Upfc an overview
- 1. Flexible AC Transmission System Overview
- 2. Flexible AC Transmission System Alternating current transmission systems incorporating power electronics-based and other static controllers to enhance controllability and increase power transfer capability
- 3. Constraints on Useable Transmission Capacity • Dynamic: – Transient and dynamic stability – Subsynchronous oscillations – Dynamic overvoltages and undervoltages – Voltage collapse – Frequency collapse
- 4. • Steady-State: – Uneven power flow – Excess reactive power flows – Voltage capability – Thermal capability
- 5. FACTS Controllers • Static VAR Compensator - SVC • Thyristor Controlled Series Compensator - TCSC • Thyristor Controlled Phase Angle Regulator - TCPAR • Static Synchronous Compensator - StatCom • Solid State Series Compensator - SSSC • Unified Power Flow Controller - UPFC
- 6. US FACTS Installations San Diego G&E/ STATCOM/100 MVA Mitsubishi Eagle Pass (Texas) Back-to-back HVDC 37 MVA/ ABB CSWS (Texas) STATCOM/ 150 MVA / W-Siemens Austin Energy STATCOM/ 100MVA ABB AEP/ Unified Power Flow Controller / 100 MVA/ EPRI TVA STATCOM/ 100MVA EPRI Northeast Utilities/ STATCOM/ 150 MVA/ Areva (Alstom) NYPA/ Convertible Static Compensator/ 200 MVA Vermont Electric/ STATCOM/ 130 MVA/ Mitsubishi
- 7. • Power transfer between areas can be affected by adjusting the net series impedance. • Transmission line capability can be increased by installing a series capacitor which reduces the net series impedance. Power Flow Control
- 8. UPFC
- 9. UPFC • may control voltage, impedance, and angle • impacts active and reactive power flow in line
- 10. Basic Operation
- 11. UPFC Capabilities • Increase transmission line capacity • Direct power flow along selected lines • Powerful system oscillation damping • Voltage support and regulation • Control of active and reactive power flow at both sending- and receiving-end
- 12. Operation • Reactive power is generated or absorbed by the shunt inverter to control bus voltage • Reactive power is generated or absorbed by the series inverter to control the real and/or reactive power flow on the transmission line
- 13. Cont’d • A portion of the real power flow on the transmission line is drawn from the bus by the shunt inverter to charge the DC capacitor. • Real power is inserted into the line through the series inverter.
- 14. jXSV RV SRP sinS R SR V V P X δ= Power flow in a transmission line δTo increase PSR, increase and R SV V jXI= + jXI SV RV δ
- 15. AV BV injV- + AV injV BV α jXSV RV SRP RV′injV- + ( )sinS R SR V V P X α δ′ ′ = + jXI injV SV RV′ δ α
- 16. How is Vinj created? V +b1 a2 a1 b2 c1 c2
- 17. V +b1 a2 a1 b2 c1 c2 a1 on, b1 on, c1 off Vab=0, Vbc=V, Vca = -V a1 on, b1 off, c1 off Vab=V, Vbc=0, Vca = -V V +a1 b1 c1 c2b2a2 V +a1 b1 c1 c2b2a2 a1 on, b1 off, c1 on Vab=V, Vbc=-V, Vca = 0
- 18. Sine-triangle PWM 0 100 200 300 400 500 600 700 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 0 100 200 300 400 500 600 700 0 0.5 1 Va 0 100 200 300 400 500 600 700 0 0.5 1 Vb 0 100 200 300 400 500 600 700 -1 0 1 Vab