| 1. |
- Bollen, Math H J, et al.
(författare)
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Harmonics and Wind Power Installations
- 2021
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Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution. - : IEEE. ; , s. 648-652
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Konferensbidrag (refereegranskat)
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| 2. |
- Espin Delgado, Angela, et al.
(författare)
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Impact of Supraharmonics and Quasi-dc On the Operation of Residual Currentdevices
- 2021
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Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution. - : Institution of Engineering and Technology. ; , s. 668-672
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Konferensbidrag (refereegranskat)abstract
- Residual current devices (RCDs) are used in low voltage installations to disconnect the circuit in case of fault when the leakagecurrent exceeds a reference magnitude. The magnitude of reference leakage current is based on the magnitude of current thathuman body can withstand without getting shocked. This reference current is defined based on the 50/60 Hz component in theleakage current. The use of power electronic converters that switch in the supraharmonics frequency range (2 to 150 kHz) andrenewable energy sources such as solar inverters, would lead to the leakage current consisting of different frequencycomponents. This paper studies the impact of quasi-dc (0-4 Hz) and supraharmonics on the tripping characteristics of differenttypes of RCDs with the aim to identify fail-to-trip and false tripping conditions.
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| 3. |
- Nakhodchi, Naser, et al.
(författare)
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Application of Transfer Function Method in a Wind Park for Harmonic Study
- 2021
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Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution. - : Institution of Engineering and Technology. - 9781839535918 ; , s. 723-727
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Konferensbidrag (refereegranskat)abstract
- Harmonic emission from a wind park to the grid and the interaction between individual turbines within a wind park are among the power quality challenges that have been studied for many years, as part of the connection of wind parks to the grid. Different methods are proposed and various simulation models are developed under some assumptions. This paper presents the results from a transfer function based model for an existing wind park, and investigates the impact of LV load modelling (residential customers) and MV cable capacitance on the interaction between turbines and between turbines and the grid. It is shown that LV loads and MV cable capacitance can have significant impact on the interactions between turbines and grid while it has only limited impact on interactions between turbines.
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| 4. |
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| 5. |
- Nakhodchi, Naser, et al.
(författare)
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Estimation of Safe Harmonic Hosting Capacity
- 2021
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Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution. - : Institution of Engineering and Technology. - 9781839535918 ; , s. 693-697
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Konferensbidrag (refereegranskat)abstract
- The capacity of a power network to host new distributed generation units and non-linear loads like PVs and EVs can be studied from different aspects, such as over voltage, unbalance and harmonic distortion. This paper proposes a new approach for estimating a safe hosting capacity in terms of harmonic distortion, considering standard limits for harmonic voltages and currents. It is shown that triple harmonics and even harmonics are the harmonic orders that determine the total hosting capacity.
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| 6. |
- Nakhodchi, Naser, et al.
(författare)
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Graphical Methods For Presenting Time-Varying Harmonics
- 2021
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Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution. - : Institution of Engineering and Technology. ; , s. 678-682
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Konferensbidrag (refereegranskat)abstract
- Several tools are available for reducing large quantities of data in order to obtain indices and reporting formats, like IEC 61000-4-30 and the recommendations by CIGRE C4.112. But those methods often suffer from a surplus of information or a lack of information. In this context, this paper introduces a number of alternative graphical methods and visualization techniques and illustrates those using real measurements. The main objective of this work is to show the most appropriate tools to present the variations of harmonics at time-scales from a few cycles through a few years.
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| 7. |
- Nakhodchi, Naser, et al.
(författare)
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Harmonic Correlations Matrices to Present Measurement Results from Single and Multiple Locations
- 2021
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Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution. - : IEEE. ; , s. 703-707
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Konferensbidrag (refereegranskat)abstract
- This paper presents results of harmonic voltage measurements at multiple locations in a low voltage network. Measurements were performed in different residential, industrial and commercial urban areas in the north of Sweden. This paper shows existing level of individual harmonics in these locations as a sample of an urban load and compares the harmonic variation between these points. The results showed during this period, characteristic harmonics are well below the standard limits. Correlation matrix is used for investigating possible correlation between individual harmonic orders in this urban area. It is observed that there is a significant correlation between 5th, 7th and 11th harmonic levels of low voltage customers connected to a common 10-kV network.
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| 8. |
- Ravindran, Vineetha, 1987-, et al.
(författare)
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Assessing time-varying harmonic interactions in a wind park
- 2021
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Ingår i: IEEE Access. - : IEEE. - 2169-3536. ; 9, s. 68151-68160
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Tidskriftsartikel (refereegranskat)abstract
- The harmonic interaction mechanism in a wind park is examined in this paper. The paper investigates the feasibility of a solution to the yet challenging harmonic contribution estimation from multiple sources in a wind park with limited available information, via an extension of a simple modeling approach as well as from detailed analysis of field measurements. The paper has two distinct objectives in assessing harmonic interactions (a) one to extend the classical Norton equivalent model to a multi-measurement wind park system and to suggest potential areas for further model developments from field measurement analysis, and (b) second to draw inferences from field measurements and to develop a new independent concept of analysis from long-term field measurements in the wind park. From practical experience, a new concept of analysis with a ‘harmonic interaction break-even point’ is introduced. With the help of it, one could identify whether the primary emission (emission from considered source) or secondary emission (emission from a distant source) dominates in the analysis period. In this way, the highest responsibility between different interacting time-varying harmonic sources is evaluated. It was concluded that from long-term measurements one can define a magnitude of power production where a certain harmonic order is canceled or reaches its lowest magnitude. If one finds this cancellation point, one can define a level of secondary/primary emission or at least a feasible range. This knowledge is a step forward towards harmonic contribution analysis.
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| 9. |
- Sutaria, Jil, et al.
(författare)
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Comparing Harmonic Unbalance At Multiple Locations To Characterize The Unbalance
- 2021
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Ingår i: CIRED 2021 - The 26th International Conference and Exhibition on Electricity Distribution. - : Institution of Engineering and Technology. ; , s. 728-732
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Konferensbidrag (refereegranskat)abstract
- Harmonic emission at any point of connection (PoC) depends on the loads connected there and the background voltage distortion at that point. Under balanced supply voltage and load, the harmonics adhere to the rule that third harmonics are zero sequence, fifth harmonic are negative sequence, etc. However, under unbalance in either load or supply voltage, this assumption is no longer true. A phasor analysis of the voltage and current measured at different locations in a city is presented in this paper. Individual harmonics are decomposed into their sequence components, and the results are presented in terms of polar plots. The components are further quantified in terms of balanced and unbalanced THD, which is an indicator of the impact of unbalance. The harmonics do not follow the defined norm of sequence component in presence of unbalance in the system. The triplen harmonics were shown to have higher unbalanced sequence components than non-triplen harmonics.
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