Download Solar Powered Charging Station: Progress Report

Solar Powered Charging
Station:
Final Presentation
Design Team:
Ben Hemp
Jahmai Turner
Rob Wolf, PE
Sponsors:
Conn Center for Renewable Energy
Dr. James Graham, PhD
Dr. Chris Foreman, PhD
Revision B, 11/27/11
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Agenda
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Project Overview
System Requirements
Detailed Design
Trade Studies and Research
Test Results
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Project Overview
Original System Goals
• Charge an electric vehicle (EV) from a charging station using
110 VAC, 60 Hz, 1ø as the charging source
• Use power created by solar panels (SP’s) for the EV charging
• For periods when an EV is not plugged into the charging
station, store energy created by SP’s into a battery bank
• If the battery bank is depleted, use grid-tied energy to make
the charging times more predictable
• Use instrumentation to detail the detail energy created by
charging station and energy used by electrical grid
• This semester’s team is expected to design the complete
system, but is only expected to implement the solar charging
aspect due to planning with subcontractors
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Project Overview
The Test Subject
• Manufactured by NoGas LLC in
Nashville, TN
• 50 MPH top speed/50 mile
range
• 72 VDC, 40 AH Lithium batteries
with Battery Management
System (BMS)
• Regenerative braking
• Built-in charger
• 340 lb carrying capacity
• 120 VAC charging with 1 to 8 hr.
max charge time
• Front and rear hydraulic disk
brakes
• Hydraulic shocks front and rear
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System Requirements
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System Requirements
First Requirement- Solar Array
• A solar array of multiple SP’s for solar charging
• A solar study should be conducted to determine the number and
size of SP’s needed to charge the scooter
• Solar study determined seven solar panels are needed to reach 3.5
kW/day for worst case month
• Conn Center funded two panels by vendor of choice
• Decisions regarding fabrication technology and make/buy
• Funded SP’s are poly-crystalline
• Mounting location and attachment techniques must be
determined (W.S. building, build structure, etc.)
• “Cart-style” structure chosen for mobility
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System Requirements
Alternative Energies (Danville, KY)
• Received two 230W poly-crystalline panels
from the Conn Center
• Alternative Energies fabricates the panels
• A preferred vendor
230 W Panel Specifications
• Each panel has 60 cells
• Vmax (1000W/m2, 25°C, AM 1.5) = 29.7 VDC
• Imax (1000W/m2, 25°C, AM 1.5) = 7.5A
• ~18% efficient
• Size = 39.375” (~3.25’) x 65.5” (~5.5’)
• ~ 2.0 yards2 or 1.9 m2
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System Requirements
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System Requirements
Second Requirement- Inverter
• Component is needed to convert DC power from SP’s to AC power
for charging station
• Determine between distributed vs. centralized
• Distributed chosen due to:
• Work at low DC voltages (150+ VDC at input required for most centralized
inverters). Shut off at ~16 VDC.
• Higher efficiency (compensates for shading, independent panel operation)
• Expandability, can add a panel and inverter at a time. Centralized inverters
are not flexible with expandibility.
• Greater safety (low DC voltages)
• Choose an inverter capable of supporting off-grid battery bank
and future grid-tie
• Distributed inverters must be grid-tied to function
• Grid-tie circuit must be implemented this semester
• Battery banks are not compatible with distributed inverters
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System Requirements
Enphase M215 Distributed Inverter
• Maximum input power: 260W
• Output power: 215W
• DC operation range: 16V – 36V
• Maximum modules for 240VAC 20A
branch circuit: 17
• Inverters operate independently
• Low-voltage operation
• 96% efficiency
• Works with 60-cell SP’s
• Plug-and-play cabling
• No high voltage DC wiring
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System Requirements
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System Requirements
Third Requirement– Charging Station
• Charging Station provides interface to :
• Building grid-tie
• Clamp-on for grounding rod
• Plug with cord for EV charging
• Provides instrumentation for system requirements:
• All instrumentation located in enclosure with clear door:
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Energy Meters
Gateway
24 VDC Power Supply
Terminal Blocks
120 VAC Receptacle
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System Requirements
Third Requirement– Charging Station (continued)
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System Requirements
Fourth Requirement– Transformer
• Converts 120 VAC, 1ɸ from W.S. Speed grid to the 240 VAC, 1ɸ
required for the M215 distributed to be grid-tied
• 2kVA power rating
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System Requirements
Fifth Requirement– Gateway
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System Requirements
Sixth Requirement – Energy Meters
• Two Eaton IQ150 energy meters. Takes measurements from two
of 3 braches of the circuit.
• Capable of measuring:
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Voltage
Amperage
kW
kVAR
Frequency
• Gathered information is sent to Gateway via RS-485
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System Requirements
Sixth Requirement – Energy Meters (continued)
Voltage (V) Line - Neutral
Power (W), Reactive Power (VAR), Power Factor
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Amperage (A)
System Requirements
Seventh Requirement – Current Transformers (CT’s)
• Measure current at specific branches in the circuit
• Wires are wrapped once around the CT’s. CT’s measure the
inside magnetic field.
• Ratio used to compare current through the CT (branch circuit) vs.
current output to the energy meters
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System Requirements
Seventh Requirement – Current Transformers (CT’s)
• Measure current at specific branches in the circuit
• Wires are wrapped once around the CT’s. CT’s measure the
inside magnetic field.
• Ratio used to compare current through the CT (branch circuit) vs.
current output to the energy meters
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System Requirements
Eighth Requirement – 24 VDC Power Supply
• Supplies 24 VDC to power the Gateway
• Powered by 120 VAC
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Detailed Design
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Trade Studies and Research
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Test Results
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Questions?
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