| 1. |
- Grahn, Pia, 1984-, et al.
(författare)
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PHEV Home-Charging Model Based on Residential Activity Patterns
- 2013
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Ingår i: IEEE Transactions on Power Systems. - 0885-8950 .- 1558-0679. ; 28:3, s. 2507-2515
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Tidskriftsartikel (refereegranskat)abstract
- Plug-in hybrid electric vehicles (PHEVs) have received an increased interest lately since they provide an opportunity to reduce greenhouse gas emissions. Based on the PHEV introduction level in the car park, the charging behaviors in an area will induce changes in the load profiles of the power system. Hence, it becomes important to investigate what impact a given PHEV introduction level has on load profiles due to expected charging behavior of residents.
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| 2. |
- Munkhammar, Joakim, 1982-, et al.
(författare)
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A Bernoulli distribution model for plug-in electric vehicle charging based on time-use data for driving patterns
- 2014
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Ingår i: 2014 IEEE International Electric Vehicle Conference, IEVC 2014. - : IEEE conference proceedings. - 9781479960750
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Konferensbidrag (refereegranskat)abstract
- This paper presents a Bernoulli distribution model for plug-in electric vehicle (PEV) charging based on high resolution activity data for Swedish driving patterns. Based on the activity 'driving vehicle' from a time diary study a Monte Carlo simulation is made of PEV state of charge which is then condensed down to Bernoulli distributions representing charging for each hour during weekday and weekend day. These distributions are then used as a basis for simulations of PEV charging patterns. Results regarding charging patterns for a number of different PEV parameters are shown along with a comparison with results from a different stochastic model for PEV charging. A convergence test for Monte Carlo simulations of the distributions is also provided. In addition to this we show that multiple PEV charging patterns are represented by Binomial distributions via convolution of Bernoulli distributions. Also the distribution for aggregate charging of many PEVs is shown to be normally distributed. Finally a few remarks regarding the applicability of the model are given along with a discussion on potential extensions.
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| 3. |
- Munkhammar, Joakim, et al.
(författare)
-
A flexible Markov-chain model for simulating demand side management strategies with applications to distributed photovoltaics
- 2012
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Ingår i: Proceedings of the World Renewable Energy Forum 2012, Denver, Colorado, USA, May 13-17, 2012. - 9781622760923 ; , s. 1858-1865
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Konferensbidrag (refereegranskat)abstract
- In this paper a stochastic model for load shifting was utilized for the purpose of investigating the potential for increased self-consumption of photovoltaic (PV) generation in households. We show the results in terms of power consumption, PV power production and solar fraction from a number of scenarios involving end-user flexibility on the order of a few percent. Simulations are performed on both an individual and an aggregate level. Results indicate that the solar fraction is only improved by a few percent both on an aggregate and individual level even for the most extreme scenarios of load shifting. The lack of substantial increase in solar fraction from imposed flexibility can partly be attributed to complementary energy use; when certain energy-demanding activities are downshifted in probability other activities are up-shifted. Another explanation for the lack of increased solar fraction is the total available fraction of flexible activities at a certain time.
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| 4. |
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| 5. |
- Munkhammar, Joakim, et al.
(författare)
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Characterizing probability density distributions for household electricity load profiles from high-resolution electricity use data
- 2014
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 135, s. 382-390
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a high-resolution bottom-up model of electricity use in an average household based on fit to probability distributions of a comprehensive high-resolution household electricity use data set for detached houses in Sweden. The distributions used in this paper are the Weibull distribution and the Log-Normal distribution. These fitted distributions are analyzed in terms of relative variation estimates of electricity use and standard deviation. It is concluded that the distributions have a reasonable overall goodness of fit both in terms of electricity use and standard deviation. A Kolmogorov-Smirnov test of goodness of fit is also provided. In addition to this, the model is extended to multiple households via convolution of individual electricity use profiles. With the use of the central limit theorem this is analytically extended to the general case of a large number of households. Finally a brief comparison with other models of probability distributions is made along with a discussion regarding the model and its applicability.
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| 6. |
- Munkhammar, Joakim, 1982-, et al.
(författare)
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Electric Vehicle Charging and Photovoltaic Power Production from Eight Solar Charging Stations in Sweden
- 2014
-
Ingår i: 4th Solar Integration Workshop. - Darmstadt : Energynautics. - 9783981654905 ; , s. 425-429
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Konferensbidrag (refereegranskat)abstract
- This paper quantifies and analyzes data for electric vehicle (EV) charging and photovoltaic(PV) power production from eight charging stations in Sweden withadjacent PV power production provided by Solelia Greentech AB. This study aims toshow the grid interaction of EV charging and PV power production from these solar charging stationswhich are distributed in pairs at four different locations across Sweden. This study utilizesone minute resolution data on power consumption and production from between 281 and310 consecutive days depending on available solar charging station data. Each site, correspondingto two adjacent solar charging stations, has a specific setup regarding EV charging consumer availability.EV charging at two of the sites were available only for the local company/municipality employees and visitors to the company/municipalitywhile the other two sites were public. There was no economical charge for EV charging at any of the stations.Results show that EV charging magnitude and use patterns over timevaried considerably between the stations. Half of the stations had a net consumption of electricityand the other half of stations had a net production of electricity during the metering period.Self-consumption of PV power production was estimated to be between 0.2 and 10 percentdepending on station.
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| 7. |
- Munkhammar, Joakim, 1982-
(författare)
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Markov-chain modeling of energy users and electric vehicles : Applications to distributed photovoltaics
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Technological improvements and falling prices on photovoltaic panels andelectric vehicles suggest that they might become more common in future households.The introduction of a photovoltaic system and an electric vehiclehas considerable impact on the energy balance of a household. This licentiate thesis investigates the power consumption- and productionpatterns associated with the photovoltaic (PV) electricity production,household electricity consumption and home charged plug-in electric vehicle(PEV) electricity consumption. This investigation is carried out on both an individual and aggregate household level. The methodology used in this thesis is interdisciplinary but the maincontributions are mathematical modeling and simulations of the three main components. Theoretical estimates of electricityconsumption were constructed from extensions to the Wid\'{e}n Markov-chain model for generating synthetichousehold electricity use patterns. The main research contribution in thisthesis is the development and analysis of two extensions of this Markov-chain model: (I) Electricity use from a home charged PEV,(II) Flexibility of end-user power use. These two extensions were used in studiesregarding the coincidence - in particular the level of self-consumption - between PV electricityproduction and household electricity use. PV electricity production was modeledfrom high resolution solar irradiance data from the Ångström laboratory.\\Results show that the home charged PEV load would increase the household loadconsiderably. It was also shown that the level of correlation between PEV load and PVelectricity production was low, but that to some extent the PEV load could help increasethe self-consumption of PV power, both on individual and aggregate household level.\\The modeling and simulations of end-user flexibility showed that the householdload profile could be altered to a certain degree. It was also shown thatcertain flexibility setup could improve the self-consumption of PV power production, more so than theintroduction of a PEV.
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| 8. |
- Munkhammar, Joakim, 1982-, et al.
(författare)
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Photovoltaic self-consumption potential of alternative year-round daylight savings time
- 2013
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Ingår i: Proceedings of the 28th European Photovoltaic Solar Energy Conference (EU PVSEC), Paris, France, September 30 - October 4, 2013.. - 3936338337 ; , s. 4753-4757
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Konferensbidrag (refereegranskat)abstract
- In a mature photovoltaic (PV) market where feed-in tariffs have declined, managing of the hosting capacity of the distribution grid becomes essential by maximizing the utilization of PV. One way to increase hosting capacity is to increase self-consumption of the self-produced PV power. This paper investigates the effect of an alternative year-round daylight savings time (DST) – where the time of the entire society is changed relative to the sun - on the level of self-consumption in terms of solar fraction and load fraction of PV power both on household- and national level. Household electricity use was modeled with a Markov-chain model, PV power production was modeled from solar irradiance data, and the national level was simulated using national electricity data. Results show that one hour year-round DST shifted ahead might increase self-consumption by a fraction of one percentage point for a net-zero energy household. For a 30 GWp PV installation on a national scale with a 140 TWh annual electricity use one hour DST shift ahead had almost no effect on self-consumption. The optimal self-consumption of PV power on the national level was concluded to be the current DST setup.
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| 9. |
- Munkhammar, Joakim, 1982-, et al.
(författare)
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Quantifying self-consumption of on-site photovoltaic power generation in households with electric vehicle home charging
- 2013
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 97, s. 208-216
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Tidskriftsartikel (refereegranskat)abstract
- Photovoltaic (PV) power production and residential power demand are negatively correlated at high latitudes on both annual and diurnal basis. If PV penetration levels increase, methods to deal with power overproduction in the local distribution grids are needed to avoid costly grid reinforcements. Increased local consumption is one such option. The introduction of a home-charged plug-in electric vehicle (PEV) has a significant impact on the household load and potentially changes the coincidence between household load and photovoltaic power production. This paper uses a stochastic model to investigate the effect on the coincidence between household load and photovoltaic power production when including a PEV load. The investigation is based on two system levels: (I) individual household level and (II) aggregate household level. The stochastic model produces theoretical high-resolution load profiles for household load and home charged PEV load over time. The photovoltaic power production model is based on high-resolution irradiance data for Uppsala, Sweden. It is shown that the introduction of a PEV improves the self-consumption of the photovoltaic power both on an individual and an aggregate level, but the increase is limited due to the low coincidence between the photovoltaic power production pattern and the charging patterns of the PEV.
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| 10. |
- Widén, Joakim, 1980-, et al.
(författare)
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Evaluating the benefits of a solar home energy management system: impacts on photovoltaic power production value and grid interaction
- 2013
-
Ingår i: Proceedings of the eceee 2013 Summer Study, Presqu'île de Giens, France, June 3-8, 2013.
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Konferensbidrag (refereegranskat)abstract
- On mature photovoltaic (PV) markets where feed-in support has declined, as well as on immature markets where there is yet no feed-in support, home energy management systems could be interesting for increasing the value of on-site PV power generation. These systems typically provide scheduling of programmable appliances and may also include battery storage for shifting surplus PV power from day to night. In this paper we investigate how these systems perform in Swedish detached single-family buildings equipped with PV systems. How much can the households’ self-consumption of the on-site PV be increased with load shifting and battery storage? How is the value of the on-site PV generation affected by these options? Is there any benefit for the distribution grid with a widespread adoption of such systems? Simulation models for energy management systems with optimized load shifting and small battery storage capabilities were developed and applied to appliance-specific and highly resolved monitoring data from 20 Swedish detached single-family buildings. These detailed data provide information on individual appliance duty cycles and allow a realistic assessment of the load shifting potential. The main conclusion is that these systems have a potential for improving the PV self-consumption and production value by a few percent, but unless extensive battery storage is introduced, they are unlikely to have any marked impact on distribution system management.
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