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Technische Universität München Department of Electrical Engineering and Information Technology
05.10.2011
Technische Universität München, Institute of Power Transmission Systems
Analyzing the Capacity of Low Voltage Grids for Electrical Vehicles
IEEE EPEC 2011
Georg Stöckl
Technische Universität München Institute of Power Transmission Systems
Outline
1. Introduction 2. LV Grids 3. Dynamic Simulation Modell 4. Simulation Model – Power Peak 5. Summary
10/26/11 2 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
Technische Universität München Institute of Power Transmission Systems
Introduction
Goals / predictions of the German Government: 1 million electric vehicles until 2020 Up to 5 million electric vehicles until 2030 2050: urban traffic will be able to do without fossil fuels
→ How will the distribution grids cope with this new challenge?
3 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles 10/26/11
Technische Universität München Institute of Power Transmission Systems
LV Reference Grids
Why? • Statistically sound simulations • To ensure realistic results • Alternative: Simulating a high amount of LV Grids → A lot of Simulations
Classification: • Rural area, village and suburban area
10/26/11 4 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
Technische Universität München Institute of Power Transmission Systems
LV Reference Grids
10/26/11 5 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
digitalization of the grids
average distance between two houses in m average distance between two houses in m
rela
tive
frequ
ency
cum
ulat
ive
frequ
ency
statistical evaluation
extreme reference grid → critical value statement
typical reference grid → general statement
Technische Universität München Institute of Power Transmission Systems
Suburban Reference Grid
10/26/11 6 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
Technische Universität München Institute of Power Transmission Systems
7 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles 10/26/11
Time in hours Time in hours
prob
abili
ty th
e ve
hicl
e w
ill c
ome
hom
e in
%
cum
ulat
ive
prob
abili
ty th
e ve
hicl
e w
ill c
ome
hom
e in
%
random number
time the EV begins to charge
Source: Bundesanstalt für Straßenwesen, “Kennlinien der Parkraumnachfrage”
Dynamic Simulation Modell
Technische Universität München Institute of Power Transmission Systems
Dynamic Simulation Modell
8 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles 10/26/11
Cha
rgin
g D
eman
d of
191
EV
s / K
w
Time in hours
▪ 11.1 kW ▪ 3.7 kW
higher charging power leads to higher peaks in the charging power demand of a grid and more fluctuation
Technische Universität München Institute of Power Transmission Systems
Dynamic Simulation Modell
9 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles 10/26/11
charging power ↑ => charging time ↓ => number of simultaneous charging cars ↓
Loading of LV grids is not proportional to the charging power
Max
imum
Cha
rgin
g D
eman
d of
191
EV
s / K
w
3.7 kW 11.1 kW
373 kW
240 kW
factor 1.55
factor 1.3
Technische Universität München Institute of Power Transmission Systems
Dynamic Simulation Modell
10 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles 10/26/11
For small amounts of electric vehicles the charging power has a stronger effect on the power peak.
Technische Universität München Institute of Power Transmission Systems
Simulation Model – Power Peak
• Peak of power demand is approximately at the same time as the peak of the charging demand.
10/26/11 11 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
Technische Universität München Institute of Power Transmission Systems
Simulation Model – Power Peak
• Peak of power demand is approximately at the same time as the peak of the charging demand.
→ worst case scenario: both peaks are simultaneous → peak of total power demand is decisive for grid capacity
→ Simulation during power demand peak advantage: faster simulations
10/26/11 12 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
Technische Universität München Institute of Power Transmission Systems
Simulation Model – Power Peak
Typical Reference Grids: • Pcharge = 3.7 kW: No overloading if every household has one EV
• Pcharge = 11.1 kW: No overloading if 29 % of the households have one EV
• Rural area grid: voltage limits are the most critical
• Village and suburban grids: transformer and line loading are the most critical
10/26/11 13 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
Technische Universität München Institute of Power Transmission Systems
Simulation Model – Power Peak
Extreme Reference Grids: • Transformer loading is very high even without EV → Transformer needs to be replaced!!
• Pcharge = 3.7 kW: No overloading if 31 % of the households have one EV (after transformer upgrade)
• Pcharge = 11.1 kW: No overloading if 9 % of the households have one EV (after transformer upgrade)
10/26/11 14 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
Technische Universität München Institute of Power Transmission Systems
Summary • Capacity for EVs varies widely between different LV grids
• Maximum charging demand of a grid increases with increasing charging power but it is not proportional to the charging power
• A high amount of EVs can be integrated into the typical LV grids in Bavaria
• A few highly loaded LV grids have to be extended in order to be able to integrate EVs
→ outlook: intelligent charging to avoid high simultaneity during power peak of household load
10/26/11 15 IEEE EPEC 2011 – Analyzing the Capacity of LV Grids for Electric Vehicles
Technische Universität München Department of Electrical Engineering and Information Technology
Thank you for your Attention
Dipl.-Ing. Georg Stöckl
Technische Universität München Institute for Power Transmission Systems Arcisstraße 21, 80333 München, Germany Tel: +49.89.289.25090 Fax: +49.89.289.25089 [email protected] www.een.ei.tum.de