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Operation Strategies of Energy Storages with Forecast Methods in … · Institute of Power...
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Technische Universität München Department of Electrical Engineering and Information Technology October 4 th 2011 Technische Universität München Institute of Power Transmission Systems Operation Strategies of Energy Storages with Forecast Methods in Low-Voltage Grids with a High Degree of Decentralized Generation Electrical Power and Energy Conference (EPEC 2011) Martin Lödl, Rolf Witzmann, Michael Metzger
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Technische Universität München Department of Electrical Engineering and Information Technology
October 4th 2011
Technische Universität München Institute of Power Transmission Systems
Operation Strategies of Energy Storages with Forecast Methods in Low-Voltage Grids
with a High Degree of Decentralized Generation
Electrical Power and Energy Conference (EPEC 2011)
Martin Lödl, Rolf Witzmann, Michael Metzger
Technische Universität München Institute of Power Transmission Systems
Presentation Outline
1. Introduction
Low-Voltage Reference Networks
Potential of Roof-Mounted Photovoltaic (PV) Power Plants
2. Decentralized Energy Storages
Storage Demand
3. Weather Forecasts
Forecast errors
4. Summary
10/26/11 2 IEEE 2011 Electrical Power and Energy Conference
Technische Universität München Institute of Power Transmission Systems
Introduction
• fast growing amount of decentralized power units in Germany currently installed: approx. 20 GWpeak of PV generation
• Assumption: small-scale PV power plants will use all available roof areas in the future
Possibilities to increase feed-in: • grid reinforcement • local energy storages optimal usage highly recommended
10/26/11 3 IEEE 2011 Electrical Power and Energy Conference
Technische Universität München Institute of Power Transmission Systems
Introduction
Low-Voltage Reference Grids • statistically sound reference networks • similar characteristics to approx. 50% of real distribution grids • to ensure realistic results
Classification: • rural areas • villages • suburban areas
10/26/11 4 IEEE 2011 Electrical Power and Energy Conference
Technische Universität München Institute of Power Transmission Systems
Introduction
Photovoltaic Power-Plants • usable surface area on rooftops of different regions statistically evaluated • average photovoltaic potential:
• a photovoltaic power plant at each rooftop • rated power gradually incremented up to the maximum potential
10/26/11 5 IEEE 2011 Electrical Power and Energy Conference
rural area village suburban residential buildings 13,7 kWp 12,5 kWp 8,7 kWp
agricultural buildings 53,9 kWp 47,3 kWp ---
Technische Universität München Institute of Power Transmission Systems
Limits of Grid Transmission Capacity
10/26/11 6 IEEE 2011 Electrical Power and Energy Conference
ΔU < 2% UN
ST < 100% Sr
U < 110% UN
I < 100% Ith
Technische Universität München Institute of Power Transmission Systems
Limits of Grid Transmission Capacity
10/26/11 7 IEEE 2011 Electrical Power and Energy Conference
ΔU < 2% UN
ST < 100% Sr
U < 110% UN
I < 100% Ith
Technische Universität München Institute of Power Transmission Systems
Decentralized Energy Storages
Development of a simulation tool • electrical structure of the reference grids • typical household energy consumption profiles • PV feed-in from measurements and forecasts • energy storages with all necessary electrical parameters
Variable parameters • PV system size • battery size (rated power and capacity) • used control strategy for storage system
8 IEEE 2011 Electrical Power and Energy Conference 10/26/11
Technische Universität München Institute of Power Transmission Systems
Decentralized Energy Storages
Development of a simulation tool • electrical structure of the reference grids • typical household energy consumption profiles • PV feed-in from measurements and forecasts • energy storages with all necessary electrical parameters
Variable parameters • PV system size • battery size (power and capacity) • used control strategy for storage system
9 IEEE 2011 Electrical Power and Energy Conference 10/26/11
Optimal Size of the Storage System:
Rated Power: 60 % - 85 % of the respective PV plant size
Capacity: for about 2.5 to 4 full load hours
Technische Universität München Institute of Power Transmission Systems
Weather Forecasts
Global Weather Data • generating courses of the solar irradiation at ground level Fdown,i • short-time (15 minutes) and long-time prediction (~ 3 days) • high resolution (< 1 km)
Goals • Maximum self-consumption • Best exploitation on days with low PV feed-in • Balancing forecast errors with storage
10 IEEE 2011 Electrical Power and Energy Conference 10/26/11
Technische Universität München Institute of Power Transmission Systems
Weather Forecasts
Forecast errors • average forecast error for the next day: 32.5 % • forecast error for two days: 39 % forecast error for three days: 47 % • relative forecast error decreases with rising maximum predicted feed-in
Possible error sources: • simplified modeling of clouds and aerosols • discretization in time and space • limited accuracy of the numeric methods • wrong estimation of the sky cover in the utilized global weather data
11 IEEE 2011 Electrical Power and Energy Conference 10/26/11
Technische Universität München Institute of Power Transmission Systems
Weather Forecasts
Balancing forecast errors • storage capacity increases only approx. 5 - 10 % • forecasts for more than one day do not further affect the size of the storage systems
Considering weather forecasts • self-consumption of local energy generation can be further increased at about 25 – 100 %
12 IEEE 2011 Electrical Power and Energy Conference 10/26/11
Technische Universität München Institute of Power Transmission Systems
Summary
• Local energy storages are necessary for further PV integration
• Shifting energy from peak production to peak load maximizes local self-consumption of regenerative generation
• By considering weather forecast and days with low PV feed-in an efficient exploitation of the storage system is assured
• Also the inaccurateness of the weather forecast can be balanced and further reduce conventional energy generation
10/26/11 13 IEEE 2011 Electrical Power and Energy Conference
Technische Universität München Department of Electrical Engineering and Information Technology
Thank you for your Attention!
Dipl.-Ing. Martin Lödl
Technische Universität München Institute for Power Transmission Systems Arcisstraße 21 80333 München Germany Tel.: +49.89.289.22017 Fax: +49.89.289.25089 [email protected] www.een.ei.tum.de
