1. Unified Power Flow Controller

2. 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

3. 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.

4. OPERATING PRINCIPLE

5. Operating Principle Conceptually, a generalized SVS
Converter2 injects a voltage Vpq with phase angle ρ 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

6. TX control capabilities
Vpq = ±ΔV (ρ = 0) Vpq = Vq
Vpq = Vб Vpq = ΔV + Vq + Vб

7. Phasor representation of the UPFC
Basic asumption (Vpq =0)
P0(δ) = {V2/X} sin δ = sin δ
Q0(δ) = Q0r(δ) = -Q0r(δ) = {V2/X}{1-cos δ } = I-cos δ

8. Phasor representation of the UPFC
For Vpq  0 ,

9. 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

10. THANK YOU