| 1. |
|
|
| 2. |
- Larsson, Tobias, et al.
(författare)
-
Project: PIEp - Product Innovation Engineering Programme
- 2011
-
Annan publikation (populärvet., debatt m.m.)abstract
- PROJEKTSAMMANFATTNINGPIEp, Product Innovation Engineering Program är ett nationellt program som syftar till att stärka förmågan till innovativ produkt- och affärsutveckling. PIEp spänner över fältet från teori till praktik, från forskning om innovationssystem till proaktivt arbete för att stärka innovationskraft och därigenom uppnå en systemförändring inom forskning, utbildning och utveckling. PIEp skall pågå under tio år, 2007-2016 och engagera flera av Sveriges lärosäten och forskningsinstitut involverade i innovation och produktutveckling. PIEp leds och administreras vid KTH i partnerskap med Lunds Tekniska Högskola, Högskolan i Jönköping, Designhögskolan vid Umeå Universitet, Centrum för Teknik, Medicin och Hälsa, Luleå Tekniska Universitet, samt en rad företag och organisationer.
|
|
| 3. |
- Lundmark, Martin, et al.
(författare)
-
Increased levels of electrical fields in buildings
- 2002
-
Ingår i: Biological effects of EMFs : proceedings, Rhodes, Greece, 7 - 11 October 2002. - Rhodes : University of Ioannina. - 960867333X
-
Konferensbidrag (refereegranskat)abstract
- In order to save energy and improve the performance, various electrical apparatus are equipped with power electronics. Normally power electronic equipment produce harmonics and high frequency noise. To handle noise emission, power electronic equipment uses EMC filters and are tested according to EMC standards. But the question is whether these tests are enough to avoid noise emissions in buildings? It has been shown, that electrical equipment distributes electrical fields inside a building using the PE wire. In order to avoid or limit electrical field it is necessary to find the sources and stop the distribution. The levels of electrical fields in the frequency range between 10 kHz and 30 MHz in office buildings and homes are rather unknown. One reason is lack of civil standards, another is lack of and difficulties in measurements.In this paper results from measurements of electrical fields in the frequency range between 10 kHz and 30 MHz at different locations is shown. An interesting result from these measurements is that the level of the electrical fields from a HF-fittings are approximately 10 times the level from video display units (VDU). This paper also shows a method to analyze sources of electrical fields.
|
|
| 4. |
- Lundmark, Martin, et al.
(författare)
-
The use of protective earth as a distributor of fields and radiation
- 2000
-
Ingår i: Biological effects of EMFs. - Heraklio : Workshop on Biological Effects of Electromagnetic Fields. - 9608673305
-
Konferensbidrag (refereegranskat)abstract
- Apart from being a safety arrangement, the protective earth, PE, is also defined as an equipotential plane which serves as a reference voltage for a circuit. Interest in the PE for EMC reasons is focused on an equipotential point. Still, most PE installation on site is carried out as a safety arrangement. In order to fulfill EMC standards regarding low emission, equipment is shielded and the shield is connected to the PE wire.The purpose of this paper is to show that electrical equipment distributes its electrical fields using the PE wire. Measurements have been taken on light fittings.
|
|
| 5. |
- Nybacka, Mikael, et al.
(författare)
-
Project: CASTT - Centre for Automotive Systems Technologies and Testing
- 2007
-
Annan publikation (populärvet., debatt m.m.)abstract
- Through the Centre for Automotive Systems Technologies and Testing, Luleå University of Technology aims to first of all support automotive winter testing in Northern Sweden. This means to support the local automotive test entrepreneurs and through them their customers: the car manufacturers and their suppliers. To succeed in this task, the center relies on the university's areas of leading research and most importantly on the cooperation between those areas.
|
|
| 6. |
- Alfieri, Luisa, et al.
(författare)
-
A Wavelet-Modified ESPRIT Hybrid Method for Assessment of Spectral Components from 0 to 150 kHz
- 2017
-
Ingår i: Energies. - : MDPI. - 1996-1073. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Waveform distortions are an important issue in distribution systems. In particular, the assessment of very wide spectra, that include also components in the 2-150 kHz range, has recently become an issue of great interest. This is due to the increasing presence of high-spectral emission devices like end-user devices and distributed generation systems. This study proposed a new sliding-window wavelet-modified estimation of signal parameters by rotational invariance technique (ESPRIT) method, particularly suitable for the spectral analysis of waveforms that have very wide spectra. The method is very accurate and requires reduced computational effort. It can be applied successfully to detect spectral components in the range of 0-150 kHz introduced both by distributed power plants, such as wind and photovoltaic generation systems, and by end-user equipment connected to grids through static converters, such as fluorescent lamps.
|
|
| 7. |
- Alfieri, Luisa, et al.
(författare)
-
Accurate assessment of waveform distortions up to 150 kHz due to fluorescent lamps
- 2017
-
Ingår i: 2017 6th International Conference on Clean Electrical Power: Renewable Energy Resources Impact, ICCEP 2017. - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 9781509046829 ; , s. 636-644
-
Konferensbidrag (refereegranskat)abstract
- Fluorescent lamps are among the most diffuse electrical components that introduce significant waveform distortions in low voltage distribution systems. These distortions involve a wide range of frequencies (i.e., from 0 kHz to 150 kHz), and spectral components characterized by a non-uniform behavior in time and frequency domains. Early IEC standards covered formally only the range from 0 kHz to 9 kHz, defining grouping and group total harmonic distortion both for the low-frequencies (i.e., from 0 kHz to 2 kHz) and for frequencies ranging from 2 kHz to 9 kHz. Recently, the IEC standards have suggested to extend the grouping, previously defined for the range from 2 kHz to 9 kHz, also to the range from 9 kHz to 150 kHz. In this paper, the waveform distortions of a variable number of fluorescent lamps were quantified by applying the main Power Quality indices currently available for such devices. Indices are evaluated using both the IEC method and an hybrid method proposed recently in the relevant literature, i.e., the sliding-window Wavelet-Modified ESPRIT method. Numerical applications on measured data show the waveform distortion levels versus the number of lamps, quantifying also the different performances of the aforesaid spectral analysis methods
|
|
| 8. |
- Alfieri, Luisa, et al.
(författare)
-
New Power Quality Indices for the Assessment of Waveform Distortions from 0 to 150 kHz in Power Systems with Renewable Generation and Modern Non-Linear Loads
- 2017
-
Ingår i: Energies. - : MDPI. - 1996-1073. ; 10:10
-
Tidskriftsartikel (refereegranskat)abstract
- The widespread use of power electronics converters, e.g., to interface renewable generation systems with the grid or to supply some high-efficiency loads, has caused increased levels of waveform distortions in the modern distribution system. Voltage and current waveforms include spectral components from 0 kHz to 150 kHz, characterized by a non-uniform time-frequency behavior. This wide interval of frequencies is currently divided into "low-frequency" (from 0 kHz to 2 kHz) and "high-frequency" (from 2 kHz to 150 kHz). While the low-frequencies have been exhaustively investigated in the relevant literature and are covered by adequate standardization, studies for the high-frequencies have been addressed only in the last decade to fill current regulatory gaps. In this paper, new power quality (PQ) indices for the assessment of waveform distortions from 0 kHz to 150 kHz are proposed. Specifically, some currently available indices have been properly modified in order to extend their application also to wide-spectrum waveforms. In the particular case of waveform distortions due to renewable generation, numerical applications prove that the proposed indices are useful tools for the characterization of problems (e.g., overheating, equipment malfunctioning, losses due to skin effects, hysteresis losses or eddy current losses) in cases of both low-frequency and high-frequency distortions
|
|
| 9. |
- Andersson, L. Robin, et al.
(författare)
-
Characterization of Flow Structures Induced by Highly Rough Surface Using Particle Image Velocimetry, Proper Orthogonal Decomposition and Velocity Correlations
- 2018
-
Ingår i: Engineering. - : Scientific Research Publishing. - 1947-3931 .- 1947-394X. ; 10, s. 399-416
-
Tidskriftsartikel (refereegranskat)abstract
- High Reynolds number flow inside a channel of rectangular cross section is examined using Particle Image Velocimetry. One wall of the channel has been replaced with a surface of a roughness representative to that of real hydropower tunnels, i.e. a random terrain with roughness dimensions typically in the range of ≈10% - 20% of the channels hydraulic radius. The rest of the channel walls can be considered smooth. The rough surface was captured from an existing blasted rock tunnel using high resolution laser scanning and scaled to 1:10. For quantification of the size of the largest flow structures, integral length scales are derived from the auto-correlation functions of the temporally averaged velocity. Additionally, Proper Orthogonal Decomposition (POD) and higher-order statistics are applied to the instantaneous snapshots of the velocity fluctuations. The results show a high spatial heterogeneity of the velocity and other flow characteristics in vicinity of the rough surface, putting outer similarity treatment into jeopardy. Roughness effects are not confined to the vicinity of the rough surface but can be seen in the outer flow throughout the channel, indicating a different behavior than postulated by Townsend’s similarity hypothesis. The effects on the flow structures vary depending on the shape and size of the roughness elements leading to a high spatial dependence of the flow above the rough surface. Hence, any spatial averaging, e.g. assuming a characteristic sand grain roughness factor, for determining local flow parameters becomes less applicable in this case.
|
|
| 10. |
- Andersson, Marcus, et al.
(författare)
-
Interfering signals and attenuation : potential problems with communication via the power grid
- 2006
-
Ingår i: Proceedings of Nordic Distribution and Asset Management Conference.
-
Konferensbidrag (refereegranskat)abstract
- This paper will give a general overview of the potential problems associated with remote-meter reading via the power grid and describe some of the technologies available. A comparison will be made between the power grid as a communication channel and other, dedicated and shared, channels. Examples will be given of practical cases in which the communication channel does not function in the intended way.
|
|
