Challenges with high PV penetrations in distribution grids

Transcription

1 Utility Activities Within Photovoltaics April Stockholm Challenges with high PV penetrations in distribution grids Dr. Joakim Widén Built Environment Energy Systems Group (BEESG) Department of Engineering Sciences Uppsala University

2 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.

3 Built Environment Energy Systems, Uppsala University

4 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 5 Integration characteristics of renewables (IPCC SRREN Report, 2011) Technology Plant size (MW) Variability Dispatchability Geographical diversity potential Bioenergy Seasons Full Moderate Hydropower Hours to years Full (excl. run of river) Moderate Ocean energy Minutes to years Low Moderate Wind energy Minutes to years Low High PV Minutes to years Low High 5

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7 Large-scale power generation (hydro, nuclear) Mediumscale distributed power generation (e.g. wind) Small-scale distributed power generation (mainly PV)

8 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

9 On-site PV generation in distribution grids Household electricity demand 3000 W kwp PV kwp PV Time 9

10 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

11 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)

12 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)

13 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, ,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

14 PV hosting capacity in Swedish grids #2 Overloading / overheating as performance index 4,5 City grid (0.4 kv) Suburban grid (0.4 kv) Rural grid (10 kv) Number of problem lines 4 3,5 3 2,5 2 1,5 Overheated and overloaded lines Overloaded lines Overheated and overloaded lines Overloaded lines Overheated cables 1 4 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

15 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, Distance from MV/LV transformer 1, Distance from MV/LV transformer 1, 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 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 17 Thanks for the attention!