# US 10,770,900 B2 · Method and control system for controlling a voltage source converter using power-synchronization control

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- Number: US 10,770,900 B2
- Document ID: US10770900B2
- Status: Granted
- Kind: B2
- Application number: 16/262,232
- Filed: 2019-01-30
- Published: 2019-08-29
- Granted: 2020-09-08
- Earliest claimed: 2018-02-28
- Assignees: ABB Schweiz AG
- Applicants: ABB Schweiz AG
- Inventors: Lennart Harnefors
- Web page: https://patentgrep.com/patent/US10770900B2

## CPC

- H02J 3/34: Arrangements for transfer of electric power between networks of substantially different frequency
- H02J 3/00: Circuit arrangements for AC mains or AC distribution networks
- H02J 3/36: Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links
- H02M 7/48: using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M 7/53875: {with analogue control of three-phase output}
- G05B 19/042: using digital processors (G05B19/05 takes precedence)
- Y02E 60/60: Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A method of controlling a grid-connected voltage source converter, VSC, using power-synchronisation control, wherein the method includes: determining an active power control error, determining a VSC phase angle based on an integration of a sum including a scaled active power control error and a scaled imaginary part of a voltage of common coupling, determining a damping component based on a virtual damping resistance, a VSC current vector and a reference current vector for the VSC current vector, determining a voltage vector based on a VSC voltage magnitude and the damping component, transforming the voltage vector to a current vector, comparing a magnitude of the current vector with a maximum threshold current value, and in case the magnitude of the current vector is greater than the maximum threshold current value: reducing the magnitude of the current vector to a value below the maximum threshold current value to obtain a limited current vector, transforming the limited current vector to a limited voltage vector, controlling the VSC based on the VSC phase angle and the limited voltage vector, multiplying an imaginary part of a voltage of common coupling with a gain to obtain a scaled imaginary part of voltage of common coupling.

## Claims

### Claim 1

A method of controlling a grid-connected voltage source converter, VSC, using power-synchronisation control, wherein the method comprises:
determining a VSC phase angle (θ) based on an integration of a sum including a scaled active power control error and a scaled imaginary part of a voltage of common coupling,
determining a damping component based on a virtual damping resistance (Ra), a VSC current vector (i) and a reference current vector (iref) for the VSC current vector (i),
determining a voltage vector (v) based on a VSC voltage magnitude (V) and the damping component,
transforming the voltage vector (v) to a current vector (irefinner),
comparing a magnitude of the current vector (irefinner) with a maximum threshold current value (Imax), and
in case the magnitude of the current vector (irefinner) is greater than the maximum threshold current value (Imax):
reducing the magnitude of the current vector (irefinner) to a value below or equal to the maximum threshold current value (Imax) to obtain a limited current vector (irefinner,limited),
transforming the limited current vector (irefinner,limited) to a limited voltage vector-(vlimited),
controlling the VSC based on the VSC phase angle (θ) and the limited voltage vector (vlimited),
multiplying an imaginary part (vpq) of a voltage of common coupling with a gain to obtain the scaled imaginary part of voltage of common coupling.

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein the gain is a PLL gain (KPLL) divided with a power control gain (Kp) and the scaled imaginary part of voltage of common coupling is added to the active power control error.

### Claim 3 (depends on 2)

The method as claimed in claim 2, comprising transforming the limited voltage vector (vlimited) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (vs), wherein the controlling involves using the transformed voltage vector (vs) to control the VSC.

### Claim 4 (depends on 2)

The method as claimed in claim 2, wherein in case the magnitude of the current vector (irefinner) is below the maximal threshold current value (Imax), the method includes:
transforming the current vector (irefinner) back to the voltage vector (v), and
controlling the VSC based on the VSC phase angle (θ) and the voltage vector (v).

### Claim 5 (depends on 1)

The method as claimed in claim 1, wherein in case the magnitude of the current vector (irefinner) is below the maximal threshold current value (Imax), the method includes:
transforming the current vector (irefinner) back to the voltage vector (v), and
controlling the VSC based on the VSC phase angle (θ) and the voltage vector (v).

### Claim 6 (depends on 5)

The method as claimed in claim 5, comprising transforming the voltage vector (v) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (vs), wherein the controlling involves using the transformed voltage vector (vs) to control the VSC.

### Claim 7 (depends on 1)

The method as claimed in claim 1, wherein the damping component is determined by determining a current error vector based on the reference current vector (iref) and the VSC current vector (i), and multiplying the virtual damping resistance (Ra) with the current error vector.

### Claim 8 (depends on 1)

The method as claimed in claim 1, wherein the gain (KPLL) is a PLL gain (KPLL) and the scaled imaginary part of voltage of common coupling is added to a scaled active power control error which is the active power control error multiplied with a power control gain (Kp) and to a nominal angular grid frequency (ω1).

### Claim 9 (depends on 1)

The method as claimed in claim 1, comprising transforming the limited voltage vector (vlimited) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (vs), wherein the controlling involves using the transformed voltage vector (vs) to control the VSC.

### Claim 10

A non-transitory computer-readable medium storing a computer program comprising computer code which when executed by processing circuitry of a control system causes the control system to perform a method including:
determining a VSC phase angle based on an integration of a sum including a scaled active power control error and a scaled imaginary part of a voltage of common coupling,
determining a damping component based on a virtual damping resistance, a VSC current vector and a reference current vector for the VSC current vector,
determining a voltage vector based on a VSC voltage magnitude and the damping component,
transforming the voltage vector to a current vector (irefinner),
comparing a magnitude of the current vector (irefinner) with a maximum threshold current value, and
in case the magnitude of the current vector (irefinner) is greater than the maximum threshold current value:
reducing the magnitude of the current vector (irefinner) to a value below or equal to the maximum threshold current value to obtain a limited current vector (irefinner,limited),
transforming the limited current vector (irefinner,limited) to a limited voltage vector,
controlling the VSC based on the VSC phase angle and the limited voltage vector,
multiplying an imaginary part of a voltage of common coupling with a gain to obtain the scaled imaginary part of voltage of common coupling.

### Claim 11

A control system for controlling a grid-connected voltage source converter, VSC, using power-synchronization control, wherein the control system comprises:
a storage medium comprising 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 phase angle (θ) based on an integration of a sum including a scaled active power control error and a scaled imaginary part of a voltage of common coupling,
determine a damping component based on a virtual damping resistance (Ra), a VSC current vector (i) and a reference current vector (iref) for the VSC current vector (i),
determine a voltage vector (v) based on a VSC voltage magnitude (V) and the damping component,
transform the voltage vector (v) to a current vector (irefinner),
compare a magnitude of the current vector (irefinner) with a maximum threshold current value (Imax), and
in case the magnitude of the current vector (irefinner) is greater than the maximum threshold current value (Imax):
reduce the magnitude of the current vector (irefinner) to a value below the maximum threshold current value to obtain a limited current vector (irefinner,limited),
transform the limited current vector (irefinner,limited) to a limited voltage vector (vlimited),
control the VSC based on the VSC phase angle (θ) and the limited voltage vector (vlimited),
multiply an imaginary part (vpq) of a voltage of common coupling with a gain to obtain a scaled imaginary part of voltage of common coupling.

### Claim 12 (depends on 11)

The control system as claimed in claim 11, wherein the control system is configured to transform the limited voltage vector (v) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (vs), wherein the control system is configured to control the VSC using the transformed voltage vector (vs).

### Claim 13 (depends on 11)

The control system as claimed in claim 11, wherein in case the magnitude of the current vector (irefinner) is below the maximal threshold current value (Imax), the control system is configured to:
transform the current vector back (irefinnerr) to the voltage vector (v), and
control the VSC based on the VSC phase angle (θ) and the voltage vector (v).

### Claim 14 (depends on 13)

The control system as claimed in claim 13, wherein the control system is configured to transform the voltage vector (v) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (vs), wherein the control system is configured to control the VSC using the transformed voltage vector (vs).

### Claim 15 (depends on 11)

The control system as claimed in claim 11, wherein the control system is configured to determine the damping component by determining a current error vector based on the reference current vector (iref) and the VSC current vector (i), and multiplying the virtual damping resistance with the current error vector.

### Claim 16 (depends on 11)

The control system as claimed in claim 11, wherein the gain is a PLL gain (KPLL), wherein the control system is configured to add the scaled imaginary part of voltage of common coupling to a scaled active power control error which is the active power control error multiplied with a power control gain (Kp), and to a nominal angular grid frequency.

### Claim 17 (depends on 11)

The control system as claimed in claim 11, wherein the gain is a PLL gain (KPLL) divided with a power control gain (Kp), wherein the control system is configured to add the scaled imaginary part of voltage of common coupling to the active power control error.

### Claim 18 (depends on 17)

The control system as claimed in claim 17, wherein the control system is configured to transform the limited voltage vector (v) to a stationary frame using the VSC phase angle (θ) to obtain a transformed voltage vector (vs), wherein the control system is configured to control the VSC using the transformed voltage vector (vs).

### Claim 19 (depends on 17)

The control system as claimed in claim 17, wherein in case the magnitude of the current vector (irefinner) is below the maximal threshold current value (Imax), the control system is configured to:
transform the current vector back (irefinner) to the voltage vector (v), and
control the VSC based on the VSC phase angle (θ) and the voltage vector (v).