Modeling Capacitor Commutated Converters in Power System Stability Studies

Transcription

1 IEEE/PES Summer Meeting, July Published in Transactions on Power Systems, May Modeling Capacitor Commutated Converters in Power System Stability Studies Sergio Gomes Jr. (CEPEL) Nelson Martins (CEPEL) Tomas Jonsson (ABB) Donald Menzies (ABB) Rolf Ljungqvist (ABB)

2 2 Paper Contents Description of a model for Capacitor Commutated Converter (CCC) suitable for power flow and power system stability studies Description of the control structure and operational details of the CCC Results on power flow, stability and small signal analysis

3 3 HVDC/CCC System Smoothing Reactor Transmission Line Smoothing Reactor Transformer Transformer Commutated Capacitor Commutated Capacitor Filter/Comp. Rectifier Inverter Filter/Comp

4 4 Capacitor Commutated Converters AC System Tap r : 1 DC System X R C R

5 5 Three-phase Representation Tap r : 1 X R C R

6 6 Reactive Consumption 1 pu j 1 pu j 1.057: : 1 AC System AC System 115 j -389 j 137 j -126 j -537 j Part of the shunt compensation is substituted by the series compensation (commutated capacitor). Low Mvar filters reduce need for switched shunt capacitor banks. Commutated capacitors increase critical SCR and improves steady state and dynamic performance.

7 7 CCC Modeling CCC Model ANAREDE Power Flow ANATEM Transient Stability PacDyn Small-Signal Stability Studies of Garabi 1100 MW (phase 1) 1999 Studies of Garabi 1100 MW (phase 2) 2002

8 8 CCC Model AC System Tap r : 1 DC System X R C R Solution by Newton-Raphson Method. AC System P dc + j Q dc u d DC System

9 CCC Control Structure Rectifier firing control I ord I0 - i d Σ + KP R KI R s α max + Σ + α max α min 1 1+ s TVCO α I ord α min Inverter Firing Control P ord 1 1+ s T u u d γ ' ref α ( γ ' ) α max I ord I0 - i d Σ + + KP I α max + Σ + α max 1 1+ s TVCO α I margin KI I s α min 9 α min

10 Test System (SCRr=2.59, SCRi=1.26 ) X R ac Transmission Line X 1 R 1 Tap R : 1 Rectifier Smoothing Reactor R S L S Inverter 1 : Tap I ac Transmission Line R 2 X X I1 X I2 2 B /2 1 B /2 1 X TR CR C I B SHR B B /2 SHI 2 Commutation Capacitor Commutation Capacitor X TI B /2 2 P + j Q AC System: DC System: 0 Base: 100 MVA AC voltage at infinite buses: 1 pu XR = 2.020% XI1 = XI2 = 1.50% TL Rectifier: 130 km, 500 kv TL Inverter: 350 km, 500 kv BSHR, BSHI yields V = 1 pu at converters P+j Q = (800+j100) MVA Base: 280 kv, 1100 MW Nominal Current : 3830 A RS = 0.4 ohms, LS = 200 mh (smoothing reactor) Four 6-pulse bridges (2 bipoles of 12 pulses) Data of Converter Transformers Base: Sb = 288 MVA, Vb (secondary) = 51.8 kv XTR = 0.12 pu (rectifier), XTI = pu (inverter) CR = 850 µf, f = 50 Hz ; CI = 420 µf, f = 60 Hz CCC: α = 5.7 o (rectifier) ; γ = 21.7 o (inverter)

11 1 Power Flow Results X R ac Transmission Line X 1 R 1 Tap R : 1 Rectifier Smoothing Reactor R S L S Inverter 1 : Tap I ac Transmission Line R 2 X X I1 X I2 2 B /2 1 B /2 1 X TR CR C I B SHR B B /2 SHI 2 Commutation Capacitor Commutation Capacitor X TI B /2 2 P + j Q u d tap µ i d P dc Q dc (deg) (pu) (pu) (deg) (pu) (MW) (Mvar) α, γ '

12 1% of step in Current Order

13 Root-Locus when varying gains in CCA a b a b a b

14 1% of Step in Current Order Point a Point b

15 5 Three-phase fault at inverter side

16 6 Three-phase fault at rectifier side Time(s) Time(s) Time(s) Time(s) Time(s) Time(s)