The discrete fourier transform for computation of symmetrical components harmonics

Henao, H.; Assaf, T.

doi:10.1109/ptc.2003.1304803

Cited by 16 publications

(5 citation statements)

References 8 publications

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“…This strategy is quite similar to that used in vibration analysis to obtain the full spectrum of two quadrature signals [26]. The full spectrum can also be obtained by performing the complex FFT to quadrature currents as proposed in [27]. The full spectrum combined with the spectrogram function allows tracking the temporal evolution of the sequence components of the stator current.…”

Section: Sequence Componentsmentioning

confidence: 99%

Speed Estimation During the Starting Transient of Induction Motors

Meira

Bossio

Verucchi

et al. 2021

IEEE Trans. Instrum. Meas.

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Typically, the rotor speed of electric motors was measured directly by the use of electromechanical sensors. Even though these devices are very precise, they are also fragile and expensive to install. Currently, some alternatives are based on speed estimations from the measurement of stator currents. Some of these, very accurate, are used in variable speed drives. In industrial power applications, many large induction motors are directly driven with special starters. For these cases, new speed estimation strategies must be developed. This paper presents a self-sensing method for speed estimation during the starting transient of both wound rotor and squirrel cage induction motors. The speed estimation is based on the simultaneous tracking of multiple harmonic components of the rotor on the spectrogram of the stator currents in sequence networks. The proposal is validated with experimental results obtained in the laboratory with a squirrel cage induction motor. It is concluded that the estimation is not sensitive to measurement noise and tracking errors caused by other harmonic components that do not depend on the rotor position.

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Section: Sequence Componentsmentioning

confidence: 99%

Speed Estimation During the Starting Transient of Induction Motors

Meira

Bossio

Verucchi

et al. 2021

IEEE Trans. Instrum. Meas.

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“…Accordingly detection of harmonics is necessary, which can be accomplished by an analogdigital converter with a maximum sampling rate according to the Nyquist-Shannon theorem. A lowpass filter is also required cutting off frequencies above the Nyquist-Shannon frequency matching the sampling problem under consideration [19]. Complying to the used analog-digital converter, the measured voltage signal has to be modified in different ways such as changing the voltage range or adding shifting the voltage range into an ever positive range by adding DC voltage.…”

Section: Detection and Correction Of Harmonicsmentioning

confidence: 99%

“…Advanced Engineering Forum Vol. 19 Timing of fed-in correction terms is very important due to distorting behavior of asynchronous coupling of an inverter. The minimal timing period is a full sine wave at 50 [Hz] causing a time interval of 20 ms for calculating the correction terms.…”

Section: Detection and Correction Of Harmonicsmentioning

confidence: 99%

Superordinate Control Structure for Hybrid Compensation Systems

Böhm

Paulsburg

Franke

2016

AEF

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Medium voltage grids are subject to a change in load situation due to the installation of decentralized generation plants. Predominantly load symmetry, active and reactive power as well as the required capacity of earth fault compensation is affected. Inverter-based plants as well as consumers using switching power supplies or phase control cause distortions of frequency. Simultaneously electrical energy storage is gaining importance within rural distribution networks to compensate fluctuating generation plants. A hybrid compensation system includes a transformer, a multi-phase inverter, diverse storage systems and a communication-capable control unit, which may be connected to the control center of the distribution system operator (DSO). It is object to current research activities to design and evaluate the functions of the superordinate control unit, which has to parametrize individual components, coordinate the energy flows between them and to embed several measuring instruments. Within the present work, basic considerations for design of system control are outlined.

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“…The steady-state study of the combined effects of waveform distortion and unbalance in three-phase systems is carried out by traditional phasor analysis linked to symmetrical component transformation [64]. This is only applied to the individual harmonics obtained from the Fourier transform of the waveforms [65,66].…”

Section: Unified Framework For Distortion and Unbalancementioning

confidence: 99%

Conflicts in the distribution network protection in the presence of large photovoltaic plants: the case ofENDESA

Hernández

Cruz

Vidal

et al. 2012

Int. Trans. Electr. Energ. Syst.

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This paper describes a hitherto unstudied malfunction that can occur in the protection system of distribution networks (DNs) in the presence of large photovoltaic plants (LPVPs). The focus here is on the phasebalance current (PBC) protection of overhead or blended feeders back-fed by LPVPs. This study used the DNs belonging to ENDESA Distribución Eléctrica S.L.U. In the ENDESA utility company, PBC protection (ANSI 46) is an obligatory DN protection practice for overhead or blended feeder types. Low power quality or two ferroresonant states were found to be the causes of the malfunction of PBC protection, which led to its untimely tripping.The results of this study highlight the need to modify current DN protection practices and to elaborate new power quality requirements for PV-distributed generation (PV-DG). Since PV-DG penetration in DNs is steadily increasing, regulators and DN operators should implement more effective practices and guidelines to offer better power quality to customers. because of low power quality and ferroresonant states. This research has been carried out in DNs belonging to ENDESA Distribución Eléctrica S.L.U., a large utility company with long experience in the connection of LPVPs to DNs. In ENDESA, all overhead/blended feeders have phase-balance current (PBC) protection. Our study focuses on the untimely tripping of the PBC protection of feeders in certain LPVP operation conditions.Before the causes of this malfunction became known, ENDESA had to contend with an excessive number of untimely trippings in its feeders. It was found that the protection system of these DNs in the presence of PV-DG units malfunctioned because of the following: (i) low power quality of the LPVP current injected into the DN at low output power levels (high harmonic or unbalance level); (ii) sudden output power changes of the LPVP at low output power levels, which led to an unexpected jump to ferroresonant states with high unbalanced currents. These types of malfunction had not previously been observed in any other DG type.The second section of this paper gives an overview of PBC protection in overhead feeders. The third section describes ferroresonance as a contextualization for the special ferroresonance that occurs in an MV unearthed feeder back-fed by an LPVP. It also outlines a unified framework for analysing three-phase systems subjected to unbalance and waveform distortion. This helps to quantitatively determine the extent to which unbalance and distortion components of the three-phase currents cause network protection conflicts. Sections 4-7 present three case studies involving the malfunction of the PBC protection of MV feeders with LPVPs. Problems are discussed, and the possible solutions are presented. PBC PROTECTION (ANSI 46)2.1. Description of the PBC protection unit PBC protection (negative-sequence protection) detects the unbalance of currents in phases. It measures the positive, negative, and zero sequence of the circulating current (I 1 , I 2 , and I 0 ) (Figure 1). The PBC detector picks up when...

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The discrete fourier transform for computation of symmetrical components harmonics

Cited by 16 publications

References 8 publications

Speed Estimation During the Starting Transient of Induction Motors

Speed Estimation During the Starting Transient of Induction Motors

Superordinate Control Structure for Hybrid Compensation Systems

Conflicts in the distribution network protection in the presence of large photovoltaic plants: the case ofENDESA

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