Utility Activities Within Photovoltaics April 19 2012 Stockholm Challenges with high PV penetrations in distribution grids Dr. Joakim Widén Built Environment Energy Systems Group (BEESG) Department of Engineering Sciences Uppsala University joakim.widen@angstrom.uu.se http://www.anst.uu.se/jowid957
About me System Studies and Simulations of Distributed Photovoltaics in Sweden (2010) Development of models for electricity use in households. Modelling of PV systems. Studies of PV system utilisation in Swedish households. Consequences of solar power integration into the Swedish power system.
Built Environment Energy Systems, Uppsala University
4 Outline of the presentation System integration of renewables Relevant properties of distributed photovoltaics Hosting capacity of photovoltaics in distribution grids: Two studies on Swedish grids Increasing the hosting capacity of distributed photovoltaics 4
5 Integration characteristics of renewables (IPCC SRREN Report, 2011) Technology Plant size (MW) Variability Dispatchability Geographical diversity potential Bioenergy 0.1 100 Seasons Full Moderate Hydropower 0.1 20 000 Hours to years Full (excl. run of river) Moderate Ocean energy 0.1 300 Minutes to years Low Moderate Wind energy 5 300 Minutes to years Low High PV 0.004 100 Minutes to years Low High 5
Large-scale power generation (hydro, nuclear) Mediumscale distributed power generation (e.g. wind) Small-scale distributed power generation (mainly PV)
8 System integration challenges Two distinctly different challenges Power distribution and transmission Capacity for increased power flows Voltage levels Correlation between demand and generation Power system balancing Production variability and dispatchability Predictability Utilisation of operating reserves 8
On-site PV generation in distribution grids 9 4000 3500 Household electricity demand 3000 W 2500 2000 3 kwp PV 1500 1000 1 kwp PV 500 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Time 9
10 Hosting capacity How much distributed generation can be integrated in a specific distribution grid before deteriorating power quality Performance index Limit Hosting capacity Penetration level
PV hosting capacity in Swedish grids #1 Demand and generation balance Joakim Widén, Ewa Wäckelgård, Jukka Paatero, Peter Lund, Impacts of distributed photovoltaics on network voltages: stochastic simulations of three Swedish low-voltage distribution grids, Electric Power Systems Research 80 (2010) 1562-1571.
PV hosting capacity in Swedish grids #1 Altered voltage distribution with increasing PV penetrations Joakim Widén, Ewa Wäckelgård, Jukka Paatero, Peter Lund, Impacts of distributed photovoltaics on network voltages: stochastic simulations of three Swedish low-voltage distribution grids, Electric Power Systems Research 80 (2010) 1562-1571.
PV hosting capacity in Swedish grids #2 Voltage as performance index 1,16 City grid (0.4 kv) Suburban grid (0.4 kv) 1,16 1,16 Rural grid (10 kv) Nominal voltage at end point 1,14 1,12 1,1 1,08 1,06 1,04 1,02 1,14 1,12 1,1 1,08 1,06 1,04 1,02 1,14 1,12 1,1 1,08 1,06 1,04 1,02 1 1 1 0,98 0% 20% 40% 60% 80% 100% Grade of energy self-sufficency 0,98 0% 20% 40% 60% 80% 100% Grade of energy self-sufficency 0,98 0% 20% 40% 60% 80% 100% Grade of energy self-sufficency Tobias Walla, on-going M.Sc. project, Fortum / Uppsala University To be presented at the 27th EU-PVSEC, Frankfurt, Germany, 2012
PV hosting capacity in Swedish grids #2 Overloading / overheating as performance index 4,5 City grid (0.4 kv) Suburban grid (0.4 kv) 140 18 Rural grid (10 kv) Number of problem lines 4 3,5 3 2,5 2 1,5 Overheated and overloaded lines Overloaded lines 120 100 80 60 40 Overheated and overloaded lines Overloaded lines 16 14 12 10 8 6 Overheated cables 1 4 0,5 20 2 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Grade of energy self-sufficency 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Grade of energy self-sufficency 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Grade of energy self-sufficency Tobias Walla, on-going M.Sc. project, Fortum / Uppsala University To be presented at the 27th EU-PVSEC, Frankfurt, Germany, 2012
PV hosting capacity in Swedish grids #2 Voltage profiles along feeders (30 % PV penetration) 1,03 City grid (0.4 kv) Suburban grid (0.4 kv) 1,06 1,065 Rural grid (10 kv) Nominal voltage at end points 1,0295 1,029 1,0285 1,028 1,0275 1,027 1,0265 1,026 1,0255 1,055 1,05 1,045 1,04 1,035 1,03 1,025 1,06 1,055 1,05 1,045 1,04 1,035 1,025 0 50 100 150 Distance from MV/LV transformer 1,02 0 100 200 300 400 500 Distance from MV/LV transformer 1,03 0 5000 10000 15000 20000 Distance from HV/MV transformer Tobias Walla, on-going M.Sc. project, Fortum / Uppsala University To be presented at the 27th EU-PVSEC, Frankfurt, Germany, 2012
16 Increasing hosting capacity Voltage control (manual or automatic) Grid reinforcements Power curtailment Reactive power control in inverters Demand side management Local energy storage
17 Thanks for the attention! joakim.widen@angstrom.uu.se http://www.anst.uu.se/jowid957