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- Busatto, Tatiano, et al.
(författare)
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Stability Analysis of PFC Converters Under Different Source Impedances and Its Consequences on Zero-Crossing Distortion
- 2022
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Ingår i: IEEE Transactions on Power Delivery. - : IEEE. - 0885-8977 .- 1937-4208. ; 37:4, s. 3235-3244
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Tidskriftsartikel (refereegranskat)abstract
- In the presence of multiple power converters in a power system the total current may exhibit zero-crossing distortion in the form of recurrent damped oscillations with high magnitude. These oscillations are synchronized with the power system frequency. This paper presents a comprehensive analysis of the input current of single-phase ac-dc converters fitted with power factor correction (PFC) controllers. Emphasis is given on the impacts of the source impedance, and on how the number of converters connected to a common coupling point (PCC) impacts the PFC controller’s performance. A system model is developed followed by simulation and measurements in a real installation with electronic ballasts used to drive fluorescent lighting tubes. Results show that the recurrent damped oscillations originating from PFC controllers are close to the harmonic range and with a very low level of cancellation between devices. The magnitude therefore increases proportionally with the number of devices. As the source impedance increases, instability may occur. Possible explanations for these observations are discussed.
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- de Oliveira, Roger Alves, et al.
(författare)
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Deep Learning Method With Manual Post-Processing for Identification of Spectral Patterns of Waveform Distortion in PV Installations
- 2021
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Ingår i: IEEE Transactions on Smart Grid. - : IEEE. - 1949-3053 .- 1949-3061. ; 12:6, s. 5444-5456
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a deep learning (DL) method for the identification of spectral patterns of timevarying waveform distortion in photovoltaic (PV) installations. The PQ big data with information on harmonic and/or interharmonics in PV installations is handled by a deep autoencoder followed by feature clustering. Measurements of voltage and current from four distinct PV installations are used to illustrate the method. This paper shows that the DL method can be used as a starting point for further data analysis. The main contributions of the paper include: (a) providing a novel DL method for finding patterns in spectra; (b) guiding the manual post-processing based on the patterns found by the DL method; and (c) obtaining information about the emission from four PV installations.
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- de Oliveira, Roger Alves, et al.
(författare)
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Third Harmonic and its Relation to Solar Elevation Angle in a PV Installation with Solar Tracking Systems
- 2022
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Ingår i: 2022 20th International Conference on Harmonics & Quality of Power (ICHQP) Proceedings. - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- This paper shows an application of a deep learning method to a solar installation with a solar tracking system. The method consists of a deep autoencoder followed by clustering. The deep learning method allows defining the most dominant component in harmonic spectra during long-term measurements. Power Quality measurements were accessed over two years in 3ϕ PV installation of 6 kVA with 2-axis tracking in northern Sweden. The deep learning results indicate that the third harmonic of current is the component that changes most over the two years. This paper demonstrates that there is a correlation between the daily and seasonal variations of the third harmonic with the solar elevation angle at the location. The main conclusion for this cause was associated with the operation of the solar tracking systems which are based on single-phase motors. The paper also discusses the possibility of correlation of the third harmonic with cloud coverage, snow on the panels, and reactive power unbalance.
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| 7. |
- De Souza Salles, Rafael, et al.
(författare)
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Interharmonic Analysis for Static Frequency Converter Station Supplying a Swedish Catenary System
- 2022
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Ingår i: 2022 20th International Conference on Harmonics & Quality of Power (ICHQP) Proceedings. - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- The paper aims to present a waveform distortion analysis focused on interharmonics in measurements from a 70 kV busbar feeding a traction supply substation with four static frequency converters (SFC). The substation supplies a Swedish catenary system from 50 Hz public grid to 15 kV 16 ⅔ Hz. The paper assesses the interharmonics for different scenarios regarding the point of a connection configuration between the traction substation and the upstream grid, as well as a change in the number of SFCs connected in the substation. The IEC 61000-4-7 grouping method and spectrograms were used to illustrate the issue. The significant presence of interharmonics calls attention to the subject in railway application. The total indexes help to evaluate the broad picture of the phenomena. The work contributes to the waveform distortion and interharmonics in railway systems studies.
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| 8. |
- De Souza Salles, Rafael, et al.
(författare)
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Waveform Distortion Emission Assessment on Pantograph Measurements from Low-Frequency Railway Electrification
- 2022
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Ingår i: 2022 20th International Conference on Harmonics & Quality of Power (ICHQP) Proceedings. - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- The paper aims to provide a waveform distortion assessment on pantograph current measurements. The data analyzed is regarding a 15 kV 16.7 Hz catenary system from Switzerland. The paper provides a characterization of the rolling stock emission content for different operation modes during a commercial utilization of the vehicle, approaching traditional harmonics, interharmonic and supraharmonic phenomena. In addition, the work provides an adaptation on the interharmonic processing proposed by the IEC 61000-4-7 regarding the 16.7 Hz fundamental frequency. The results contribute to the waveform distortion emission on pantograph measurements subject and railway systems investigation in general.
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- Espín-Delgado, Angela, et al.
(författare)
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Evaluation of Supraharmonic Propagation in LV Networks Based on the Impedance Changes Created by Household Devices
- 2020
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Ingår i: Proceedings of 2020 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe) 26-28 October, 2020. - : IEEE. ; , s. 754-758
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the characteristics of emission in the frequency range 2-150 kHz (supraharmonics) in time and frequency domain and how it propagates under different scenarios posed by the customer connections and changes in the grid. The analysis is based on measurements performed in a low-voltage installation, considering the simultaneous operation of a set of PV inverters and LED lamps in order to create changes in both impedance and emissions. The results confirm that supraharmonics tend to interact with nearby devices in the customer installation. As the number and constellation of emitting devices change so does the propagation of the supraharmonics. The propagation towards the grid can either increase or decrease with the increasing number of connected devices depending on the ratio between the impedances of the device and the grid impedance. Devices’ technology plays an important role in defining supraharmonic characteristics, emission levels and propagation. Finally, a qualitative analysis of the individual devices’ impedance and discussion of some of the practical aspects is provided.
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| 10. |
- Espín-Delgado, Ángela, et al.
(författare)
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Failure of MV Cable Terminations due to Supraharmonic Voltages : A Risk Indicator
- 2020
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Ingår i: IEEE Open Journal of Industry Applications. - : IEEE. - 2644-1241. ; 1, s. 42-51
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the accelerated aging of medium-voltage (MV) cable terminations with resistive stress-grading due to supraharmonics. The paper introduces a simple and quick way to relate the risk of cable termination failure to the characteristics of supraharmonic distortion in the system. The motivation is to give practical recommendations and guidelines to evaluate the risk of failure of cable terminations under the presence of supraharmonics in MV networks. The underlying model relates the heating in the cable termination linearly with the frequency of the voltage applied and proportionally with the square of the magnitude of the voltage. The indicator can be used to decide whether given levels and frequencies of supraharmonics in the MV network represent a risk to cable terminations. The parameters of the cable termination design are not needed for that decision. However, the decision criterion is based on one sample data (Eagle Pass) and more field information is crucial to improve the approach.
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