HVDC Multi-infeed Commutation Failure Analysis within the Brazilian System with the Insertion of Bipoles A and B

Transcription

1 HVDC Multi-infeed Commutation Failure Analysis within the Brazilian System with the Insertion of Bipoles A and B José A. Jardini Renato Biase Ricardo L. V. Arnez John F. Graham Liu Guijun

2 Contents Introduction Multiple commutation failure a) example of commutation failure b) Area where Faults lead to Multiple Commutation Failure c) Mitigation Alternatives d) Transient and Electromechanical Oscillations Insertion of Bipole A and B A) Stability software Analysis B) EMT software Analysis Conclusions 2/27

3 Introduction 3/27

4 Table 1 Existing and planned HVDC links in Brazil. DC Link Rectifier Inverter MW kv km Inv kv Itaipu Foz do Iguacu Ibiuna (IB) 2x3150 ± Madeira Porto Velho Araraquara 2 (AR) 2x3150 ± B Monte 1 Xingu Estreito (ES) 4000 ± B Monte 2 Xingu Terminal Rio (TR) 4000 ± Bipole A Paraupebas Assis 4000 ± Bipole B Graça Aranha Silvania 4000 ± /27

5 Inverter locations and transmission lines 5/27

6 Multiple Commutation Failure Year 2020 a) Example of Multiple Commutation Failure (LCC) 6/27

7 b) Area where Faults lead to Multiple Commutation Failure MIIFi = Δ Vc_i / Δ Vf Δ Vc_i = Voltage variation in the AC inverter bus i. Δ Vf = Voltage variation in the AC faulted bus. MIIF indexes lower than 0.15 indicate no relevant interaction; from 0.15 to 0.3 it indicates the existence of some degree of interaction, above 0.3 it indicates concern with the interactions 7/27

8 Depends on bus short circuit value ESCR (Effective Short Circuit Ratio) and MIESCR (Multi-infeed Interaction Effective Short Circuit Ratio). 8/27

9 Multi-Infeed - MIESCR Multi-Infeed Short Circuit Ratio MIESCR 2.5 são tipicamente estáveis 9/27

10 How to calculate MIIF SCR MIESCR? a) use of short circuit software (Anafas) b) use of stability software (Anatem) Use of EMT (PSCAD; EMTP; Hypersim) new procedure 1) For each converter apply a fault in AC side through a reactance. 2) Vary (reduce) the reactance if commutation failure does not occur. 3) If such reactance produces commutation failure, mark (set) previous reactance as limit and measure AC voltage variation in inverter (critical voltage variation). 4) Run short circuit calculation applying single-phase and three-phase faults in all buses of SE region; measure voltage variation in AC side of all the inverters. Check if voltage variation is below limit (area of risk determined). 5) Build map. 10/27

11 Methodology- EMT 1φ short circuit through gradual reduction of reactance (EMT) ΔV invcreasing 11/27

12 c) Mitigation Alternatives 1. Increase of inverter extinction angle from 18 to 24 (for LCC-HVDC, steady state). 2. Installation of additional synchronous condensers. 3. Installation of additional static compensators (STATCOM). 4. Use of CCC-HVDC instead of LCC-HVDC at inverters of Belo Monte link. 5. Use of VSC (Voltage Source Converters) instead of LCC based converters. 12/27

13 Minimum system short circuit. Extintion angle (γ =24 left and 18 º right) 13/27

14 Figure 3 - Example of a critical area minimum short circuit scenario (γ =18 ). Figure 4 - Map of critical short circuit with CCC Minimum short circuit 14/27

15 Line Commutated Converter Components LCC requires: reactive compensation 50/60% of the link MW. SCR >3 15/27

16 Configuration modeled in EMT software CCC (capacitor commutated converter) AC System Tap r : 1 X R C R B 1 75% in series and remaining in parallel 16/27

17 d) Transient and Electromechanical Oscillations three-phase solid fault; duration = 80 ms; applied at Araraquara AC bus. There is commutation failure in ARARAQUARA Also in others inverters 17/27

18 18/27

19 A) Stability Stability can also be calculated with EMT 19/27

20 Stability with electromechanical transient software (Anatem) 20/27

21 21/27

22 Insertion of Bipole A and B B. EMT software Analysis (single phase to ground fault at Araraquara) 22/27

23 23/27

24 4. Conclusions Multi commutation failure may occur in Brazilian system. With temporary reduction of DC power in HVDC links. However, in analyzed cases there is no instability ( better investigation is recommended). Synchronous compensator and Statcom system reduce area of risk (but do not eliminate). Better performance is obtained using higher gamma ( previous to fault), or CCC. VSC (in new bipoles A and B) may not lead to simultaneous commutation failure. 24/27

25 Bipole Blocking 2.7% de chance de comportamento instável, caso haja bloqueio em ES ou TR. 25/27

26 One pole blocking (not a problem) LCC CCC 26/27

27 Thank you. 27/27