Study of Håkon Molland Edvardsen & Dietmar Winkler from Telemark University College Norway (Modelica Conference 2014). Modelon's Electric Power Library helps in the model-based reconstruction of events behind an earth circuit fault in Grunnåi, Norway.

1. Telemark University College
Norway
Modelling the system dynamics of islanding asynchronous
generators
10th International Modelica Conference 2014
Håkon Molland Edvardsen Dietmar Winkler
Telemark University College
Norway
12th
March 2014

2. I. Introduction What is it about?
What is it about?
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 2 / 18

3. I. Introduction What is it about?
What is it about?
Figure : Broken surge arrester
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 2 / 18

4. I. Introduction What is it about?
What is it about?
Figure : Broken surge arrester
Figure : End-termination of supply cable
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 2 / 18

5. II. Practical Background Location
Location
Where in Europe?
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 3 / 18

6. II. Practical Background Location
Location
Locally
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 4 / 18

7. II. Practical Background The power stations
The power stations
Grunnå and Sagbekken 1 and Sagbekken 2&3
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 5 / 18

8. II. Practical Background The power stations
The power stations
Grunnå and Sagbekken 1 and Sagbekken 2&3
Figure : Grunnåi (Synch - 15MW)
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 5 / 18

9. II. Practical Background The power stations
The power stations
Grunnå and Sagbekken 1 and Sagbekken 2&3
Figure : Grunnåi (Synch - 15MW)
Figure : Sagbekken 2&3 (Asynch 75+75 &
75+250 kW)
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 5 / 18

10. II. Practical Background The power stations
The power stations
Reinstul - 18kW (traditional Norwegian power station)
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 6 / 18

11. II. Practical Background The power stations
The power stations
Reinstul - 18kW (traditional Norwegian power station)
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 6 / 18

12. II. Practical Background The power stations
The power stations
Total capacity
Grunnåi: 15MW - synchronous
Sagbekken 1: 2x100kW & 200kW - asynchronous
Sagbekken 2: 75kW & 250kW - asynchronous
Sagbekken 3: 75kW & 75kW - asynchronous
Total: 15.85MW
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 7 / 18

13. II. Practical Background What happend?
What happend?
Possible sequence
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 8 / 18

14. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

15. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

16. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

17. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

18. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

19. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

20. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

21. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

22. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

23. II. Practical Background Reconstruction of events
Reconstruction of events
Difficult...
1 Earth circuit fault in Grunnåi (Terminator)
2 The protection relay disconnected the Lønnestad radial
3 Result: heavy imbalance of active power and reactive power in the now
islanded radial.
4 Rapid frequency increase since Grunnåi did not correct for the
overproduction
5 The generator circuit breaker disconnected Grunnåi from the grid, due to
triggering of the over-frequency relay (51Hz and 0.1 seconds).
6 Asynchronous generators in Sagbekken 1, 2 & 3 alone in the island.
7 Sufficient amount of reactive power in the grid to initiate self-excitation.
8 Successive voltage build-up, which resulted in significant over-voltages in
the grid.
9 Surge arresters to breakdown.
10 Arcing ⇒ low impedance in the grid ⇒ stops self-excitation
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 9 / 18

24. IV. Modelling The Lønnestad radial
The Lønnestad radial
Using Electric Power Library
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 10 / 18

25. IV. Modelling The self-excitation
The self-excitation
Model of one asynchronous generator
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 11 / 18

26. IV. Modelling The self-excitation
The self-excitation
Simulation results, no capacitance, disconnection at t = 1s
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 12 / 18

27. IV. Modelling The self-excitation
The self-excitation
Simulation results, influence of reactive and active load, disconnection at t = 1s
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 13 / 18

28. IV. Modelling The self-excitation
The self-excitation
Simulation results, influence of reactive and active load, disconnection at t = 1s
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 13 / 18

29. IV. Modelling Ground fault
Ground fault
Sub-model Sagbekken 1
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 14 / 18

30. IV. Modelling Ground fault
Ground fault
Model of Lønnestad radial with phase to ground fault
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 15 / 18

31. IV. Modelling Ground fault
Ground fault
Simulation results
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 16 / 18

32. IV. Modelling Ground fault
Ground fault
Simulation results
Took 1.5 seconds from ground
fault until total disconnect
Maximum voltage reached:
53.36kV
Phase C over 30kV for
0.7 seconds
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 16 / 18

33. Conclusions
Conclusions
Asynchronous generators can operate stand-alone when enough
capacitance available
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 17 / 18

34. Conclusions
Conclusions
Asynchronous generators can operate stand-alone when enough
capacitance available
Capacitance can come from long supply lines
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 17 / 18

35. Conclusions
Conclusions
Asynchronous generators can operate stand-alone when enough
capacitance available
Capacitance can come from long supply lines
Self-excitation leads to fast voltage build-ups
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 17 / 18

36. Conclusions
Conclusions
Asynchronous generators can operate stand-alone when enough
capacitance available
Capacitance can come from long supply lines
Self-excitation leads to fast voltage build-ups
Simulations showed possible voltage build-up of 50kV within 0.4s!
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 17 / 18

37. Conclusions
Conclusions
Asynchronous generators can operate stand-alone when enough
capacitance available
Capacitance can come from long supply lines
Self-excitation leads to fast voltage build-ups
Simulations showed possible voltage build-up of 50kV within 0.4s!
Correct parameterisation of protection relays crucial
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 17 / 18

38. Conclusions
Conclusions
Asynchronous generators can operate stand-alone when enough
capacitance available
Capacitance can come from long supply lines
Self-excitation leads to fast voltage build-ups
Simulations showed possible voltage build-up of 50kV within 0.4s!
Correct parameterisation of protection relays crucial
Need to take self-excitation effect into account
Edvardsen & Winkler (TUC) Modelica’2014 12th March 2014 17 / 18

39. Telemark University College
Norway Thank you for your attention!
Questions?
Dietmar.Winkler@hit.no
Acknowlegdements: