradation. A dual extended Kalman filter is used to filter the measurement data and to estimate the change in thermal model. The article shows the measurement circuits together with proof of concept lab results in a solar photovoltaic use case. The main aim is to show that the resistance measurement can be compensated for mission profile temperature variations and that the thermal resistance can be estimated, reflecting bond wire and die attach solder layer degradation.Flanders Innovation & Entrepreneurship and Flux50 under project DAPPE
Simulation-Based Investigation of Wind Turbine Induced Shadow Flicker on IGBT Reliability and Energy Yield in Solar Converters in Hybrid Wind-Solar Systems
No full textWith the growing adoption of renewable energy, hybrid wind-solar plants are gaining interest because they allow the increase of energy yield per unit of surface area. However, the presence of wind turbines creates unique shading scenarios for the solar panels. This work presents a simulation-based approach to investigate the solar plant's energy yield and converter IGBT lifetime in the presence of dynamic and fast-moving shadows created by the wind turbine blades. First, the need for a dynamic simulation as opposed to a static one is examined. Next, the sensitivity of Photovoltaic (PV) string orientation, PV string location, wind direction, Maximum Power Point Tracker (MPPT) control speed, and turbine rotor speeds on energy yield and IGBT lifetime are investigated in a case study. Results show that dynamic and static simulations can show vastly different results. MPPT can have difficulty with shadow flicker, resulting in different string voltages depending on the MPPT update speed and wind turbine rotor speed. The shadow flicker introduces additional temperature swings in the IGBT, but these are too small to add any significant lifetime consumption (<1.2%). Thus, the observed changes in lifetime consumption are caused mainly by controller behavior and static shadows. Finally, it is concluded that PV strings are better placed south, east, or west of the wind turbine for optimal energy yield and lifetime consumption. A northern placement can be suitable if there is a significant distance (+50 m) between the PV string and the wind turbine.This work was supported by the Belgian Energy Transition Funds/Met de steun van het Energietransitiefonds
A Real-time Physics Based Digital Twin for Online MOSFET Condition Monitoring in PV Converter Applications
No full textThis article proposes a fast, lightweight and physics-based digital twin to estimate the real-time junction, case and heat sink temperatures of the switching device in a photovoltaic (PV) boost converter. A lookup table approach is used to model the electric behavior while a traditional Cauer approach is used for the thermal model. To extract the thermal resistances of the MOSFET layers and convection, a finite element method (FEM) simulation is performed. To validate the digital twin, a physical replica of the boost converter is built and a real mission profile is applied. The resulting heat sink temperature profile has a mean average error of 0.8 °C with an increase in error at higher temperatures. In future work this twin will be used to separate the effect of temperature and degradation on the on resistance of the MOSFET to monitor degradation during operation.status: Published onlin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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