T 2nd Inverter and PV System Technology Forum 2012 Measured effects of a high PV penetration to a communal low voltage grid of Ulm Holger Ruf Gerd Heilscher Florian Meier 1
Contents Distribution grid - utility of Ulm High penetration of PV in low voltage grid Grid operators point of view Test site Definition Measurements Potential Conclusion & Outlook 2
City of Ulm Highest church tower in the world Number One in the German Solar Bundes League ULM Source: www.wolframalpha.com tourismus.ulm.de 3
Key Figures of the Distribution Grid Utility of ULM, Germany Low voltage grid 252 km aerial line 1446 km cable 5523 transformers 49,771 loads 332 km² grid area > 200 000 inhabitants Load 110 MW on summer Sundays 220 MW maximum 86 MW complete, 42 MWp PV in low voltage Source: www.swu.de, EEG Anlagenregister, October 2011 4
Feed in to Grid greater than Load Utility of Ulm, Germany 220.000 Solar Power (EEG) Max Load 200.000 Biomass (EEG) 180.000 Hydro Power (EEG) 160.000 Grid Load kW 140.000 120.000 Max Load Sunday Feed in greater than load 100.000 80.000 60.000 Real Estimate 40.000 20.000 0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 Source: www.swu.de, EEG Anlagenregister, August 2011, own calculation 5
Grid Operators Point of View Solar power is driving day to day grid upgrades Forward looking planning impossible today Drafted budget for transformer exchange already used in first half of the year 6 6
First test site • > 130 houses • 17 PV, total ~200kWp • 1 transformer (630kVA) • 0,2 km² 7 Only 17 PV Systems on the 130 Roofs up to now Holger Ruf ZSW-BMU_Quer 7
First test site grid measurement = + Voltage and 0.176 km² area Real time Power measurements 630 kVA 1 s resolution transformer Since 30th March 2011 10 channels 8 outgoing lines Large memory > 130 Loads 17 PVs (~200kWp) 8
Active Power 9
Voltage 10
Active Power 11
Voltage 12
Solar Potential of Test Site – Today and Tomorrow Maximum development Today: 133 Houses 200 kWp / 17 PV = ~12kWp/House Tomorrow: 133 Houses conservative (5kWp/House) 650 kWp actual (12kWp/House) 1560 kWp 13
Solar Potential of Test Site – Tomorrow Effects Problems without grid development Violation of voltage tolarance according to EN 60038 (± 10% Vn) Violation of fast voltage transient according to VDE-AR- N 4105 (≤ 3% Vn) Reduced life time of transformers caused of thermal overload Increase of power electronics electromagnetic compatibility (EMC) problems 14
PV influence on the grid (1) Voltage tolerance violation Reversal load flow Source: TU München, Prof. Witzmann 15
PV influence on the grid (2) Thermal overload transformer and cable possible P PV /S Tr >1,5 increase ageing Source: TU München, Prof. Witzmann 16
ENDORSE - Local solar power forecast Consumption 122 kW Generation 5 minutes 3x5 km/pixel 250 kW 1h predicted Generation 5 kW Clouds detected 17
Next Steps to Smart Solar Grid • Calculation of • Determination • Detailed plan/cost energy flow of solar potential for grid upgrade • Evaluation of • Smart Metering for every roof / • Solar power forecast grid access point influences to • Load management the grid 18
Contact Florian Meier SWU Netze GmbH Karlstr. 1 D-89075 Ulm florian.meier@swu.de Prof. Gerd Heilscher, Holger Ruf Ulm University of Applied Sciences Eberhard Finckh Str. 11 D-89075 Ulm heilscher@hs-ulm.de ruf@hs-ulm.de 19
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