Combining synergetic control and super twisting algorithm to reduce the active power undulations of doubly fed induction generator for dual-rotor wind turbine system

Aim. This work presents the amelioration of direct power control using synergetic-super twisting algorithms for asynchronous generators integrated into dual-rotor wind turbine systems. Method. The main role of the direct power control is to control the active and reactive powers and reduce the harmonic distortion of stator current of asynchronous generator for variable speed dual-rotor wind turbine systems. The traditional strategy is more attractive due to its high efficiency and simple algorithm. Super twisting algorithms are a non-linear command strategy; characterized by robustness against the parameters change or disturbances, it gives a good power quality under different conditions such as changing generator parameters. Novelty. Synergetic-super twisting algorithms are designed. Synergetic-super twisting algorithms construction is based on synergetic command and super twisting algorithms in order to obtain a robust control strategy and a fast system with acceptable precision. We use in our study a 1.5 MW asynchronous generator integrated to dual-rotor wind turbine system in order to regulate the active and reactive powers. Results. As shown in the results figures using synergetic-super twisting algorithms the ameliorate performances especially minimizes the torque, active and reactive power undulations, and reduces harmonic distortion of stator current (THD = 0.19 %) compared to traditional strategy.Мета. Робота представляє вдосконалення безпосереднього регулювання потужності за допомогою синергетичих алгоритмів супер-скручування для асинхронних генераторів, інтегрованих у системи вітряних генераторів з подвійним ротором. Метод. Основна роль безпосереднього регулювання потужності полягає у керуванні активною та реактивною потужностями та зменшенні гармонічних спотворень струму статора асинхронного генератора для вітряних генераторів з подвійним ротором зі змінною швидкістю обертання. Традиційна стратегія є більш привабливою завдяки її високій ефективності та простому алгоритму. Алгоритми супер-скручування – це нелінійна командна стратегія; характеризується стійкістю до зміни параметрів або порушень, це забезпечує хорошу якість енергії в різних умовах, таких як зміна параметрів генератора. Новизна. Розроблені синергетичні алгоритми супер-скручування. Побудова алгоритмів синергетичного супер-скручування базується на алгоритмах синергетичних команд та супер-скручування, для того щоб отримати надійну стратегію керування та швидку систему з прийнятною точністю. У нашому дослідженні ми використовуємо асинхронний генератор потужністю 1,5 МВт, інтегрований в систему вітряних турбін з подвійним ротором для регулювання активної та реактивної потужностей. Результати. Як показано на рисунках з результатами, із використанням алгоритмів синергетичного супер-скручування, покращені характеристики особливо мінімізують крутний момент, коливання активної та реактивної потужності та зменшують гармонічні спотворення струму статора (THD = 0,19%) порівняно з традиційною стратегією

Indirect active and reactive powers control of doubly fed induction generator fed by three-level adaptive-network-based fuzzy inference system – pulse width modulation converter with a robust method based on super twisting algorithms

Aim. This paper presents the minimization of reactive and active power ripples of doubly fed induction generators using super twisting algorithms and pulse width modulation based on neuro-fuzzy algorithms. Method. The main role of the indirect active and reactive power control is to regulate and control the reactive and active powers of doubly fed induction generators for variable speed dual-rotor wind power systems. The indirect field-oriented control is a classical control scheme and simple structure. Pulse width modulation based on an adaptive-network-based fuzzy inference system is a new modulation technique; characterized by a simple algorithm, which gives a good harmonic distortion compared to other techniques. Novelty. adaptive-network-based fuzzy inference system-pulse width modulation is proposed. Proposed modulation technique construction is based on traditional pulse width modulation and adaptive-network-based fuzzy inference system to obtain a robust modulation technique and reduces the harmonic distortion of stator current. We use in our study a 1.5 MW doubly-fed induction generator integrated into a dual-rotor wind power system to reduce the torque, current, active power, and reactive power ripples. Results. As shown in the results figures using adaptive-network-based fuzzy inference system-pulse width modulation technique ameliorate effectiveness especially reduces the reactive power, torque, stator current, active power ripples, and minimizes harmonic distortion of current (0.08 %) compared to classical control.Мета У статті представлено мінімізацію пульсацій реактивної та активної потужності асинхронних генераторів подвійного живлення з використанням алгоритмів суперскрутки та широтно-імпульсної модуляції на основі нейро-нечітких алгоритмів. Метод. Основна роль непрямого управління активною та реактивною потужністю полягає у керуванні та регулюванні реактивної та активної потужностей асинхронних генераторів з подвійним живленням для вітроенергетичних систем з подвійним ротором змінної швидкості. Непряме керування, орієнтоване на поле, - це класична схема керування та проста структура. Широтно-імпульсна модуляція, заснована на системі нечітких висновків на основі адаптивної мережі, є новим методом модуляції; характеризується простим алгоритмом, який дає гарні гармонічні спотворення порівняно з іншими методами. Новизна. Пропонується адаптивна мережа на основі нечіткого висновку із широтно-імпульсною модуляцією. Запропонована побудова методу модуляції базується на традиційній широтно-імпульсній модуляції та системі нечітких висновків на основі адаптивних мереж для отримання надійного методу модуляції та зменшення гармонічних спотворень струму статора. У нашому дослідженні ми використовуємо асинхронний генератор з подвійним живленням потужністю 1,5 МВт, інтегрований у вітроенергетичну систему з подвійним ротором, щоб зменшити пульсації крутного моменту, струму, активної потужності та реактивної потужності. Результати. Як показано на рисунках з результатами, використання методу широтно-імпульсної модуляції на основі нечітких висновків системи адаптивних мереж покращує ефективність, особливо зменшує реактивну потужність, крутний момент, струм статора, пульсації активної потужності, та мінімізує гармонійне спотворення струму (0,08 %) порівняно з класичним керуванням

Study of nonthermal continuum patches : wave propagation and plasmapause study

Nonthermal continuum (NTC) radiation is believed to be emitted at the plasmapause and near the magnetic equator. We present a particular type of NTC radiation, referred to as NTC patch, which appears over a wide frequency range and within a relatively short time interval. NTC patches are observed in all magnetospheric plasma environments of the Cluster 2 orbit and are shown to represent a quarter of the NTC events observed in 2003. A statistical analysis of the frequency pattern performed on the 2003 Cluster 2 Waves of High frequency and Sounder for Probing of Electron Density by Relaxation data indicates that the NTC patches can be divided into two classes: Those with banded emission in frequency are only observed close to the source region and are thus termed "plasmaspheric," while the others, nonbanded, are termed "outer magnetospheric." In an event on 26 September 2003, we localize the sources positions and study the expected propagation of each NTC frequency beam of a plasmaspheric patch. From the observations, we show that the sources are located very close to the satellite and to each other at positions projected on the XY GSE plane. Using a ray tracing code, we demonstrate that, close to the source regions, the satellite observes all frequency rays at the same time which overlap in the spectrogram making up the plasmaspheric patch. After the satellite crossing, the rays follow diverging paths and cannot therefore be observed further out by the same satellite simultaneously. Plasmaspheric patches are thus specific signatures of close and distorted source regions

Harmonic signatures of NTC waves observed by WHISPER instruments on board the Cluster mission: interpretations and questions

International audienc

Enhancement of the electron gyroharmonics amplitude close to the plasma frequency observed by the WHISPER/CLUSTER experiment.

International audienceThe Wave of HIgh frequency and Sounder for Probing of Electron density by Relaxation WHISPER performs the measurement of the electron density on the four satellites of the CLUSTER project The two main purposes of the WHISPER experiment are to record the natural waves and to make a diagnostic of the electron density using the sounding technique The various working modes and the fourier transforms calculated on board provide a good frequency resolution obtained in the bandwidth 2-80 kHz and a well instrumental adaptability to determine the electron density in various plasma In this presentation we will focus on the plasmaspheric region where the plasma frequency Fpe is above the electron gyrofrequency Fce In active mode the spectrum exhibits various resonance frequencies as upper hybrid frequency Fuh Bernstein mode Fqn electron gyroharnomics nFce and plasma frequency To extract the electron density it is necessary to clearly identify and name these various resonances This task could be difficult when several electron populations and thermal effects exist In previous works Trotignon et al 1986 it has been shown that the plasma frequency is usually close to the maximum amplitude of the spectrum which allows the frequency domain where to look for the plasma frequency resonance to be determined In this work we will show that the amplitude of the electron gyroharmonics depend strongly of the frequency distance Fpe --nFce In addition we will present a simular study for the Bernstein s resonance

Periodic narrowband continuum oscillations

International audienceNon-Thermal Continuum (NTC) radiation is believed to be emitted from sources located in the vicinity of the plasmapause region. Cluster orbit is well adapted to study the NTC radiations near their sources. The two main purposes of the WHISPER experiment are to record the natural waves in the bandwidth 2-83 kHz and to make a diagnostic of the electron density using the sounding technique. The various working modes and the Fourier transforms calculated on board provide a good time and frequency resolution and allow us to detect the fine structure of NTC emissions as well as their spectral characteristics in relation to the local plasma regime (gyro-frequency fce and plasma frequency fpe). On August, 14, 2003, Cluster observes NTC radiation in the plasmapause vicinity, hence near the source region. A series of distinct and oscillating NTC narrowbands are observed covering a 25 kHz frequency range above the local plasma frequency. These bands are parallel, very close in frequency and oscillate with a precise period. Some periodic oscillations are also observed in the local DC magnetic field vector, not necessarily exactly at the same time. These oscillations suggest a global oscillation of the magnetosphere (Sauvaud et al., JGR, 1999, Kivelson et al., JGR, 1984). We compare in this paper oscillations observed respectively by the FGM and WHISPER instruments and discuss a possible scenario linking both phenomena. Such study can yield useful information toward identifying the NTC generation mechanism

Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

International audienceThe Cluster mission operated a "tilt campaign" during the month of May 2008. Two of the four identical Cluster spacecraft were placed at a close distance (~50 km) from each other and the spin axis of one of the spacecraft pair was tilted by an angle of ~46°. This gave the opportunity, for the first time in space, to measure global characteristics of AC electric field, at the sensitivity available with long boom (88 m) antennas, simultaneously from the specific configuration of the tilted pair of satellites and from the available base of three satellites placed at a large characteristic separation (~1 RE). This paper describes how global characteristics of radio waves, in this case the configuration of the electric field polarization ellipse in 3-D-space, are identified from in situ measurements of spin modulation features by the tilted pair, validating a novel experimental concept. In the event selected for analysis, non-thermal continuum (NTC) waves in the 15-25 kHz frequency range are observed from the Cluster constellation placed above the polar cap. The observed intensity variations with spin angle are those of plane waves, with an electric field polarization close to circular, at an ellipticity ratio e = 0.87. We derive the source position in 3-D by two different methods. The first one uses ray path orientation (measured by the tilted pair) combined with spectral signature of magnetic field magnitude at source. The second one is obtained via triangulation from the three spacecraft baseline, using estimation of directivity angles under assumption of circular polarization. The two results are not compatible, placing sources widely apart. We present a general study of the level of systematic errors due to the assumption of circular polarization, linked to the second approach, and show how this approach can lead to poor triangulation and wrong source positioning. The estimation derived from the first method places the NTC source region in the dawn sector, at a large L value (L ~ 10) and a medium geomagnetic latitude (35° S). We discuss these untypical results within the frame of the geophysical conditions prevailing that day, i.e. a particularly quiet long time interval, followed by a short increase of magnetic activity

Wide-banded NTC radiation: local to remote observations by the four Cluster satellites

International audienceThe Cluster multi-point mission offers a unique collection of non-thermal continuum (NTC) radio waves observed in the 2-80 kHz frequency range over almost 15 years, from various view points over the radiating plasmasphere. Here we present rather infrequent case events, such as when primary electrostatic sources of such waves are embedded within the plasmapause boundary far from the magnetic equatorial plane. The spectral signature of the emitted electromagnetic waves is structured as a series of wide harmonic bands within the range covered by the step in plasma frequency encountered at the boundary. Developing the concept that the frequency distance df between harmonic bands measures the magnetic field magnitude B at the source (df = Fce, electron gyrofrequency), we analyse three selected events. The first one (studied in Grimald et al., 2008) presents electric field signatures observed by a Cluster constellation of small size (~ 200 to 1000 km spacecraft separation) placed in the vicinity of sources. The electric field frequency spectra display frequency peaks placed at frequencies fs = n df (n being an integer), with df of the order of Fce values encountered at the plasmapause by the spacecraft. The second event, taken from the Cluster tilt campaign, leads to a 3-D view of NTC waves ray path orientations and to a localization of a global source region at several Earth radii (RE) from Cluster (Décréau et al., 2013). The measured spectra present successive peaks placed at fs ~ (n 1/2) df. Next, considering if both situations might be two facets of the same phenomenon, we analyze a third event. The Cluster fleet, configured into a constellation of large size (~ 8000 to 25 000 km spacecraft separation), allows us to observe wide-banded NTC waves at different distances from their sources. Two new findings can be derived from our analysis. First, we point out that a large portion of the plasmasphere boundary layer, covering a large range of magnetic latitudes, is radiating radio waves. The radio waves are issued from multiple sources of small size, each related to a given fs series and radiating inside a beam of narrow cone angle, referred to as a beamlet. The beamlets illuminate different satellites simultaneously, at different characteristic fs values, according to the latitude at which the satellite is placed. Second, when an observing satellite moves away from its assumed source region (the plasmapause surface), it is illuminated by several beamlets, issued from nearby sources with characteristic fs values close to each other. The addition of radio waves blurs the spectra of the overall received electric field. It can move the signal peaks such that their position fs satisfiesfs = (n alpha) df, with 0 < alpha < 1. These findings open new perspectives for the interpretation of NTC events displaying harmonic signatures