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LUND UNIVERSITY LIBRARIES

Solceller i elnät - Betydande andel solcellers inverkan på lågspänningsnätet

Berg, Niklas and Estenlund, Samuel (2013) In CODEN:LUTEDX/TEIE EIE920 20131
Industrial Electrical Engineering and Automation
Abstract
PV power production is becoming more and more common and one can easily imagine that a so called boom is near in southern Sweden. As the distribution grids are designed for power flow out to the households, and not the other way around, the question is what will happen that sunny day when the households in a neighborhood produce more electricity
than they consume.
This master thesis project was carried out at Lund University in collaboration with the local Distribution System Operator (DSO), Lunds Energi. It brings up the question of how a considerable amount of PV systems in the low-voltage grid affects power quality. This was made through simulations of three different model representations of existing low-voltage grids in Lund.... (More)
PV power production is becoming more and more common and one can easily imagine that a so called boom is near in southern Sweden. As the distribution grids are designed for power flow out to the households, and not the other way around, the question is what will happen that sunny day when the households in a neighborhood produce more electricity
than they consume.
This master thesis project was carried out at Lund University in collaboration with the local Distribution System Operator (DSO), Lunds Energi. It brings up the question of how a considerable amount of PV systems in the low-voltage grid affects power quality. This was made through simulations of three different model representations of existing low-voltage grids in Lund. Voltage variations, asymmetry and harmonics were the investigated power quality issues.
The thesis was limited to PV systems of a size that can be expected to reach a larger incidence. The concluded guidelines should be applied to low-voltage grids similar to those modeled. The simulations have been made in DIgSILENT PowerFactory. The report also summerizes interviews with different Swedish DSOs and previous work reported in literature.
Current regulations and standards were also reviewed.
Results show that asymmetry is the most critical restriction, when a sufficient amount of single phase installations are unevenly distributed on the three phases throughout the grid. If all customers in a low-voltage grid install the amount of PV systems that their roofs allow, the
voltage variations will only be unacceptable in the weakest points in the weakest grid.
Voltage varations due to clouds passing the sun will not cause problems, based on the results from the simulations. Harmonics may form a potential danger to power quality, and depend on the quality of the inverters. The DSOs cannot deny an application for installation of a PV system that fulfill the requirements, and can only make sure that their grids can support the new installation. To this day, the amount of applications in Sweden is small enough for the DSO to investigate each one. But if a PV boom takes place with more than 100 applications per day on average, this is not realistic anymore. Therefore, a few simple guidelines are suggested to advise the DSOs, helping them recognize which applications that need extra consideration while unproblematic cases are approved without detailed investigation. (Less)
Please use this url to cite or link to this publication:
author
Berg, Niklas and Estenlund, Samuel
supervisor
organization
course
EIE920 20131
year
type
H3 - Professional qualifications (4 Years - )
subject
keywords
Photovoltaic systems, distributed generation, power quality, low-voltage grid, voltage variations, asymmetry, harmonics
publication/series
CODEN:LUTEDX/TEIE
report number
5314
language
Swedish
id
4533684
date added to LUP
2014-10-16 14:07:55
date last changed
2014-10-16 14:07:55
@misc{4533684,
  abstract     = {PV power production is becoming more and more common and one can easily imagine that a so called boom is near in southern Sweden. As the distribution grids are designed for power flow out to the households, and not the other way around, the question is what will happen that sunny day when the households in a neighborhood produce more electricity
than they consume.
This master thesis project was carried out at Lund University in collaboration with the local Distribution System Operator (DSO), Lunds Energi. It brings up the question of how a considerable amount of PV systems in the low-voltage grid affects power quality. This was made through simulations of three different model representations of existing low-voltage grids in Lund. Voltage variations, asymmetry and harmonics were the investigated power quality issues.
The thesis was limited to PV systems of a size that can be expected to reach a larger incidence. The concluded guidelines should be applied to low-voltage grids similar to those modeled. The simulations have been made in DIgSILENT PowerFactory. The report also summerizes interviews with different Swedish DSOs and previous work reported in literature.
Current regulations and standards were also reviewed.
Results show that asymmetry is the most critical restriction, when a sufficient amount of single phase installations are unevenly distributed on the three phases throughout the grid. If all customers in a low-voltage grid install the amount of PV systems that their roofs allow, the
voltage variations will only be unacceptable in the weakest points in the weakest grid.
Voltage varations due to clouds passing the sun will not cause problems, based on the results from the simulations. Harmonics may form a potential danger to power quality, and depend on the quality of the inverters. The DSOs cannot deny an application for installation of a PV system that fulfill the requirements, and can only make sure that their grids can support the new installation. To this day, the amount of applications in Sweden is small enough for the DSO to investigate each one. But if a PV boom takes place with more than 100 applications per day on average, this is not realistic anymore. Therefore, a few simple guidelines are suggested to advise the DSOs, helping them recognize which applications that need extra consideration while unproblematic cases are approved without detailed investigation.},
  author       = {Berg, Niklas and Estenlund, Samuel},
  keyword      = {Photovoltaic systems,distributed generation,power quality,low-voltage grid,voltage variations,asymmetry,harmonics},
  language     = {swe},
  note         = {Student Paper},
  series       = {CODEN:LUTEDX/TEIE},
  title        = {Solceller i elnät - Betydande andel solcellers inverkan på lågspänningsnätet},
  year         = {2013},
}