Control of Electrical Drives

Original scientific paperFaults of wind turbine generator electromechanical parts are common and very expensive. This paper introduces a generator fault-tolerant control scheme for variable-speed variable-pitch wind turbines that can be applied regardless to the AC generator used. The focus is on generator stator isolation inter-turn fault that can be diagnosed and characterised before triggering the safety device. An extension of the conventional wind turbine control structure is proposed that prevents the fault propagation while power delivery under fault is deteriorated as less as possible compared to healthy machine conditions. Fault-induced and inherent asymmetries of the generator are estimated and respected by the field-oriented control of the generator to eliminate torque oscillations. An approach for asymmetry detection based on an unscented Kalman filter is proposed. Presented fault-tolerant control strategy is developed taking into account its modular implementation and installation in available control systems of existing wind turbines to extend their exploitable life span and increase energy production. Simulation results for the case of a megawatt class wind turbine are presented.Key words: Wind turbine control, Generator fault-tolerant control, Stator winding isolation fault, Nonlinear estimation, Asymmetric field-oriented controlUpravljanje vjetroagregatom otporno na me uzavojske kvarove statorskog namota generatora. Kvarovi elektromehaničkih dijelova generatora vjetroagregatačesti su i izrazito skupi. U ovom radu predstavljen je koncept na kvarove otpornog upravljanja generatorom vjetroagregata s promjenjivom brzinom vrtnje i zakretom lopatica primjenjiv bez obzira na tip korištenog izmjeničnog generatora. Naglasak je stavljen na oštećenje izolacije unutar namota jedne faze statora generatora koje se može dijagnosticirati i okarakterizirati prije aktiviranja sustava zaštite. Predložena je nadogradnja postojećeg sustava upravljanja vjetroagregatom koja sprječava širenje kvara i pritom postižečim manje smanjenje proizvodnje električne energije u odnosu na normalan režim rada. Tako er je prikazano vektorsko upravljanje generatorom koje uzima u obzir nesimetrije generatora, kako one nastale uslijed djelovanja kvara, tako i one inherentne. U radu je prikazan pristup za otkrivanje nesimetrija generatora zasnovan na nederivacijskom Kalmanovu filtru. Predstavljena strategija upravljanja razvijena je uvažavajući mogućnost modularnog nadovezivanja na postojeće algoritme upravljanja već postavljenih vjetroagregata s ciljem produženja njihova životnog vijeka i povećanja proizvodnje energije. Dani su simulacijski rezultati za slučaj vjetroagregata iz megavatne klase.Ključne riječi: upravljanje vjetroagregatom, upravljanje otporno na kvarove generatora, kvar izolacije statorskog namota, nelinearna estimacija, vektorsko upravljanje nesimetričnim strojem

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“…Mathematical model of an AC squirrel-cage induction machine can be represented in the two-phase (d, q) rotating coordinate system [18][19][20]:…”

Section: Mathematical Model Of An Induction Machinementioning

confidence: 99%

Fault-tolerant Control of a Wind Turbine with Generator Stator Inter-turn Faults

et al. 2013

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“…The disk speed control loop is based on a PI speed controller, while the normal force core control strategy comprises a cascade control system, where a superimposed proportional force controller (P controller) commands the reference for the inner proportional-integral (PI) speed controller. The latter approach may be in contrast with the traditional cascade control systems where the position controller typically commands the inner speed control loop [6], and the force control loop is superimposed to the position control loop [7]. However, by avoiding the inner position control loop altogether, and commanding the speed reference directly through the force controller, a faster force control system response can be obtained.…”

Section: Pin-on-disk Tribometer Control Sys-temmentioning

confidence: 99%

“…Note that, unlike the more commonly used symmetrical optimum tuning method [6] (used for the tuning of the disk drive PI speed controller, see next subsection), the proposed tuning method adjusts the PI speed controller parameters with respect to the natural frequency of vertical vibrations. Thus, it provides favorable damping of drive vibrations by means of control regardless of vertical axis compliance.…”

Section: Control System Structurementioning

confidence: 99%

“…5). Since the disk drive is characterized by negligible compliance effects (due to rather "stiff" belt drive), the PI speed controller can be tuned according to the symmetrical optimum tuning procedure [6], which gives a fast and well-damped response of the speed control loop (J r is the equivalent disk drive inertia referred to servomotor shaft):…”

Section: Disk Speed Control Systemmentioning

confidence: 99%

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Design of Normal Force Control System for a Pin-on-Disk Tribometer including Active and Passive Suppression of Vertical Vibrations

2013

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Original scientific paperThis paper presents the design of a computer-controlled pin-on-disk tribometer for friction characterization of various friction sliding pairs. The tribometer setup comprises two high-bandwidth servomotors for the control of the rotating disk and the normal load-related spindle drive, as well as a high-precision tri-axial piezoelectric force sensor for normal and tangential forces measurement. Since the spindle drive system is characterized by notable compliance effects, the normal force cascade control system is designed with the aim of vertical vibrations active damping. In order to compensate for the unevenness of the rotating disk surface and associated high-level perturbations in the specimen normal force, the normal force control system is extended with a feedforward compensator of the disk unevenness disturbance, and a dedicated leaf spring suspension system is designed. The effectiveness of the proposed system of vertical vibrations damping is verified experimentally.Key words: Vibration suppression, Normal force control, Pin-on-disk tribometer Projektiranje sustava regulacije vertikalne sile tribometra s uzorkom na disku uključujući aktivno i pasivno prigušenje vertikalnih vibracija. Učlanku je prikazan dizajn računalom upravljanog tribometra s uzorkom na disku za karakterizaciju različitih kliznih parova. Postav tribometra sadrži dva električna servomotora visokih dinamičkih performansi koji se koriste za regulaciju rotacijskog diska i navojnog vretena za generiranje normalne sile, te tro-osni piezoelektrični senzor za mjerenje normalne i tangencijalne sile. Kako je pogon navojnog vretena karakteriziran značajnom elastičnošću, kaskadni sustav regulacije sile je projektiran s ciljem aktivnog prigušenja vertikalnih vibracija. U svrhu kompenzacije značajnih neravnina površine rotacijskog diska i s njima povezanih velikih amplituda perturbacija normalne sile na uzorak, sustav regulacije normalne sile proširuje se unaprijednim kompenzatorom poremećaja uslijed neravnina površine diska, te za tu svrhu namijenjenim sustavom ovjesa s lisnatim oprugama. Učinkovitost predloženog sustava za prigušenje vertikalnih vibracija provjerena je eksperimentalnim putem.Ključne riječi: prigušenje vibracija, regulacija vertikalne sile, tribometar s uzorkom na disku

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“…As background, field-oriented control provides a means to obtain high-performance control of an induction machine for use in applications such as traction drives. This field-oriented control methodology requires knowledge of the rotor flux linkages, which are not usually measured [12] [13]. To get around this problem, the rotor flux linkages are usually estimated using a state observer, and this observer requires the value of the rotor time constant   .…”

Section: Mathematical Model Of An Induction Machinementioning

confidence: 99%