| 1. |
- Bagheri, Azam, et al.
(författare)
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Big data from smart grids
- 2018
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Ingår i: 2017 IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT-Europe 2017. - New York : Institute of Electrical and Electronics Engineers (IEEE). - 9781538619537
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Konferensbidrag (refereegranskat)abstract
- This paper gives a general introduction to “Big Data” in general and to Big Data in smart grids in particular. Large amounts of data (Big Data) contains a lots of information, however developing the analytics to extract such information is a big challenge due to some of the particular characteristics of Big Data. This paper investigates some existing analytic algorithms, especially deep learning algorithms, as tools for handling Big Data. The paper also explains the potential for deep learning application in smart grids.
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| 2. |
- Bagheri, Azam, et al.
(författare)
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Improved characterization of multi-stage voltage dips based on the space phasor model
- 2018
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Ingår i: Electric power systems research. - : Elsevier. - 0378-7796 .- 1873-2046. ; 154, s. 319-328
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a method for characterizing voltage dips based on the space phasor model of the three phase-to-neutral voltages, instead of the individual voltages. This has several advantages. Using a K-means clustering algorithm, a multi-stage dip is separated into its individual event segments directly instead of first detecting the transition segments. The logistic regression algorithm fits the best single-segment characteristics to every individual segment, instead of extreme values being used for this, as in earlier methods. The method is validated by applying it to synthetic and measured dips. It can be generalized for application to both single- and multi-stage dips.
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| 3. |
- Bracale, A., et al.
(författare)
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A new joint sliding-window ESPRIT and DFT scheme for waveform distortion assessment in power systems
- 2012
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Ingår i: Electric Power Systems Research. - : Elsevier BV. - 0378-7796 .- 1873-2046. ; 88, s. 112-120
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a novel scheme that jointly employs a sliding-window ESPRIT and DFT for estimating harmonic and interharmonic components in power system disturbance data. In the proposed scheme, separate stages are utilized to estimate the voltage fundamental component, harmonics and interharmonics. This includes the estimation of the fundamental component from lowpass filtered data using a sliding-window ESPRIT, of harmonics from a sliding-window DFT with a synchronized window, and of interharmonics from the residuals by applying the sliding-window ESPRIT. Main advantages of the approach include high resolution and accuracy in parameter estimation and significantly reduced computational cost. Experiments and comparisons are made on both synthetic and measurement data. Results have shown the effectiveness and efficiency of the proposed scheme.
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| 4. |
- Ehnberg, Jimmy, 1976, et al.
(författare)
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Reliability of a small power system using solar power and hydro
- 2005
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Ingår i: Electric Power Systems Research. - : Elsevier BV. - 0378-7796 .- 1873-2046. ; 74:1, s. 119-127
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the availability of the electricity supply when the sources consist of a combination of solar energy and a small hydro installation. Instead of flow-of-river, a small reservoir is used. By not using the hydro energy during sunny periods, the natural flow-of-river fills up the reservoir for later use. A model for global solar radiation is proposed with an astronomical part (deterministic) and a meteorological part (stochastic). The meteorological part is based on a Markov model of the cloud coverage. The solar model does not require solar radiation measurements, just cloud observations. A case study has been performed for Timbuktu (16.75degreesN, 0.07degreesW) in which generation availability is simulated for four different cases: solar power only; solar power with storage; solar and hydro power and solar and hydro, power with storage. To be able to use exclusively renewable energy sources, a combination of sources is needed to secure the reliability of the supply. Using solar cells in combination with a small reservoir is favorable. Even with a weak flow the affect of the flow on the day time reliability is minor, but great benefits can be found for reliability during low load hours (night time).
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| 5. |
- Ehnberg, Jimmy, 1976, et al.
(författare)
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Simulation of global solar radiation based on cloud observations
- 2005
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 78:1, s. 157-162
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Tidskriftsartikel (refereegranskat)abstract
- A stochastic model for simulating global solar radiation on a horizontal surface has been developed for use in power systems reliability calculations. The importance of an appropriate model for global solar radiation has increased with the increased use of photovoltaic power generation. The global solar radiation shows not only regular yearly and daily variations but also a random behaviour. The yearly and daily variations can be described in a deterministic way while the random behaviour has a high correlation with the state of the atmosphere. The astronomic effects can easily be described mathematical with only some minor simplifications but the atmospheric effects are more complicated to describe. The transmittivity of solar radiation in the atmosphere depends on various factors, e.g. humidity, air pressure and cloud type. By using cloud observations as input for the simulations, the local meteorological conditions can be accounted for. The model is usable for any geographical location if cloud observations are available at the location or at locations with similar climatological conditions. This is especially useful for development countries where long-term solar radiation measurement can be hard to obtain. Cloud observations can be performed without any expensive equipment and have been a standard parameter for many years throughout the world. Standard observations are done according to the Oktas-scale. It is the interval between observations that sets the resolution of the simulation: the observations are normally only every hour or every third hour. The model can easily be combined with cloud coverage simulations, has been proposed, for a more general model. For some calculations higher resolution may be needed. This can be obtained by including a stochastic model for the short-term variations and simple model has been proposed. Errors and limitations of the model are estimated and discussed.
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| 6. |
- Gu, Irene Yu-Hua, 1953, et al.
(författare)
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Practical applications of automatic image analysis for overhead lines
- 2013
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Ingår i: 22nd International Conference & exhibition on Electricity Distribution (CIRED 2013), Stockholm, 10-13 June, 2013. - Red Hook, NY : Institution of Engineering and Technology. - 9781849197328 ; 2013:615 CP, s. Article no. 0802-
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Konferensbidrag (refereegranskat)abstract
- This paper proposes novel techniques for automatically extracting information from overhead lines based on automatic image/video processing. Three application scenarios are presented: (a) detecting snow and ice coverage on insulators for overhead lines; (b) detecting swing angles of insulators; (c) quantifying the visibility of insulators at transmission lines with typical backgrounds. Experiments have been conducted on recordedvideos/images of insulators (with different prototypes) for overhead lines in a remote test station in Norway. Results show that the proposed automatic image analysis methods are promising for extracting the status (snow/ice coverage, swing angle, visibility) of insulators and might be applied in the future for other components of the overhead line.
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| 7. |
- Gu, Irene Yu-Hua, 1953, et al.
(författare)
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Signal Processing and Classification Tools for Intelligent Distributed Monitoring and Analysis of the Smart Grid
- 2011
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Ingår i: IEEE PES Innovative Smart Grid Technologies Conference Europe. 2011 2nd IEEE PES International Conference and Exhibition on Innovative Smart Grid Technologies, ISGT Europe 2011, Manchester, 5 - 7 December 2011. - Piscataway, N.J : IEEE Communications Society. - 9781457714214
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a novel framework for an intelligent monitoring system that supervises the performance of the future power system. The increased complexity of the power system could endanger the reliability, voltage quality, operational security or resilience of the power system. A distributed structure for such a monitoring system is described and some of the advanced signal processing techniques or tools that could be used in such a monitoring system are given. Several examples for seeking the spatial locations and finding the underlying causes of disturbances are included.
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| 8. |
- Le, Cuong, 1982, et al.
(författare)
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A method to evaluate harmonic model-based estimations under non-white measured noise
- 2011
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Ingår i: 2011 IEEE PES Trondheim PowerTech. - Piscataway, NJ : IEEE Communications Society. - 9781424484195 - 9781424484171
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Konferensbidrag (refereegranskat)abstract
- Automatic extracting information from power-system event recordings requires applications of signal-processing estimation techniques whose performance has been verified under white noise. This paper proposes a method to test these techniques under real power-system noise, which is very different from white noise, to evaluate their application feasibility. The first part of the paper describes the evaluation method used to evaluate the techniques in a statistical sense and a method to extract noise from measured power-system recordings. The second part of the paper focuses on the evaluation of a number of harmonic model-based techniques under non-white noise, including: Kalman filter, MUSIC, ESPRIT, and segmentation algorithms. The paper shows that for the Kalman filter, a very high order with high computational burden is necessary only if high frequency components are of interest. The application of MUSIC, ESPRIT, and the segmentation algorithms under natural power-system noise is shown to be feasible.
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| 9. |
- Morena-Garcia, Isabel, et al.
(författare)
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Tests and Analysis of a novel Segmentation method using Measurement Data
- 2015
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Ingår i: CIRED 23rd Int’l Conf. on Electricity Distribution, 15-18 June, 2015, Lyon, France.. ; , s. 5-
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Konferensbidrag (refereegranskat)abstract
- Fault detection in power systems and its diagnosis are highly relevant issues within a power quality scope. Detailed analysis of disturbance recordings, like voltage dips, requires accurate segmentation methods. A joint causal and anti-causal (CaC) segmentation method has been introduced but only been tested with synthetic signals. In this paper, its performance has been analysed with a set of real measurement signals.
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| 10. |
- Abid, Fahim, et al.
(författare)
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Intermodulation due to interaction of photovoltaic inverter and electric vehicle at supraharmonic range
- 2016
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Ingår i: 2016 17th International Conference on Harmonics and Quality of Power. - Piscataway. NJ. - 9781509037926 ; , s. 685-690
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Konferensbidrag (refereegranskat)abstract
- Advent of power electronic switching is introducing more and more non-linear loads in the low voltage grid. Besides harmonic current generation in the frequency range below 2 kHz, these non-linear loads are also responsible for current emission in the range of 2 kHz to 150 kHz, commonly known as supraharmonic emission. Supraharmonic currents mainly flow between nearby appliances and heavily influence the overall emission of neighboring devices. This paper presents an analysis of supraharmonic interaction between a photovoltaic inverter and an electric vehicle. It has been noticed that intermodulation distortion arises as a result of interaction between different switching frequencies used by the devices. Later, additional household equipment were added to photovoltaic and electric vehicle to observe their effect on intermodulation distortion. All the measurements were conducted in a controlled laboratory environment imitating a domestic customer.
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