326
Electrochemical Supercapacitors for Energy Storage and Delivery
maintenance and incur high replacement costs. In this regard, the use of ESs
offers significant advantages over the use of batteries. The initial cost per
kilowatt hour of commercial ESs available today is higher than cost for conventional batteries. However, ESs are good alternatives because they offer
much longer cycle lives and lower maintenance costs.
8.7 Adjustable Speed Drives (ASDs)
Adjustable speed drives (ASDs) are commonly used in industrial applications because of their efficiency, but they are often susceptible to power
fluctuations and interruptions. Disruptions in industrial settings are
highly undesirable, and down time of a machine in a continuously running process can cause significant monetary losses. Adjustable speed
drives that can “ride-through” power supply disturbances are valuable
tools for industry.
The major reasons for ASD shutdown are transients, interruptions,
sags (under-voltages), swells (over-voltages), waveform distortions, voltage fluctuations, and frequency variations [11–13]. These problems can
cause ADS symptoms such as premature trips or shuts down, resets and
restarts, frequent repairs and replacements, erratic control of process
parameters, unexplained fuse blowing and/or component failures, and
frequent motor overheating trips and/or continuous operation of motor
cooling systems.
For an ASD to ride-through disturbances at full power, an energy storage device must act as a backup power source. A number of options are
available. Batteries and flywheel systems can provide ride-through up to
an hour. The major disadvantages of batteries and flywheel systems are
their sizes and maintenance requirements, although batteries are economic
options. Fuel cells can store large amounts of energy but cannot respond
quickly. Super-conducting magnetic energy storage (SMES) systems can
provide reasonable ride-through capabilities but require sophisticated
cooling systems.
In relation to these devices, ESs present unique advantages such as quick
responses to voltage fluctuations, long lifetimes, and minimal maintenance. Furthermore, they can be monitored easily because their charge
state depends on voltage [14]. However, the choice of energy storage option
relies largely on power requirements and the desired ride-through time
(Figure 8.6). Normally, the durations of most power fluctuations do not
exceed 0.8 sec. An ES can provide ride-through times up to 5 sec to a rating of 100 kVA. Therefore, ESs are likely provide satisfactory ride-through in
most applications.
Electrochemical Supercapacitors for Energy Storage and Delivery
maintenance and incur high replacement costs. In this regard, the use of ESs
offers significant advantages over the use of batteries. The initial cost per
kilowatt hour of commercial ESs available today is higher than cost for conventional batteries. However, ESs are good alternatives because they offer
much longer cycle lives and lower maintenance costs.
8.7 Adjustable Speed Drives (ASDs)
Adjustable speed drives (ASDs) are commonly used in industrial applications because of their efficiency, but they are often susceptible to power
fluctuations and interruptions. Disruptions in industrial settings are
highly undesirable, and down time of a machine in a continuously running process can cause significant monetary losses. Adjustable speed
drives that can “ride-through” power supply disturbances are valuable
tools for industry.
The major reasons for ASD shutdown are transients, interruptions,
sags (under-voltages), swells (over-voltages), waveform distortions, voltage fluctuations, and frequency variations [11–13]. These problems can
cause ADS symptoms such as premature trips or shuts down, resets and
restarts, frequent repairs and replacements, erratic control of process
parameters, unexplained fuse blowing and/or component failures, and
frequent motor overheating trips and/or continuous operation of motor
cooling systems.
For an ASD to ride-through disturbances at full power, an energy storage device must act as a backup power source. A number of options are
available. Batteries and flywheel systems can provide ride-through up to
an hour. The major disadvantages of batteries and flywheel systems are
their sizes and maintenance requirements, although batteries are economic
options. Fuel cells can store large amounts of energy but cannot respond
quickly. Super-conducting magnetic energy storage (SMES) systems can
provide reasonable ride-through capabilities but require sophisticated
cooling systems.
In relation to these devices, ESs present unique advantages such as quick
responses to voltage fluctuations, long lifetimes, and minimal maintenance. Furthermore, they can be monitored easily because their charge
state depends on voltage [14]. However, the choice of energy storage option
relies largely on power requirements and the desired ride-through time
(Figure 8.6). Normally, the durations of most power fluctuations do not
exceed 0.8 sec. An ES can provide ride-through times up to 5 sec to a rating of 100 kVA. Therefore, ESs are likely provide satisfactory ride-through in
most applications.