9.6 Application of HTS FESS Ë 361For example, this HTS FESS prototype needs an ESC of 100 kWh to support the I/O
power of 100 kW for 1 hour. The design and manufacture of a 100-kWh FESS unit is
very difficult, so the HTS FESS unit used for the long-term LS applications will have a
smaller I/O power level, to reduce the individual ESC, such as a HTS FESS unit with
the I/O power of 10 kW and ESC of 10 kWh, respectively.
9.6.4Uninterrupted power supply
The most commercial FESS products are used in the UPS application. Because of
the numerous and different operation conditions, it is difficult to design a single
FESS module to satisfy most of the requirements for UPS. It is better to choose a
modularization scheme to improve the flexibility of application and reduce the cost
of research and development. For example, four 1.6-MVA FESS UPS units combined
with a diesel generator could easily supply voltage protection and power relay to a
20-kV distribution network [85]. The simulation results display the feasibility of this
FESS UPS and the improvement in power quality. By the introduction of FESS unit, the
voltage dips are divided by a factor of 3, even in the worst case. If the I/O power of our
HTS FESS prototype could be improved to 400 kW, using 4 HTS FESS units can provide
similar operation performance to the test FESS of 1.6 MVA. Furthermore, the individual
I/O power of most types of the commercial FESS UPS products is 100–250 kW, with a
discharge time of 10–30 seconds, which can provide useful reference for the design of
a HTS FESS for the application of UPS [84].
9.6.5Electromagnetic launch and weapon
The HTS FESS is a suitable power source for the electromagnetic launch (EML) system.
The electric machine of HTS FESS unit should be redesigned to the compulsator type
to produce a large pulsed power supply. The compulsator is a special synchronous
machine with a damping winding to minimize the interior impedance of the machine,
which can output peak power or peak current maximally during a very short time.
A 50-MW/650-MJ FESS system consisted of 25 FESS units was investigated for the
operation performance of an EML system [82]. This FESS system can output the peak
power of 50 MW within 13 s, with maximal overall efficiency of 95%. The FESS units
were arrayed in the parallel connection style to output a 1200-V DC voltage. The
requirements of FESS system were quite different for various EM launch and weapon
systems. For example, the ESC and peak power of the electromagnetic aircraft launch
system was 122 MJ and 326 MW, respectively [86]. The available ESC of our HTS FESS
prototype is 5.75 kWh, namely, about 21 MJ, so it needs six HTS FESS units to satisfy
the requirement of 122 MJ ESC. The US Army has contracted a hypervelocity railgun
of 2-MJ muzzle kinetic energy, based on the electrothermal chemical technology and