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

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Technology Variant T&D Application Size* kW
Pulse Type II
Capacitors
Pulse Type II
Capacitors ($/kW)
Traction Type III
Capacitors
Traction Type III
Capacitors ($/kw)
Pulse Type II
Capacitors
Pulse Type II
Capacitors ($/kW)
Mini FACTs
Controller
Mini FACTs
Controller
Battery-less
Substation UPS
Battery-less
Substation UPS
Support of Substation
High-Inrush Loads
Support of Substation
High-Inrush Loads
Stg Capacity
kW-hours
A. Power-
Related
Equipment
Cost
B. Energy-
Related
Equipment
Cost
Table 5 Summary of system costs by application and variation of technology
The following is an explanation of benefits in each application:
C. Installation-
Related Cost
Total Capital
Costs
(A + B+ C)
Annual
Estimated
O&M Costs
3000 1.67 $270,000 $180,000 $180,000 $630,000 $87,627
3000 1.67 $0.09 $0.06 $0.06 $0.21 $0.03
25 0.139 $11,000 $11,000 $3,300 $25,300 $4,594
25 0.139 $0.44 $0.44 $0.13 $1.01 $0.18
36 0.060 $1,830 $7,320 $1,373 $10,523 $407
36 0.060 $0.07 $0.20 $0.04 $0.29 $0.01
*Note: Capacitor modules are connected in series to achieve the operating voltage and in parallel for increased current capacity and use dc
to dc boost converters to achieve the higher voltages needed for a distribution level voltage interface.
Mini-FACTS Controller - The major benefits associated with grid stabilization, via the
mini FACTS, includes VAR control to maintain power flow and voltage stability, and to
increase capacity of the T&D system. Grid voltage stabilization, providing fast VAR or
watts, can enhance frequency, power flow and voltage stability, and increase power
throughput of the T&D. This will increase asset utilization and in some cases defer
capital investments for T&D upgrades. This benefit or cost savings is highly site
dependent. For illustration purposes it has been estimated at $500/day for this single
feeder case.
Battery-less Substation UPS – In this case the benefit was estimated by the life-cycle
costs of the UPS/standby generator with the electrochemical capacitors compared to the
same UPS/standby generator with a conventional lead-acid battery. Included in the
benefit is a savings in space, $25/sqft per year, assuming that the capacitor will be in an
outdoor package. Also included is two battery replacements in 20 years compared to one
capacitor replacement. As can be seen, the capacitor application is not currently cost
competitive with batteries. However the cost tend of batteries, assumed to be level,
compared to electrochemical capacitors, which are going down, indicates that there will
be a crossover where battery-less will be more economic in near future.
Support of Substation High-Inrush Loads – This application raises some interesting
questions for future design of station battery systems. As in other applications the
benefits will be very site specific and will depend on the individual utility practices. The
benefit calculation in this case assumed a 50% reduction in the battery size. In this case
the substation battery was estimated $36k, two parallel (redundant) strings at 250 AH and
120Vdc each. There for the savings was assumed to be $18k. Additional benefits of
$500 per year were assumed based on space freed up in the control house. There was not
consideration for any differences in operating efficiency. Both the battery and the
capacitor are assumed to be replaced after 10 years, or once in a 20-year life.
Table 6 shows the costs and benefits for each application, per kilowatt costs, as well as
cost benefit ratios. What is not included in the table is the opportunity for making these
applications. For example the mini FACTS benefits are highly site and utility specific,
and only a few such applications are likely to available to any one utility. Substation
Electrochemical Capacitors 52