| 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. |
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| 3. |
- 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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| 4. |
- 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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| 5. |
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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- Nakhodchi, Naser, et al.
(författare)
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Impact of modelling of MV network and remote loads on estimated harmonic hosting capacity for an EV fast charging station
- 2023
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Ingår i: International Journal of Electrical Power & Energy Systems. - : Elsevier. - 0142-0615 .- 1879-3517. ; 147
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Tidskriftsartikel (refereegranskat)abstract
- The ability of the distribution network to host electric vehicle (EV) charging might be limited by the harmonic voltages due to their harmonic emission. Network harmonic impedance seen from the point of connection of the charging station plays an important role in harmonic voltage calculation. In this paper, the hosting capacity is estimated for a fast charging station close to a distribution transformer considering different scenarios in terms of network modelling. Data from a typical Swedish distribution network is used, together with a one-month measurement of the emission from state-of-the-art EV charging. The hosting capacity using harmonic voltage limits is compared with the hosting capacity using the transformer rating. A stochastic approach is used for both. This paper shows that harmonic hosting capacity studies are needed; it shows that details of the distribution network must be included to get an accurate estimation of the harmonic hosting capacity; it also shows that a stochastic approach is needed for estimating the harmonic hosting capacity.
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| 10. |
- Nakhodchi, Naser, et al.
(författare)
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Including Load Impedance Uncertainty in Harmonic Impedance Seen from a Low-voltage Customer
- 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 presents the impact of load impedance uncertainty on harmonic source and transfer impedance and consequently on harmonic propagation in distribution networks. A generic MV/LV model of the network and a more detailed model of an existing network are used. Both models include MV network and remote LV customers. Utilizing a Monte Carlo simulation method, it is shown that variation in load impedance has a big impact on the main resonant frequency of the local network but only limited influence on resonant frequency caused by remote loads connected to other LV networks.
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