DOWEC Blade pitch control algorithms for blade optimisation ... - ECN

DOWEC Blade pitch control algorithms
for blade optimisation purposes
E.L. van der Hooft
28th February 2001

Abstract
As part of the first stage of the DOWEC project, a base control structure for a 3MW
HAWT has been developed to support the evaluation of different rotor designs by means of
load set calculations with PHATAS.
During full load operation the rotorspeed is controlled by blade pitch speed adjustments
towards feathering position to limit aerodynamic power. The basic controller consists of a
rotorspeed feedback structure using a scheduled linear PD-compensator with non-linear
extensions. At partial load operation, the blade pitch angle is simply set to a constant value
at which optimal tip-speed occurs.
The report describes the structure and stability of the basic control algorithm, used for
each rotor concept, and emphasizes the used assumptions and limitations. Rotor specific
tuned parameter sets have been calculated. Time domain simulations driven by rotor
effective windspeed, results in comparable control performance and energy yield of the
FORTRAN algorithm for each proposed rotor design.
As soon as a final rotor design has been defined, additional features to the basic control
structure and detailed analysis are recommended. Energy yield improvements will be
possible by feedforward control based on wind speed estimation and more extended
controller scheduling. Active damping of tower and drive train resonances will be
important to reduce fatigue.
Acknowledgement
The reported work is carried out within the scope of the DOWEC research and
development project, partly funded by the Dutch EET program. Tim van Engelen
(ECN) is acknowledged for helpfull development support and his pleasant commitment.
Thanks to Frank Goezinne (NEG-MICON Holland), Rene van den Berg
(LM Glasfiber Holland) Koert Lindenburg (ECN) and Edwin Bot (ECN) for good
cooperation and handing turbine data. Finally, Ben Hendriks is acknowledged for
project management.
2 ECN-CX--00-083

Distribution
NEG-MICON Holland 1-2
LM Glasfiber Holland 3
F.W. Saris 4
W. Schatborn 5
H.J.M. Beurskens 6
L.W.M.M Rademakers 7
H.B. Hendriks 8
T.G. van Engelen 9
J.T.G. Pierik 10
P. Schaak 11
C. Lindenburg 12
E.L. van der Hooft 13-14
M.S.J. Bruin 15
ECN Centraal Archief 16
ECN-DE Archief 17-21
ECN-CX--00-083 3

CONTENTS
1. INTRODUCTION 5
2. POINTS OF DEPARTURE 7
2.1 Control objective and restrictions . . . . . . . . . . . . . . . . 7
2.2 Turbine constants . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Rotor aerodynamic characteristics . . . . . . . . . . . . . . . . 8
2.4 Generator characteristics . . . . . . . . . . . . . . . . . . . . . 9
2.5 Pitch actuation system and control equipment . . . . . . . . . . 10
3. CONTROLLER DESIGN 11
3.1 Control structure . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2 Linear PD compensator . . . . . . . . . . . . . . . . . . . . . 12
3.3 Parameters and setpoints . . . . . . . . . . . . . . . . . . . . . 13
3.4 Time domain simulation . . . . . . . . . . . . . . . . . . . . . 15
4. CONCLUSIONS 19
REFERENCES 21
APPENDIX A. CONTROL ALGORITHM (LMH95) 23
A.1 Parameters and setpoints: DATBLOK1.fi . . . . . . . . . . . . 23
A.2 Control code: SBAGPRD1.f . . . . . . . . . . . . . . . . . . . 25
APPENDIX B. CONTROL ALGORITHM (LMH46-5-X00) 37
B.1 Modification with respect to LMH95 . . . . . . . . . . . . . . . 37
B.2 Parameters and setpoints: DATBLOK3.fi . . . . . . . . . . . . 37
APPENDIX C. CONTROL ALGORITHM (LMH46-5-X01) 41
C.1 Modification with respect to LMH46-5-X00 . . . . . . . . . . . 41
C.2 Parameters and setpoints: DATBLOK4.fi . . . . . . . . . . . . 41
APPENDIX D. CONTROL ALGORITHM (LMH46-5-X02) 45
D.1 Modification with respect to LMH46-5-X00 . . . . . . . . . . . 45
D.2 Parameters and setpoints: DATBLOK5.fi . . . . . . . . . . . . 45
APPENDIX E. CONTROL ALGORITHM (LMH46-5-X00-A) 49
E.1 Modification with respect to LMH46-5-X00 . . . . . . . . . . . 49
E.2 Parameters and setpoints: DATBLOK6.fi . . . . . . . . . . . . 50
APPENDIX F. CONTROL ALGORITHM (LMH46-5-X00-B) 53
F.1 Modification with respect to LMH46-5-X00 . . . . . . . . . . . 53
F.2 Parameters and setpoints: DATBLOK7.fi . . . . . . . . . . . . 54
APPENDIX G. CONTROL ALGORITHM (LMH46-5-X01-HI) 57
G.1 Modification with respect to LMH46-5-X00 . . . . . . . . . . . 57
G.2 Parameters and setpoints: DATBLOK8.fi . . . . . . . . . . . . 58
4 ECN-CX--00-083

1. INTRODUCTION
In favour of the DOWEC project 1 blade pitch algorithms has to be designed.
Stage I of the DOWEC project implies development of a 3MW prototype windturbine
(NM3000), initially for onshore operation and later (stage II) for offshore
operation. The concept of the NM3000 is determined as a 3-bladed horizontal axis
wind turbine (HAWT) with a variable speed driven 3MW double fed generator
and an active pitch system.
As part of stage I, different blade designs have been defined. To evaluate these
designs, load set calculations with PHATAS [14] have to prove both the aerodynamic
and structural properties of each rotor design 2 . To take realistic blade
pitching actions into account, for each blade design a basic blade pitch algorithm
has to be designed to control the rotor speed in full operation by means of pitch
angle adjustments. As soon as a final rotor design is defined and turbine data
is more valid, additional features (reducing resonance effects, improvements of
energy yield) will be added to the basic blade pitch algorithm.
This report describes briefly the points of departure (chapter 2), the controller
design (chapter 3) and FORTRAN algorithm (Appendix A) of the basic blade pitch
controller (Appendix A) based on a rotor (95m) having three LMH95-X00 blades.
Afterwards, a so called ‘new baseline’ rotor (96m) has been defined by using
LMH46-5-X00 blades and changing rated speed from 15.1rpm to 14.9rpm. Because
the structure of the controller remains similar, only relevant modifications
and a modified (control)parameter set are listed in (Appendix B).
With respect to the ‘baseline’ (LMH46-5-X00) the load consequenses of 10%
slender blades (LMH46-5-X01) and 10% wider blades (LMH46-5-X02) were investigated
by the PHATAS. The adapted (control)parameter sets are respectively
listed in Appendix C and Appendix D.
Another change with respect to the ‘baseline’ is based on reducing the rotor speed.
PHATAS calculations have to prove whether the loss of 2% and 4% energy yield
will fulfill the expected reduction of fatique (‘Low Lambda approach’). The
(control)parameter sets are respectively listed in Appendix E and Appendix F.
Finally, the rotor speed of the rotor with twist optimised LMH46-5-X01 blades
(LMH46-5-X01-Hi) has been increased to a rated tip-speed of 79m/s (rated rotor
speed 15.9 rpm). The adapted (control)parameter set is listed in Appendix G.
1 DOWEC means Dutch Offshore Wind Energy Converter and implies development of a 5-6MW
offshore turbine by the DOWEC consortium in 2008
2 in [14], the term ‘configuration’ instead of ‘design’ is used
ECN-CX--00-083 5

Blade pitch control algorithms DOWEC
6 ECN-CX--00-083

2. POINTS OF DEPARTURE
2.1 Control objective and restrictions
The control objective is defined as:
‘Rotor speed regulation at rated rotor speed during full load operation (3MW
electric power) by controlling the blade pitch angle in such a manner, that the lift
coefficient lowers by decreasing the angle of attack and oppositely (‘pitch angle
control to vane’)’. The amount of crossing the rated rotor speed is restricted by
the maximum speed of the generator.
Above cut-in and below rated rotor speed (partial load) the energy yield is maximised
by an optimal tip speed ratio. In this region the blade pitch angle is forced
to a constant value, (-1 o , see figure 2.1) without further optimisation to improve
energy yield or to lower noise.
For convenience start-up has been carried out by controlling the blade pitch angle
from feathering position to working position with (relative slow) constant blade
angular velocity (0.5 o /s).
In this stage of the DOWEC project (with objective ‘blade optimisation’) the following
additional control features and enhancements have NOT been incorporated
3 :
Scheduling of controller gains based on rotor- and windspeed;
Feed forward control based on rotor effective wind speed estimation [4];
Active damping of in plane tower resonances [6];
Active damping of fore-aft tower resonances [9];
Active damping of drive train resonances [15];
Facility to avoid tower resonances in first bending mode during partial load.
Fractional loss of energy yield or material fatique damage due to these assumptions
are taken for granted in the concept stage of the DOWEC project. If required,
these features will be added or developed in a next stage.
2.2 Turbine constants
Design of the blade pitch controller is based on the following turbine data and
constants [7], [2], [4].
Vcutin = 3.5; % Cut-in windvelocity [m/s]
Vcutout = 25.0; % Cut-out windvelocity [m/s]
VwAnnual = 10; % Annual windvelocity [m/s]
RpmDsgn = 13.7; % Synchronous speed of generator [rpm]
RpmMin = 0.7*RpmDsgn; % Lowest partial load rotor speed of generator
RpmMax = 1.3*RpmDsgn; % Highest rotor speed of generator
RpmPartin = 9.6; % Cut-in rotor speed [rpm]
RpmOptout = 14.5; % End of optimal lambda control (partial load operation)
RpmRat = 15.1; % Rated rotor speed [rpm]
Pelrat = 3e6; % Rated electric power [W]
LAMBDA1 = 21; % Turbulence scale parameter (because hubheight >30m)
L1 = 8.1*LAMBDA1; % Integral scale parameter in longitudinal direction
3
Research and concepts of these listed items are part of the ECN-project 7.4046 [5], funded by
Dutch Ministery of Economic Affairs.
ECN-CX--00-083 7

Blade pitch control algorithms DOWEC
aIB = 3; % WTGS class (turbulence)
I15IB = 0.16; % Turbulence intensity by 15m/s windvelocity at hubheight
Etarat = 0.9386; % Gearbox and generator efficiency at rated conditions
Rbs = 47.5; % Rotor radius (to rotorcenter) [m]
Rhub = 1.2; % Hub radius [m]
rho = 1.225; % Air density [kg/m^3]
B = 3; % Number of blades
Jrs = 12619598; % Rotor inertia [kg*m^2]
Jg = 200; % Generator inertia related HSS [kg*m^2]
iTran = 109.5; % Gear box ratio [-]
Zt = 100; % Hub Height [m]
w0t = 2*pi*0.2; % Natural frequency of 1st bending mode of tower [rad/s]
mt = 167670; % Tower top equivalent mass of 1st bending mode [kg]
betat = 0.005; % Damping rate 1st bending mode of tower [-]
alphac = 0; % Cone angle [dg]
alphan = 5; % Tilt angle [dg]
alphashear = 0.2; % Shearcoefficient [-]
dtowtop = 3.5;, % Towertop diameter [m]
dtowbase = 4.2; % Torenbase diameter [m]
dn = 5.6; % Distance between rotor-center and toren-axis [m]
TdelCtrl = 0.1; % Sample time control equipment [s]
TdelNrpm = 0.5*TdelCtrl; % Measurementdelay rotor speed samples [s]
TdelPtLoad = 0.1; % Extra delay pitch-actuator during speed reversal [s]
TdelPtTrans = 0.0; % Representative delay pitch dynamics [s]
TdelPtBase = 0.04; % Delay pitch actuator during normal operation [s]
MaxRandNrpm = 0.05; % Amplitude random uniform speed measurement noise
Tgen = 0.3; % Generator time constant [s]
grav = 9.83; % Gravity constant [m/s^2]
2.3 Rotor aerodynamic characteristics
Power coefficient and thrust coefficient characteristics of the turbine rotor with
three LMH95 blades are shown as function of tipspeed ratio for different blade
pitch angles in figure 2.1 and 2.2 (dashed lines respresents zero pitch angle).
power coefficient [−]
0.7
0.6
0.5
0.4
0.3
0.2
0.1
power coefficient curves for pitch angles from −2 o , step 2 o , to 30 o
0
2 4 6 8 10 12 14 16
tip to wind speed ratio [−]
file C:\vdhooft\nm3000ct\DATA\PS\rot1\cpcurves.ps 30−Jun−2000
by C:\vdhooft\nm3000ct\DATA\M\modpar.m
Figure 2.1 Power coefficient curves at different pitch angles
Both power- and thrust coefficient data are based on profile calculations obtained
with Blade Optimisation Tool (BOT) [1].
8 ECN-CX--00-083

thrust coefficient [−]
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
thrust coefficient curves for pitch angles from −2 o , step 2 o , to 30 o
POINTS OF DEPARTURE
0
2 4 6 8 10 12 14 16
tip to wind speed ratio [−]
file C:\vdhooft\nm3000ct\DATA\PS\rot1\ctcurves.ps 30−Jun−2000
by C:\vdhooft\nm3000ct\DATA\M\modpar.m
Figure 2.2 Thrust coefficient curves at different pitch angles
2.4 Generator characteristics
The steady state behaviour of the double fed induction generator is calculated in
accordance with the values of RpmDsgn, RpmMin, RpmMax, RpmPartin, RpmOptout,
RpmRat, Pelrat as given in section 2.2. Five ranges are distinguished and shown in
figure 2.3, viz.
no production below Vcutin;
transition from start-up to optimal tipspeed ratio control;
optimal tip-speed ratio control during partial load (variable speed control);
transition from optimal tipspeed ratio control to rated speed;
constant power control from rated load up to Vcutout (‘constant speed control’).
and shown in figure 2.3.
generator torque (slow shaft equiv) [kNm]
electric power [kW]
2000
1500
1000
500
torque rotorspeed curve
0
8 10 12 14 16 18
power rotorspeed curve
3500
3000
2500
2000
1500
1000
500
0
8 10 12 14 16 18
rotorspeed [rpm]
electric power [kW]
3500
3000
2500
2000
1500
1000
rotor speed [rpm]
500
file C:\vdhooft\nm3000ct\DATA\PS\rot1\TPNVCurv.ps 30−Jun−2000
by C:\vdhooft\nm3000ct\DATA\M\modpar.m
power windspeed curve
0
0 5 10 15 20 25
18
16
14
12
10
rotorspeed windspeed curve
8
0 5 10 15 20 25
wind speed [m/s]
Figure 2.3 Steady state figures of generator torque, -power and -speed
ECN-CX--00-083 9

Blade pitch control algorithms DOWEC
Generator dynamics have been included with a conservative first order approximation.
To achieve maximum energy yield it seems to be attractive to minimise the
transition range from optimal speed-tip control to constant power control (steep
slope). However, to ensure sufficient suppression of undesirable 3p wind excitation
noise in the electric power, this is limited. The 3p reduction is determined
by this ‘slope’ (gain), the effective inertia and the generator time constant. In a
later stage of the DOWEC project (when more detailed generator data is available)
more analysis will be carried out to specify possible restrictions due to this phenomenon.
In the concept stage the transisition range is defined between 14.5rpm
(1198kNm) and 15.1rpm (1898kNm) or a stiffness of 1170kNm/rpm related to
slow shaft equivalent 4 , and the first order time constant is set to Tgen= 0.3s. In
the region of ‘optimum tipspeed’ (between 9.6 and 14.5 rpm) a tip-speed ratio of
7.0 is calculated.
2.5 Pitch actuation system and control equipment
For lack of detailed data of the pitch system in this stage of DOWEC, it was
supposed to be valid to assume a pitch-actuating system with similar performance
as used in the NW62- [3] and NM2000 turbine, [4]: a double acting hydraulic
actuator with proportional servo.
It seemed realistic to model the pitching system as a pure delay amounted to 0.04s
for speed setpoint changes in the same direction of pitching. Additionally a delay
of 0.1s has been applied to setpoint changes in reverse pitching direction.
For the development of the controller, only the expected measurement noise on
the rotor speed was considered to be relevant, because of the differentiating action
(D-action). Therefore a uniformly distributed random error of ± 0.05 rpm on the
turbine rotor shaft was assumed. Measurement of blade angle was not corrupted
with noise.
4 for comparison, this corresponds with a virtual ‘slip’ of 11%
10 ECN-CX--00-083

3. CONTROLLER DESIGN
3.1 Control structure
The structure of the blade pitch angle controller is shown in figure 3.1. In full load
nom
Ωr
setpoint
adaptor
Ω ref
r
+
-
PD
linear
PD controller
gain
scheduler
+
+
Rotorspeed
limiter
Θ full
Θ lim( Ω )
r
Figure 3.1 Structure blade pitch angle controller NM3000
partial load
pitch control
part
Θ part
partial/full load
selector
3pfilt
Ω r
full
LPF
dead zone &
pitching bounds
low-pass ` 3p' filter
operation, a linear PD controller (Kprop,Kdiff) 5 sets the pitch speed dependent
on the error between rotor speed setpoint and the actual rotor speed. Due to
the heavily non linear character of the windturbine dynamics, some non linear
extensions were necessary to meet satisfied performance:
Linear controller gains have been scheduled (pInvSchFac) dependent on the
actual blade angle; with gain scheduling the linear controller is adapted to the
operation envelope of the windturbine.
A dead zone to avoid undesired pitch angle adjustments due to small controller
corrections caused by noise, tower pass influences etc. The dead zone (dThdtsetInacBase)
has also been scheduled by the actual pitch angle to achieve a
relative equal pitch speed inactivation zone over the whole operation range.
Additional magnification of linear controller gains below rated rotor speed
(MuKsubNom) because of the stabilizing generator properties in this range.
rotor speed setpoint adaptation proportionally with pitch angle (NrpmRatOff-
Max, WeightNrpmRefOld, ThLLAdapNref, ThULAdapNref), which supports the
linear controller to avoid energy yield loss in case of falling wind gusts (storing
kinetic energy in rotor).
rotor speed limitation which forces the pitch angle with maximum pitch speed
in feathering direction as soon as the actual rotor speed exceeds a certain
5
Terms between brackets refer to names of variables as used in the algorithm code Appendix A
through Appendix D
ECN-CX--00-083 11
Θ meas
Θ set
Ω meas
r

Blade pitch control algorithms DOWEC
safety level and is still accellerating (NrpmLimFuz, NrpmDdtLimFuz, DeltaThFuz,
dThdtFuzTarg).
A low pass filter to reduce measurement noise and 3p components (tower
shadow, rotational sampling) of the measured rotor speed. To achieve sufficient
suppression at least phase shift (delay), a fourth order invers Chebychev filter
was used (aLo3p, bLo3p, cLo3p, dLo3p, gLo3p).
Pitching bounds were incorporated to limit the calculated pitch speed values at
the minimum and maximum pitch speed boundaries of the actuator and pitch
mechanism (Thmax, Thmin, dThdtmax, dThdtmin).
Dependent on the rotor speed value,a selector switches between full load operation
or partial load operation. A transition from full load to partial load is based on first
order filtered rotor speed and a transition from partial to full load (NrpmToFull)
is based on the actual rotor speed value. A switching hysteresis (NrpmToPartial,
NrpmToFull) is incorporated to avoid repeatable transitions between full- and
partial load. Partial load pitch control is simply implemented by setting the
pitch angle to a constant value (ThetaPartConstant) with a certain pitch speed
(dThdtsetPart) and an allowable error (ThSetPartDev).
3.2 Linear PD compensator
As mentioned before in full load operation, a linear proportional/differential feedback
structure (PD) sets the pitch speed dependent on the error between rotor
speed setpoint and the actual filtered rotor speed. The linear PD compensator is
dimensioned by phase- and amplitude margin criteria of Bode to ensure sufficient
stability and robustness [5]. The linear design has been based on the following
assumptions and restrictions:
Operation envelope defined as:
– aerodynamic torque between 90% and 140% with respect to rated torque
– rotor speed range between 14.1rpm and 17.1rpm
– windspeed range between 10.3m/s and 26m/s
Phase margin of 45 o and amplitude margin of 0.5
Proces transfer function (pitch speed vs rotor speed) has been simplified to
– maximum value of aerodynamic torque to pitch angle sensitivity 6
– overall delay which represents worst case pitch dynamics, computer calculation
and measurement delays and rotor speed filter delay (phase shift)
– integrator incorporating the effective rotor inertia
Stability analysis of the designed PD compensator and accompanying schedulefactor
incorporates the following additional turbine modelling aspects (which were
not taken into account during linear controller design):
rotor speed influences caused by indirect fore-aft tower deformation including
aerodynamic rotor damping 7
Pitch angle influences caused by indirect fore-aft tower deformation including
aerodynamic rotor damping 7
Natural rotor speed feedback (aerodynamic torque to rotor speed sensitivity)
Electric torque influence by generator through speed curve
rotor speed low pass filter dynamics (3p filtering).
6
the schedulefactor is a non linear extension which achieve a suitable magnification of the PD
gains over the whole operation envelope
7
aerodynamic damping is here defined as thrustforce to windspeed sensitivity
12 ECN-CX--00-083

CONTROLLER DESIGN
For clarity, in plane tower movement influences to electric torque were NOT taken
into account.
In figure 3.2, the Nyquist stability diagrams are shown for four classified blade
angles areas centered around 5 o ,10 o ,15 o and 20 o .
Im(Hrond)
Im(Hrond)
2
1
0
−1
100.0m toren; Th = 5.00dg
−2
−2 −1 0
Re(Hrond)
1 2
2
1
0
−1
100.0m toren; Th = 15.00dg
−2
−2 −1 0 1 2
re(Hrond)
Im(Hrond)
Im(Hrond)
2
1
0
−1
file C:\vdhooft\nm3000ct\DESIGN\PS\rot1\DFNyqB1a.ps 23−Jun−2000
100.0m toren; Th = 10.00dg
−2
−2 −1 0
Re(Hrond)
1 2
2
1
0
−1
100.0m toren; Th = 20.00dg
−2
−2 −1 0
Re(Hrond)
1 2
Figure 3.2 Nyquist diagrams for the windturbine with scheduled PD-feedback and lowpass
3p filter; aerodynamic torquelevels between 90% and 140% of the rated
value; wind speed range [10.3m/s - 26m/s]; rotor speed range [14.1rpm -
17.1 rpm]
According to figure 3.2 there’s no danger of closed loop instability (no curve is
passing the instability point (-1,0) from the wrong side and sufficient margins
are guaranteed). The encirceling of the (0,0) point visualises the indirect torque
influences by pitching in and around the tower eigenfrequency.
3.3 Parameters and setpoints
The control structure as described in section 3.1 has tuned to match with typical
turbine characterstics. The parameters as given in table 3.1 corresponds with the
parameters and setpoints as used in the control algorithm (Appendix A) 8 .
Tuning of the non-linear parameters and setpoints was done by running time
domain simulations at different windspeeds (see section 3.4). The rotor speed
limitation has been set to the maximum allowable generatorspeed (17.8rpm). A
hysteresis of 0.75 rpm between full load and partial load operations has been used
to avoid too many transitions.
8 Note that both the proportional and differential gain of the PD controller have been designed in
dimensions [( o /s)/(rad/s)], [( o /s)/(rad/s 2 )] respectively. In the control algorithm the dimensions
[( o /s)/(rpm/s)][( o /s)/(rpm/s 2 )] are used!
ECN-CX--00-083 13

Blade pitch control algorithms DOWEC
Table 3.1 Parameters and setpoints in control algorithm
item symbol meaning value-specification
Low-pass 3p filter
aLo3p(4,4) A State transition matrix +5.579203e−1 −2.477898e−1 +0.000000e+0 +0.000000e+0
+2.477898e−1 +9.605886e−1 +0.000000e+0 +0.000000e+0
−2.521691e−1 +1.061609e+0 +8.810910e−1 −2.067648e−1
−2.771780e−2 +1.166894e−1 +2.067648e−1 +9.772729e−1
bLo3p(4,1) B Input-columnvector +2.817506e−1 +4.481290e−2 2.945912e−1 3.238074e−002
cLo3p(1,4) C Output-rowvector −1.015047e−1 +4.273256e−1 −3.272979e−2 +5.445901e−2
dLo3p D Throughput-scalar +1.185808e−1
gLo3p(1,4) (I − A) −1 · B Initialisation vector +0.000000e+0 +1.137055e+0 +0.000000e+0 +7.262833e+0
PD-compensator
Kprop K dsgn
p Design value proportional gain -0.8439 ( o Kdiff K
/s)/(rad/s)
dsgn
d Design value differential gain -11.2195 ( o /s)/(rad/s 2 pInvSchFac(2) µPD Coefficients schedule factor
)
(4.424134e-2/ o ), 1.629493e-1
rotor speed setpoint adaptation
RpmRat Ωnom Rated rotor speed 15.1 rpm
RpmRatOffMax Ω r offmax Maximum offset on Ωnom 2 rpm
WeightNrpmRefOld wΩ r old Weightfactor of 1 st order LPF 0.9901
ThLLAdapNref θ min
Ω r
off
ThULAdapNref θ max
Ωr off
Min. pitchangle for adap.Ω r
Max. pitchangle for adap.Ω r
PD magnification factor below rated operation
MuKsubnom µk Gain factor for Ω

3.4 Time domain simulation
CONTROLLER DESIGN
Rotor effective windspeed
To verify the performance of the control algorithm as depicted in figure 3.1 with
parameters and setpoints as defined in table 3.1, simulations in time domain are
necessary. The simulations were driven by so called ‘rotor effective windspeed’.
Rotoreffective windspeed is described as: ‘a single point windsignal which causes
wind torque variations through power- and thrustcoefficient, that are stochasticly
equivalent to those calculated through blade element theory in a turbulent windfield’
[5]. The stochastic signal is constructed from the autopower spectrum of
the (longitudinal) windspeed variations and the lateral coherence, according to
IEC-class IB and turbulence intensity 16% [2]. The rotor effective windspeed
signal has been normalised by the meanvalue of windspeed and consists of:
0p mode of the turbulent windfield
3p- and 6p effects of the rotationally sampled windfield
tower shadow influences
wind shear variations
Figure 3.3 shows these components in detail.
tower+shear infl. [m/s]
turb.mode 3 6 [m/s]
turb.mode 0 [m/s]
0.5
0
−0.5
wind speed variations at 1.76 r/s (16.8rpm) rotor speed and 11.3 m/s mean wind
−1
0 2 4 6 8 10 12 14 16 18 20
2
1
0
−1
−2
0 2 4 6 8 10 12 14 16 18 20
2
1.5
1
0.5
0
0 2 4 6 8 10 12 14 16 18 20
time [s]
file C:\vdhooft\nm3000ct\SCOPE\PS\vwexcitm.ps 09−May−2000
by C:\vdhooft\nm3000ct\SCOPE\M\scsmlvwe.m
Figure 3.3 Details of contributions to rotor effective windspeed; tower and shear, rotational
sampling, 0p mode
Turbine model
The turbine model [5] [3] used for time domain simulations is based on the
following assumptions and restrictions:
quasi stationary aerodynamic conversion (without dynamic stall)
rigid rotor blades (no flapwise, no lead-lag movements)
stiff drive train (no torsion)
first order generator dynamics and quasi stationary torque speed curve
fore-aft tower deformation in only the first bending mode
neglection of influences on electric power due to lateral tower deformation
constant torque losses
simplified pitch system approached (§2.5)
ECN-CX--00-083 15

Blade pitch control algorithms DOWEC
The turbine model has been dimensioned using turbine constants as defined in
§2.2, generator characteristics in §2.4 and aerodynamic characteristics in §2.3.
Simulation results
Several time simulations at different mean windspeed values, were calculated with
the proposed control structure (§3.1) using parameters and setpoints as defined in
table 3.1 and the rotor effective windspeed and turbine model as described before
in this section.
In figure 3.4 the overall results (400s) of a time simulations at mean windspeed
of 12.3 m/s are shown. The simulation shows both partial load operation (for
example between 120s and 160s, the pitch angle is set to -1 o ) and full load
operation. The overall performance of the controller and the energy yield is quite
satisfying. There are no undesired pitch speed control actions because rotor speed
filtering and dead zone are working properly.
However the rotor speed setpoint is raised by the setpoint adaptation mechanism
of the controller, some energy yield is lost in case of falling windgusts at 75s,
100s and 350s. In [4] is proved that an additional feedforward control based on
windspeed estimation will improve this performance.
In figure 3.5 a detail (50s) at mean windspeed of 13.3 m/s is shown. This detail
shows both rotor speed setpoint adaptation and rotor speed limitation. The rotor
speed setpoint is being increased to 17.1 rpm (15.2 + 2 rpm) as soon as the
pitch angle crosses 12 o . At 334s the rotor speed exceeds, due to an increasing
windgust, the safetylevel of 17.8rpm. Additional kinetic energy has stored in the
turbine rotor. The rotor speed limitation forces with maximum pitch speed (5
o /s) the blade angle in feathering direction, until the rotor accelleration has been
decreased to zero value. Despite of the fact that aerodynamic power is strongly
reduced by this forced action, no loss of electric power is caused because the stored
kinetic rotor energy is adopted to prevent this. After the rotor speed limitation the
transition to the ‘linear’ controller is smoothly.
Remark that the dead zone prevents small undesired pitch speed changes in the
first part of the detail.
The FORTRAN code of the blade pitch control algorithm is added in Appendix
A. For convenience, parameters and setpoints were separated in an
includable file: ../datblok1.fi. The control code is called: ../sbagprd1.f. Index
‘1’ refers to the LMH95 blades and turbine constants as defined in [7] (dated
03/05/2000). Both FORTRAN-files are stored on PC-platform P2352 in directory
c:/vdhooft/nm3000ct/algo/src. All development data (including source codes) and
results are also stored on CD-ROM.
16 ECN-CX--00-083

P (el; −−ae) [kW]
dΩ r /dt (lo3p) [rpm/s]
Vw effectief [m/s]
16
14
12
10
5000
4500
4000
3500
3000
2500
2000
NM3000 bij V w =12.3m/s; η regeling 99.1% (src: dssimp12.mat)
CONTROLLER DESIGN
8
0 50 100 150 200 250 300 350 400 450
1500
0 50 100 150 200 250 300 350 400 450
Ω r (:smp; lo3p; −−ref) [rpm]
Θ [ o ]
dΘ/dt [ o /s]
18
17
16
15
14
file C:\vdhooft\nm3000ct\DESIGN\PS\rot1\dssp12a0.ps 06−Jun−2000
by C:\vdhooft\nm3000ct\DESIGN\M\dssimprd.m
13
0 50 100 150 200 250 300 350 400 450
0.6
0.4
0.2
0
−0.2
−0.4
−0.6
−0.8
0 50 100 150 200 250 300 350 400 450
12
10
8
6
4
2
0
file C:\vdhooft\nm3000ct\DESIGN\PS\rot1\dssp12b0.ps 06−Jun−2000
by C:\vdhooft\nm3000ct\DESIGN\M\dssimprd.m
−2
0 50 100 150 200 250 300 350 400 450
4
2
0
−2
−4
−6
0 50 100 150 200 250 300 350 400 450
tijd [s]
file C:\vdhooft\nm3000ct\DESIGN\PS\rot1\dssp12c0.ps 06−Jun−2000
by C:\vdhooft\nm3000ct\DESIGN\M\dssimprd.m
Figure 3.4 Turbine-performance at mean windspeed of 12.4 m/s; overall figure
ECN-CX--00-083 17

Blade pitch control algorithms DOWEC
P (el; −−ae) [kW]
Ω r (:smp; lo3p; −−ref) [rpm]
dΩ r /dt (lo3p) [rpm/s]
Θ [ o ]
dΘ/dt [ o /s]
Vw effectief [m/s]
20
18
16
14
12
NM3000 bij V w =14.3m/s; η regeling 98.8% (src: dssimp13.mat)
10
300 305 310 315 320 325 330 335 340 345 350
5000
4000
3000
2000
1000
17.5
16.5
15.5
0
300 305 310 315 320 325 330 335 340 345 350
18
17
16
15
file C:\vdhooft\nm3000ct\DESIGN\PS\rot1\dssp13a2.ps 06−Jun−2000
by C:\vdhooft\nm3000ct\DESIGN\M\dssimprd.m
14.5
300 305 310 315 320 325 330 335 340 345 350
0.6
0.4
0.2
0
−0.2
−0.4
−0.6
−0.8
300 305 310 315 320 325 330 335 340 345 350
18
16
14
12
10
8
file C:\vdhooft\nm3000ct\DESIGN\PS\rot1\dssp13b2.ps 06−Jun−2000
by C:\vdhooft\nm3000ct\DESIGN\M\dssimprd.m
6
300 305 310 315 320 325 330 335 340 345 350
5
4
3
2
1
0
−1
−2
300 305 310 315 320 325 330 335 340 345 350
tijd [s]
file C:\vdhooft\nm3000ct\DESIGN\PS\rot1\dssp13c2.ps 06−Jun−2000
by C:\vdhooft\nm3000ct\DESIGN\M\dssimprd.m
Figure 3.5 Turbine-performance at mean windspeed of 13.4 m/s; detail figure
18 ECN-CX--00-083

4. CONCLUSIONS
A basic blade pitch control algorithm for full load operation of the DOWEC 3MW
turbine, has been designed for making aerodynamic and structural comparisons
[14] between different rotor designs (LMH95, LMH46-5-X00/X01/X02, 2-4%
speed reduction,LMH46-5-X01-Hi). The control structure for all rotor designs
are similar, however for each rotor design a specific parameterset is determined
(Appendix A through Appendix G).
The basic blade pitch control algorithm consists of a rotor speed feedback structure
with a linear PD-compensator which sets the pitch speed dependent on the
error between rotor speed setpoint and the actual rotor speed. Stability and robustness
is guaranteed by Bode’s amplitude- and phasemargins and proved by
Nyquist diagrams and time domain simulations with representative rotor effective
windspeed. Non linear extensions have been added to meet better energy yield
and to improve control performance.
For each rotor, specific tuned parametersets have been calculated. Time domain
simulations driven by rotor effective windspeed, result in comparable control
performance and energy yield of the FORTRAN algorithm for each rotor design.
The basic blade pitch control algorithm doesn’t provide:
a feed forward control based on windspeed estimation to achieve improved
energy yield in case of falling windgusts
a more dimensional, and therefore more effective scheduling of controller gains
active damping facilities to reduce in-plane and fore-aft tower resonances or to
reduce drive train dynamics
More detailed analysis and research is recommended to implement these features
in the final control structure. Some feasibility studies on these subjects have
already be done [5], [6], [9], [15].
During partial load operation the blade pitch angle is simply set to a constant value
(maximum power coefficient) and start-up is integrated by increasing the pitch
angle from feathering position to working position by a constant speed (0.5 o /s).
In a more definite stage, it’s also recommended to look at a facility which avoid
tower resonances in first bending mode during partial load operation and/or a more
advanced start-up algorithm to ensure a smooth rotor accelleration [5].
When more detailed generator data is available, it will be needed to consider the
influence of a ‘stiff’ transition from optimal speed-tip control to constant power
control and generator dynamics with respect to energy yield and 3p wind excitation
reduction in the electric power.
Stability analysis of the control algorithm dimensioned for use at reduced rotor
speed (‘Low Lambda approach’, see Appendix E and Appendix F), shows worrying
operating points at small pitch angles due to destabilising effects of both
natural and electric rotor speed feedback. If the ‘Low Lambda approach’ fulfills
fatigue reduction (PHATAS calculations [14] ) this phenomenon needs more
attention for controller design.
ECN-CX--00-083 19

Blade pitch control algorithms DOWEC
20 ECN-CX--00-083

REFERENCES
[1] E.T.G. Bot. Cp en Ct data ‘LMH95 bladen’. ECN Wind Energy Petten
The Netherlands. Email aan Eric van der Hooft (ECN) 02 mei 2000 ref:
c:/vdhooft/nm3000ct/admin/CPCT3MWOOC6.xls.
[2] Int. Electrotechnical Commission. Wind turbine generator systems - part 1:
Safety requirements. Technical Report IEC 61400-1, IEC, February 1999.
[3] T.G. van Engelen. Control algorithm for power regulation and transient
speed control of NW62 vol.II and III. Technical Report ECN-CX-98-144,
ECN Petten, 29th June 1999.
[4] T.G. van Engelen. Blade pitch adjustment algorithm for full load control of
NM2000 HAWT (draft). Technical Report ECN-CX-00-xxx, ECN Petten,
6th April 2000.
[5] T.G. van Engelen, E.L. van der Hooft, and J.T.G. Pierik. Ontwerpgereedschappen
voor de regeling van windturbines. Technical Report
ECN-I–00-xxx, ECN Petten, In preparation.
[6] T.G. van Engelen and J.T.G. Pierik. Active
damping of in-plane tower resonance. Technical Report ECN-I–00-xxx,
ECN Wind Energy Petten the Netherlands, In preparation 1999.
[7] F. Goezinne. 3MW turbine data for blade optimisation. Technical Report
001-FG-R0067, NEG Micon, 03 May 2000.
[8] H.B. Hendriks. Sub optimaal toerental’. ECN Wind Energy Petten the
Netherlands. Email aan Eric van der Hooft (ECN) 17 juli 2000, ref:
c:/vdhooft/nm3000ct/admin/emBH170700EH.txt.
[9] E.L. van der Hooft and T.G. van Engelen. Actieve demping via bladhoek
van voor- en achterwaartse torentrillingen. Technical Report ECN-I–00-xxx,
ECN Wind Energy Petten the Netherlands, In preparation 2000.
[10] C. Lindenburg. Cp en Ct data ‘LMH46-5-X00 bladen’. ECN Wind
Energy Petten The Netherlands. Email aan Eric van der Hooft (ECN)
20 juni 2000, ref: c:/vdhooft/nm3000ct/admin/CpLMH46-5-X00.txt ref:
c:/vdhooft/nm3000ct/admin/CtLMH46-5-X00.txt.
[11] C. Lindenburg. Cp en Ct data ‘LMH46-5-X01 bladen’. ECN
Wind Energy Petten The Netherlands. email aan Eric van der Hooft
(ECN) 10 juli 2000, ref: c:/vdhooft/nm3000ct/admin/X01Char.Cp ref:
c:/vdhooft/nm3000ct/admin/X01Char.Ct.
[12] C. Lindenburg. Cp en Ct data ‘LMH46-5-X01-Hi bladen’. ECN
Wind Energy Petten the Netherlands. Email aan Eric van der Hooft
(ECN) 11 juli 2000, ref: c:/vdhooft/nm3000ct/admin/cpdataX01hi.txt ref:
c:/vdhooft/nm3000ct/admin/ctdataX01hi.txt.
[13] C. Lindenburg. Cp en Ct data ‘LMH46-5-X02 bladen’. ECN
Wind Energy Petten the Netherlands. Email aan Eric van der Hooft
(ECN) 11 juli 2000, ref: c:/vdhooft/nm3000ct/admin/X02Char.Cp ref:
c:/vdhooft/nm3000ct/admin/X02Char.Ct.
[14] C. Lindenburg. Nm3000 - lmh46-5 blade design - aerodynamic parameter
sensitivity study (draft). Technical Report ECN-CX–00-77, ECN Petten,
December 2000.
[15] J.T.G. Pierik, P.M.M. Bongers, T.G. van Engelen, and G.E. van Baars.
Damping of mechanical resonance and protection against grid failure for
variable speed wind turbines (IRFLET). Technical Report ECN-C–93-004,
ECN Wind Energy Petten the Netherlands, January 1993.
ECN-CX--00-083 21

Blade pitch control algorithms DOWEC
22 ECN-CX--00-083

APPENDIX A. CONTROL ALGORITHM
(LMH95)
A.1 Parameters and setpoints: DATBLOK1.fi
c Regelparameters en setpoints t.b.v. NM3000-Standaard bladen
c Datum: 24-May-2000
c Constanten
c ==========
DATA CD01TdelCtrl /0.1/
c Parameters
c ==========
c Let op dimensie in declaratie van PD01alo3p!
DATA PD01alo3p/
& 5.579203e-001, -2.477898e-001, 0.000000e+000, 0.000000e+000,
& 2.477898e-001, 9.605886e-001, 0.000000e+000, 0.000000e+000,
& -2.521691e-001, 1.061609e+000, 8.810910e-001, -2.067648e-001,
& -2.771780e-002, 1.166894e-001, 2.067648e-001, 9.772729e-001/
c Let op dimensie in declaratie van PD02blo3p!
DATA PD02blo3p/
& 2.817506e-001, 4.481290e-002, 2.945912e-001, 3.238074e-002/
c Let op dimensie in declaratie van PD03clo3p!
DATA PD03clo3p/
& -1.015047e-001, 4.273256e-001, -3.272979e-002, 5.445901e-002/
DATA PD04dlo3p/
& 1.185808e-001/
c Let op dimensie in declaratie van PD04glo3p!
DATA PD04bglo3p/
& -4.410867e-017, 1.137055e+000, -1.481174e-015, 7.262833e+000/
c Let op dimensie in declaratie van PD05pInvSchFac!
DATA PD05pInvSchFac/
& 4.134071e-002, 1.670273e-001/
DATA PD06ThULAdapNref/12.0/
DATA PD07ThLLAdapNref/ 5.0/
DATA PD08WeightNrefOld/ 9.9900e-001/
DATA PD09KpropRpm/ -0.08828/
DATA PD10KdiffRpm/ -1.17369/
DATA PD11MuKsubnom/ 1.75/
DATA PD12dThdtFuzTarg/ 5.0/
DATA PD13WeightNswitchOld/ 9.9900e-001/
ECN-CX--00-083 23

Blade pitch control algorithms DOWEC
c Let op dimensie in declaratie van PD14NrpmList en PD15ThdgList!
DATA PD14NrpmList/ -30.20, 9.60, 10.39, 11.17, 11.96,
& 12.74, 13.53, 14.31, 15.10, 30.20/
c Deellastbladhoeken zijn NIET geoptimaliseerd
DATA PD15ThdgList/ -1.00, -1.00, -1.00, -1.00, -1.00,
& -1.00, -1.00, -1.00, -1.00, -1.00/
c Deze parameter is niet automatisch gegenereerd
DATA PD16KsynDgr/1.52/
DATA PD17dThdtZoneInacBase/0.12/
DATA PD18dThdtmax/ 5.0/
DATA PD19dThdtmin/-5.0/
DATA PD20Thmax/ 90.0/
DATA PD21Thmin/ -1.0/
c Setpoints
c ----------
DATA SD01NrpmNom/15.1/
DATA SD02NrpmRatOffMax/ 2.0/
DATA SD03NrpmLimFuz/17.8/
DATA SD04NrpmDdtLimFuz/ 0.0/
DATA SD05DeltaThFuz/ 3.0/
DATA SD06NrpmToPartial/14.6/
DATA SD07NrpmToFull/15.4/
c Data directieven voor parameters specifiek voor simulatie
c ----------
DATA sPD1TdelPtTrans/0.000/
DATA sPD2TdelPtLoop/0.039/
DATA sPD3TdelPtLoad/0.100/
c Let op gedeclareerde lengte van dit polynoom!
DATA sPD4pTe/
& 0.0000e+000, 5.3589e+005, 4.6856e+002, -2.4817e+002/
DATA sPD5Tgen/ 0.1/
DATA sPD6PwattNom/ 3e+006/
24 ECN-CX--00-083

A.2 Control code: SBAGPRD1.f
CONTROL ALGORITHM (LMH95)
c File sbagprd1.f : subroutine sbagprd1() met vollast en deellastregeling
c voor NM3000 standaard rotor,
c De naam sbagprd1 staat voor SuBroutine met regelAlGorithme voor PRoDuctiec
klasse bedrijf voor rotor 1
c
c logstaat:
c ------c
c 000523: regelparameters en setpoints worden nu
c ge-included vanuit datblok#.f (met #=iRot)
c 000519: NM3000 eerste versie gebaseerd op (7.4302)
subroutine sbagprd1
& (sIV1t, sOI1t_pre, IV04NrpmSmp, sOV1dThdt, sIV2H,
& sIV3domeg, IV05InitCall, IV01Theta1, OV01dThdtset1
& , sIV4OmegaR, sOV2Te
& , TV07NrpmRef, TV03NrpmDdtLo3p, TV04NrpmLo3p, TV13ThetaSet
& )
c Regeling NM3000 standaard rotor Fortran versie tbv FLEXLAST,
c Geschreven door Tim van Engelen ECN oct 99
c Bewerkt door Eric van der Hooft, ECN mei 2000
c Bronnen: Matlab file ‘dsalgprd.m’, Tim van Engelen, Eric van der Hooft, ECN,
c sept. 99; Fortran versie ‘tvecontrol()’, Ilya Kraan SPE, juli 99
c
c Variabelen in aanroep van routine sbagprd1()
c ------------------------------------------c
R*4 sIV1t [I] actuele simulatie tijdstip
c R*4 sOI1t_pre [O/I] eerder simulatie-tijdstip; ter bepaling verstrijken regelcyc.tijd.
c R*4 IV04NrpmSmp [I] toerentalmeting (halve regelcyclustijd delayed)
c R*4 sOV1dThdt [O] bladverstelsnelheid [dg/s] NA overall delay regeling+servo
c => dekt volledige pitch-servo dynamica af!
c R*4 sIV2H [I] simulatie-rekenstap
c R*4 sIV4OmegaR [I] rotortoerental [rad/s]
c R*4 sIV3domeg [I] rotoracceleratie [rad/s^2] (niet gebruikt)
c I*4 IV05InitCall [I] initialisatie vlag (1: eerste aanroep; 0: volgende)
c R*4 IV01Theta1 [I] bladhoekwaarde van blad 1 (’referentie-blad’)
c R*4 OV01dThdtset1 [O] gewenste verstelsnelh. blad 1 (’referentie-blad’)
c R*4 sOV2Te [O] elektro-mechanisch koppel [Nm]
c
c De laatste variabele OV01dThdtset1 wordt WEL gebruikt in MATLAB-simulaties,
c alwaar de pitch-servo dynamica bij de turbine simulatie is ondergebracht,
c maar wordt NIET gebruikt in FLEXLAST-simulaties, alwaar de pitch-servo
c dynamica via een overall delay in de regelroutine is ondergebracht.
c
c Bijzonderheid
c -----------c
Regel (label) 100 geeft in woorden aan dat hier het juiste moment
c uitgekozen moet worden voor de regelaarstap, dit afh. van simulatie
c omgeving)
c Uitgangspunten programmeringswijze
c --------------------------------c
Ter voorbereiding op de PLC-implementatie door PROLION wordt slechts
c gebruik gemaakt van program-control via
c - if then else ;
ECN-CX--00-083 25

Blade pitch control algorithms DOWEC
c - goto .
c Verder worden alleen 1-d arrays gebruikt.
c
c Door markering van code-fragmenten wordt binnen sbagprd1() onderscheid
c gemaakt naar
c * ingangs- en uitgangsvariabelen (I/O) die specifiek zijn voor simulatie
c en die zich zowel in simulatie als ook in de PLC-implementatie doen gelden
c * programma-variabelen voor onveranderlijke data en tijdelijke variabelen
c mbt het eigenlijke regelalgorithme en pitch-servo simulatie
c * programma-directieven mbt het eigenlijke regelalgorithme en simulatie van
c de overall delay in het bladverstelsysteem.
c
c Als gevolg van ‘de beperking tot 6 karakters voor wat betreft eenduidige
c aanduiding van programma-variabelen in ANSI-Fortran 77’ beginnen alle
c (interne) variabelen in deze regelroutine met twee letters en twee cijfers,
c gevolgd door een alfa-numerieke code van ten hoogste 18 karakters waarmee een
c betekenis-omschrijving beoogd wordt. De volgende combinaties van kenletters
c worden gebruikt voor datatypering:
c
c CD : ‘constant data’; onveranderlijk gegeven binnen regeling
c (cyclustijd, conversiegegevens)
c PD : ‘parameter data’; parametriserende gegevens (regel- en
c filterparameters, constraints; bepaald tijdens regec
laarontwerp; in beperkte mate voor fine-tuning)
c SD : ‘setpoint data’; doelniveau gegevens (nominaal toerental,
c drempeltoerentallen vollast en deellast; gereserveerd
c voor fine-tuning)
c IV : ‘input variable’; meetsignalen (toerental, 3 bladhoeken, init-vlag)
c TV : ‘temporary variable’; hulp variabele in regeling zonder
c geheugen functie
c MV : ‘memory variable’; hulp variabele in regeling met
c geheugen functie
c OV : ‘output variabele’; regelsignalen (3 gewenste bladhoekc
verstelsnelheden).
c
c De twee cijfers bepalen een uniek variabele-nummer (01 t/m 99)
c
c Programma-variabelen specifiek voor simulatie beginnen met 3 kenletters,
c gevolgd door 1 cijfer; betekenis kenletters
c sCD : ’cosntant data’ (rekentijdstap)
c sPD : ’parmater data’
c sIV : ’input variable’ (tijd, versnelling)
c sMV : ’memory variable’
c sTV : ’temporary variable’
c sOV : ’output variable’ (delayed verstelsnelheid pitch-systeem)
c sOI : ’output/input variable’ (simulatie hulp tijdvariabele)
c DECLARATIE PROGRAMMA-VARIABELEN EIGENLIJKE REGELING
c =====================================================
c Input & Outputs
c -------------real
IV01Theta1 ! bladhoekwaarde van blad 1 (’referentie-blad’)
real IV04NrpmSmp ! toerentalmeting (halve regelcyclustijd delayed)
integer IV05InitCall ! initialisatie vlag (1: eerste aanroep; 0: volgende)
real IV02Theta2 ! hoekwaarde blad 2 (niet gebruik in simulatie)
real IV03Theta3 ! hoekkwaarde blad 3 (niet gebruik in simulatie)
26 ECN-CX--00-083

CONTROL ALGORITHM (LMH95)
real OV01dThdtset1 ! gewenste verstelsnelh. blad 1 (’referentie-blad’)
real OV02dThdtset2 ! gewenste verstelsnelh. blad 2 (niet in simulatie’)
real OV03dThdtset3 ! gewenste verstelsnelh. blad 3 (’niet in simulatie’)
c Constanten
c ----------c
cyclus tijd van de regeling [s]
real CD01TdelCtrl
c Parameters
c --------c
parametrisering 4e orde filter voor dN/dt; (toestandmatrix ’kolomsgewijs’)
real PD01alo3p(16), PD02blo3p(4), PD03clo3p(4), PD04dlo3p,
& PD04bglo3p(4)
c 1e orde fit voor reciproke schedule factor tbv P- en D-actie en dode zone
real PD05pInvSchFac(2)
c boven- en ondergrens voor bladhoek waarbinnen toerensetpoint-aanpassing
c plaatsvindt [dg]; onthoudfactor voor setpoint-aanpassing.
real PD06ThULAdapNref, PD07ThLLAdapNref, PD08WeightNrefOld
c basis-waarden P- en D-regelaarversterking [(dg/s)/rpm, ./(rpm/s)], subnominaalc
multiplier en bladverstelsnelheid [dg/s] bij harde ingreep op hoogtoerental
real PD09KpropRpm, PD10KdiffRpm, PD11MuKsubnom,
& PD12dThdtFuzTarg
c onthoudfactor voor toerentalgemiddelde voor omschakelen vollast->deellast
real PD13WeightNswitchOld
c toerentallen [rpm] en bijbehorende bladhoeken [dg] voor bladsturing in deellast
c 220200: lengte wordt 10, dit was 19
real PD14NrpmList(10), PD15ThdgList(10)
c P-terugkopfactor van bladhoekfout naar bladverstelsnelheid [(dg/s) / dg]
real PD16KsynDgr
c Basis-waarde inactivity zone bladverstelsnelheid [dg/s]
real PD17dThdtZoneInacBase
c maximum en minimum waarde bladverstelsnelheid [dg/s]
real PD18dThdtmax, PD19dThdtmin
c maximum en minimum waarde bladhoek [dg/s]
real PD20Thmax, PD21Thmin
c Setpoints
c -------c
nominale toerental en maximale offset (naar boven) van het nominale toerental
c bij stijgende glijdend gemiddelde bladhoek
real SD01NrpmNom, SD02NrpmRatOffMax;
c toerentalgrens waarboven harde ingreep plaatsvindt, rotorracceleratie
c waarbeneden ingreep voortijdig stopt en maximale bladhoekvergroting daarvan
real SD03NrpmLimFuz, SD04NrpmDdtLimFuz, SD05DeltaThFuz
c toerentalgrenzen waarboven omgeschakeld wordt van deellast naar vollast
c en waarbeneden omgeschakeld wordt van vollast naar deellast
real SD06NrpmToPartial, SD07NrpmToFull
c Hulpvariabelen met geheugenfunctie
ECN-CX--00-083 27

Blade pitch control algorithms DOWEC
c ---------------------------------------real
MV01NrpmSmpOld, MV02XrpmDdtLo3pOld(4),
& MV02bXrpmLo3pOld(4), MV03NrpmRefOld,
& MV05ThstartFuz, MV06NrpmSwitchOld, MV09ThOld
integer MV04BusyFuzCtrl, MV07SpUpIndex, MV08ProductionState,
& MV10dThdtsetState
c Hulpvariabelen zonder geheugenfunctie
c =====================================
real TV01NrpmSmpDdt, TV02XrpmDdtLo3p(4),
& TV02bXrpmLo3p(4), TV03NrpmDdtLo3p,
& TV04NrpmLo3p, TV05SchFac, TV06NrpmRatOff,
& TV07NrpmRef, TV08dThdtsetP, TV09dThdtsetD,
& TV10dThdtsetFuz, TV11NrpmSwitch, TV13ThetaSet,
& TV14dThdtsetTmp, TV15dThdtZoneInac, TV18r
integer TV12SpLoIndex, TV16i, TV17j
c DECLARATIE PROGRAMMA-VARIABELEN SPECIFIEK VOOR SIMULATIE
c ========================================================
c Inputs & Outputs
c --------------real
sIV1t ! simulatie-tijdstip [s]
real sIV2H ! rekentijdstap simulatie in regeling-inbeddend programma [s]
real sOV1dThdt ! bladverstelsnelheid [dg/s] NA overall delay regeling+servo
real sOI1t_pre ! eerder simulatie-tijdstip; ter bepalig verstrijken regelcyclustijd.
real sIV4OmegaR ! rotortoerental [rad/s]
real sOV2Te ! elektromechanisch koppel [Nm]
real sIV3domeg ! rotoracceleratie [rad/s^2] (niet gebruikt)
c Parameters
c --------c
vervangende delay voor transiente dynamica in pitch-servo, voor echter
c loop delay daarin en voor extra delay in geval van bewegingsommekeer
real sPD1TdelPtTrans, sPD2TdelPtLoop, sPD3TdelPtLoad
c polynoomcoefficienten voor koppelsetpoint; tijdconstante "orde 1 dynamica"
real sPD4pTe(4), sPD5Tgen, sPD6PwattNom
c Hulpvariabelen met geheugenfunctie
c ==================================
integer sMV1basicdelayratio, sMV2loaddelayratio
real sMV3dThdtsetHist(50), sMV4dThdtsetOld
real sMV5TeOld, sMV6WeightTeOld, sMV7NrpsNom
c Modif 991111 begin; toegevoegd
c Input vanuit regelgedeelte (ook hulpvariabelen met geheugenfunctie)
real sMV8dThdtset1
c Modif 991111 einde
c Hulpvariabelen zonder geheugenfunctie
c =====================================
integer sTV1PitchsignReverse
real sTV2dThdtInter
real sTV3Teset
c SAVE-DIRECTIEVEN VOOR INTERNE VARIABELEN MET GEHEUGEN FUNCTIE
c =============================================================
28 ECN-CX--00-083

c Regeling
c ------save
MV01NrpmSmpOld, MV02XrpmDdtLo3pOld, MV03NrpmRefOld,
& MV05ThstartFuz, MV06NrpmSwitchOld, MV09ThOld
c toegevoegd 4 mei 2000
save MV02bXrpmLo3pOld
c end
save MV04BusyFuzCtrl, MV07SpUpIndex, MV08ProductionState,
& MV10dThdtsetState
c Simulatie
c -------save
sMV1basicdelayratio, sMV2loaddelayratio
save sMV3dThdtsetHist, sMV4dThdtsetOld, sMV7NrpsNom
c Modif 991111 begin; toegevoegd
save sMV8dThdtset1
c Modif 991111 einde
CONTROL ALGORITHM (LMH95)
c DATA-DIRECTIEVEN VOOR CONSTANTEN, PARAMETERS EN SETPOINTS REGELING
c ==================================================================
c datblok1.f wordt aangemaakt door MATLAB programma agsimprd.m
c het index refereert aan de rotorkeuze iRot
include ’datblok1’
c Doe de volgende initialisaties achter elke start-up procedure
c -----------------------------------------------------------if
(IV05InitCall .EQ. 1)then
c initialisaties tbv regeling
MV01NrpmSmpOld = IV04NrpmSmp
TV16i = 0
8999 TV16i = TV16i + 1
MV02XrpmDdtLo3pOld(TV16i) = 0.0
MV02bXrpmLo3pOld(TV16i) = PD04bglo3p(TV16i)*IV04NrpmSmp
if(TV16i .LT. 4)goto 8999
MV03NrpmRefOld = SD01NrpmNom
MV06NrpmSwitchOld = IV04NrpmSmp
MV04BusyFuzCtrl = 0
MV07SpUpIndex = 2
MV07SpUpIndex = 0
7999 MV07SpUpIndex = MV07SpUpIndex + 1
if( PD14NrpmList(MV07SpUpIndex) < MV01NrpmSmpOld )goto 7999
if(IV04NrpmSmp .LT. SD01NrpmNom)then
MV08ProductionState = 0 ! deellastregeling actief
else
MV08ProductionState = 1 ! vollastregeling actief
endif
MV09ThOld = IV01Theta1
MV10dThdtsetState = 0 ! pitch speed setting in dode zone
c Modif 991111 begin ; toegevoegd
OV01dThdtset1 = 0.0
OV02dThdtset2 = 0.0
OV03dThdtset3 = 0.0
c Modif 991111 eind
ECN-CX--00-083 29

Blade pitch control algorithms DOWEC
c initialisaties tbv pitch-servo simulatie
sOI1t_pre = sIV1t
TV18r = (sPD1TdelPtTrans+sPD2TdelPtLoop+CD01TdelCtrl)/sIV2H
c TV18r = TV18r+(0.5+sign(0.5,TV18r))*0.9999
sMV1basicdelayratio = int(TV18r+0.5)
sMV2loaddelayratio = 0 ! initialisatie extra pitch-delay [samples]
9999
sMV4dThdtsetOld = 0.0
TV16i = 0
TV16i = TV16i+1
sMV3dThdtsetHist(TV16i) = sMV4dThdtsetOld
if(TV16i .LT. sMV1basicdelayratio)goto 9999
TV18r = sIV4OmegaR*sIV4OmegaR
c Modif 991111 begin ; naar boven geplaatst: VOOR de volgende if(..)
sMV7NrpsNom = SD01NrpmNom * 1.047197551196598e-001
c Modif 991111 eind
if(sIV4OmegaR .LT. sMV7NrpsNom)then
sMV5TeOld = sPD4pTe(1)*sIV4OmegaR*TV18r+ sPD4pTe(2)*TV18r+
& sPD4pTe(3)*sIV4OmegaR + sPD4pTe(4)
if(sMV5TeOld .LT. 0.0)then
sMV5TeOld= 0.0
endif
else
sMV5TeOld
endif
= sPD6PwattNom / sIV4OmegaR
sMV6WeightTeOld = 1.0 / (1.0 + sIV2H / sPD5Tgen)
c Modif 991111 begin ; toegevoegd
sMV8dThdtset1 = OV01dThdtset1
c Modif 991111 einde
endif
c eind initialisatie
c REGELALGORITHME SIMULATIE: ALGORITHME MET CYCLUS TIJD TdelCtrl sec
c SPE OUD: 100 if((regelloop) .and. (t-t_pre is een veelvoud van tDelCtrl)
c SPE OUD: & .and. goede moment in integratie routine)then
if(sOI1t_pre .LT. sIV1t + sIV2H/2.0)then ! timing regelcyclus-uitvoering
sOI1t_pre = sOI1t_pre + CD01TdelCtrl
c bepaal momentane rotorversnelling
TV01NrpmSmpDdt = (IV04NrpmSmp-MV01NrpmSmpOld)/CD01TdelCtrl
c update de toestandsvectoren van 4e orde low pass filter filters
TV16i = 0
8998 TV16i = TV16i+1
TV02XrpmDdtLo3p(TV16i) =
& PD01alo3p( (TV16i-1)*4 + 1)*MV02XrpmDdtLo3pOld(1)
& + PD02blo3p(TV16i)*TV01NrpmSmpDdt
TV02bXrpmLo3p(TV16i) =
& PD01alo3p( (TV16i-1)*4 + 1)*MV02bXrpmLo3pOld(1)
& + PD02blo3p(TV16i)*IV04NrpmSmp
TV17j = 1
8997 TV17j = TV17j+1
TV02XrpmDdtLo3p(TV16i) = TV02XrpmDdtLo3p(TV16i) +
& PD01alo3p( (TV16i-1)*4+TV17j)* MV02XrpmDdtLo3pOld(TV17j)
TV02bXrpmLo3p(TV16i) = TV02bXrpmLo3p(TV16i) +
30 ECN-CX--00-083

CONTROL ALGORITHM (LMH95)
& PD01alo3p( (TV16i-1)*4+TV17j)* MV02bXrpmLo3pOld(TV17j)
if(TV17j .LT. 4)goto 8997
if(TV16i .LT. 4)goto 8998
c bepaal de uitgangswaarde van de filters (snelheid in TV04NrpmLo3p, versnelling in TV03NrpmDdtLo3p)
TV03NrpmDdtLo3p = PD03clo3p(1) * MV02XrpmDdtLo3pOld(1) +
& PD04dlo3p*TV01NrpmSmpDdt
TV04NrpmLo3p = PD03clo3p(1) * MV02bXrpmLo3pOld(1) +
& PD04dlo3p*IV04NrpmSmp
TV17j = 1
8996 TV17j = TV17j+1
TV03NrpmDdtLo3p = TV03NrpmDdtLo3p +
& PD03clo3p(TV17j)* MV02XrpmDdtLo3pOld(TV17j)
TV04NrpmLo3p = TV04NrpmLo3p +
& PD03clo3p(TV17j)* MV02bXrpmLo3pOld(TV17j)
if(TV17j .LT. 4)goto 8996
c maak shift voor oude toestandsvector
TV16i = 0
8995 TV16i = TV16i+1
MV02XrpmDdtLo3pOld(TV16i) = TV02XrpmDdtLo3p(TV16i)
MV02bXrpmLo3pOld(TV16i) = TV02bXrpmLo3p(TV16i)
if(TV16i .LT. 4)goto 8995
c bepaal laagdoorlaat toerental waarde voor overgang vollast => deellast
TV11NrpmSwitch = PD13WeightNswitchOld*MV06NrpmSwitchOld +
& (1-PD13WeightNswitchOld)* IV04NrpmSmp
c bepaal actuele bedrijfstoestand: vollast of deellast
if(MV08ProductionState .EQ. 1)then ! vollastbedrijf
if (TV11NrpmSwitch .LT. SD06NrpmToPartial)then
MV08ProductionState = 0 ! ga naar deellast
endif
else ! deellastbedrijf
if (IV04NrpmSmp .GT. SD07NrpmToFull)then
MV08ProductionState = 1 ! ga naar vollast
TV11NrpmSwitch = IV04NrpmSmp ! her-intialiseer LF-toerental
endif
endif
MV06NrpmSwitchOld = TV11NrpmSwitch
c bepaal eventuele opwaartse toerensetpoint verschuiving
TV06NrpmRatOff = SD02NrpmRatOffMax *
& (min(PD06ThULAdapNref,max(IV01Theta1, PD07ThLLAdapNref))-
& PD07ThLLAdapNref) /
& (PD06ThULAdapNref-PD07ThLLAdapNref)
TV07NrpmRef = PD08WeightNrefOld*MV03NrpmRefOld +
& (1-PD08WeightNrefOld)* (SD01NrpmNom + TV06NrpmRatOff)
MV03NrpmRefOld = TV07NrpmRef
c bepaal actuele schedule factor
TV05SchFac = 1 / (min(1.0, PD05pInvSchFac(1)* IV01Theta1 +
& PD05pInvSchFac(2)))
c bepaal PD-terugkoppeling op bladverstelsnelheid
TV08dThdtsetP = TV05SchFac*PD09KpropRpm*
& (TV07NrpmRef-IV04NrpmSmp) !P-actie
ECN-CX--00-083 31

Blade pitch control algorithms DOWEC
TV09dThdtsetD = TV05SchFac*PD10KdiffRpm*(-TV03NrpmDdtLo3p) !D-actie
if(IV04NrpmSmp .LT. SD01NrpmNom)then !regelaarversterking +30% "ondernom."
C vanwege tegenkoppeling generator beneden nom. toeren
TV08dThdtsetP = PD11MuKsubnom * TV08dThdtsetP
TV09dThdtsetD = PD11MuKsubnom * TV09dThdtsetD
endif
c bepaal gedwongen bladhoeksturing in geval overschrijding limietwaarde
if(MV04BusyFuzCtrl .EQ. 0 .AND. IV04NrpmSmp .GT. SD03NrpmLimFuz
& .AND. TV03NrpmDdtLo3p .GT. SD04NrpmDdtLimFuz)then
MV04BusyFuzCtrl = 1 ! start gedwongen bladhoeksturing
&
MV05ThstartFuz = IV01Theta1
endif
if(MV04BusyFuzCtrl .EQ. 1)then ! gedwongen bladhoeksturing actief
TV10dThdtsetFuz = PD12dThdtFuzTarg -
(TV08dThdtsetP+TV09dThdtsetD)
if (IV01Theta1 .GT. MV05ThstartFuz+SD05DeltaThFuz .OR.
& TV03NrpmDdtLo3p .LT. SD04NrpmDdtLimFuz)then
MV04BusyFuzCtrl = 0 ! stop gedwong bladhoeksturing
endif
else
TV10dThdtsetFuz = 0.0
endif
c bepaal deellast bladhoeksetting
if( TV04NrpmLo3p .GT. PD14NrpmList(MV07SpUpIndex) )then
MV07SpUpIndex = MV07SpUpIndex + 1
else
if( TV04NrpmLo3p .LT. PD14NrpmList(MV07SpUpIndex-1))then
MV07SpUpIndex = MV07SpUpIndex - 1
endif
endif
TV12SpLoIndex = MV07SpUpIndex - 1
TV13ThetaSet = PD15ThdgList(TV12SpLoIndex) +
& (PD15ThdgList(MV07SpUpIndex) - PD15ThdgList(TV12SpLoIndex))*
& ( TV04NrpmLo3p - PD14NrpmList(TV12SpLoIndex)) /
& (PD14NrpmList(MV07SpUpIndex) - PD14NrpmList(TV12SpLoIndex))
if(MV08ProductionState .EQ. 0)then ! deellastbedrijf
c DEELLAST
c bepaal actuele bladhoeksturing in deellast
if(TV13ThetaSet .GT. IV01Theta1 + 0.20)then
TV14dThdtsetTmp = 1.0
else
if(TV13ThetaSet .LT. IV01Theta1 - 0.20)then
if(TV13ThetaSet .LT. IV01Theta1 - 5.0)then
TV14dThdtsetTmp = -0.5
else
TV14dThdtsetTmp = -1.0
endif
else
TV14dThdtsetTmp = 0.0
endif
endif
c
else ! vollastbedrijf
c VOLLAST
c pas verlopende regelaarversterking en dynamische dode zone toe in vollast
32 ECN-CX--00-083

CONTROL ALGORITHM (LMH95)
TV14dThdtsetTmp =TV08dThdtsetP+TV09dThdtsetD+TV10dThdtsetFuz
c pas 1.01 keer de regelaarversterking tot aan de grens van de inactivity zone;
c laat daarbuiten de regelaarversterking lineair terug lopen tot de ‘nominale
c waarde’ (bladhoekafhankelijk) bij tweemaal de grens van de inactivity zone;
TV15dThdtZoneInac = TV05SchFac * PD17dThdtZoneInacBase
if (TV14dThdtsetTmp .gt. 0.)then
TV14dThdtsetTmp =
& max(TV14dThdtsetTmp,min(1.01*TV14dThdtsetTmp,
& 1.01*TV15dThdtZoneInac))
else
TV14dThdtsetTmp =
& min(TV14dThdtsetTmp,max(1.01*TV14dThdtsetTmp,
& -1.01*TV15dThdtZoneInac))
endif
c pas de dode zone toe met hysteresis
if(MV10dThdtsetState .EQ. 0)then ! bladverstelsysteem in rust
if(TV14dThdtsetTmp .LT. 1.5*TV15dThdtZoneInac .AND.
& TV14dThdtsetTmp .GT. -1.5*TV15dThdtZoneInac)then
TV14dThdtsetTmp = 0.0; !blijf binnen inactivity zone ’+ delta’
else
MV10dThdtsetState = 1; !komt buiten inactiv.zone + delta => uit rust
endif
else ! bladverstelsysteem actief
if (TV14dThdtsetTmp .LT. 0.5*TV15dThdtZoneInac .AND.
& TV14dThdtsetTmp .GT. -0.5*TV15dThdtZoneInac)then
MV10dThdtsetState = 0; !komt binnen activity zone ’-delta’=>in rust
TV14dThdtsetTmp = 0.0;
endif
endif ! einde if on dode zone hysteresis
endif !einde if on ProductionState !
c laat geen bladverstelling toe als buiten de extremen getreden zou gaan worden
if (((TV14dThdtsetTmp .gt. 0.) .and.
& (MV09ThOld .lt. PD20Thmax)) .or.
& ((TV14dThdtsetTmp .lt. 0.) .and.
& (MV09ThOld .gt. PD21Thmin))) then
OV01dThdtset1 = TV14dThdtsetTmp
else
OV01dThdtset1 = 0.0
endif
c begrens de verstelsnelheid op extremen
OV01dThdtset1 =
& max(PD19dThdtmin, min(OV01dThdtset1, PD18dThdtmax))
MV09ThOld = IV01Theta1
MV01NrpmSmpOld = IV04NrpmSmp
c Modif 991111 begin ; toegevoegd
sMV8dThdtset1 = OV01dThdtset1
c Modif 991111 einde
c Modif 991111 begin ; toegevoegd
else
OV01dThdtset1 = sMV8dThdtset1
OV02dThdtset2 = sMV8dThdtset1
OV03dThdtset3 = sMV8dThdtset1
c Modif 991111 einde
ECN-CX--00-083 33

Blade pitch control algorithms DOWEC
endif ! eind regeling
c PITCH-SERVO DYNAMICS SIMULATIE VIA DELAY: ALGORITHME MET CYCLUS TIJD H sec
c simul. de basis-delay in algor en actuator (TdelPtTrans+TdelPtLoop+TdelCtrl)
sTV2dThdtInter = sMV3dThdtsetHist(sMV1basicdelayratio)
TV16i = sMV1basicdelayratio+1
9998 TV16i = TV16i-1
sMV3dThdtsetHist(TV16i) = sMV3dThdtsetHist(TV16i-1)
if(TV16i .GT. 2)goto 9998
c Modif 991111 begin ; sMV8dThdtset1 ipv OV01dThdtset1
sMV3dThdtsetHist(1) = sMV8dThdtset1
c Modif 991111 einde
c simuleer extra delay in actuator bij 0-doorgang voor dThdt ter grootte 0.08s
c Modif 991111 begin; sMV8dThdtset1 ipv OV01dThdtset1
if ((sMV8dThdtset1.gt.0.) .and. (sMV4dThdtsetOld .le. 0.))then
sTV1PitchsignReverse=1 ! from in to out
else
if ((sMV8dThdtset1 .lt. 0.) .and. (sMV4dThdtsetOld.ge.0.))then
sTV1PitchsignReverse=-1 ! from out to in
else
sTV1PitchsignReverse = 0
endif
endif
c Modif 991111 einde
if ((sTV1PitchsignReverse .ne. 0) .and.
& (sMV2loaddelayratio .eq. 0))then
TV18r= sPD3TdelPtLoad / sIV2H
sMV2loaddelayratio=int(TV18r+0.50) +
& sMV1basicdelayratio
endif
if (sMV2loaddelayratio .gt. 0)then
sOV1dThdt=0
sMV2loaddelayratio = sMV2loaddelayratio-1
else
sOV1dThdt = sTV2dThdtInter
endif
c simuleer electro-mechanische conversie via 1e orde dynamica
TV18r = sIV4OmegaR*sIV4OmegaR
if(sIV4OmegaR .LT. sMV7NrpsNom)then
sTV3Teset = sPD4pTe(1)*sIV4OmegaR*TV18r+ sPD4pTe(2)*TV18r+
& sPD4pTe(3)*sIV4OmegaR + sPD4pTe(4)
if(sTV3Teset .LT. 0.0)then
sTV3Teset = 0.0
endif
else
sTV3Teset = sPD6PwattNom / sIV4OmegaR
endif
sOV2Te = sMV6WeightTeOld * sMV5TeOld +
& (1.0-sMV6WeightTeOld) * sTV3Teset
sMV5TeOld = sOV2Te
c Modif 991111 begin; sMV8dThdtset1 ipv OV01dThdtset1
sMV4dThdtsetOld = sMV8dThdtset1
34 ECN-CX--00-083

c Modif 991111 einde
return
end
CONTROL ALGORITHM (LMH95)
ECN-CX--00-083 35

Blade pitch control algorithms DOWEC
36 ECN-CX--00-083

APPENDIX B. CONTROL ALGORITHM
(LMH46-5-X00)
B.1 Modification with respect to LMH95
The structure of the control algorithm remains similar with respect to the algorithm
as used for LMH95 rotor (chapter 3), therefore only the modifications and/or
changes of turbine- and controlparameters are listed below
1. Rotoraerodynamic characteristics (Cp-Ct curves as function of λ for different
pitch angles) as given by [10]
2. RpmPartin = 9.5 (Cut-in rotor speed [rpm])
3. RpmOptout = 13.9 (End of optimal lambda control, partial load operation [rpm])
4. RpmRat = 14.9 (Rated rotor speed [rpm])
5. Rbs = 48.0 (Rotor radius (to rotor center) [m])
6. Jrs = 13450000 (Rotor inertia [kg · m 2 ])
7. iTran = 110.3 (Gear box ratio [-])
Therefore, the optimum tip-speed ratio becomes 7.5 and the ‘stiffness’ of the
transition from optimum tip-speed to rated speed about 810 kNm/rpm.
Because of change of rated rotor speed RpmRat from 15.1rpm to 14.9 rpm, not only
the parameters of the linear PD compensator and gain scheduling has been changed
(due to Cp-curves), but the parameters of the rotor speed lowpass filter (aLo3p,
bLo3p, cLo3p, dLo3p), rotor speed limitation (NrpmLimFuz) and the parameters of
partial- to full load transition (NrpmToPartial, NrpmToFull) as well.
During partial load operation, the pitch angle was set to a constant value (Theta-
PartConstant) of 0.6 o .
The results of stability analysis and time domain simulations with parameters as
given in section B.2 were comparable to the results in chapter 3.
B.2 Parameters and setpoints: DATBLOK3.fi
c Regelparameters en setpoints t.b.v. NM3000-LMH46-5-X00 bladen
c Datum: 26-Jun-2000
c Constanten
c ==========
DATA CD01TdelCtrl /0.1/
c Parameters
c ==========
c Let op dimensie in declaratie van PD01alo3p!
DATA PD01alo3p/
& 5.673184e-001, -2.430629e-001, 0.000000e+000, 0.000000e+000,
& 2.430629e-001, 9.623053e-001, 0.000000e+000, 0.000000e+000,
& -2.508988e-001, 1.036672e+000, 8.844083e-001, -2.019599e-001,
& -2.688986e-002, 1.111045e-001, 2.019599e-001, 9.783551e-001/
c Let op dimensie in declaratie van PD02blo3p!
DATA PD02blo3p/
& 2.763758e-001, 4.286091e-002, 2.880477e-001, 3.087127e-002/
ECN-CX--00-083 37

Blade pitch control algorithms DOWEC
c Let op dimensie in declaratie van PD03clo3p!
DATA PD03clo3p/
& -1.034826e-001, 4.275728e-001, -3.291897e-002, 5.438949e-002/
DATA PD04dlo3p/
& 1.188045e-001/
c Let op dimensie in declaratie van PD04glo3p!
DATA PD04bglo3p/
& -2.657900e-016, 1.137055e+000, 3.083043e-015, 7.262833e+000/
c Let op dimensie in declaratie van PD05pInvSchFac!
DATA PD05pInvSchFac/
& 4.124546e-002, 1.525675e-001/
DATA PD06ThULAdapNref/12.0/
DATA PD07ThLLAdapNref/ 5.0/
DATA PD08WeightNrefOld/ 9.9010e-001/
DATA PD09KpropRpm/ -0.10906/
DATA PD10KdiffRpm/ -1.47836/
DATA PD11MuKsubnom/ 1.75/
DATA PD12dThdtFuzTarg/ 5.0/
DATA PD13WeightNswitchOld/ 9.9010e-001/
c Let op dimensie in declaratie van PD14NrpmList en PD15ThdgList!
DATA PD14NrpmList/ -29.80, 9.50, 10.27, 11.04, 11.81,
& 12.59, 13.36, 14.13, 14.90, 29.80/
c Deellastbladhoeken zijn NIET geoptimaliseerd
DATA PD15ThdgList/ 0.60, 0.60, 0.60, 0.60, 0.60,
& 0.60, 0.60, 0.60, 0.60, 0.60/
c Deze parameter is niet automatisch gegenereerd
DATA PD16KsynDgr/1.52/
DATA PD17dThdtZoneInacBase/0.20/
DATA PD18dThdtmax/ 5.0/
DATA PD19dThdtmin/-5.0/
DATA PD20Thmax/ 90.0/
DATA PD21Thmin/ -1.0/
c Setpoints
c ----------
DATA SD01NrpmNom/14.9/
DATA SD02NrpmRatOffMax/ 2.0/
38 ECN-CX--00-083

DATA SD03NrpmLimFuz/17.6/
DATA SD04NrpmDdtLimFuz/ 0.0/
DATA SD05DeltaThFuz/ 3.0/
DATA SD06NrpmToPartial/14.4/
DATA SD07NrpmToFull/15.2/
c Data directieven voor parameters specifiek voor simulatie
c ----------
DATA sPD1TdelPtTrans/0.000/
DATA sPD2TdelPtLoop/0.039/
DATA sPD3TdelPtLoad/0.100/
c Let op gedeclareerde lengte van dit polynoom!
DATA sPD4pTe/
& 0.0000e+000, 5.3389e+005, 3.1188e+002, -1.5207e+002/
DATA sPD5Tgen/ 0.3/
DATA sPD6PwattNom/ 3e+006/
CONTROL ALGORITHM (LMH46-5-X00)
ECN-CX--00-083 39

Blade pitch control algorithms DOWEC
40 ECN-CX--00-083

APPENDIX C. CONTROL ALGORITHM
(LMH46-5-X01)
C.1 Modification with respect to LMH46-5-X00
The structure of the control algorithm remains similar with respect to the algorithm
as used for LMH95 rotor (chapter 3), only the aerodynamic characteristics has
been changed (10% slender blades) [11].
The optimum tip-speed ratio becomes 8 and the ‘stiffness’ of the transition from
optimum tip-speed to rated speed about 1001 kNm/rpm. The consequences of
different aerodynamic rotor properties (Cp- and Ct-curves), without any other
adaption (like rated rotor speed or rotor inertia), are restricted to different values of
proportional- and differential gain of the compensator (Kprop, Kdiff) and different
polynomial coefficients of the gain scheduling (pInvSchFac).
During partial load operation, the pitch angle was again set to a constant value
(ThetaPartConstant) of 0.6 o .
The results of stability analysis and time domain simulations with parameters as
given in section C.2 were comparable to former results.
C.2 Parameters and setpoints: DATBLOK4.fi
c Regelparameters en setpoints t.b.v. NM3000-LMH46-5-X01 bladen
c Datum: 12-Jul-2000
c Constanten
c ==========
DATA CD01TdelCtrl /0.1/
c Parameters
c ==========
c Let op dimensie in declaratie van PD01alo3p!
DATA PD01alo3p/
& 5.673184e-001, -2.430629e-001, 0.000000e+000, 0.000000e+000,
& 2.430629e-001, 9.623053e-001, 0.000000e+000, 0.000000e+000,
& -2.508988e-001, 1.036672e+000, 8.844083e-001, -2.019599e-001,
& -2.688986e-002, 1.111045e-001, 2.019599e-001, 9.783551e-001/
c Let op dimensie in declaratie van PD02blo3p!
DATA PD02blo3p/
& 2.763758e-001, 4.286091e-002, 2.880477e-001, 3.087127e-002/
c Let op dimensie in declaratie van PD03clo3p!
DATA PD03clo3p/
& -1.034826e-001, 4.275728e-001, -3.291897e-002, 5.438949e-002/
DATA PD04dlo3p/
& 1.188045e-001/
c Let op dimensie in declaratie van PD04glo3p!
DATA PD04bglo3p/
& -2.657900e-016, 1.137055e+000, 3.083043e-015, 7.262833e+000/
ECN-CX--00-083 41

Blade pitch control algorithms DOWEC
c Let op dimensie in declaratie van PD05pInvSchFac!
DATA PD05pInvSchFac/
& 4.217839e-002, 1.556636e-001/
DATA PD06ThULAdapNref/12.0/
DATA PD07ThLLAdapNref/ 5.0/
DATA PD08WeightNrefOld/ 9.9010e-001/
DATA PD09KpropRpm/ -0.11559/
DATA PD10KdiffRpm/ -1.56688/
DATA PD11MuKsubnom/ 1.75/
DATA PD12dThdtFuzTarg/ 5.0/
DATA PD13WeightNswitchOld/ 9.9010e-001/
c Let op dimensie in declaratie van PD14NrpmList en PD15ThdgList!
DATA PD14NrpmList/ -29.80, 9.50, 10.27, 11.04, 11.81,
& 12.59, 13.36, 14.13, 14.90, 29.80/
c Deellastbladhoeken zijn NIET geoptimaliseerd
DATA PD15ThdgList/ 0.60, 0.60, 0.60, 0.60, 0.60,
& 0.60, 0.60, 0.60, 0.60, 0.60/
c Deze parameter is niet automatisch gegenereerd
DATA PD16KsynDgr/1.52/
DATA PD17dThdtZoneInacBase/0.20/
DATA PD18dThdtmax/ 5.0/
DATA PD19dThdtmin/-5.0/
DATA PD20Thmax/ 90.0/
DATA PD21Thmin/ 0.0/
c Setpoints
c ----------
DATA SD01NrpmNom/14.9/
DATA SD02NrpmRatOffMax/ 2.0/
DATA SD03NrpmLimFuz/17.6/
DATA SD04NrpmDdtLimFuz/ 0.0/
DATA SD05DeltaThFuz/ 3.0/
DATA SD06NrpmToPartial/14.4/
DATA SD07NrpmToFull/15.2/
c Data directieven voor parameters specifiek voor simulatie
42 ECN-CX--00-083

c ----------
DATA sPD1TdelPtTrans/0.000/
DATA sPD2TdelPtLoop/0.039/
DATA sPD3TdelPtLoad/0.100/
c Let op gedeclareerde lengte van dit polynoom!
DATA sPD4pTe/
& 0.0000e+000, 4.4117e+005, 4.8306e+002, -2.6992e+002/
DATA sPD5Tgen/ 0.3/
DATA sPD6PwattNom/ 3e+006/
CONTROL ALGORITHM (LMH46-5-X01)
ECN-CX--00-083 43

Blade pitch control algorithms DOWEC
44 ECN-CX--00-083

APPENDIX D. CONTROL ALGORITHM
(LMH46-5-X02)
D.1 Modification with respect to LMH46-5-X00
The structure of the control algorithm remains similar with respect to the algorithm
as used for LMH95 rotor (chapter 3), only the aerodynamic characteristics has
been changed (10% wider blades) [13].
The optimum tip-speed ratio becomes 7 and the ‘stiffness’ of the transition from
optimum tip-speed to rated speed about 545 kNm/rpm. The consequences of
different aerodynamic rotor properties (Cp- and Ct-curves), without any other
adaption (like rated rotor speed or rotorinertia), are restricted to different values of
proportional- and differential gain of the compensator (Kprop, Kdiff) and different
polynomial coefficients of the gain scheduling (pInvSchFac).
During partial load operation, the pitch angle was again set to a constant value
(ThetaPartConstant) of 0.6 o .
The results of stability analysis and time domain simulations with parameters as
given in section D.2 were comparable to former results.
D.2 Parameters and setpoints: DATBLOK5.fi
c Regelparameters en setpoints t.b.v. NM3000-LMH46-5-X02 bladen
c Datum: 13-Jul-2000
c Constanten
c ==========
DATA CD01TdelCtrl /0.1/
c Parameters
c ==========
c Let op dimensie in declaratie van PD01alo3p!
DATA PD01alo3p/
& 5.673184e-001, -2.430629e-001, 0.000000e+000, 0.000000e+000,
& 2.430629e-001, 9.623053e-001, 0.000000e+000, 0.000000e+000,
& -2.508988e-001, 1.036672e+000, 8.844083e-001, -2.019599e-001,
& -2.688986e-002, 1.111045e-001, 2.019599e-001, 9.783551e-001/
c Let op dimensie in declaratie van PD02blo3p!
DATA PD02blo3p/
& 2.763758e-001, 4.286091e-002, 2.880477e-001, 3.087127e-002/
c Let op dimensie in declaratie van PD03clo3p!
DATA PD03clo3p/
& -1.034826e-001, 4.275728e-001, -3.291897e-002, 5.438949e-002/
DATA PD04dlo3p/
& 1.188045e-001/
c Let op dimensie in declaratie van PD04glo3p!
DATA PD04bglo3p/
& -2.657900e-016, 1.137055e+000, 3.083043e-015, 7.262833e+000/
ECN-CX--00-083 45

Blade pitch control algorithms DOWEC
c Let op dimensie in declaratie van PD05pInvSchFac!
DATA PD05pInvSchFac/
& 4.418588e-002, 1.252048e-001/
DATA PD06ThULAdapNref/12.0/
DATA PD07ThLLAdapNref/ 5.0/
DATA PD08WeightNrefOld/ 9.9010e-001/
DATA PD09KpropRpm/ -0.09646/
DATA PD10KdiffRpm/ -1.30757/
DATA PD11MuKsubnom/ 1.75/
DATA PD12dThdtFuzTarg/ 5.0/
DATA PD13WeightNswitchOld/ 9.9010e-001/
c Let op dimensie in declaratie van PD14NrpmList en PD15ThdgList!
DATA PD14NrpmList/ -29.80, 9.50, 10.27, 11.04, 11.81,
& 12.59, 13.36, 14.13, 14.90, 29.80/
c Deellastbladhoeken zijn NIET geoptimaliseerd
DATA PD15ThdgList/ 0.60, 0.60, 0.60, 0.60, 0.60,
& 0.60, 0.60, 0.60, 0.60, 0.60/
c Deze parameter is niet automatisch gegenereerd
DATA PD16KsynDgr/1.52/
DATA PD17dThdtZoneInacBase/0.20/
DATA PD18dThdtmax/ 5.0/
DATA PD19dThdtmin/-5.0/
DATA PD20Thmax/ 90.0/
DATA PD21Thmin/ 0.0/
c Setpoints
c ----------
DATA SD01NrpmNom/14.9/
DATA SD02NrpmRatOffMax/ 2.0/
DATA SD03NrpmLimFuz/17.6/
DATA SD04NrpmDdtLimFuz/ 0.0/
DATA SD05DeltaThFuz/ 3.0/
DATA SD06NrpmToPartial/14.4/
DATA SD07NrpmToFull/15.2/
c Data directieven voor parameters specifiek voor simulatie
46 ECN-CX--00-083

c ----------
DATA sPD1TdelPtTrans/0.000/
DATA sPD2TdelPtLoop/0.039/
DATA sPD3TdelPtLoad/0.100/
c Let op gedeclareerde lengte van dit polynoom!
DATA sPD4pTe/
& 0.0000e+000, 6.5995e+005, 7.2261e+002, -4.0378e+002/
DATA sPD5Tgen/ 0.3/
DATA sPD6PwattNom/ 3e+006/
CONTROL ALGORITHM (LMH46-5-X02)
ECN-CX--00-083 47

Blade pitch control algorithms DOWEC
48 ECN-CX--00-083

APPENDIX E. CONTROL ALGORITHM
(LMH46-5-X00-A)
E.1 Modification with respect to LMH46-5-X00
The structure of the control algorithm remains similar with respect to the algorithm
as used for LMH46-5-X00 rotor (Appendix B), the following modifications
and/or changes are listed below
1. RpmPartin = 8.6 (Cut-in rotor speed [rpm])
2. RpmDsgn = 12.3 (Synchronous rotor speed)
3. RpmOptout = 12.4 (End of optimal lambda control, partial load operation [rpm])
4. RpmRat = 13.5 (Rated rotor speed [rpm])
These modifications result in new generatorcurves with reduced rotor speed
(90.3%, [8]). For clarity in figure E.1 the ‘baseline’ generatorcurves (dashed
lines) and the ‘reduced’ generatorcurves are given. The optimum tip-speed ratio
becomes 6.8 and the ‘stiffness’ of the transition from optimum tip-speed to rated
speed about 978 kNm/rpm. A loss of 2% annual energy yield has been determined
by Blade Optimisation Tool (BOT).
generator torque (slow shaft equiv) [kNm]
electric power [kW]
2500
2000
1500
1000
500
3500
3000
2500
2000
1500
1000
torque rotorspeed curve
0
8 10 12 14 16 18
500
power rotorspeed curve
0
8 10 12 14 16 18
rotorspeed [rpm]
electric power [kW]
3500
3000
2500
2000
1500
1000
rotor speed [rpm]
500
file C:\vdhooft\nm3000ct\data\ps\genkar36.ps 20−Jul−2000
by C:\vdhooft\nm3000ct\DATA\M\cpgenkar.m
power windspeed curve
0
0 5 10 15 20 25
18
16
14
12
10
rotorspeed windspeed curve
8
0 5 10 15 20 25
wind speed [m/s]
Figure E.1 Generatorcurve comparison between ‘baseline’ (dashed lines) and the ‘10%
reduced’
Because of change of rated rotor speed RpmRat from 14.9rpm to 13.5 rpm, not
only the parameters of the linear PD compensator and gain scheduling has been
changed (due to Cp-curves), but the parameters of the rotor speed lowpass filter
(aLo3p, bLo3p, cLo3p, dLo3p), rotor speed limitation (NrpmLimFuz) and the
parameters of partial- to full load transition (NrpmToPartial, NrpmToFull) as well.
During partial load operation, the pitch angle was set to a constant value (Theta-
PartConstant)of1 o . In case of small pitch angles (

Blade pitch control algorithms DOWEC
ponential instability. This is due to the destabilising effect of the ‘natural speed
feedback’ (aerodynamic torque to rotor speed sensitivity) and generatorcharacteristic
(electric torque to rotor speed) in this range. In most cases these effects will
be sufficiently compensated by the linear PD-controller, except at some operating
points with pitch angles below 5 o During time domain simulations, driven by
stochastic wind, no negative effects of importance have been noticed. Parameters
are listed in section E.2.
E.2 Parameters and setpoints: DATBLOK6.fi
c Regelparameters en setpoints t.b.v. NM3000-LMH46-5-X00 bladen sub-opt
c Datum: 19-Jul-2000
c Constanten
c ==========
DATA CD01TdelCtrl /0.1/
c Parameters
c ==========
c Let op dimensie in declaratie van PD01alo3p!
DATA PD01alo3p/
& 6.372817e-001, -2.070875e-001, 0.000000e+000, 0.000000e+000,
& 2.070875e-001, 9.738071e-001, 0.000000e+000, 0.000000e+000,
& -2.357119e-001, 8.536955e-001, 9.078485e-001, -1.667643e-001,
& -2.060348e-002, 7.462117e-002, 1.667643e-001, 9.854232e-001/
c Let op dimensie in declaratie van PD02blo3p!
DATA PD02blo3p/
& 2.354698e-001, 2.978281e-002, 2.404825e-001, 2.102048e-002/
c Let op dimensie in declaratie van PD03clo3p!
DATA PD03clo3p/
& -1.184874e-001, 4.291346e-001, -3.428739e-002, 5.385848e-002/
DATA PD04dlo3p/
& 1.208855e-001/
c Let op dimensie in declaratie van PD04glo3p!
DATA PD04bglo3p/
& 2.903769e-016, 1.137055e+000, -1.749839e-015, 7.262833e+000/
c Let op dimensie in declaratie van PD05pInvSchFac!
DATA PD05pInvSchFac/
& 3.934832e-002, 1.202982e-001/
DATA PD06ThULAdapNref/12.0/
DATA PD07ThLLAdapNref/ 5.0/
DATA PD08WeightNrefOld/ 9.9010e-001/
DATA PD09KpropRpm/ -0.08535/
DATA PD10KdiffRpm/ -1.35646/
50 ECN-CX--00-083

DATA PD11MuKsubnom/ 1.75/
DATA PD12dThdtFuzTarg/ 5.0/
DATA PD13WeightNswitchOld/ 9.9010e-001/
CONTROL ALGORITHM (LMH46-5-X00-a)
c Let op dimensie in declaratie van PD14NrpmList en PD15ThdgList!
DATA PD14NrpmList/ -26.91, 8.58, 9.28, 9.97, 10.67,
& 11.36, 12.06, 12.76, 13.45, 26.91/
c Deellastbladhoeken zijn NIET geoptimaliseerd
DATA PD15ThdgList/ 1.00, 1.00, 1.00, 1.00, 1.00,
& 1.00, 1.00, 1.00, 1.00, 1.00/
c Deze parameter is niet automatisch gegenereerd
DATA PD16KsynDgr/1.52/
DATA PD17dThdtZoneInacBase/0.20/
DATA PD18dThdtmax/ 5.0/
DATA PD19dThdtmin/-5.0/
DATA PD20Thmax/ 90.0/
DATA PD21Thmin/ 0.0/
c Setpoints
c ----------
DATA SD01NrpmNom/13.5/
DATA SD02NrpmRatOffMax/ 2.0/
DATA SD03NrpmLimFuz/15.9/
DATA SD04NrpmDdtLimFuz/ 0.0/
DATA SD05DeltaThFuz/ 3.0/
DATA SD06NrpmToPartial/13.0/
DATA SD07NrpmToFull/13.7/
c Data directieven voor parameters specifiek voor simulatie
c ----------
DATA sPD1TdelPtTrans/0.000/
DATA sPD2TdelPtLoop/0.039/
DATA sPD3TdelPtLoad/0.100/
c Let op gedeclareerde lengte van dit polynoom!
DATA sPD4pTe/
& 0.0000e+000, 6.9764e+005, 6.1452e+002, -2.8695e+002/
DATA sPD5Tgen/ 0.3/
DATA sPD6PwattNom/ 3e+006/
ECN-CX--00-083 51

Blade pitch control algorithms DOWEC
52 ECN-CX--00-083

APPENDIX F. CONTROL ALGORITHM
(LMH46-5-X00-B)
F.1 Modification with respect to LMH46-5-X00
The structure of the control algorithm remains similar with respect to the algorithm
as used for LMH46-5-X00 rotor (Appendix B), the following modifications
and/or changes are listed below
1. RpmPartin = 8.2 (Cut-in rotor speed [rpm])
2. RpmDsgn = 11.8 (Synchronous rotor speed)
3. RpmOptout = 11.9 (End of optimal lambda control, partial load operation [rpm])
4. RpmRat = 12.9 (Rated rotor speed [rpm])
These modifications result in new generatorcurves with reduced rotor speed
(86.6%, [8]). For clarity in figure E.1 the ‘baseline’ generatorcurves (dashed
lines) and the ‘reduced’ generatorcurves are given.
The optimum tip-speed ratio becomes 6.5 and the ‘stiffness’ of the transition from
optimum tip-speed to rated speed about 1047.63 kNm/rpm. A loss of 4% energy
yield has been determined by Blade Optimisation Tool (BOT).
generator torque (slow shaft equiv) [kNm]
electric power [kW]
2500
2000
1500
1000
500
3500
3000
2500
2000
1500
1000
torque rotorspeed curve
0
8 10 12 14 16 18
500
power rotorspeed curve
0
8 10 12 14 16 18
rotorspeed [rpm]
electric power [kW]
3500
3000
2500
2000
1500
1000
rotor speed [rpm]
500
file C:\vdhooft\nm3000ct\data\ps\genkar37.ps 20−Jul−2000
by C:\vdhooft\nm3000ct\DATA\M\cpgenkar.m
power windspeed curve
0
0 5 10 15 20 25
18
16
14
12
10
rotorspeed windspeed curve
8
0 5 10 15 20 25
wind speed [m/s]
Figure F.1 Generatorcurve comparison between ‘baseline’ (dashed lines) and the ‘13%
reduced’
Because of change of rated rotor speed RpmRat from 14.9rpm to 12.9 rpm, not only
the parameters of the linear PD compensator and gain scheduling has been changed
(due to Cp-curves), but the parameters of the rotor speed lowpass filter (aLo3p,
bLo3p, cLo3p, dLo3p), rotor speed limitation (NrpmLimFuz) and the parameters of
partial- to full load transition (NrpmToPartial, NrpmToFull) as well.
During partial load operation, the pitch angle was set to a constant value (Theta-
PartConstant)of1 o .
ECN-CX--00-083 53

Blade pitch control algorithms DOWEC
As described in Appendix E, stability analysis show risk to exponential instability
due to destabilising effects of the ‘natural speed feedback and generatorcurve.
In Nyquist diagrams this effect has been observed increasingly with respect to
Appendix E. However during time domain simulations, driven by stochastic
wind, no negative effects of importance have been noticed. Parameters are listed
in section F.2.
F.2 Parameters and setpoints: DATBLOK7.fi
c Regelparameters en setpoints t.b.v. NM3000-LMH46-5-X00 bladen sub-opt b
c Datum: 21-Jul-2000
c Constanten
c ==========
DATA CD01TdelCtrl /0.1/
c Parameters
c ==========
c Let op dimensie in declaratie van PD01alo3p!
DATA PD01alo3p/
& 6.649516e-001, -1.924847e-001, 0.000000e+000, 0.000000e+000,
& 1.924847e-001, 9.777469e-001, 0.000000e+000, 0.000000e+000,
& -2.269356e-001, 7.827247e-001, 9.165370e-001, -1.531230e-001,
& -1.813117e-002, 6.253631e-002, 1.531230e-001, 9.877661e-001/
c Let op dimensie in declaratie van PD02blo3p!
DATA PD02blo3p/
& 2.188656e-001, 2.530300e-002, 2.221059e-001, 1.774530e-002/
c Let op dimensie in declaratie van PD03clo3p!
DATA PD03clo3p/
& -1.245583e-001, 4.296148e-001, -3.480976e-002, 5.364258e-002/
DATA PD04dlo3p/
& 1.219075e-001/
c Let op dimensie in declaratie van PD04glo3p!
DATA PD04bglo3p/
& 3.469447e-016, 1.137055e+000, 3.084063e-015, 7.262833e+000/
c Let op dimensie in declaratie van PD05pInvSchFac!
DATA PD05pInvSchFac/
& 3.705102e-002, 1.340215e-001/
DATA PD06ThULAdapNref/12.0/
DATA PD07ThLLAdapNref/ 5.0/
DATA PD08WeightNrefOld/ 9.9010e-001/
DATA PD09KpropRpm/ -0.07862/
DATA PD10KdiffRpm/ -1.34198/
DATA PD11MuKsubnom/ 1.75/
54 ECN-CX--00-083

DATA PD12dThdtFuzTarg/ 5.0/
DATA PD13WeightNswitchOld/ 9.9010e-001/
CONTROL ALGORITHM (LMH46-5-X00-b)
c Let op dimensie in declaratie van PD14NrpmList en PD15ThdgList!
DATA PD14NrpmList/ -25.81, 8.23, 8.90, 9.56, 10.23,
& 10.90, 11.57, 12.24, 12.90, 25.81/
c Deellastbladhoeken zijn NIET geoptimaliseerd
DATA PD15ThdgList/ 1.00, 1.00, 1.00, 1.00, 1.00,
& 1.00, 1.00, 1.00, 1.00, 1.00/
c Deze parameter is niet automatisch gegenereerd
DATA PD16KsynDgr/1.52/
DATA PD17dThdtZoneInacBase/0.20/
DATA PD18dThdtmax/ 5.0/
DATA PD19dThdtmin/-5.0/
DATA PD20Thmax/ 90.0/
DATA PD21Thmin/ 0.0/
c Setpoints
c ----------
DATA SD01NrpmNom/12.9/
DATA SD02NrpmRatOffMax/ 2.0/
DATA SD03NrpmLimFuz/15.3/
DATA SD04NrpmDdtLimFuz/ 0.0/
DATA SD05DeltaThFuz/ 3.0/
DATA SD06NrpmToPartial/12.4/
DATA SD07NrpmToFull/13.2/
c Data directieven voor parameters specifiek voor simulatie
c ----------
DATA sPD1TdelPtTrans/0.000/
DATA sPD2TdelPtLoop/0.039/
DATA sPD3TdelPtLoad/0.100/
c Let op gedeclareerde lengte van dit polynoom!
DATA sPD4pTe/
& 0.0000e+000, 7.8215e+005, 8.7812e+002, -4.0445e+002/
DATA sPD5Tgen/ 0.3/
DATA sPD6PwattNom/ 3e+006/
ECN-CX--00-083 55

Blade pitch control algorithms DOWEC
56 ECN-CX--00-083

APPENDIX G. CONTROL ALGORITHM
(LMH46-5-X01-HI)
G.1 Modification with respect to LMH46-5-X00
The structure of the control algorithm remains similar with respect to the algorithm
as used for LMH46-5-X01 rotor (Appendix C), but the aerodynamic characteristics
(optimised twist) and generator curves has been changed [12]. The consequences
of both different aerodynamic rotor properties (Cp- and Ct-curves) and rated rotor
speed results in different control parameters and setpoints.
The following modifications and/or changes are listed below
1. RpmPartin = 8.75 (Cut-in rotor speed [rpm])
2. RpmDsgn = 14.51 (Synchronous rotor speed)
3. RpmOptout = 14.83 (End of optimal lambda control, partial load operation
[rpm])
4. RpmRat = 15.92 (Rated rotor speed [rpm])
These modifications result in new generatorcurves with increased rotor speed
(106.7%). For clarity in figure G.1 the ‘baseline’ generatorcurves (dashed lines)
and the ‘reduced’ generatorcurves are given.
The optimum tip-speed ratio becomes 8 and the ‘stiffness’ of the transition from
optimum tip-speed to rated speed about 804.53 kNm/rpm.
generator torque (slow shaft equiv) [kNm]
electric power [kW]
2000
1500
1000
500
3500
3000
2500
2000
1500
1000
torque rotorspeed curve
0
5 10 15 20
500
power rotorspeed curve
0
5 10 15 20
rotorspeed [rpm]
electric power [kW]
3500
3000
2500
2000
1500
1000
rotor speed [rpm]
500
file C:\vdhooft\nm3000ct\data\ps\genkar38.ps 22−Sep−2000
by C:\vdhooft\mfiles\addfiles.m
power windspeed curve
0
0 5 10 15 20 25
20
18
16
14
12
10
rotorspeed windspeed curve
8
0 5 10 15 20 25
wind speed [m/s]
Figure G.1 Generatorcurve comparison between ‘baseline’ (dashed lines) and the ‘6.7%
increased’
Because of change of rated rotor speed RpmRat from 14.9rpm to 15.9 rpm, not only
the parameters of the linear PD compensator and gain scheduling has been changed
(due to Cp-curves), but the parameters of the rotor speed lowpass filter (aLo3p,
bLo3p, cLo3p, dLo3p), rotor speed limitation (NrpmLimFuz) and the parameters of
ECN-CX--00-083 57

Blade pitch control algorithms DOWEC
partial- to full load transition (NrpmToPartial, NrpmToFull) as well.
During partial load operation, the pitch angle was set to a constant value (Theta-
PartConstant)of1 o .
The results of stability analysis and time domain simulations with parameters as
given in section G.2 were satisfying. Parameters are listed in section F.2.
G.2 Parameters and setpoints: DATBLOK8.fi
c Regelparameters en setpoints t.b.v. NM3000-LMH46-5-X00 hi bladen
c Datum: 22-Sep-2000
c Constanten
c ==========
DATA CD01TdelCtrl /0.1/
c Parameters
c ==========
c Let op dimensie in declaratie van PD01alo3p!
DATA PD01alo3p/
& 5.210661e-001, -2.660790e-001, 0.000000e+000, 0.000000e+000,
& 2.660790e-001, 9.534550e-001, 0.000000e+000, 0.000000e+000,
& -2.553807e-001, 1.160135e+000, 8.676759e-001, -2.257837e-001,
& -3.087303e-002, 1.402490e-001, 2.257837e-001, 9.727050e-001/
c Let op dimensie in declaratie van PD02blo3p!
DATA PD02blo3p/
& 3.025463e-001, 5.292420e-002, 3.206922e-001, 3.876854e-002/
c Let op dimensie in declaratie van PD03clo3p!
DATA PD03clo3p/
& -9.383533e-002, 4.262721e-001, -3.197521e-002, 5.472692e-002/
DATA PD04dlo3p/
& 1.178329e-001/
c Let op dimensie in declaratie van PD04glo3p!
DATA PD04bglo3p/
& 2.498002e-016, 1.137055e+000, -6.886100e-016, 7.262833e+000/
c Let op dimensie in declaratie van PD05pInvSchFac!
DATA PD05pInvSchFac/
& 4.549378e-002, 1.438044e-001/
DATA PD06ThULAdapNref/12.0/
DATA PD07ThLLAdapNref/ 5.0/
DATA PD08WeightNrefOld/ 9.9010e-001/
DATA PD09KpropRpm/ -0.12995/
DATA PD10KdiffRpm/ -1.61874/
DATA PD11MuKsubnom/ 1.75/
58 ECN-CX--00-083

DATA PD12dThdtFuzTarg/ 5.0/
DATA PD13WeightNswitchOld/ 9.9010e-001/
CONTROL ALGORITHM (LMH46-5-X01-Hi)
c Let op dimensie in declaratie van PD14NrpmList en PD15ThdgList!
DATA PD14NrpmList/ -31.80, 8.75, 9.77, 10.79, 11.81,
& 12.83, 13.86, 14.88, 15.90, 31.80/
c Deellastbladhoeken zijn NIET geoptimaliseerd
DATA PD15ThdgList/ 1.00, 1.00, 1.00, 1.00, 1.00,
& 1.00, 1.00, 1.00, 1.00, 1.00/
c Deze parameter is niet automatisch gegenereerd
DATA PD16KsynDgr/1.52/
DATA PD17dThdtZoneInacBase/0.20/
DATA PD18dThdtmax/ 5.0/
DATA PD19dThdtmin/-5.0/
DATA PD20Thmax/ 90.0/
DATA PD21Thmin/ 0.0/
c Setpoints
c ----------
DATA SD01NrpmNom/15.9/
DATA SD02NrpmRatOffMax/ 2.0/
DATA SD03NrpmLimFuz/18.4/
DATA SD04NrpmDdtLimFuz/ 0.0/
DATA SD05DeltaThFuz/ 3.0/
DATA SD06NrpmToPartial/15.4/
DATA SD07NrpmToFull/16.1/
c Data directieven voor parameters specifiek voor simulatie
c ----------
DATA sPD1TdelPtTrans/0.000/
DATA sPD2TdelPtLoop/0.039/
DATA sPD3TdelPtLoad/0.100/
c Let op gedeclareerde lengte van dit polynoom!
DATA sPD4pTe/
& 0.0000e+000, 4.3214e+005, 2.6750e+002, -1.3707e+002/
DATA sPD5Tgen/ 0.3/
DATA sPD6PwattNom/ 3e+006/
ECN-CX--00-083 59

Blade pitch control algorithms DOWEC
60 ECN-CX--00-083

Date: 28th February 2001 Number of report: ECN-CX--00-083
Title DOWEC Blade pitch control algorithms
for blade optimisation purposes
Author E.L. van der Hooft
Principal(s) Partly funded by EET
ECN project number 7.4218
Principal’s order number EETK98031/398410-0810
Programmes ECN Wind Energy
Abstract
As part of the first stage of the DOWEC project, a base control structure for a 3MW
HAWT has been developed to support the evaluation of different rotor designs by means of
load set calculations with PHATAS.
During full load operation the rotorspeed is controlled by blade pitch speed adjustments
towards feathering position to limit aerodynamic power. The basic controller consists of a
rotorspeed feedback structure using a scheduled linear PD-compensator with non-linear
extensions. At partial load operation, the blade pitch angle is simply set to a constant value
at which optimal tip-speed occurs.
The report describes the structure and stability of the basic control algorithm, used for
each rotor concept, and emphasizes the used assumptions and limitations. Rotor specific
tuned parameter sets have been calculated. Time domain simulations driven by rotor
effective windspeed, results in comparable control performance and energy yield of the
FORTRAN algorithm for each proposed rotor design.
As soon as a final rotor design has been defined, additional features to the basic control
structure and detailed analysis are recommended. Energy yield improvements will be
possible by feedforward control based on wind speed estimation and more extended
controller scheduling. Active damping of tower and drive train resonances will be
important to reduce fatigue.
Keywords
DOWEC, Wind turbine control, Pitch control, Power control, Variable speed control
Authorization Name Signature Date
Checked
Approved
Authorised