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Luthander, R., Shepero, M., Munkhammar, J. & Widén, J. (2019). Photovoltaics and opportunistic electric vehicle charging in the power system: a case study on a Swedish distribution grid. IET Renewable Power Generation, 13(5), 710-716
Open this publication in new window or tab >>Photovoltaics and opportunistic electric vehicle charging in the power system: a case study on a Swedish distribution grid
2019 (English)In: IET Renewable Power Generation, ISSN 1752-1416, E-ISSN 1752-1424, Vol. 13, no 5, p. 710-716Article in journal (Refereed) Published
Abstract [en]

Renewable distributed generation and electric vehicles (EVs) are two important components in the transition to a more sustainable society. However, both pose new challenges to the power system due to the intermittent generation and EV charging load. In this case study, a power system consisting of a low- and medium-voltage rural and urban distribution grid with 5174 customers, high penetration of photovoltaic (PV) electricity and a fully electrified car fleet were assumed, and their impact on the grid was assessed. The two extreme cases of two summer weeks and two winter weeks with and without EV charging and a PV penetration varying between 0 and 100% of the annual electricity consumption were examined. Active power curtailment of the PV systems was used to avoid overvoltage. The results show an increased electricity consumption of 9.3% in the winter weeks and 17.1% in the summer weeks, a lowering of the minimum voltage by 1% at the most, and a marginal contribution by the EV charging to lower the need of PV power curtailment. This shows the minor impact of EV charging on the distribution grid, both in terms of allowing more PV power generation and in terms of lower voltage levels.

Keywords
battery powered vehicles, power grids, power consumption, photovoltaic power systems, power distribution economics, distributed power generation, power generation economics, demand side management, opportunistic electric vehicle, power system, Swedish distribution grid, renewable distributed generation, electric vehicles, intermittent generation, EV charging load, photovoltaic electricity, fully electrified car fleet, summer weeks, winter weeks, PV penetration, annual electricity consumption, active power curtailment, PV systems, PV power curtailment, PV power generation, EV, medium-voltage rural distribution grid, medium-voltage urban distribution grid, low-voltage rural distribution grid, low-voltage urban distribution grid
National Category
Infrastructure Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-359430 (URN)10.1049/iet-rpg.2018.5082 (DOI)000462942900008 ()
Funder
Swedish Energy Agency, P41015-1
Available from: 2018-09-02 Created: 2018-09-02 Last updated: 2019-04-25Bibliographically approved
Hasan, S., Luthander, R. & de Santiago Ochoa, J. (2018). Reactive Power Control for LV Distribution Networks Voltage Management. In: 2018 IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe): . Paper presented at IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe),Sarajevo, Bosnia and Herzegovina, October 21-25, 2018. IEEE
Open this publication in new window or tab >>Reactive Power Control for LV Distribution Networks Voltage Management
2018 (English)In: 2018 IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe), IEEE, 2018Conference paper, Published paper (Refereed)
Abstract [en]

The high photovoltaic (PV) penetration into existing distribution networks leads to voltage profile violation. The main objective of this paper is to study the interaction of traditional static synchronous compensator (STATCOM) with the reactive power capable PV inverter in order to provide voltage support to the low voltage (LV) distribution network. In this paper, we propose an effective coordinated voltage control structure. The control structure has a hierarchical approach where reactive power compensation by PV inverters is prioritized. The STATCOMs are only used when the PV inverters are not capable enough to provide or consume enough reactive power to provide the voltage support. Also, we show that the reactive power supply at night by the PV inverters can be an important resource for effective voltage regulation by using this technique. Data from the existing LV distribution network are used for a case study. The simulation results indicate that the proposed voltage control method is able to control both the over and under voltage situations for the test distribution network without curtailing any active power from PV.

Place, publisher, year, edition, pages
IEEE, 2018
Series
IEEE PES Innovative Smart Grid Technologies Conference Europe, ISSN 2165-4816
Keywords
Photovoltaic (PV), Low voltage (LV), PV inverter, static synchronous compensator (STATCOM), Reactive power control, Voltage control
National Category
Energy Engineering
Identifiers
urn:nbn:se:uu:diva-377034 (URN)10.1109/ISGTEurope.2018.8571817 (DOI)000458690200172 ()978-1-5386-4505-5 (ISBN)
Conference
IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe),Sarajevo, Bosnia and Herzegovina, October 21-25, 2018
Available from: 2019-02-12 Created: 2019-02-12 Last updated: 2019-03-08Bibliographically approved
Luthander, R. (2018). Self-Consumption of Photovoltaic Electricity in Residential Buildings. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Self-Consumption of Photovoltaic Electricity in Residential Buildings
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Egenanvändning av solel i bostadshus
Abstract [en]

Worldwide installations of photovoltaics (PV) have increased rapidly due to national subsidies and decreasing prices. One important market segment is building-applied PV systems, for which the generated electricity can be self-consumed. Self-consumption is likely to become important both for the profitability and to facilitate integration of high shares of PV in the power system. The purpose of this doctoral thesis is to examine opportunities and challenges with distributed PV in the power system on four system levels: detached houses, communities, distribution systems and national level. This was done through literature studies and computer simulations. Previous research has shown a larger potential to increase the PV self-consumption in detached houses by using battery storage rather than shifting the household appliance loads. This thesis shows that, on the community level, the self-consumption increased more when sharing one large storage instead of individual storages in each house. On the distribution system level, PV power curtailment was identified as an effective solution to reduce the risk of overvoltage due to high PV penetration levels. However, the curtailment losses were high: up to 28% of the electricity production had to be curtailed in the studied distribution grid with a PV penetration of 100% of the yearly electricity consumption. However, the penetration of distributed PV on a national level is not likely to reach these levels. Around 12% of the Swedish households were estimated to have PV systems in 2040, although the uncertainties in the results were high, mainly related to the development of the electricity prices. The low profits from both PV but especially battery systems reduce future market shares. If residential batteries could also be used for primary frequency control, the profitability and thus the market shares for PV and battery systems could increase. The overall conclusions are that improved self-consumption can increase the profitability of PV systems and lower the negative impacts on grids with high PV penetration. Energy storage has a large potential to increase the self-consumption, but the profitability is still low for a storage that is only used to increase the self-consumption.     

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 113
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1728
Keywords
Photovoltaics, Solar energy, Self-consumption, Grid integration, Distributed generation, Energy storage, Curtailment, Power system
National Category
Energy Engineering
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-362819 (URN)978-91-513-0470-0 (ISBN)
Public defence
2018-11-29, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency, P37511-1
Available from: 2018-11-06 Created: 2018-10-10 Last updated: 2018-11-19
Luthander, R. & Forsberg, S. (2018). The potential of using residential PV-battery systems to provide primary frequency control on a national level. In: Proceedings of the 8th International Workshop on Integration of Solar into Power Systems: . Paper presented at 8th International Workshop on Integration of Solar into Power Systems, 16-17 October 2018, Stockholm, Sweden. Energynautics GmbH
Open this publication in new window or tab >>The potential of using residential PV-battery systems to provide primary frequency control on a national level
2018 (English)In: Proceedings of the 8th International Workshop on Integration of Solar into Power Systems, Energynautics GmbH, 2018Conference paper, Published paper (Refereed)
Abstract [en]

To keep the frequency stable in a synchronous electric grid, power sources providing primary frequency control (PFC) are needed. Today, hydro power dominates the PFC  market in the Nordic countries. However, if PFC can be offered as an ancillary service from PV-battery systems, the hydro power could be used more efficiently for low-cost electricity production. This can also improve the profitability of PV-battery systems. In this study of 2231 detached houses in Sweden, the potential to use residential PV-battery systems for PFC is examined. The results show that prices of up to 500 EUR/kWh excluding VAT for a 2.5 kW/5 kWh battery storage system can make enough PV-battery systems profitable to replace existing PFC sources in Sweden. The results are based on hourly electricity and PFC prices from 2015-2017 and a discount rate of 0%. If the prices for PFC are reduced by 50% and the discount rate is 5%, a system price of roughly 100 EUR/kWh excluding VAT would be enough to reach the same goal. The battery storage needs to be replaced during the lifespan of the PV system, meaning that the battery system prices are the average of the expected prices during the coming 25 years.

Place, publisher, year, edition, pages
Energynautics GmbH, 2018
Keywords
Photovoltaics, PV, battery storage, primary frequency control
National Category
Energy Engineering
Identifiers
urn:nbn:se:uu:diva-362754 (URN)
Conference
8th International Workshop on Integration of Solar into Power Systems, 16-17 October 2018, Stockholm, Sweden
Available from: 2018-10-09 Created: 2018-10-09 Last updated: 2019-01-09Bibliographically approved
Psimopoulos, E., Leppin, L., Luthander, R. & Bales, C. (2017). Control algorithms for PV and Heat Pump system using thermal and electrical storage. In: Proceedings of the 11th ISES EuroSun 2016 International Conference on Solar Energy for Buildings and Industry: . Paper presented at EuroSun 2016 International Conference on Solar Energy for Buildings and Industry, 11-14 October 2016, Palma de Mallorca, Spain. (pp. 1283-1293). International Solar Energy Society
Open this publication in new window or tab >>Control algorithms for PV and Heat Pump system using thermal and electrical storage
2017 (English)In: Proceedings of the 11th ISES EuroSun 2016 International Conference on Solar Energy for Buildings and Industry, International Solar Energy Society, 2017, p. 1283-1293Conference paper, Published paper (Refereed)
Abstract [en]

In this study a detailed model of a single-family house with an exhaust air heat pump and photovoltaic system is developed in the simulation software TRNSYS. The model is used to evaluate three control algorithms using thermal and electrical storage in terms of final energy, solar fraction, self-consumption and seasonal performance factor. The algorithms are tested and compared with respect to energetic improvement for 1) use of the heat pump plus storage tank for domestic hot water and space heating, 2) use of the electrical storage in batteries and 3) use of both electrical and thermal storage. Results show the highest increase of self-consumption to 50.5%, solar fraction to 40.6% and final energy decrease to 6923 kWh by implementing the third algorithm in a system with 9.36 kW PV capacity and battery storage of 10.8 kWh. The use of electrical energy storage has higher positive impact compared to the thermal storage with the settings and component sizes used. The combined use of thermal storage and batteries leads to final energy savings that are nearly the same as the combined savings of thermal storage and batteries separately, showing that they are mostly independent of one another for the settings of this study.

Place, publisher, year, edition, pages
International Solar Energy Society, 2017
Keywords
Photovoltaics, heap pump, thermal storage, electrical storage, solar fraction, self-consumption
National Category
Energy Engineering
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-328068 (URN)10.18086/eurosun.2016.08.13 (DOI)000426895100130 ()978-3-9814659-6-9 (ISBN)
Conference
EuroSun 2016 International Conference on Solar Energy for Buildings and Industry, 11-14 October 2016, Palma de Mallorca, Spain.
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2019-11-22Bibliographically approved
Luthander, R., Lingfors, D. & Widén, J. (2017). Large-scale integration of photovoltaic power in a distribution grid using power curtailment and energy storage. Solar Energy, 155, 1319-1325
Open this publication in new window or tab >>Large-scale integration of photovoltaic power in a distribution grid using power curtailment and energy storage
2017 (English)In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 155, p. 1319-1325Article in journal (Refereed) Published
Keywords
Photovoltaics, Power distribution system, Energy storage, Power and voltage control, Overvoltage
National Category
Energy Engineering
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-328066 (URN)10.1016/j.solener.2017.07.083 (DOI)000414819900057 ()
Projects
Småskalig solel i byggnader – kraft för förändring i energisystem och vardaglivetUtvärdering av tekniska lösningar för att hantera omfattande anslutning av solcellssystem i eldistributionsnät
Funder
Swedish Energy Agency, P37511-1
Note

Photovoltaic (PV) power generation is an important component for the future energy system. High penetrationof PV power in a power distribution system might however lead to problems with overvoltage and overload. In this study, a method for PV power curtailment and placement of decentralized energy storage is developed to control voltage, feeder currents and distribution substation overloading. The method determines an individual feed-in power limit for each PV system owner based on a voltage-power relationship. Measured data from a 10 kV/400 V three-phase distribution grid in the Swedish municipality of Herrljunga with more than 5000 end-users and simulated PV electricity production data are used for a case study to verify the model. The method is evaluated for yearly PV electricity productionof up to 100% of the yearly electricity consumption. The results show that the method is able to prevent overvoltage for all penetration levels in the studied distribution grid, reduce the number of feeders affected by overcurrent and lower the maximum load on the two substations.

Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2018-10-10Bibliographically approved
Luthander, R., Shepero, M., Munkhammar, J. & Widén, J. (2017). Photovoltaics and opportunistic electric vehicle charging in a Swedish distribution grid. In: Proceedings of the 7th International Workshop on Integration of Solar into Power Systems: . Paper presented at 7th International Workshop on Integration of Solar into Power Systems, 24-25 October 2017, Berlin, Germany. Darmstadt, Germany: Energynautics GmbH
Open this publication in new window or tab >>Photovoltaics and opportunistic electric vehicle charging in a Swedish distribution grid
2017 (English)In: Proceedings of the 7th International Workshop on Integration of Solar into Power Systems, Darmstadt, Germany: Energynautics GmbH, 2017Conference paper, Published paper (Refereed)
Abstract [en]

Renewable distributed generation and electric vehicles (EVs) are two important components in the transitions to a more sustainable society. However, both distributed generation and EV charging pose new challenges to the power system due to intermittent generation and high-power EV charging. In this case study, a power system consisting of a low- and medium-voltage distribution grid with more than 5000 customers, high penetration of roof-top mounted photovoltaic (PV) power systems and a fully electrified car fleet is used to assess the impact of the intermittent PV generation and high-power EV charging loads. Two summer weeks and two winter weeks with and without EV charging and a PV penetration varying between 0% and 100% of the annual electricity consumption are examined using measured and simulated data. Results show that the electricity consumption increases with 9% and 18% during the studied periods, and that EV charging only marginally can contribute to lowering the risk of overvoltage for customers resulting from PV overproduction. The most significant result is the increase in undervoltage in the winter when EV charging is introduced. The share of customers affected by undervoltage increases from 0% to close to 1.5% for all PV penetration levels.

Place, publisher, year, edition, pages
Darmstadt, Germany: Energynautics GmbH, 2017
National Category
Energy Engineering
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-332680 (URN)978-3-9816549-5-0 (ISBN)
Conference
7th International Workshop on Integration of Solar into Power Systems, 24-25 October 2017, Berlin, Germany
Funder
Swedish Energy Agency
Available from: 2017-10-31 Created: 2017-10-31 Last updated: 2018-02-02Bibliographically approved
Psimopoulos, E., Bee, E., Bales, C. & Luthander, R. (2017). Smart Control Strategy for PV and Heat Pump System Utilizing Thermal and Electrical Storage and Forecast Services. In: Proceedings of the ISES Solar World Congress 2017: . Paper presented at ISES Solar World Congress, 29 October-2 November, 2017, Abu Dhabi, UAE.
Open this publication in new window or tab >>Smart Control Strategy for PV and Heat Pump System Utilizing Thermal and Electrical Storage and Forecast Services
2017 (English)In: Proceedings of the ISES Solar World Congress 2017, 2017Conference paper, Published paper (Refereed)
Abstract [en]

In this study, a detailed model of a single-family house with exhaust air heat pump, PV system and energy hub developed in the simulation software TRNSYS 17 is used to evaluate energy management algorithms that utilize weather and electricity price forecasts. A system with independent PV and heat pump is used as a base case. The proposed control strategy is applied to the base case to optimize the available PV electricity production using short-term weather and electricity price forecasts. The three smart and predictive control algorithms were developed with the scope to minimize final energy by the use of the thermal storage of the building, the hot water tank and electrical storage. Results show reduction of the final energy by 26.4%, increase of the self-consumption of 49.5% and decrease of the annual cost of 15% when using the forecast services in combination with thermal and electrical storage, in comparison to the base case.

National Category
Energy Engineering
Identifiers
urn:nbn:se:uu:diva-358048 (URN)10.18086/swc.2017.33.07 (DOI)
Conference
ISES Solar World Congress, 29 October-2 November, 2017, Abu Dhabi, UAE
Available from: 2018-08-23 Created: 2018-08-23 Last updated: 2019-01-09Bibliographically approved
Luthander, R. (2016). Improved Self-Consumption of Photovoltaic Electricity in Buildings: Storage, Curtailment and Grid Simulations. (Licentiate dissertation). Uppsala: Institutionen för teknikvetenskaper
Open this publication in new window or tab >>Improved Self-Consumption of Photovoltaic Electricity in Buildings: Storage, Curtailment and Grid Simulations
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The global market for photovoltaics (PV) has increased rapidly: during 2014, 44 times more was installed than in 2004, partly due to a price reduction of 60-70% during the same time period. Economic support schemes that were needed to make PV competitive on the electricity market have gradually decreased and self-consumption of PV electricity is becoming more interesting internationally from an economic perspective.

This licentiate thesis investigates self-consumption of residential PV electricity and how more PV power can be allowed in and injected into a distribution grid. A model was developed for PV panels in various orientations and showed a better relative load matching with east-west-oriented compared to south-oriented PV panels. However, the yearly electricity production for the east-west-system decreased, which resulted in less self-consumed electricity. Alternatives for self-consumption of PV electricity and reduced feed-in power in a community of detached houses were investigated. The self-consumption increased more with shared batteries than with individual batteries with identical total storage capacity. A 50% reduction in feed-in power leads to losses below 10% due to PV power curtailment. Methodologies for overvoltage prevention in a distribution grid with a high share of PV power production were developed. Simulations with a case with 42% of the yearly electricity demand from PV showed promising results for preventing overvoltage using centralized battery storage and PV power curtailment.

These results show potential for increasing the self-consumption of residential PV electricity with storage and to reduce stress on a distribution grid with storage and power curtailment. Increased self-consumption with storage is however not profitable in Sweden today, and 42% of the electricity from PV is far more than the actual contribution of 0.06% to the total electricity production in Sweden in 2014.

Place, publisher, year, edition, pages
Uppsala: Institutionen för teknikvetenskaper, 2016. p. 71
Keywords
Photovoltaics, Solar energy, Self-consumption, Grid integration, Distributed generation, Energy storage, Curtailment, Power system
National Category
Energy Engineering Energy Systems
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-284091 (URN)
Presentation
2016-05-20, 2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2016-05-09 Created: 2016-04-14 Last updated: 2016-12-02Bibliographically approved
Luthander, R., Lingfors, D., Widén, J. & Munkhammar, J. (2016). Preventing overvoltage in a distribution grid with large penetration of photovoltaic power. In: Uta Betancourt / Thomas Ackermann (Ed.), Proceedings of the 6th International Workshop on Integration of Solar into Power Systems: . Paper presented at 6th International Workshop on Integration of Solar into Power Systems, Vienna, Austria, 14-15 November 2016 (pp. 113-118). Darmstadt, Germany: Energynautics GmbH
Open this publication in new window or tab >>Preventing overvoltage in a distribution grid with large penetration of photovoltaic power
2016 (English)In: Proceedings of the 6th International Workshop on Integration of Solar into Power Systems / [ed] Uta Betancourt / Thomas Ackermann, Darmstadt, Germany: Energynautics GmbH, 2016, p. 113-118Conference paper, Published paper (Other academic)
Abstract [en]

Photovoltaic (PV) power generation is an important component in the future energy system. High penetration of PV power in a distribution power grid might however lead to overvoltage, i.e. +10% of rated voltage, for end-users. This study compares PV power curtailment and decentralized energy storage for overvoltage prevention in a 400V/10 kV distribution grid with large penetration of PV. LiDAR analysis is used to identify rooftops suitable for PV in a Swedish distribution grid with more than 5000 end-users. Results show that power curtailment allows 22% PV electricity (19 GWh) relative to total consumption on a yearly basis without overvoltage. PV production is reduced with 0.35 GWh due to curtailment. Decentralized energy storage of in total 86 MWh capacity achieves the same result.

Place, publisher, year, edition, pages
Darmstadt, Germany: Energynautics GmbH, 2016
Keywords
Photovoltaics, distributed generation, energy storage, distribution grid, power curtailment, Solel, distribuerad generation, energilagring, elnät
National Category
Energy Engineering
Identifiers
urn:nbn:se:uu:diva-308821 (URN)9783981654936 (ISBN)
Conference
6th International Workshop on Integration of Solar into Power Systems, Vienna, Austria, 14-15 November 2016
Projects
Småskalig solel i byggnader - kraft för förändring i energisystem och vardagslivetUtvärdering av tekniska lösningar för att hantera omfattande anslutning av solcellssystem i eldistributionsnät
Funder
Swedish Energy Agency, P37511-1Swedish Energy Agency, P40864-1
Available from: 2016-11-30 Created: 2016-11-30 Last updated: 2018-02-20
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6745-3635

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