Change search
ReferencesLink to record
Permanent link

Direct link
On Harmonic Emission, Propagation and Aggregation in Wind Power Plants
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The increasing use of wind energy is a global trend as part of the overall transition to a more sustainable energy system. By using modern technologies, the wind energy is converted into electric power which is transported to the consumers by means of the electric power system. The use of these technologies, in the meantime, plays a significant role in maintaining power quality in the electric power system; including positive as well as negative impacts. This thesis emphasises on harmonic distortion within a wind power plant (WPP), for a wind turbine and for the plant level.The harmonic study presented in this thesis has been based on field measurements at a few different individual wind turbines and at a second location in one WPP. In general, the levels of harmonic distortion as percentage of the turbine and WPP ratings are low. Among the frequency components, even harmonics and especially interharmonics are present at levels comparable with the levels of characteristic harmonics. The measurements show that both harmonics and interharmonics vary strongly with time. Interharmonics further show a strong dependence on the active power production of the turbine, while characteristic harmonics are independent on the power production. The even harmonics and interharmonics may excite any resonance in the collection grid or in the external grid.The origin of interharmonic emission due to power converters has been verified through a series of measurements over a two-week period. The interharmonic emission originates from the difference between the generator-side frequency and the power system frequency. A series of interharmonic frequencies are produced and they vary in accordance with the generator-side frequency. Both these interharmonic frequencies and the magnitudes are related to each other, and the theoretical relations have been confirmed through the measurements.The harmonic propagation in a collection grid has been studied by using transfer functions. Without the need to know the harmonic sources, the characteristics of harmonic propagations are quantified through transfer functions. The method has been used to estimate the total harmonic level in a WPP, by combining knowledge of the transfer function with information from harmonic emission of the individual wind turbines. The harmonic aggregation of the emission from the individual turbines towards the point of connection (PoC) has been studied as well. From the studies it was found that interharmonics show a stronger cancellation compared to harmonics, especially compared to lower-order harmonics.According to the object of interest and the harmonic propagation, a distinction has been made between primary and secondary emission. A more detailed classification of the different propagations within a WPP has been proposed. A systematic approach for harmonic studies in association with WPPs has resulted from this. The harmonic voltages and currents at any location are obtained as the superposition of the contribution from different emission sources to this specific location. This location can be either within the WPP or in the external grid. The studies presented conclude that all the contributions should be included to get a reasonable overview of the harmonic distortion in the WPP.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2015. , 184 p.
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Research subject
Electric Power Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-18678Local ID: 9c8d5902-9d7c-4409-864b-532b0c6ba651ISBN: 978-91-7583-260-9ISBN: 978-91-7586-261-6 (PDF)OAI: oai:DiVA.org:ltu-18678DiVA: diva2:991689
Note
Godkänd; 2015; 20150130 (kaiyan); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Kai Yang Ämne: Elkraftteknik /Electric Power Engineering Avhandling: On Harmonic Emission, Propagation and Aggregation in Wind Power Plants. Opponent: Professor Roberto Langella, Scientific Responsible of the Second University of Naples local Research Section of EnSiEL, Naples, Italien. Ordförande: Professor Math Bollen, Avd för Energivetenskap, Institutionen för Teknikvetenskap och matematik, Luleå tekniska universitet, Skellefteå. Tid: Fredag 17 april kl 10.00 Plats: Hörsal A, Campus SkellefteåAvailable from: 2016-09-29 Created: 2016-09-29Bibliographically approved

Open Access in DiVA

fulltext(15062 kB)31 downloads
File information
File name FULLTEXT01.pdfFile size 15062 kBChecksum SHA-512
aa13b3bc1281a8225ed299894087c9af018685670a0452f2cbddd781b37f1e40144db5648ca0824c8de4a37d092c2036f2e713ee3edd889b81655f2bf8ce6960
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Yang, Kai
By organisation
Energy Science

Search outside of DiVA

GoogleGoogle Scholar
Total: 31 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 107 hits
ReferencesLink to record
Permanent link

Direct link