Method and control system for controlling a voltage source converter using power-synchronization control

1. A method of controlling a grid-connected voltage source converter, VSC, using power-synchronisation control, wherein the method comprises the steps:

determining a VSC current vector (i) based on a VSC phase angle (θ) which is determined based on an integration of a power control error,

determining an active power producing current component (i d ref ) of a reference current vector (i ref ) based on an active power reference (P ref ) for the VSC,

determining the reference current vector (i ref ) based on the active power producing current component (i d ref ),

determining a damping component based on a virtual damping resistance (R a ), the reference current vector (i ref ) and the VSC current vector (i),

determining a voltage vector (v) based on a VSC voltage magnitude (V) and the damping component, and

controlling the VSC based on the voltage vector (v).

2. The method according to claim 1 , wherein the active power producing current component (i d ref ) is determined based on setting it proportional to the active power reference (P ref ).

3. The method according to claim 2 , wherein the active power producing current component (i d ref ) is determined by

i

d

ref

=

P

ref

κ

⁢

V

where P ref is the active power reference for the VSC, κ is a space-vector scaling constant and V is the VSC voltage magnitude (V).

4. The method according to claim 2 , including transforming the voltage vector (v) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (v s ), wherein the controlling involves using the transformed voltage vector (v s ) to control the VSC.

5. The method according to claim 2 , including determining a reactive power producing current component (i q ref ) of the reference current vector (i ref ) using low-pass filtering of an imaginary part of the VSC current vector (i), wherein the reference current vector (v) is further determined based on the reactive power producing current component (i q ref ).

6. The method according to claim 2 , wherein the damping component is determined by determining a current error vector based on the reference current vector (i ref ) and the VSC current vector (i), and multiplying the virtual damping resistance with the current error vector.

7. The method according to claim 1 , including transforming the voltage vector (v) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (v s ), wherein the controlling involves using the transformed voltage vector (v s ) to control the VSC.

8. The method according to claim 1 , including determining a reactive power producing current component (i q ref ) of the reference current vector (i ref ) using low-pass filtering of an imaginary part of the VSC current vector (i), wherein the reference current vector (v) is further determined based on the reactive power producing current component (i q ref ).

9. The method according to claim 1 , wherein the damping component is determined by determining a current error vector based on the reference current vector (i ref ) and the VSC current vector (i), and multiplying the virtual damping resistance with the current error vector.

10. The method according to claim 1 , wherein the VSC current vector (i) is determined by transforming a stationary VSC current vector (i s ), obtained by measurement, using the VSC phase angle (θ).

11. A non-transitory computer-readable medium storing a computer program that includes computer code which when executed by processing circuitry of a control system causes the control system to perform the method according to the steps:

determining a VSC current vector (i) based on a VSC phase angle (θ) which is determined based on an integration of a power control error,

determining an active power producing current component (i d ref ) of a reference current vector (i ref ) based on an active power reference (P ref ) for the VSC,

determining the reference current vector (i ref ) based on the active power producing current component (i d ref ),

determining a damping component based on a virtual damping resistance (R a ), the reference current vector (i ref ) and the VSC current vector (i),

determining a voltage vector (v) based on a VSC voltage magnitude (V) and the damping component, and

controlling the VSC based on the voltage vector (v).

12. A control system for controlling a grid-connected voltage source converter, VSC, using power-synchronisation control, wherein the control system includes:

a storage medium including computer code, and

processing circuitry,

wherein when the computer code is executed by the processing circuitry, the control system is configured to:

determine a VSC current vector (i) based on a VSC phase angle (θ) which is determined based on an integration of a power control error,

determine an active power producing current component (i d ref ) of a reference current vector (i ref ) based on an active power reference (P ref ) for the VSC,

determine the reference current vector (i ref ) based on the active power producing current component (i d ref ),

determine a damping component based on a virtual damping resistance (R a ), the reference current vector (i ref ) and the VSC current vector (i),

determine a voltage vector (v) based on a VSC voltage magnitude (V) and the damping component, and

control the VSC based on the voltage vector (v).

13. The control system according to claim 12 , wherein the control system is configured to determine the active power producing current component (i d ref ) based on setting it proportional to the active power reference (P ref ).

14. The control system according to claim 13 , wherein the active power producing current component (i d ref ) is determined by

i

d

ref

=

P

ref

κ

⁢

V

where P ref is the active power reference for the VSC, κ is a scaling constant and V is the VSC voltage magnitude (V).

15. The control system according to claim 13 , wherein the processing circuitry is configured to transform the voltage vector (v) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (v s ), wherein the control system is configured to control the VSC using the transformed voltage vector (v s ).

16. The control system according to claim 13 , wherein the control system is configured to determine a reactive power producing current component (i q ref ) of the reference current vector (i ref ) using low-pass filtering of an imaginary part of the VSC current vector (i), wherein the reference current vector (i ref ) is further determined based on the reactive power producing current component (i q ref ).

17. The control system according to claim 13 , wherein the damping component is determined by determining a current error vector based on the reference current vector (i ref ) and the VSC current vector (i), and by multiplying the virtual damping resistance with the current error vector.

18. The control system according to claim 12 , wherein the processing circuitry is configured to transform the voltage vector (v) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (v s ), wherein the control system is configured to control the VSC using the transformed voltage vector (v s ).

19. The control system according to claim 12 , wherein the control system is configured to determine a reactive power producing current component (i q ref ) of the reference current vector (i ref ) using low-pass filtering of an imaginary part of the VSC current vector (i), wherein the reference current vector (i ref ) is further determined based on the reactive power producing current component (i q ref ).

20. The control system according to claim 12 , wherein the damping component is determined by determining a current error vector based on the reference current vector (i ref ) and the VSC current vector (i), and by multiplying the virtual damping resistance with the current error vector.