Εργαστήριο Φωτοβολταϊκής Τεχνολογίας Πανεπιστημίου Κύπρου

Guidelines for the Design of Residential and
Community Level Storage Systems Combined
with Photovoltaics (PV)
Stavros Afxentis
PV Technology Laboratory
Outline
• Introduction
• Sizing of Battery Storage Systems
• Storage System Topologies
• Storage System Design
• Conclusions
2
•
•
•
Introduction
Low-carbon or even zero-carbon energy generation
GREEN and RESILIENT Energy SYSTEM
Higher shares of renewables
o Intermittent nature of PV
o Control unobstructed deployment
o Prevent distribution grid issues
3
Introduction
ENERGY STORAGE
•
•
•
•
Support operation of the grid
Provide flexibility to the energy system
Balance PV intermittency
Achieve higher PV penetration
4
Case Study
5
Sizing of Battery Storage System
Typical household
• Annual energy yield of 1600 kWh/kWp
• Installed PV system capacity: 3 kWp
• Expected annual energy consumption of 5000 kWh
Battery Technology
• Deep cycle Lithium-ion battery
6
Sizing of Battery Storage System
7
Sizing of Battery Storage System
Residential Storage
Community Storage
• Maximum annual load power: 1.68 kW
For example
10 Households
Same feeder
Rated converter power: 2.5 kW
• Usable Battery Capacity: 6.4 kWh
Converter power: 25 kW
• Recommended Battery DoD: 80%
Nominal Battery Capacity: 8 kWh
Battery Capacity: 80 kWh
8
System Configuration – AC Coupled
9
System Configuration – DC Coupled
10
Important Design Parameters
Electrical Parameters
1.
Converter Power:
• Maximum power derating of the PCS with ambient temperature
(Typical specified ambient temperature is 25oC)
• Nominal PCS grid power scaled based on load demand
• Max injected power to grid follow grid codes of each country
• Withstand required reactive power exchange/active power
• Nominal PV input at least equal to the max PV array power
11
Important Design Parameters
Electrical Parameters
2.
Nominal Voltage:
• DC Voltage range to handle maximum PV array voltage
• AC Voltage follow grid codes
• Allow for short voltage surges/dips
• Off-grid voltage regulation at least as good as grid regulation
3.
Nominal Frequency:
• Follow grid codes
• Allow frequency support
4.
Total Harmonic Distortion (THD):
• Affects power quality
• Comply with relevant standards
12
Important Design Parameters
Electrical Parameters
5.
Power Factor:
• Adjustable within acceptable limits
• Important for VAr control
6.
Inverter Design and Peak Efficiency:
• Transformer-less or with transformer
• Recommended: Transformer-less – Higher efficiency (>95%)
13
Important Design Parameters
• Minimum Recommended Power Converter Standards:
Category
Number
EN61000-3-2
EN61000-3-12b
EMC
EN61000-3-3a
EN61000-3-11b
EN61000-6-1 or EN61000-6-2
EN61000-6-3 or EN61000-6-4
Electrical
Safety
EN50178 [replaced by EN62477-1]
EN62109c
Description
Harmonic current emissions
(≤ 16 A per phase).
Harmonic current emissions
(≤ 75 A per phase).
Voltage changes, fluctuations and flicker
(≤ 16 A per phase).
Voltage changes, fluctuations and flicker
(≤ 75 A per phase).
Immunity.
Emissions.
Power electronic converters and
equipment.
Power converters for PV systems.
a)Applicable to distributed household systems b)Applicable to centralised systems
c)Only required for PV and Hybrid converters.
14
Important Design Parameters
• Minimum Recommended Battery Unit Standards:
Category
Battery
Safety
Number
Description
IEC62281 or UN/DOT 38.3
Transportation testing for lithium
batteries.
IEC62133 or UL1642
Safety test for lithium batteries.
EN62619
Safety requirements for secondary
lithium cells and batteries.
EN61000-6-1 or EN61000-6-2
Immunity.
EN61000-6-3 or EN61000-6-4
Emissions.
EN50178 [replaced by EN62477-1]
Power electronic converters and
equipment.
EMC
Electrical
Safety
15
Important Design Parameters
Mechanical Parameters
1.
Ingress Protection (IP):
• Minimum IP20 indoor use, IP65 outdoor use
2.
Ambient Temperature and Relative Humidity:
• Power Converter: -40oC to 50oC , 5% to 95%
• Battery Unit: 25oC ± 10oC
3.
Cooling:
• Natural Convection (Indoor), Forced Air (Outdoor)
4.
Installation:
• Proper ventilation, Adequate thermal parameters
16
Data Acquisition – Residential ESS
17
Electrical Sensors – Residential ESS
Smart Meters (SM)
• Measure import and export energy
• Regulate energy flow
• Embedded communication
• Usually equipped with serial communication (i.e. RS485)
• Fast and reliable data transfer over long distances
19
Data Acquisition – Community ESS
• SCADA or Battery Converter: Voltage, Frequency, Power
• SCADA recommended for Frequency measurement
• SCADA for future communication with the DSO
21
Electrical Sensors – Community ESS
• Distribution feeder voltage
• Grid frequency
• CTs to measure the 3-PH line current (usually analogue output)
• Battery Converter compatible with CTs
• Additional A/D converter may be required
22
Conclusions
•
Methodology for sizing Battery Energy Storage Systems

Power Converter Power: 150% of the maximum demand

Battery Unit: 80% DoD

Strongly depend on the load profile and PV production
•
Electrical and Mechanical Parameters
•
Electrical Sensors for Data Acquisition
•
Communication Protocols (i.e. RS485, web-server, SCADA)
for secure transfer and remote supervision
23
Together we do more for PV and
Smart Grids
Team
• 3 countries
• Over 100
Expert
Researchers,
Trainers
• One stop shop
(cells to
modules to
Grid)
• Training,
Testing,
Research
24
Mr. Stavros Afxentis
University of Cyprus
PV Technology Laboratory
FOSS Research Centre for Sustainable Energy
1 University Avenue
New Campus
P.O. 20537
1678, Nicosia
Tel: +357 22-892272
Email: afxentis.stavros@ucy.ac.cy
Website: www.pvtechnology.ucy.ac.cy
Thank you for your attention
Questions?
25