25-04-2014, 11:58 AM
POWER QUALITY IMPROVEMENT WITH SOLID STATE TRANSFER SWITCHES
POWER QUALITY IMPROVEMENT.ppt (Size: 853 KB / Downloads: 24)
ABSTRACT
The solid state transfer switch (SSTS) is designed to replace the mechanical auto transfer equipment currently in use to switch major industrial and commercial facilities from one feeder to another - a process that typically takes 0.3 to several seconds.
A SSTS can also provide large customers with a cost-effective alternative to an in-house uninterruptible power supply system.
INTRODUCTION
Power quality issues are currently receiving a great deal of attention in the light of deregulation, liberalization and privatization of the electrical energy market.
The overriding concern is that poor power supply quality may cause disruption to a consumer's process leading to a loss in revenues.
An essential prerequisite to a profitable process-oriented industrial operation is therefore a safe, reliable and clean power supply.
SSTS process typically takes 0.3 to several seconds.
For sensitive electronic based electrical equipment this transfer time and momentary interruption result in voltage deviations which may be beyond the designed ride-through capabilities of the equipment.
THYRISTOR TECHNOLOGIES FOR SSTS IMPLEMENTATION
The thyristor technology most suitable for a particular SSTS application depends on the response time required, the load current, the short-circuit requirements and application voltage level.
Thyristor technologies that are considered in this section are:
Conventional Phase Control Thyristors,
Bi-Directional Control Thyristor (BCT),
Integrated Gate Commutated Thyristor (IGCT).
CONCLUSION
The basic medium voltage solid state transfer switch configurations and technology have been presented and a specific SSTS utility application described, The new BCT and IGCT technologies described can be used to meet the complete range of requirements demanded by even the most stringent SSTS applications.
These SSTS systems provide high reliability due to well proven components and low part counts.
Using BCT units, SSTS systems can be more economically constructed and implemented due to the encapsulated anti-parallel thyristors.