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Assessing Kalman filter in the identification of synchronous machine stability parametersBorrero, Antonio J. January 1983 (has links)
No description available.
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Design, Analysis and Experimental Evaluation of a Virtual Synchronous Machine Based Control Scheme for STATCOM ApplicationsLi, Chi 23 September 2015 (has links)
Because renewable energy sources are environment-friendly and inexhaustible, more and more renewable energy power plants have been integrated into power grids worldwide. To compensate for their inherent variability, STATCOMs are typically installed at the point of common coupling (PCC) to help their operation by regulating the PCC voltage. However under different contingencies, PCC voltage fluctuations in magnitude and frequency may impede the STATCOM from tracking the grid frequency correctly, hence worsening its overall compensation performance, and putting at risk the operation of the power plant. Further, the virtual synchronous machine (VSM) concept has recently been introduced to control grid-connected inverters emulating the behavior of rotating synchronous machines, in an effort to eliminate the shortcomings of conventional d-q frame phase-locked loops (PLL).
In this dissertation, the VSM concept is extended by developing a STATCOM controller with it, which then behaves like a fully-adjustable synchronous condenser, including the adjustment of its "virtual" inertia and impedance. An average model in two D-Q frames is proposed to analyze the inherent dynamics of the VSM-based STATCOM controller with insight into impacts from the virtual parameters and a design guideline is then formulated. The proposed controller is compared against existent d-q frame STATCOM control strategies, evincing how the VSM-based approach guarantees an improved voltage regulation performance at the PCC by adjusting the phase of its compensating current during frequency fluctuations, in both simulation and experiment.
Secondly, the dynamics of the VSM-based STATCOM controller in large signal sense is studied, especially its capability to ride through faults. Analysis is carried out with phasors to obtain a fundamental understanding at first and followed by state space equations to predict the transients analytically, which is validated by matching both simulation and experiment. The effects of two outer loops are also reviewed and some possible solutions are suggested and evaluated. Moreover, the relationship between the virtual inertia and the actual inertia is established and the dc capacitor sizing is discussed in a possibly more economical way. The start-up process of a VSM-based STATCOM is presented to implement a practical prototype as well. / Master of Science
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Design, Analysis, and Driver Control of Disc-type Permanent Magnet Linear Synchronous MachineChen, Jyh-Wei 28 August 2001 (has links)
The design, analysis, and control of Disc-type Linear Permanent Magnet Synchronous Machines are presented in this dissertation. The machine is designed in order to have the features of high power density, high efficiency, direct drive without extra transmission device, simple mechanical structure, and wide operating speed range for the electric vehicle applications. The Feasible Triangle Technique for permanent magnet synchronous machine design is employed to increase torque density and reduce torque ripple. Magnetic theory and the finite element method are involved to establish machine mathematical model to simulate and analyze the proposed machine. The coupling field between rotor and stator can be analyzed from flux distribution by using three-dimensional finite element method. The numerical simulation and experimental results are used to verify the machine model and the operational characteristics of machine. The dissertation provides the procedures for design, analysis, and control of the proposed machine.
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Thermal modelling of a high speed permanent magnet synchronous machine / Andries J. GroblerGrobler, Andries Johannes January 2011 (has links)
Thermal modelling is of great importance in all electric machines but especially in permanent
magnet synchronous machines (PMSMs). The thermally fragile permanent magnets (PMs) can
more easily be demagnetized at high temperatures. When high speed machines are considered,
heat extraction surfaces are small due to the higher energy density. This thesis focuses on the
thermal modelling of a high speed slotless PMSM using analytical techniques. From literature
it is clear that analytical distributed models have not reached its full potential in thermal modelling
of electric machines. Thermal experiments on high speed electric machine, including
rotor PM temperature measurements are not commonly found in literature.
The thermal behaviour of each component of the machine is influenced by the overall temperature
distribution. The widely used lumped parameter (LP) cylindrical component model
derived by Mellor et al. is used to derive a LP model of the entire machine. A two dimensional
(2-D) analytical distributed model is derived for the rotor PM using the separation of variables
method. Three of the boundaries are assumed to be of the convection type and the fourth of
constant heat flow type. Different convection coefficients are assumed to exist in the radial and
axial directions. The distributed model is verified using COMSOL
R and good correlation is
shown. The distributed model is used to determine the temperature distribution in the PM
and the convection heat flow in the axial direction.
Loss calculation is an integral part of thermal modelling. Temperature changes in an electric
machine is due to the interaction between the heat generation (losses) and heat removal. The
losses found in a high speed slotless PMSM are investigated. A 2-D analytical magnetic model
is used to determine the stator lamination loss as well as the stator winding eddy current loss. A
simple LP model is derived for the rotor eddy current loss. Due to the relatively large resistivity
of the shielding cylinder and PM material, the rotor eddy current loss is a significant part of the
total machine loss. The tangential current width is determined empirically in this thesis but a
3-D distributed model which includes end space effects and skin depth could also be used.
A large part of thermal modelling is empirically based. The convection and interface resistances
are determined through a set of experiments in this thesis. The measured and calculated
convection coefficients correlated well for both forced and natural convection cooling. A large
temperature increase found during the no-load test can be attributed to large bearing loss, possibly
due to axial loading. The LP model is modified to include the phenomena found during
the experiments.
The thermal model is used to predict the temperatures of a high speed PMSM at rated load and speed. Although the PM is not heated above the Curie temperature, demagnetization is
still possible. According to the model, the machine will not be able to operate at full load and
speed for extensive periods due to mechanical stress limits being exceeded. The temperature
distribution of the PM could not be verified since the temperatures in the air gap and end space
could not be measured. It is expected that axial heat flow will be larger than what is currently
predicted by the distributed model. A sensitivity analysis was used to investigate the influence
of the thermal resistances and losses on the machine temperatures. Methods for reducing the
rotor eddy current loss and interface resistances are also discussed.
The first contribution of this thesis is the 2-D analytical distributed model for the PM of a high
speed PMSM. Hot spots and 2-D heat flow can be analysed using this model. Combining the
LP and 2-D analytical distributed models is another contribution. This combines the simplicity
and fast solution times of the LP model with the 2-D thermal distribution of the analytical
distributed model. The systematic experimental investigation of the thermal behaviour of a
high speed PMSM is a further contribution. / Thesis (Ph.D. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2011.
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Thermal modelling of a high speed permanent magnet synchronous machine / Andries J. GroblerGrobler, Andries Johannes January 2011 (has links)
Thermal modelling is of great importance in all electric machines but especially in permanent
magnet synchronous machines (PMSMs). The thermally fragile permanent magnets (PMs) can
more easily be demagnetized at high temperatures. When high speed machines are considered,
heat extraction surfaces are small due to the higher energy density. This thesis focuses on the
thermal modelling of a high speed slotless PMSM using analytical techniques. From literature
it is clear that analytical distributed models have not reached its full potential in thermal modelling
of electric machines. Thermal experiments on high speed electric machine, including
rotor PM temperature measurements are not commonly found in literature.
The thermal behaviour of each component of the machine is influenced by the overall temperature
distribution. The widely used lumped parameter (LP) cylindrical component model
derived by Mellor et al. is used to derive a LP model of the entire machine. A two dimensional
(2-D) analytical distributed model is derived for the rotor PM using the separation of variables
method. Three of the boundaries are assumed to be of the convection type and the fourth of
constant heat flow type. Different convection coefficients are assumed to exist in the radial and
axial directions. The distributed model is verified using COMSOL
R and good correlation is
shown. The distributed model is used to determine the temperature distribution in the PM
and the convection heat flow in the axial direction.
Loss calculation is an integral part of thermal modelling. Temperature changes in an electric
machine is due to the interaction between the heat generation (losses) and heat removal. The
losses found in a high speed slotless PMSM are investigated. A 2-D analytical magnetic model
is used to determine the stator lamination loss as well as the stator winding eddy current loss. A
simple LP model is derived for the rotor eddy current loss. Due to the relatively large resistivity
of the shielding cylinder and PM material, the rotor eddy current loss is a significant part of the
total machine loss. The tangential current width is determined empirically in this thesis but a
3-D distributed model which includes end space effects and skin depth could also be used.
A large part of thermal modelling is empirically based. The convection and interface resistances
are determined through a set of experiments in this thesis. The measured and calculated
convection coefficients correlated well for both forced and natural convection cooling. A large
temperature increase found during the no-load test can be attributed to large bearing loss, possibly
due to axial loading. The LP model is modified to include the phenomena found during
the experiments.
The thermal model is used to predict the temperatures of a high speed PMSM at rated load and speed. Although the PM is not heated above the Curie temperature, demagnetization is
still possible. According to the model, the machine will not be able to operate at full load and
speed for extensive periods due to mechanical stress limits being exceeded. The temperature
distribution of the PM could not be verified since the temperatures in the air gap and end space
could not be measured. It is expected that axial heat flow will be larger than what is currently
predicted by the distributed model. A sensitivity analysis was used to investigate the influence
of the thermal resistances and losses on the machine temperatures. Methods for reducing the
rotor eddy current loss and interface resistances are also discussed.
The first contribution of this thesis is the 2-D analytical distributed model for the PM of a high
speed PMSM. Hot spots and 2-D heat flow can be analysed using this model. Combining the
LP and 2-D analytical distributed models is another contribution. This combines the simplicity
and fast solution times of the LP model with the 2-D thermal distribution of the analytical
distributed model. The systematic experimental investigation of the thermal behaviour of a
high speed PMSM is a further contribution. / Thesis (Ph.D. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2011.
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Non-invasive detection of air gap eccentricity in synchronous machines using current signature analysisThirumarai Chelvan, Ilamparithi 13 December 2012 (has links)
Air gap eccentricity fault is one of the major faults that afflict the life and performance of rotating machines. Eccentricity fault, in the worst case, causes a stator rotor rub. Thus, a condition monitoring scheme to identify eccentricity fault at its initial stage is necessary. The most widely practised air gap monitoring schemes for synchronous machines are expensive and invasive sensors based. This work has focussed on developing an inexpensive, non-invasive, air gap monitoring technique especially for salient pole synchronous machines. Motor current signature analysis has been mostly preferred for the above mentioned purpose. By monitoring the frequency spectrum of the machine’s current, faulty condition can be isolated provided the fault specific frequency components are known beforehand.
The research work, therefore, has developed a specific permeance function using binomial series for salient pole machines that can be used to identify eccentricity specific harmonic components in the line current spectrum. Then by performing the magneto-motive force – specific permeance analysis the characteristic frequency components have been predicted. In order to validate the prediction as well as to identify a trend in the variation of these harmonic components with changing levels of eccentricity, mathematical models of a three phase reluctance synchronous machine and a three phase salient pole synchronous machine based on modified winding function approach have been developed. The models have been made to incorporate static, dynamic and mixed eccentricity conditions of varying severity. Also time stepped finite element based models have been simulated in Maxwell-2D to verify the theoretical predictions. With the help of eccentrically cut bushings, experiments were then conducted in the laboratory to corroborate the proposed eccentricity detection scheme.
It has been observed that non-idealities such as supply time harmonics, machine constructional asymmetry, supply voltage unbalance etc. negatively impact the diagnostic technique. Consequently, a residual estimation based fault detection scheme has been implemented successfully to distinguish eccentricity fault from healthy condition. Moreover, detection logic have been put forth to discriminate the type of eccentricity and to estimate the severity of the fault. / Graduate
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Development of a converter-fed reluctance synchronous generator wind turbine controllerDu Plooy, Jon-Pierre 03 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The growing contribution of wind energy to utility grids has sparked interest in small-scale wind
turbines and thus a growing global cumulative installed capacity. Small-scale wind turbines find
use in the saving of cost of electricity or for the carbon footprint reduction of small farms and
small-holdings, as well as the electrification of rural communities.
A goal of any wind turbine is to produce power at as low of a cost per unit energy as possible.
Thus, a generator with a high power density and high efficiency is essential. The reluctance
synchronous machine (RSM) is a strong competitor in this regard. Additionally, the RSM is
a robust brushless topology that has good properties of manufacturability. However, studies
published on the use of RSMs as generators in wind turbines is limited. This study serves to
explore the performance and controllability of an RSM as a generator in a small-scale 9:2 kW
wind turbine.
For maximum power capture, it is desirable to have a wind turbine vary its rotor speed.
However, there is a limit to the power that the generator may produce and so techniques
are employed to reduce the captured power when operating above the rated wind speed. A
turbine controller is developed that employs a speed-controlled maximum power point tracking
(MPPT) technique for maximum power capture and soft-stalling of the blades to reduce power
capture at excessive wind speeds. The RSM is modelled along with a turbine simulation model,
complete with a wind source generator, to evaluate the performance of the system.
Speed-controlled MPPT is known to sacrifice torque smoothness for fast tracking performance.
To mitigate these harsh effects on the drivetrain, the speed reference of the generator
is filtered to provide an average response to the optimal speed reference. This is shown to
reduce the frequent and excessive speed, torque, and electrical power variations though optimal
performance is not possible. However, any reduction on drivetrain fatigue that will maximise
operation time of the turbine is considered an important gain.
The RSM proves to have qualities that are applicable to wind turbine applications with its
high efficiency, good manufacturability properties, low cost, and high robustness. Its higher
power density over induction machines is also favourable though power electronics are required
for optimal operation of the machine. / AFRIKAANSE OPSOMMING: Die groeiende bydrae van wind energie te nut roosters het aanleiding gegee tot belangstelling in
kleinskaalse wind turbines en dus 'n groeiende w^ereldwye kumulatiewe geïnstalleerde kapasiteit.
Kleinskaalse wind turbines vind ook gebruik in die besparing van koste van elektrisiteit, of vir
die koolstofvoetspoor vermindering van klein plase en klein-hoewes, sowel as die elektrifisering
van landelike gemeenskappe.
Een van die doelwitte van enige wind turbine is om krag te produseer teen so laag van
'n koste per eenheid energie as moontlik. Dus, 'n kragopwekker met 'n hoë krag digtheid
en hoë doeltreffendheid is noodsaaklik. Die reluktansie sinchroonmajien (RSM) is 'n sterk
mededinger in hierdie verband. Daarbenewens is die RSM 'n robuuste borsellose topologie
wat goeie eienskappe van vervaardigbaarheid het. Maar studies oor die gebruik van RSMs as
kragopwekkers gepubliseer in die wind turbines is beperk. Hierdie studie dien om die prestasie
te ondersoek en die beheerbaarheid van 'n RSM as 'n a kragopwekker in 'n klein-skaal 9:2 kW
wind turbine te verken.
Vir maksimum krag vang is dit wenslik dat die wind turbine sy rotor spoed wissel. Maar daar
is 'n beperking op die krag wat die kragopwekker kan produseer en daarom work tegnieke gebruik
om die gevange krag te verminder wanneer daar bo die gegradeerde wind spoed gewerk word.
'n Turbine beheerder word ontwikkel wat werk om 'n spoedbeheer maksimum kragpunt dop
tegniek vir maksimum krag vang en die sagtestaking van die lemme krag vang deur oormatige
wind spoed te verminder. Die RSM is gemodeleer saam met 'n turbine simulasie model kompleet
met 'n wind bron kragopwekker om die prestasie van die stelsel te evalueer.
Spoedbeheerde maksimum kragpunt dop is bekend om wringkrag gladheid vir 'n vinnige dop
prestasie te offer. Om hierdie harde gevolge op die kragoorbringstelsel te versag is die spoed
verwysing van die kragopwekker gefiltreer om 'n gemiddelde reaksie op die optimale spoed
verwysing te verskaf. Dit word getoon om gereelde en hoë spoed, wringkrag en elektriese krag
variases te verminder al is optimale prestasie nie moontlik nie. Enige afname van aandrystelsel
moegheid wat operasie tyd van die turbine maksimeer word beskou as 'n belangrike gewin.
Die RSM bewys eienskappe wat van toepassing is op die turbine aansoeke na aanleiding met
sy hoë doeltreffendheid, goeie vervaardigbaarheid eienskappe, lae koste end ' hoë robuustheid.
Sy hoër krag digtheid oor induksiemasjien is ook gunstig al is drywingselektronika nodig vir
optimale werking van die masjien.
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Analýza tepelných vlastností synchronního stroje / Analysis of thermal properties of the synchronous machinePaszek, Michal January 2012 (has links)
In this Master´s thesis will be performed an analysis of thermal properties of synchronous machines in the program Ansys Workbench on a simplified model of synchronous traction motor. In the first section will be performed thermal analysis without cooling followed by analysis of air flow and finally thermal analysis with cooling for fan speed 1500 min-1 and 3000 min-1. The second section will describe the principle, construction and losses on the synchronous machine. The third chapter will describe concepts such as heat, temperature, heat transfer, types of the heat transfer, specific heat capacity, emisivity and thermal conductivity. The fourth chapter will introduce the program Ansys Workbench, finite element method and Ansys CFX. In the fifth chapter will be described how to perform thermal analysis on the created model of motor. The sixth chapter will describe how to analyze the air flow of the created model of motor. The flow analysis will be performed for fan speed 1500 min-1 and 3000 min-1. In the seventh chapter will be compared the results of the air flow and pressure field in the motor model. In the eighth chapter will be performed a thermal analyzis on the created motor model with cooling for fan speed 1500 min-1 and 3000 min-1. The nineth chapter will compare the results of temperatures and heat fluxes obtained from the thermal analysis witnout cooling, with cooling for fan speed 1500 min-1 and 3000 min-1 for full losses, half losses of continous running, and full losses of interrupt running for 9000 seconds (2 hours 30 minutes).
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Analýza budicího proudu u synchronních strojů / Analysis of field current in synchronous machinesKocman, Roman January 2013 (has links)
This master’s thesis is focused on the analysis of the excitation current in synchronnous machines. Contains a description of excitation systems for synchronous machines, meaning and design of the sliding contact ant its representation in electrical machines. The main part of the work is focused on the evaluation of the field current of the three plants. The work includes graphic record of the excitation current of the hydroelectric power station Slapy, provided record from the power plant Opatovice was for evaluating load of turbo-generators. Provided record from the nuclear power plant Temelín was for evaluating.current division into individual brushes. The conclusion is a summary of the achieved knowledge.
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Modélisation basée sur la méthode des réseaux de perméances en vue de l’optimisation de machines synchrones à simple et à double excitation / Modeling method based on magnetic equivalent circuit for the optimization of single and double excitation synchronous machinesNedjar, Boumedyen 07 December 2011 (has links)
La traction hybride et/ou électrique est un domaine d’application en pleine croissance présentant une forte restriction en termes d’encombrement. Cela a poussé les concepteurs à créer des structures de machine adaptées. Parmi ces topologies, nous trouvons les machines synchrones à double excitation (MSDE). Ces machines permettent de combiner les avantages d’une machine à aimants et ceux d’une machine à excitation bobinée. Le choix d’un modèle pour ces machines est un élément important dans les étapes d’analyse, d’optimisation et de pré-dimensionnement. Ce mémoire présente une contribution à la modélisation des machines synchrones à simple et à double excitation basée sur la méthode des réseaux de perméances. Trois parties sont ainsi proposées. La première partie de la thèse présente deux états de l’art- un sur les machines synchrones à double excitation et l’autre sur les méthodes de modélisation des machines électriques et principalement la modélisation par réseau de perméances. Dans la deuxième partie, nous abordons la modélisation 2D de la machine synchrone à aimants permanents à concentration de flux avec prise en compte de la rotation et de la saturation. Le but de cette partie est de trouver des méthodes permettant de combiner à la fois temps de calcul et précision. On commence par la modélisation par réseau de perméances en se basant sur un maillage de l’espace d'étude par des réluctances bidirectionnelles, ainsi qu’une comparaison entre calcul du couple par le tenseur de Maxwell et flux-FMM. La deuxième section présente un couplage entre réseaux de perméances et éléments finis. La méthode proposée consiste à résoudre les deux modèles (réluctant et éléments finis) simultanément avec un logiciel EF. Le couplage s’effectue par une équivalence entre les dimensions géométriques et les caractéristiques magnétiques des matériaux. La présentation des différents modèles dans le plan précision-temps de calcul montre l’efficacité de l’utilisation des réseaux de perméances et du couplage comparé au modèle éléments finis. La troisième partie porte sur la modélisation tridimensionnelle des machines synchrones à double excitation. Dans un premier temps, nous présentons une adaptation de la modélisation par réseau de perméances aux structures tridimensionnelles. Puis, nous appliquons ce modèle aux machines synchrones à double excitation. La machine à double excitation à concentration de flux est présentée avec une étude de l’influence du feuilletage sur la capacité de contrôle du flux. Pour améliorer le contrôle du flux d'excitation, une machine à aimants enterrés homopolaire est également étudiée avec l'approche développée. La validation du modèle est réalisée par des éléments finis et des mesures expérimentales. Dans la dernière partie, une comparaison entre configurations homopolaire et bipolaire de la structure à aimants enterrés est effectuée, puis le rotor à concentration de flux est optimisé afin de le comparer à la machine à aimants enterrés. / The electric and / or hybrid driveis are an application area growing with a strong restriction in terms of congestion. This prompted the designers to create appropriate structures. Among these topologies, we find the double-excitation synchronous machine (MSDE). These machines can combine the advantages of permanent magnets machine and those of a coils excited machine.The choice of a model for these machines is an important step in the analysis, optimization and pre-sizing. This thesis presents a contribution to the modeling by magnetic equivalent circuit (MEC) of single and double excitation synchronous machines. Three parties are offered as well. The first part of the thesis presents two states of the art: one on the double-excitation synchronous machines and the other on the modeling of electrical machines, mainly in the modeling by magnetic equivalent circuit. In the second part, we discuss the 2D modeling of flux concentration permanent magnet synchronous machine taking into account the rotation and saturation. The purpose of this section is to find ways to combine both computational time and accuracy. We start by using the magnetic equivalent circuit modeling based on a mesh of the structure and each mesh is replaced by two-way reluctances, then a torque estimation are obtened by two methods flux-FMM and Maxwell stress Tensor. The second section presents a coupling between magnetic equivalent circuit and finite element method. The proposed method is to solve the two models (reluctant and finite elements) simultaneously with software EF. The coupling is performed by an equivalence between the geometric dimensions and magnetic properties of materials. The presentation of different models in terms of time-accurate calculation shows the effectiveness of the use of MEC and coupling method compared to FEM. The third part concerns the three-dimensional modeling of double excitation synchronous machines. At first, we present an adaptation of the MEC to the three-dimensional structures. Then we apply this model to the double excitation synchronous machines (DESM). The DESM with flux concentration configuration is presented. To better control the wund flux of excitation, a buried magnet homopolar machine is also studied with the same approach. Model validation is performed by finite element and experimental measurements. In the last part, a comparison between homopolar and bipolar configurations is made, then the rotor flux concentration is optimized in order to compare it to the machine magnets buried.
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