Handbook of Energy Storage for Transmission or ... - W2agz.com

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1.2.3 NAS Battery Module Design
NGK has developed the NAS
T5 cell for use in their
commercial battery modules
which are designated the NAS
PS (for peak shaving) Module
and the NAS PQ (for power
quality) Module. The
properties of the NAS T5 cell
and the PS and PQ Modules
are provided in Table 1-1.
While both the PS and PQ
Modules use the same T5 cell,
the PS Module is designed for
long duration discharge with
modest voltage drop, and the
PQ Module for pulse power
delivery with voltage as low
as 0.9 V pc
. The most notable
design differences are in cell
arrangements and electrical
protection. PS Modules use
384 cells in arrays of 8 cells in
series to yield module
voltages of 64 or 128, while
all 320 cells within a PQ
Module are series connected
for 640V. 1
The PS Module
arrangement allows fuses to
be incorporated within each 8-
Table 1-1.. NAS Cell and Module Properties
Parameter NAS T5 Cell NAS PS Module NAS PQ Module
Nominal Voltage, V dc
2 64 or 128 640
Operating Temperature [290 to 360C]
Cell Arrangement
("s" series; "p" parallel)
Electrical Protection
Rated PS Capacity
(Notes 1, 2)
cell string. Electrical protection for the deeper voltage drops and higher currents encountered in
PQ Module applications are addressed via an external DC breaker and a fuse at the terminals of
each module.
A NAS Battery Module consists of the cell arrangements described above within a thermally
insulated enclosure equipped with electric heaters to maintain a minimum operating temperature
of about 290C, depending on the application. Cells are closely spaced and connected in series
and parallel. A vacuum is drawn on the gap between the inner and outer walls of the enclosure
to manage heat loss. This design feature enables the heat transfer characteristics of the PQ
Modules to be adjusted to the needs of the application. As indicated in Table 1-1, units used in
standby applications reject heat at about 2.2 kW under design basis conditions, while units for
combined PQ and PS functions lose about 3.4 kW during standby. Figure 1.3 is a photograph of
Single
NA
(8sx6p)x8s or
(8sx12p)x4s
Internal fuse within
each 8s string
320s
DC breaker and
external fuse
628 Ah 430 kWh ac
360 kWh ac
Rated PS Power (Notes 1, 3) NA 50 kW ac
Max Power for Interval
Noted (Note 1, 4)
NA
60 kW ac
for 3hr
250 kW ac
for 30sec
Pulse Factor (Note 5) NA 1.2 5
Projected Calendar
& Cycle Life
15 years; 2500, 100% DOD cycles
Avg DC Efficiency, % 90 85
Standby Heat Loss, kW NA 3.4
2.2 (PQ)
3.4 (PQ+PS)
Dimensions, mm (in)
515Lx91
2,270Wx1,740Dx720H
(20.3Lx3.6 )
(89.4Wx68.5Dx28.4H)
Weight, kg (lb) 5.5 (12.1) 3500 (7920)
Notes:
1. AC rating based on 95% inverter efficiency
2. Design basis Rated PS Capacity based on 1.82Vpc OCV at end of discharge and end-of-life
3. Design basis Rated PS Power for reference peak shaving profile yielding 100% DOD
4. Maximum power for short duration discharges (typically yield less than 100% DOD)
5. Pulse Factor: Ratio of maximum power to rated power for stated duration.
(Values above are the maximum achievable with operating temperature and electrical
protection designs for the battery module.)
1
A 320-cell variant of the PS Module is also available. Rated PS Capacity is the same as for the PQ Module, while
Rated PS Power and voltage options are the same as the PS Module (64 and 128 V) described above.
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