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See detailEntwicklung einer Regelungsstrategie für eine PVT-basierte CO2-Wärmepumpe
Rullof, Johannes UL; Lambers, Klaus Jürgen; Blieske, Ulf et al

in KI - Kälte Luft Klimatechnik (2018), 01-02

Die Kombination aus thermischen Absorber und Photovoltaik (PV) in einem Hybrid-Modul (PVT-Modul) vereint PV mit der (solarthermischen) Verdampfung des Kältemittels CO2 als Teilprozess einer Wärmepumpe und ... [more ▼]

Die Kombination aus thermischen Absorber und Photovoltaik (PV) in einem Hybrid-Modul (PVT-Modul) vereint PV mit der (solarthermischen) Verdampfung des Kältemittels CO2 als Teilprozess einer Wärmepumpe und kann zukünftig eine Alternative zu Luft-Wärmepumpen sein. Im Rahmen dieses Beitrags wird auf die Entwicklung einer Regelungsstrategie der PVT-basierten Wärmepumpe eingegangen, welche verschiedene Betriebsmodi in Abhängigkeit von dem Solarstrahlungsangebot sowie der Umgebungstemperatur vorsieht. [less ▲]

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See detailDevelopment of a Control Strategy for a PVT-based CO2 Heat Pump
Rullof, Johannes UL; Lambers, Klaus Jürgen; Blieske, Ulf et al

in Proceedings of 7th International Energy and Sustainability Conference (IESC) (2018)

In recent years, the possibility of combining photovoltaics (PV) and solar thermal collectors into one solar hybrid module (PVT-module) has been increasingly investigated. PVT-modules produce thermal and ... [more ▼]

In recent years, the possibility of combining photovoltaics (PV) and solar thermal collectors into one solar hybrid module (PVT-module) has been increasingly investigated. PVT-modules produce thermal and electrical energy at the same time. Since the efficiency of a photovoltaic module decreases with increasing temperature, the temperature of the heat transfer media is often limited to about 30 °C and the PVT-module is combined with a heat pump, which increases the temperature on the “warm side”. A common approach is to integrate the PVT-module directly as an evaporator in a heat pump system (PVT-direct). This paper presents the development of a control strategy for a PVT-based CO2 heat pump that takes into account solar radiation, ambient temperature, wind speed, evaporator temperature and compressor power. The developed control strategy provides different operating modes depending on the solar radiation supply as well as the ambient temperature. [less ▲]

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See detailModellierung eines PVT-basierten Wärmepumpensystems auf der Basis von CO2 Direktverdampfung
Rullof, Johannes UL; Lambers, Klaus Jürgen; Blieske, Ulf et al

in Proceedings of Deutsche Kälte- und Klimatagung DKV 2018 (2018)

Die Systemkombination aus Wärmepumpe und solarthermischen Absorber, basierend auf freier Konvektion und Strahlung, und Photovoltaik (PV) in einem Modul (PVT-Modul) kann aufgrund der Reduzierung des ... [more ▼]

Die Systemkombination aus Wärmepumpe und solarthermischen Absorber, basierend auf freier Konvektion und Strahlung, und Photovoltaik (PV) in einem Modul (PVT-Modul) kann aufgrund der Reduzierung des Heizwärmebedarfs von Gebäuden und des verstärkten Betriebs von Wärmepumpen während der Niedrigstrompreiszeiten am Tage und dem damit verbundenen höheren Strahlungsanteil der Umweltwärme zukünftig eine Alternative zu zwangskonvektions-basierten Luft-Wärmepumpen sein. Der Beitrag beschäftigt sich mit einem CO2-Wärmepumpensystem, bestehend aus einem neuartigen Solar-Hybridmodul, welches einen mikrokanal-basierten Verdampfer einer CO2-Wärmepumpe mit einem PV-Modul vereint (PVT-direkt). Um die Machbarkeit des neuartigen PVT-direkt-Wärmepumpensystems zu demonstrieren, wird im Rahmen eines Forschungsprojekts ein funktionsfähiges PVT-direkt-Modul konstruiert und schließlich als Teil eines CO2-Wärmepumpensystems getestet und modelliert. Die Besonderheit der Kombination eines thermischen Absorbers mit einer Wärmepumpe liegt in der Erschließung der Solarenergie und Umgebungsenergie als Energiequelle. Hierbei ist die Kenntnis über die thermische Leistung des PVT-Moduls unter anderem durch den konvektiven Wärmeübergang zwischen dem PVT-Modul und der Umgebung relevant. Sowohl der Modulneigungswinkel (Anströmwinkel) und die Windrichtung (Azimutwinkel) haben einen nicht zu vernachlässigenden Einfluss auf den resultierenden Wärmeübergangskoeffi-zienten der erzwungenen Konvektion. Da im Rahmen einer Literaturrecherche keine für das PVT-Modul direkt zu übertragenden experimentelle Untersuchungen und Berechnungsgrundlagen zur Bestimmung des konvektiven Wärmeübergangs gefunden werden konnten, wurde mit Hilfe der Software ANSYS Fluent eine CFD-Simulation zum konvektiven Wärmeübergang am PVT-Modul durchgeführt, deren Ergebnisse in dieser Arbeit präsentiert werden. [less ▲]

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See detailEntwicklung eines PV/Thermie-basierten Wärmepumpensystems auf der Basis von CO2 Direktverdampfung
Rullof, Johannes UL; Lambers, Klaus Jürgen; Blieske, Ulf et al

Poster (2018)

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See detailDesign of an Electromechanical Prosthetic Finger using Shape Memory Alloy Wires
van der Elst, Louis UL; Quintanar Guzman, Serket UL; Hadji-Minaglou, Jean-Régis UL

in IEEE 5th International Symposium on Robotics and Intelligent Sensors, Ottawa, Canada, 5-7 October 2017 (2017, October)

This research concerns the design and prototyping of an artificial middle finger, using Shape Memory Alloys (SMAs), PolyLactic Acid (PLA), and other technologies. The design is a biomimicry of the human ... [more ▼]

This research concerns the design and prototyping of an artificial middle finger, using Shape Memory Alloys (SMAs), PolyLactic Acid (PLA), and other technologies. The design is a biomimicry of the human biological anatomical and muscular systems. After briefly describing the operational features and functioning of natural striated muscles, the document reviews the features, advantages and disadvantages of SMAs in the perspective of their use as an actuator of a prosthetic finger.Using different design parameters, such as the lightness of the device, actuation complexity, and resilience, a working prototype is proposed meeting the established criteria. [less ▲]

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See detailA New Synchronization Method for Three - phase Grid - tied LC-Filtered Voltage Source Inverters
Kobou Ngani, Patrick UL; Hadji-Minaglou, Jean-Régis UL; De Jaeger, Emmanuel et al

in International Journal of Emerging Engineering Research and Technology (2017), 5(5), 7-15

In order to identify and to track the phase angle and magnitude of the grid voltage, several synchronization methods exist, among which the phase-locked loop (PLL) algorithm is the most popular. This ... [more ▼]

In order to identify and to track the phase angle and magnitude of the grid voltage, several synchronization methods exist, among which the phase-locked loop (PLL) algorithm is the most popular. This paper presents a new synchronization method for grid-tied voltage source inverters (VSIs) based on the intrinsic inverter synchronous reference frame. The absolute phase angle of the grid voltage is not required but its voltage direct and quadrature components into the well-known inverter frame. The advantages of this method is its low computational load with a reduced number of control parameters, as well as its robustness and effectiveness. This property makes it very convenient for embedded control systems with limited computing resources. Simulations and experimental test results are presented to prove the performance of the proposed method. [less ▲]

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See detailEntwicklung eines PVT-basierten CO2- Wärmepumpensystems
Rullof, Johannes UL; Lambers, Klaus Jürgen; Blieske, Ulf et al

in KI - Kälte Luft Klimatechnik (2017), 8-9

Die Kombination aus thermischen Absorber und Photovoltaik (PV) in einem Hybrid-Modul (PVT-Modul) vereint PV mit der (solarthermischen) Verdampfung des Kältemittels CO2 als Teilprozess einer Wärmepumpe und ... [more ▼]

Die Kombination aus thermischen Absorber und Photovoltaik (PV) in einem Hybrid-Modul (PVT-Modul) vereint PV mit der (solarthermischen) Verdampfung des Kältemittels CO2 als Teilprozess einer Wärmepumpe und kann zukünftig eine Alternative zu Luft-Wärmepumpen sein. Im Rahmen dieses Beitrags wird auf die Motivation und die Konstruktion eines funktionsfähigen PVT-Moduls eingegangen. [less ▲]

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See detailMethodology for Optimally Sizing a Green Electric and Thermal Eco-Village
Rafii-Tabrizi, Sasan UL; Hadji-Minaglou, Jean-Régis UL; Scholzen, Frank UL et al

in Rafii-Tabrizi, Sasan; Hadji-Minaglou, Jean-Régis; Scholzen, Frank (Eds.) et al From Science to Society-New Trends in Environmental Informatics (2017)

This paper presents an energy system for a future eco-village, situated in Luxembourg’s city center, whose thermal and electrical energy needs are covered by renewable resources. Specifically, electrical ... [more ▼]

This paper presents an energy system for a future eco-village, situated in Luxembourg’s city center, whose thermal and electrical energy needs are covered by renewable resources. Specifically, electrical energy is provided by a biogas driven combined heat and power plant, and photovoltaic panels. Lithium-ion accumulators are used for storing the surplus of electrical energy production. Thermal energy needs are mainly covered by a dual source heat pump which draws environmental energy from an ice tank or solar air absorbers. A heat buffer stores heat produced by the combined heat and power plant, a power to heat module and the heat pump. This work focuses on optimally sizing, in terms of power rating, capacity or volume, the energy system components. To this end, a combinatorial simulation-based optimization approach has been developed using MATLAB. The optimal set-up is determined by minimizing the overall cost of the energy system with additional constraints to be respected. Annual needs in thermal and electrical energy, photovoltaic electricity production and the corresponding weather data are based on real data. [less ▲]

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See detailEntwicklung einer Regelungsstrategie eines PVT-basierten Wärmepumpensystems auf der Basis von CO2 Direktverdampfung
Rullof, Johannes UL; Lambers, Klaus Jürgen; Blieske, Ulf et al

in Proceedings of Deutsche Kälte- und Klimatagung (DKV) (2017)

Bereits Ende der 1970iger Jahre wurden Wärmepumpen in Kombination mit glykolbasierten großflächigen kombinierten Strahlungs-Umweltwärme-Absorber als Verdampfer entwickelt, welche sich im Vergleich zu ... [more ▼]

Bereits Ende der 1970iger Jahre wurden Wärmepumpen in Kombination mit glykolbasierten großflächigen kombinierten Strahlungs-Umweltwärme-Absorber als Verdampfer entwickelt, welche sich im Vergleich zu zwangskonvektions-basierten Luft-Wärmepumpen nicht nur die Umgebungsenergie, sondern auch die Solar-energie als Energiequelle zu Nutze machen. Aufgrund der nach der Ölkrise fallenden Ölpreise, der meist noch nicht wirtschaftlichen Anlagentechnik und der benötigten großen Absorberflächen konnten sich diese Anlagen nicht durchsetzen. Durch die starke Reduzierung des Heizwärmebedarfs eines Neubaus werden heutzutage deutlich kleinere Absorberflächen in Kombination mit einer Wärmepumpe benötigt, was die Systemkombination aus Wärmepumpe und Absorber aktuell wieder interessant werden lässt. Vor allem die Kombination aus thermi-schem Absorber, basierend auf freier Konvektion und Strahlung, und Photovoltaik (PV) in einem Modul (PVT-Modul) kann aufgrund der Reduzierung des Heizwärmebedarfs von Gebäuden und des verstärkten Betriebs von Wärmepumpen während der solarstrombedingten Niedrigstrompreiszeiten am Tage und dem damit verbunde-nen höheren Strahlungsanteil der Umweltwärme zukünftig eine Alternative zu zwangskonvektions-basierten Luft-Wärmepumpen sein. Der Beitrag beschäftigt sich mit einem CO2-Wärmepumpensystem, bestehend aus einem neuartigen PVT-Modul, welches einen mikrokanal-basierten Verdampfer einer CO2-Wärmepumpe mit einem PV-Modul vereint (PVT-direkt). Um die Machbarkeit des neuartigen PVT-direkt-Wärmepumpensystems zu demonstrieren, wird im Rah-men eines Forschungsprojekts ein funktionsfähiges PVT-direkt-Modul konstruiert und schließlich als Teil eines CO2-Wärmepumpensystems getestet und modelliert. Die Leistung eines PVT-basierten Wärmepumpensystems ist stark von klimatischen Randbedingungen abhängig. Im Rahmen dieser Arbeit wird die Entwicklung einer Regelungsstrategie eines PVT-basierten Wärmepumpensys-tems präsentiert, welche die Solarstrahlung, Umgebungstemperatur, Windgeschwindigkeit, Verdampfungstem-peratur und Verdichterleistung berücksichtigt. Zusätzlich werden die reale Antriebsleistung und der optimale Betriebspunkt des Verdichters einschließlich des optimalen Hochdruckes berücksichtigt. Die entwickelte Rege-lungsstrategie der PVT-basierten Wärmepumpe sieht verschiedene Betriebsmodi in Abhängigkeit von dem So-larstrahlungsangebot sowie der Umgebungstemperatur vor. Der Betrieb der Wärmepumpe erfolgt zwischen Deckung des Heizbedarfs in der Heizperiode und möglichst hoher Effizienz in Zeiten hoher Einstrahlungswerte und hoher Umgebungstemperaturen. [less ▲]

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See detailThermal Model of a Solar Hybrid Module as the Heat Source for a CO2 Heat Pump
Rullof, Johannes UL; Lambers, Klaus Jürgen; Blieske, Ulf et al

in Proceedings of 2017 International Energy and Sustainability Conference (IESC 2016) (2017)

In recent years, the possibility of combining photovoltaics (PV) and solar thermal collectors into one solar hybrid module (PVT-module) has been increasingly investigated. PVT-modules produce thermal and ... [more ▼]

In recent years, the possibility of combining photovoltaics (PV) and solar thermal collectors into one solar hybrid module (PVT-module) has been increasingly investigated. PVT-modules produce thermal and electrical energy at the same time. Since the efficiency of a photovoltaic module decreases with increasing temperature, the temperature of the heat transfer media is often limited to about 30 °C and the PVT-module is combined with a heat pump, which increases the temperature on the “warm side”. A common approach is to integrate the PVT-module directly as an evaporator in a heat pump system (PVT-direct). This paper presents a thermal model of a PVT-direct module as the heat source for a R744/CO2 heat pump. Due to the combined effect of flow channel patterns, solar radia-tion, the ambient conditions and possible condensation and frost formation, heat transfer and thermal distribution conditions of the PVT-direct evaporator are inevitably com-plicated to determine. The proposed thermal model of this hybrid solar module that has CO2 direct evaporation in microchannels will be used to simulate the behavior of the module under different climatic operating conditions. Fur-thermore, it will quantify all energy inputs and/or losses as well as their influence on the total energy supplied by the PVT-module. This will be used to investigate the overall CO2-PVT heat pump system performance in prospective simulations. [less ▲]

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See detailA Fast Model-Predictive Speed Controller for Minimised Charge Consumption of Electric Vehicles
Schwickart, Tim Klemens UL; Voos, Holger UL; Hadji-Minaglou, Jean-Régis UL et al

in Asian Journal of Control (2016), 18(5),

This paper presents the design of a real-time implementable energy-efficient model-predictive cruise controller for electric vehicles including the driving speed reference generation. The controller is ... [more ▼]

This paper presents the design of a real-time implementable energy-efficient model-predictive cruise controller for electric vehicles including the driving speed reference generation. The controller is designed to meet the properties of a series-production electric vehicle whose characteristics are identified and validated by measurements. The predictive eco-cruise controller aims at finding the best compromise between speed-reference tracking and energy consumption of the vehicle using an underlying dynamic model of the vehicle motion and charge consumption. The originally non-linear motion model is transformed into a linear model mainly by using a coordinate transform. To obtain a piecewise linear approximation of the charge consumption map, the measured characteristics are approximated by a convex piecewise linear function represented as the maximum of a set of linear constraint functions. The reformulations finally lead to a model-predictive control approach with quadratic cost function, linear prediction model and linear constraints that corresponds to a piecewise linear system behaviour and allows a fast real-time implementation with guaranteed convergence. Simulation results of the closed-loop operation finally illustrate the effectiveness of the approach. [less ▲]

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See detailExperimental Lifetime Investigation of Series Connected Li-ion Cells at Different Operation Strategies
Brühl, Manuel UL; Sauer, Dirk Uwe; Hadji-Minaglou, Jean-Régis UL

Poster (2016, April 26)

Battery systems consisting of serially connected cells suffer from uneven cell degradation. This phenomenon can be observed, even if li-ion cells of the same type and batch are cycled in a fixed voltage ... [more ▼]

Battery systems consisting of serially connected cells suffer from uneven cell degradation. This phenomenon can be observed, even if li-ion cells of the same type and batch are cycled in a fixed voltage window at the same temperature. The uneven cell degradation has a significant impact on the usable capacity of a battery system as the system capacity is limited by the capacity of the weakest cell. This issue reduces the battery lifetime and increases the costs. In a former work, li-ion cells were cycled individually and the different cell degradation could be observed significantly. In this work, aging tests are conducted with cells in series connected conditions to investigate the uneven cell degradation behavior. Cyclization of series connected cells could lead to a higher spread of cell degradation as weaker cells are deeper cycled. Three aging tests, each consisting of eight li-ion cells are conducted in this work. The eight cells of each test are cycled with the same current to investigate the aging behavior under comparable conditions as in a series connection. The first test is conducted to investigate the aging behavior of a conventional system with series connected cells and passive balancing. In the second and third test, the uneven cell degradation is actively compensated with the operation strategy of the balancing circuit. In the second test the voltage window are changed with respect to the cell’s state of health. In the third test the cell current of each cell is changed with respect to the cell’s state of health. Preliminary results show that cells in the first test suffer a bigger capacity diversion over time than cells in the second and third test. Such operation strategies could be implemented in real systems to reduce the different cell degradation and to prolong the systems lifetime. Further analysis and conclusions will be given on the conference poster. [less ▲]

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See detailExperimental studies on the development of a solar hybrid module with an aluminum microchannel evaporator
Rullof, Johannes UL; Lambers, Klaus Jürgen; Dick, Christian et al

in Proceedings of 2016 International Energy and Sustainability Conference (IESC 2016) (2016)

In recent years, the possibility to combine photovoltaics (PV) and solar thermal collectors into one hybrid module (PVT-module) has been increasingly investigated. PVT-modules produce thermal and ... [more ▼]

In recent years, the possibility to combine photovoltaics (PV) and solar thermal collectors into one hybrid module (PVT-module) has been increasingly investigated. PVT-modules produce thermal and electrical energy at the same time. As the efficiency of a photovoltaic module decreases with temperature, the temperature of the heat transfer media is often limited to about 30 °C and the PVT-module is combined with a heat pump, which increases the temperature on the “warm side”. This paper deals with a PVT-module, which combines a microchannel based evaporator of a CO2 (R744) heat pump with a PV panel (PVT-direct). The PVT-direct overall system is reduced to the refrigerant circuit due to the direct refrigerant expansion in the PVT-module. A conventional PVT heat pump system has an additional glycol-water circuit. Since a pump and an additional heat exchanger for the secondary cycle were omitted, the system has increased efficiency. Due to lower module temperatures, the increase of the photovoltaic efficiency is a further advantage of the PVT-direct-module. To prove the feasibility of the PVT-direct heat pump system, the Cologne Institute for Renewable Energy (CIRE) is developing and modeling a test facility for this purpose within the research project “PVT-direkt”. Furthermore, a functional PVT-direct-module with a microchannel based evaporator was designed and built. Much importance has been given to experimental studies under laboratory conditions in order to investigate (1) the adjustment of the functionality and layout of the PVT-direct-module for characterizing the joining of brazed joints in aluminum microchannel evaporators and (2) the influence of the backside aluminum plate of the PVT-direct-module regarding leakage currents and parasitic capacitances. The overall results obtained in these experimental studies are analyzed in this paper. [less ▲]

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See detailEntwicklung eines PVT-basierten Wärmepumpensystems auf der Basis von CO2 Direktverdampfung
Rullof, Johannes UL; Lambers, Klaus Jürgen; Hadji-Minaglou, Jean-Régis UL et al

in Proceedings of Deutsche Kälte- und Klimatagung (DKV) (2016)

Bereits Ende der 1970’iger Jahren wurden Wärmepumpen in Kombination mit glykolbasierten großflächigen Absorbern entwickelt, welche sich die Umgebungsenergie und Solarenergie als Energiequelle zu Nutze ... [more ▼]

Bereits Ende der 1970’iger Jahren wurden Wärmepumpen in Kombination mit glykolbasierten großflächigen Absorbern entwickelt, welche sich die Umgebungsenergie und Solarenergie als Energiequelle zu Nutze machen. Aufgrund der nach der Ölkrise fallenden Ölpreise, der meist noch nicht wirtschaftlichen Anlagentechnik und den benötigten großen Absorberflächen, konnten sich diese Anlagen nicht durchsetzen. Durch die starke Reduzierung des Heizwärmebedarfs eines heutigen Neubaus werden heutzutage deutlich kleinere Absorberflächen in Kombination mit einer Wärmepumpe benötigt, was die Systemkombination aus Wärmepumpe und Absorber aktuell wieder interessant werden lässt. Vor allem die Kombination aus thermischen Absorber, basierend auf freier Konvektion und Strahlung, und Photovoltaik (PV) in einem Modul (PVT-Modul) kann aufgrund der Reduzierung des Heizwärmebedarfs von Gebäuden und des verstärkten Betriebs von Wärmepumpen während der Niedrigstrompreiszeiten am Tage und dem damit verbundenen höheren Strahlungsanteil der Umweltwärme zukünftig eine Alternative zu zwangskonvektions-basierten Luft-Wärmepumpen sein. Im Rahmen dieser Arbeit wird auf die Konstruktion eines funktionsfähigen PVT-direkt Moduls eingegangen, welches einen mikrokanalbasierten Verdampfer einer transkritischen CO2-Wärmepumpe mit einem PV-Modul kombiniert. Im ersten Teil dieser Arbeit wird ein thermisches Modell des PVT-direkt Moduls hergeleitet, welches in zukünftigen Untersuchungen Anwendung findet, um eine Aussage über die PV-seitige Wirkungsgradsteigerung durch niedrigere Modultemperaturen aufgrund der Kältemittelverdampfung an der Modulrückseite treffen zu können. Der zweite Teil dieser Arbeit präsentiert die Auslegung zweier Verdampfer-Designvarianten (Mäander und Harfendesign) und eine Temperaturverteilungsanalyse. Bei beiden Konzepten fällt die Temperaturverteilung annähernd homogen aus. [less ▲]

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See detailA new Single-phase PLL based on the input voltage magnitude estimation
Kobou Ngani, Patrick UL; Hadji-Minaglou, Jean-Régis UL; Marso, Michel UL et al

Scientific Conference (2015, December 17)

Many automatic control applications such as wide scale power grid management and local power conditioning rely on the fast and accurate detection of the voltage signal phase and amplitude. These ... [more ▼]

Many automatic control applications such as wide scale power grid management and local power conditioning rely on the fast and accurate detection of the voltage signal phase and amplitude. These information are almost all the time given by the Phase –locked Loop (PLL) systems and can be single-phase or three-phase and have many different structures. Many single-phase PLLs core structure are based on the regulation to zero of the voltage direct component in the rotating d-q frame obtained through the Park-transform. Their accuracy and dynamic rely on how quick and accurate the second voltage’s component in the static α-β frame is estimated. This paper presents a new single-phase PLL structure, also based on the same core structure as described before, but implementing a novel voltage β-component generation. A brief review of some single-phase PLLs is made, then the proposed novel PLL structure is detailed and its performance is compared with that of the other PLL’s taking into consideration the following signal disturbances: amplitude variations, phase step variation and frequency fluctuations as well as harmonic distortion. [less ▲]

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See detailPhase-error correction by single-phase phase-locked loops based on transfer delay
Kobou Ngani, Patrick UL; Hadji-Minaglou, Jean-Régis UL; Marso, Michel UL et al

in Journal of Electrical & Electronic Systems (2015, November 04)

Comparative studies of different single-phase phase-locked loops (PLL) algorithms have been made. They show that the PLL based on sample delay (dPLL), presents the lowest computational load and is as ... [more ▼]

Comparative studies of different single-phase phase-locked loops (PLL) algorithms have been made. They show that the PLL based on sample delay (dPLL), presents the lowest computational load and is as robust as the three-phase synchronous reference frame PLL dqPLL by input signal amplitude and phase variations. Its weakness appears when the input signal frequency differs from its rated frequency: It depicts a steady error on the calculated signal phase-angle. After a brief review of the dqPLL which constitutes debase structure of the dPLL, the following work will present three methods that improve the phase detection accuracy of dPLL. It is shown that the modifications brought in the original structure do not influence the robustness and stability of the algorithm but reduce the phase angle offset error by input signal frequency variation. This is corroborated by tests including not only the fundamental input voltage disturbance like amplitude, phase and frequency variation but also harmonic voltage distortion. [less ▲]

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See detailDistributed Harmonic Compensation for Power Quality in Smart Grids
Kobou Ngani, Patrick UL; Hadji-Minaglou, Jean-Régis UL; Marso, Michel UL et al

in Cahier Scientifique - Revue Technique Luxembourgeoise (2014)

It is now well known that the quality of electric power is a key factor for the electricity service. It defines how good the characteristics (amplitude and frequency) of the supplied power meet the rated ... [more ▼]

It is now well known that the quality of electric power is a key factor for the electricity service. It defines how good the characteristics (amplitude and frequency) of the supplied power meet the rated ones. Voltage dip (or sag) and swell, short and long interruptions, voltage spike, under and over voltage, harmonic distortion, voltage unbalance are the common power quality problems. Among these last, the harmonics issue is getting more and more important over the last decades and this trend will surely continue its race. This is essentially due to the widespread use of electronic components in electric equipment: it changes the nature of the electric loads from linear to non-linear and makes them, on the one hand, responsible for the harmonics generation in the power grid but very sensitive to the power quality problems on the other hand. [less ▲]

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See detailDecentralized Power Supply for Small and Medium User Facilities
Hadji-Minaglou, Jean-Régis UL; Hoben, Ralf UL; Peters, Bernhard UL

Patent (2014)

The world-wide energy consumption has almost doubled since 1980 despite efforts towards energy saving and efficiency. This trend is supposed to continue for the decades to come so that major energy crises ... [more ▼]

The world-wide energy consumption has almost doubled since 1980 despite efforts towards energy saving and efficiency. This trend is supposed to continue for the decades to come so that major energy crises with electricity cuts and shortage of petrol or gas are anticipated. Furthermore, an ever increasing consumption of fossil fuels significantly contributes to further emissions of greenhouse gases and consequently to global warming in conjunction with catastrophic climate changes. These impacts are reduced to a large extent through utilisation of renewable energy sources for and within decentralised user facilities. The present invention relates to a method of communicating operation modes between a user facility control unit at a user facility and a utility grid control unit of a utility grid. In particular, it relates to a decentralised method of communicating operation modes between a user facility control unit at a user facility with renewable energy supply and a utility grid control unit of a utility grid. [less ▲]

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See detailMethods and Means for Harmonics Compensation in Electrical Power Generation
Hadji-Minaglou, Jean-Régis UL

Patent (2014)

Feeding more and more multiple non-linear and unsymmetrical power consumers (TV, Computers etc…) cause serious disturbances for the grid quality in terms of voltage harmonics and distortion power in ... [more ▼]

Feeding more and more multiple non-linear and unsymmetrical power consumers (TV, Computers etc…) cause serious disturbances for the grid quality in terms of voltage harmonics and distortion power in particular in decentralised low power supplies like solar photovoltaic (PV) in households. The use of inverter-fed power devices with modern high speed micro-controllers and an intelligent management of the different powers to be generated can help improving the power quality under any operating conditions. The invention provides a compensation algorithm implemented in a micro-controller combining the use of Finite Impulse Response (FIR) filters to extract the different harmonics from the original voltage signal and applies a Phase Locked Loop (PLL) to every extracted harmonic signal, which is finally compensated via a Proportional-Integral (PI) controller. All the PI controllers outputs are superposed in the final voltage source in such a way that they don’t conflict with each other, leading to a stable voltage source generation with a total harmonic distortion (THD) smaller than the limit of 8% requested by the global European power quality norm EN50160. The active harmonics compensator is able to compensate individually the strongest harmonics due to the feedback effect on the voltage source of any kind of non-linear load at partial-load as well as overload operation. The compensation can be implemented on a self-sufficient single voltage generating power source running in stand-alone or grid-tied. It can also be shared and distributed on multiple voltage source inverters (VSI) of different powers connected on a utility grid. That allows an optimisation of the power production of each device, in particular supplied by variable renewable energy sources (solar PV, wind), taking into consideration its capacity currently available. [less ▲]

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See detailStructured Analysis of Arbitrary Island Grids
Jostock, Markus UL; Sachau, Jürgen UL; Hadji-Minaglou, Jean-Régis UL et al

Scientific Conference (2013, October 08)

This paper recapitulates an analytic control model for arbitrary island grids and presents findings on the dynamic behaviour of purely inverter driven island grids. Pole zero plots of different grid ... [more ▼]

This paper recapitulates an analytic control model for arbitrary island grids and presents findings on the dynamic behaviour of purely inverter driven island grids. Pole zero plots of different grid structures are presented and the influence of several inverter parameters on the grid stability is analysed. Findings show that for improved grid stability the inverter’s time constants should also relate to their rated power. Further it is shown how P-Q rotation in the droop control can improve the integration density of renewable power sources in the distribution grid. [less ▲]

Detailed reference viewed: 187 (22 UL)