22-03-2010, 09:53 PM
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Unified Power Flow Controller
INTRODUCTION
Two main objectives of FACTS
Increase the TX capability of AC line
Control of power flow over the TX routes
UPFCs - most effective FACTS device
UPFC “ a device which control TX line impedance, voltage and phase angle
BASIC CONSTRUCTION OF A UPFC
Consists of two switching GTO converters
Shunt-connected
Series-connected
Both converters can operate in a rectifier mode or in an inverter mode
A DC branch links these two converters by a storage capacitor.
Operating Principle
Conceptually, a generalized SVS
Converter2 injects a voltage Vpq with phase angle in series with TX line via an insertion transformer
Main function of converter1 is to supply the real power demanded by converter2 at the DC link
No reactive power flow through DC link
Conclusion
Most sophisticated power flow controller Expensive
Gives better performance as compared to STATCOM,SSSC and TCSC
Provide simultaneous, real-time control of all basic power system parameters (transmission voltage, impedance and phase angle) and dynamic compensation of ac system
