anaya-lara power system stabilisers

Power system stabilisers for DFIG-based wind generation

Dr Olimpo Anaya-Lara

GreenNet Expert Discussion Platform: Power System Stability and Wind Power Integration in the Nordel System

October 11-12, Oslo, Norway

© Dr Olimpo Anaya-Lara 2

Outline

Doubly-Fed Induction Generator (DFIG) wind turbineConventional DFIG control schemeProvision of Power System Stabiliser (PSS)Impact of wind farms on transient and dynamic stabilityPSS for a generic DFIG controller


Typical DFIG wind turbine

CONTROL SYSTEMNetworkoperator

Gearbox

Crowbar

DFIG

Windmill

PWM Converters PowerNetworkC1 C2

Wound rotor induction generator


qrvoptTT

ω

rω

+ -

Σqrrefi

qri

PI controller

Torque to current

transformation

+ -

Σdrrefi drv

dri

Σ+

-

s refv

sv

PI controller

Voltage or Power factor

control

Voltage control loop:

Torque control loop:

Control scheme based on the current-mode methodology

Conventional DFIG control scheme


Synchronous Generatorand DFIG vector diagrams

Round rotor synchronous generator Doubly fed induction generator

fdψ = rotor field flux vector

fd fdEψ = Efd = dc field voltage

tE = terminal voltage vector

gE = generator internal voltage (voltage behind synchronous reactance)

sI = stator current vector δr = rotor angle XS = synchronous reactance

rψ = rotor flux vector

sV = terminal voltage vector

igE = generator internal voltage vector (voltage behind transient reactance)

isI = stator current vector

rV = rotor voltage vector δig = generator load angle δir = rotor voltage angle X’ = transient reactance

rψ

d

q

igE

sV

isI

isjXI′

δig

δig

rVδir

d

q

ssjXI

δr

gE

tE

sIfdψ

Source: Ref [3]


DFIG rotor flux magnitude and angle control

Flux and Magnitude Angle Controller (FMAC)Source: Ref [3]

-

PSS1

Con

trolle

r A

Speed

igangrefe

eP

erefP

1pssu

sv

s refv igmagrefe - rv

ippp

kk

s+

ivpv

kks

+ ( )vg s

AVR controller

11 fsT+ Filter

Max. power transfer

characteristic

PSS2

2pssu

eP eP

irδ(1) (2)


FMAC basic scheme

-

rv

Polarto dq

Transf.

irδ

drv

qrv

Σ++

-

sV

refsVΣ

-Σ

++

-

Σ ippp

kk

s+

impm

kks

+ ( )mg s

iapa

kks

+ ( )ag s

ivpv

kks

+ ( )vg s

AVR compensator

refe

δ

FMAC Controller

E

refδ

Controller AeP

erefP

Power-speed function for max. power extraction

11 fsT+

Filter

Source: Ref [3]

( ) 1 0.024 1 0.0351 0.004 1 0.05v

s sg ss s

+ += ⋅

+ +( ) ( ) 1 0.4

1 2m asg s g s

s+⎛ ⎞= = ⎜ ⎟+⎝ ⎠


Power System Stabiliser

-

magrV

Polarto dq

Transf.

angrV

rdV

rqV

Σ++

-

sV

refsVΣ

++ -

Σ+

Σ+

-

Σ _ig Tδ

ippp

kk

s+

impm

kks

+ ( )mg s

iapa

kks

+ ( )ag s

Auxiliary loop to provide Power System Stabiliser

ivpv

kks

+ ( )vg s

AVR compensator

DfigrefE

Dfigδ

FMAC basic scheme

DfigE

Dfigrefδ

Controller AeP

erefP

Power-speed function for max. Power extraction

11 fsT+

Filter

slip

2auxuslip

Wash-out Compensator

1sT

sT+( )2ag s

Limiter

Source: Ref [3]

( )2

21 0.042001 0.2a

sg ss

+⎛ ⎞= − ⋅ ⎜ ⎟+⎝ ⎠


Generic network model

SynchronousGenerator

DFIGWind Farm

or synchronous

generator

MainSystem

LoadZF

Fault 1

Generator 1 Generator 2

Source: Ref [3]


Conventional synchronous plant operation

Generator 1 (G1): Synchronous generatorGenerator 2 (G2): Synchronous generator

FAULT 1 applied at t=0.2 s. Clearance time 150 ms.

(a) Synchronous generator (G1)

(b) Synchronous generator (G2)

G1 G2

G3

Source: Ref [3]


DFIG with PSS capability

Generator 1 (G1): Synchronous generatorGenerator 2 (G2): DFIG with FMAC basic control

scheme plus auxiliary loop 2G1 G2

G3

(b) DFIG wind farm (G2)

FAULT 1 applied at t=0.2 s. Clearance time 150 ms.

(a) Synchronous generator (G1)

Source: Ref [3]


Influence of wind generation on dynamic stability

installed capacity of generator G2 (MVA)Capacitor factor 2maximum capacity of G2 MVA (2400 MVA)

f =

G2f2 G1

Rating(MVA)

G1Rating(MW)

G2Rating(MVA)

G2Rating(MW)

1 2,800 2,520 2,400 2,240

2/3 2,800 2,520 1,600 1,500

1/3 2,800 2,520 800 750

1/10 2,800 2,520 240 224

Operating situations

Fixed power P1 of G1

G1 (SouthernScotland)

G2 (Northern Scotland)

Main System (England-Wales)

Load L1

Bus1 Bus2

Bus3

Bus4X1 X2

X3

Load

Eigenvalue analysis

Source: Ref [2]


Generator 2: Synchronous generator

Variation of dominant eigenvalue loci with generation capacitySource: Ref [2]

AVR Control AVR + PSS Control



Generator 2: Wind generation

FSIG-wind farm

Variation of dominant eigenvalue loci with generation capacity

DFIG wind farm with current-mode control


Source: Ref [2]


Generator 2: DFIG wind farm with FMAC control

Variation of dominant eigenvalue loci with generation capacity

FMAC basic FMAC basic + PSS control



PSS for a generic DFIG controller

GenericDFIG

Control

srefV

erefP

drV ′

qrV ′

Rectan.to polartransf. rangV

Polar to rectan. transf.

drV

qrV

rmagV

PSSslip

+ +

PSSu

Source: Ref [5]


DFIG Power System Stabiliser

GenericDFIG

Control

srefV

erefP

drV ′

qrV ′

Rectan. to polar transf. rangV

Polar to rectan. transf.

drV

qrV

rmagV

++

PSSuslip

Washout Compensator

51 5

ss+

21300

1 0.2s⎛ ⎞− ⋅⎜ ⎟+⎝ ⎠

Limiter

0.8

0.8−

Source: Ref [5]


Control performance (transient stability)Generator 1 (G1): Synchronous generatorGenerator 2 (G2): DFIG

Fault applied at t=0.2 s with a clearance time of 150ms. (Full line: DFIG with PSS; dotted line: DFIG without PSS)

DFIG in super synchronous Operation (slip = -0.2)

DFIG in sub synchronous Operation (slip = 0.2)

G1 G2

G3

Source: Ref [5]


Control performance (dynamic stability)Generator 1 (G1): Synchronous generatorGenerator 2 (G2): DFIG

Operating situations

G1 G2

G3

Slip DFIG Stator power MW

Converter powerMW

Total power Output MW

-0.2 1,928 375 2,303

0.2 857 -182 675

Influence of PSS loop on the dominant eigenvalue for sub synchronous (s=0.2) and super synchronous operation (s=-0.2). (With PSS •; without PSS ▪)

Source: Ref [5]


Reference for further reading

1. P. Kundur: "Power systems stability and control," McGraw-Hill, 1994.

2. O. Anaya-Lara, F. M. Hughes, N. Jenkins, and G. Strbac, “Influence of wind farms on power system dynamic and transient stability,” Wind Engineering, Vol. 30, No. 2, pp. 107-127, March 2006.

3. F. M. Hughes, O. Anaya-Lara, N. Jenkins, and G. Strbac, “Control of DFIG-based wind generation for power network support,” IEEE Transactions on Power Systems, Vol. 20, No. 4, pp. 1958-1966, November 2005.

4. O. Anaya-Lara, F. M. Hughes, N. Jenkins, and G. Strbac, “Rotor flux magnitude and angle control strategy for doubly fed induction generators,” Wind Energy, Vol. 9. No. 5, pp. 479-495, June 2006.

5. O. Anaya-Lara, F. M. Hughes, N. Jenkins, and G. Strbac, “Power system stabiliser for a generic DFIG-based wind farm controller,” Proceedings of the IEE AC/DC Conference, March, 2006

Power system stabilisers for DFIG-based wind generation

Dr Olimpo Anaya-Lara

GreenNet Expert Discussion Platform: Power System Stability and Wind Power Integration in the Nordel System

October 11-12, Oslo, Norway

anaya-lara power system stabilisers

Documents