167 research outputs found

    Modeling and Simulation of Sensorless Induction Motor Drive Using MRAS Observers

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    Tato práce se zabývá implementací vektorového bezsenzorového řízení asynchronního motoru na principu MRAS. Po důkladné rešerši možných variant bezsenzorového přístupu je pro vlastní realizace zvolen X-MRAS. V odborné literatuře je tento poměrně nový typ MRASu, který je založený na bezrozměrné veličině X, považován za velmi robustní a umožňuje řízení ve všech 4 kvadrantech. Za účelem ověření těchto vlastností je v programu Matlab-simulink vytvořen model vektorového řízení na principu nepřímého výpočtu toku tzv. Indirect Field Oriented Control (IFOC), model trojfázového asynchronního motoru a model vlastní X-MRAS struktury. Nejdříve je kompletně otestován model vektorového regulátoru a asynchronního motoru s čidlem otáček. Poté se systematicky otestuje několik možných implementací bezsenzorové struktury v otevřené a uzavřené smyčce a jsou sledovány důležité parametry. Jak je v této práci ukázáno, tak X-MRAS struktura implementovaná tak, jak je popsáno v odborné literatuře, nezaručuje regulaci pohonu v orientovaných souřadnicích, které umožňují regulaci asynchronních motorů obdobné té, která se používá u regulace motorů stejnosměrných s cizím buzením. Simulace dále ukazují, že bezsenzorové řízení na principu X-MRAS není vhodné pro vysoké rychlosti, časově dlouhé rozběhy a nominální zatěžovací momenty, kde dochází k větší odchylce od řízení v orientovaných souřadnicích oproti nižším rychlostem, kratším rozběhům a menším zatěžovacím momentům. Dále je v práci ukázáno, že v případě kdy je pohon provozován mimo orientované souřadnice, není schopný dodat požadovaný nominální moment a dochází k poruše regulace pohonu. V důsledku identifikovaných problémů je v této práci navrženo a porovnáno několik možných postupů, jak vylepšit v literatuře popsanou variantu X-MRASu a docílit regulaci pohonu v souřadnicích blízkých orientovaných popř. přímo orientovaných. Pomocí simulací je ukázáno, že zvýšené nabuzení motoru, DFOC struktura pro výpočet toku, dynamické nastavení rotorové časové konstanty v adaptivním modelu a přídavný regulátor toku, dokáží zlepšit parametry regulace. Z těchto variant je nejvhodnější doplnění struktury X-MRAS o proudový model motoru a přídavný regulátor toku. Tato implementace v ustálených jevech zaručuje řízení motoru v orientovaných souřadnicích. Závěrečné simulace testují tuto konfiguraci a ukazují, že je možné motor bezsenzorově regulovat jak při velmi nízkých otáčkách, tak i vysokých až do nominálního zatěžovacího momentu včetně generátorického režimu. Poslední část práce se zabývá jednoduchou citlivostní analýzou, kde je ukázána značná závislost na rotorové časové konstantě jak pro vlastní vektorové řízení, tak pro estimaci otáček. Dále práce ověřila použití střídače na principu pulzně šířkové modulace (SVPWM), který nahrazuje abstraktní harmonický střídač, který je prakticky používaný v celé části práce.The main objective of this work was to implement sensorless control of an induction motor based on Model Reference Adaptive System (MRAS). After in-depth literature survey of MRAS approaches, MRAS based on fictitious quantity X was selected as a suitable candidate for further implementation. As presented in the literature such relatively novel approach is said to be robust and enables motor to be controlled in all four quadrants. In order to verify parameters of such MRAS, time based model was created in Matlab-simulink which included indirect field oriented control (IFOC) controller, three-phase induction motor and X-MRAS estimation structure. After verification of IFOC controller and induction motor, several implementations of X-MRAS sensorless model were tested in both open and close loop and various parameters were monitored. Results have shown that implementation as presented in state-of-the-art literature does not always guarantee field oriented control which enables induction motors to be controlled like DC counterparts. Moreover, simulations have shown that high speed, long start-up time and large up to nominal load torques are rather problematic due to the loss of oriented coordinates as opposed to low speed, short start-up time and light load torques which performed relatively satisfactory. The results of the simulations also proved that the more the control is from the oriented coordinates, the less torque the motor is capable of delivering. Based on the findings several approaches capable of increasing the range of operation have been proposed and compared. DFOC based control scheme, increase of magnetic excitation, dynamic adjustment of rotor constant within adaptive MRAS model or auxiliary magnetic flux controller are all capable of increasing the range of operation for X-MRAS. Nonetheless, it has been proven that the best approach is to incorporate within the X-MRAS structure the auxiliary magnetic flux controller with current model of induction machine. Such approach is well capable of controlling the motor in oriented coordinates in steady state. The final simulations investigated performance of this adjusted X-MRAS in both low and high speed simulations including nominal load torque applied and all 4 quadrant operation. Last part of the work evaluated sensitivity of different parameters when those parameters differ from nominal ones. It has been demonstrated that rotor time constant plays important role in precise estimation for both IFOC and X-MRAS. Lastly, the non-viable harmonic inverter was replaced by Space Vector Pulse Width Modulator and performance verified.430 - Katedra elektronikyvýborn

    Modelling, Monitoring, Control and Optimization for Complex Industrial Processes

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    This reprint includes 22 research papers and an editorial, collected from the Special Issue "Modelling, Monitoring, Control and Optimization for Complex Industrial Processes", highlighting recent research advances and emerging research directions in complex industrial processes. This reprint aims to promote the research field and benefit the readers from both academic communities and industrial sectors

    An Accurate Efficiency Calculation for PMSG Utilized in Renewable Energy Systems

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    Considering the importance of optimizing renewable energy systems, this paper aims at calculating the exact efficiency of a stand-alone wind turbine connected to a synchronous generator with permanent magnet excitation (PMSG). By accounting for mechanical and electrical losses (copper losses, stray load losses, iron core losses, friction losses, windings losses, and magnetizing saturation effect), the study investigates the impact of wind speed on the generator's performance and efficiency in addition to the impact of losses on the overall efficiency of (PMSG). The simulation of the PMSG dynamic model 8.5×(10)^3 V․A is executed using MATLAB/Simulink, employing a simplified equivalent circuit that accurately represents the PMSG's behavior under steady-state conditions with resistive loads. Wind speeds of 12 and 14 meters/second are chosen as fixed values to demonstrate the effect of varying wind speed on efficiency. The obtained results reveal the influence of wind speed on the PMSG efficiency. The presented findings contribute to the understanding of PMSG performance and can aid in optimizing the stand-alone wind turbine systems, they also show that the wind had an effect on the efficiency values that were obtained (97.86% at 12m/s and 97.91% at 14 m/s), while the effect of losses was very few around 3%. However, the obtained results are very good compared to previous studies to show the accuracy and validity of the suggested dynamic model

    Small-Scale Hydropower and Energy Recovery Interventions: Management, Optimization Processes and Hydraulic Machines Applications

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    Several topics in the small-scale hydropower sector are of great interest for pursuing the goal of a more sustainable relationship with the environment. The goal of this Special Issue entitled “Small-Scale Hydropower and Energy Recovery Interventions: Management, Optimization Processes and Hydraulic Machines Applications” was to collect the most important contributions from experts in this research field and to arouse interest in the scientific community towards a better understanding of what might be the main key aspects of the future hydropower sector. Indeed, the Guest Editors are confident that the Special Issue will have an important impact on the entire scientific community working in this research field that is currently facing important changes in paradigm to achieve the goal of net-zero emissions in both the energy and water sectors

    Modelling and Detecting Faults of Permanent Magnet Synchronous Motors in Dynamic Operations

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    Paper VI is excluded from the dissertation until the article will be published.Permanent magnet synchronous motors (PMSMs) have played a key role in commercial and industrial applications, i.e. electric vehicles and wind turbines. They are popular due to their high efficiency, control simplification and large torque-to-size ratio although they are expensive. A fault will eventually occur in an operating PMSM, either by improper maintenance or wear from thermal and mechanical stresses. The most frequent PMSM faults are bearing faults, short-circuit and eccentricity. PMSM may also suffer from demagnetisation, which is unique in permanent magnet machines. Condition monitoring or fault diagnosis schemes are necessary for detecting and identifying these faults early in their incipient state, e.g. partial demagnetisation and inter-turn short circuit. Successful fault classification will ensure safe operations, speed up the maintenance process and decrease unexpected downtime and cost. The research in recent years is drawn towards fault analysis under dynamic operating conditions, i.e. variable load and speed. Most of these techniques have focused on the use of voltage, current and torque, while magnetic flux density in the air-gap or the proximity of the motor has not yet been fully capitalised. This dissertation focuses on two main research topics in modelling and diagnosis of faulty PMSM in dynamic operations. The first problem is to decrease the computational burden of modelling and analysis techniques. The first contributions are new and faster methods for computing the permeance network model and quadratic time-frequency distributions. Reducing their computational burden makes them more attractive in analysis or fault diagnosis. The second contribution is to expand the model description of a simpler model. This can be achieved through a field reconstruction model with a magnet library and a description of both magnet defects and inter-turn short circuits. The second research topic is to simplify the installation and complexity of fault diagnosis schemes in PMSM. The aim is to reduce required sensors of fault diagnosis schemes, regardless of operation profiles. Conventional methods often rely on either steady-state or predefined operation profiles, e.g. start-up. A fault diagnosis scheme robust to any speed changes is desirable since a fault can be detected regardless of operations. The final contribution is the implementation of reinforcement learning in an active learning scheme to address the imbalance dataset problem. Samples from a faulty PMSM are often initially unavailable and expensive to acquire. Reinforcement learning with a weighted reward function might balance the dataset to enhance the trained fault classifier’s performance.publishedVersio

    Improved vector control methods for brushless double fed induction generator during inductive load and fault conditions

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    A Brushless Double-Fed Induction Generator (BDFIG) has shown tremendous success in wind turbines due to its robust brushless design, less maintenance, smooth operation, and variable speed characteristics. These generators are composed of two back-to-back voltage source converters, a Grid Side Converter (GSC) and a Rotor Side Converter (RSC). Existing control techniques use a “trial and error” method that results in a poor dynamic response in machine parameters during the absence of load. The RSC control is used for reactive current control during the inductive load insertion. However, it is more suitable for stabilizing steady-state behaviour, but it suffers from slow response and introduces a double fundamental frequency component to the Point of Common Coupling (PCC) voltage. In addition, generally, a Low Voltage Ride Through (LVRT) fault is detected using a hysteresis comparison of the power winding voltage. The LVRT capability is provided by using fixed reference values to control the winding current. This approach results in an erroneous response, sub-optimal control of voltage drops at PCC, and false alarms during transient conditions. This thesis aims to solve the mentioned issues by using an improved vector control method. Internal Model Control (IMC) based Proportional-Integral (PI) gains calculation is used for GSC and RSC. These are controlled to enhance the transient response and power quality during no-load, inductive load, and fault conditions. Firstly, a GSC-based vector control method is proposed to suppress the PCC voltage fluctuations when a large inductive load is suddenly connected. The proposed technique is based on an analytical model of the transient behaviour of the voltage drop at the PCC. To block a double fundamental frequency component as a result of reactive current compensation, a notch filter is designed. Secondly, an RSC-based vector control method is proposed using an analytical model of the voltage drop caused by a short circuit. Moreover, using a fuzzy logic controller, the proposed technique employs the voltage frequency in addition to the power winding voltage magnitude to detect LVRT conditions. The analytical model helps in reducing the power winding voltage drop while the fuzzy logic controller leads to better response and faster detection of faults. However, the reference value for reactive current compensation is analysed using an analytical model of the voltage drop at the PCC in the event of a short-circuit fault. The results obtained from MATLAB/Simulink show that the GSC-based vector control method technique can effectively reduce about 10% voltage drop at PCCs. Total Harmonics Distortion (THD) is improved to 22.3% by notch filter in comparison with an existing technique such as instantaneous reactive power theory. The RSC-based vector control method can achieve up to 11% voltage drop reduction and improve the THD by 12% compared to recent synchronous control and flux tracking methods

    Haptics: Science, Technology, Applications

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    This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

    THIESEL 2022. Conference on Thermo-and Fluid Dynamics of Clean Propulsion Powerplants

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    The THIESEL 2022. Conference on Thermo-and Fluid Dynamic Processes in Direct Injection Engines planned in Valencia (Spain) for 8th to 11th September 2020 has been successfully held in a virtual format, due to the COVID19 pandemic. In spite of the very tough environmental demands, combustion engines will probably remain the main propulsion system in transport for the next 20 to 50 years, at least for as long as alternative solutions cannot provide the flexibility expected by customers of the 21st century. But it needs to adapt to the new times, and so research in combustion engines is nowadays mostly focused on the new challenges posed by hybridization and downsizing. The topics presented in the papers of the conference include traditional ones, such as Injection & Sprays, Combustion, but also Alternative Fuels, as well as papers dedicated specifically to CO2 Reduction and Emissions Abatement.Papers stem from the Academic Research sector as well as from the IndustryXandra Marcelle, M.; Payri Marín, R.; Serrano Cruz, JR. (2022). THIESEL 2022. Conference on Thermo-and Fluid Dynamics of Clean Propulsion Powerplants. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thiesel.2022.632801EDITORIA

    Modeling, Simulation and Control of Wind Diesel Power Systems

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    Wind diesel power systems (WDPSs) are isolated microgrids that combine diesel generators (DGs) with wind turbine generators (WTGs). Often, WDPS are the result of adding WTGs to a previous existing diesel power plant located in a remote place where there is an available wind resource. By means of power supplied by WTGs, fuel consumption and CO2 emissions are reduced. WDPSs are isolated power systems with low inertia where important system frequency and voltage variations occur. WDPS dynamic modeling and simulation allows short-term simulations to be carried out to obtain detailed electrical variable transients so that WDPS stability and power quality can be tested. This book includes papers on several subjects regarding WDPSs: the main topic of interest is WDPS dynamic modeling and simulation, but related areas such as the sizing of the different WDPS components, studies concerning the control of WDPSs or the use of energy storage systems (ESSs) in WDPSs and the benefits that ESSs provide to WDPS are also discussed. The book also deals with related AC isolated microgrids, such as wind-hydro microgrids or wind-photovoltaic-diesel microgrids
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