Current harmonic modeling of aggregated electric vehicle loads in the low voltage grid
2021 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]
The proliferation of Electric Vehicles (EVs) poses new challenges for the Distribution System Operator (DSO). For example, the rectifiers that are used for charging EV batteries could significantly influence Power Quality (PQ), in terms of harmonic distortion. The emissions from individual EV, are well regulated by current harmonic emission standards. But what the aggregation of multiple EV loads will look like is still uncertain and the research being made in this area is still in its early stage.
The DSO responsibilities include ensuring grid code compliance confirmed by PQ metering. In general, 10 minute RMS values are sufficient. However, the large scale integration of non-linear loads, like EVs, could lead to new dynamic phenomena, possibly lost in the process of time aggregation.
In this thesis PQ and, in more detail, the concept of harmonics, and how this is related to EVs, is presented. A current-harmonic load model using power exponential functions and built from actual measurement data during the individual charging of four different fully electric vehicles was constructed. The model was based on individual emitted current harmonics as a function of state of charge (SOC), and was used to deterministically simulate the simultaneous charging of six vehicles fed from the same bus. The aggregation of current harmonics up to the 11th was simulated while randomizing battery SOC, the start of charging, and the kind of vehicle. Additionally, an investigation of the impact on aggregation in time was conducted.
The analysis clearly shows the importance of phase angle information, its correlation to SOC, and how the aggregation of EV loads is influenced by these factors. The analysis also shows that 10 minute RMS aggregation could lead to significant deviations from the “actual” (200ms) data. This indicates that 10 minute value monitoring could lead to information losses.
Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2021. , p. 59
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 302
Keywords [en]
Electric Vehicles, current harmonics, modeling, aggregation, power-exponential functions
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-53169ISBN: 978-91-7485-494-7 (print)OAI: oai:DiVA.org:mdh-53169DiVA, id: diva2:1521978
Presentation
2021-03-05, Delta + digitalt via Zoom, Högskoleplan 1, Västerås, 09:00 (English)
Opponent
Supervisors
Funder
Knowledge Foundation2021-01-252021-01-252021-03-03Bibliographically approved
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