Laboratory measurements on the generator of the 2 kW
dunlite wind generator
Citation for published version (APA):
Pieterse, N. W. M. (1981). Laboratory measurements on the generator of the 2 kW dunlite wind generator. (TU Eindhoven. Vakgr. Transportfysica : rapport; Vol. R-492-D). Technische Hogeschool Eindhoven.
Document status and date: Published: 01/01/1981
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LABORATORY MEASUREMENTS ON THE GENERATOR OF THE 2 kW DUNLITE WIND GENERATOR
N. PIETERSE
May 1981 R 492 D
Wind Energy Group
Laboratory of Fluid Dynamics and Heat Transfer Department of Physics
CONTENTS Page
List of symbols
I . Introduction 2
2. Description of test stand 2
3. Measurements 2 4. Discussion 3 5. Conclusion 3 Figure 4 Figure 2 5 Figure 3 6 Figure 4 7 Figure 5 8 Table I 9 Table IIa 10 Table IIb I J
List of symbols IF IG n P mech Q.w Pel = VG• IG RG
~
Q n = -Q.w -1-Field current Generator current rotational speed (rpm) mechanical power electrical powerelectrical load of generator adjustable resistance in field current circuit
torque
regulator voltage generator voltage
efficiency
angular speed (rads/sec.)
(rnA) (A) -I (min ) (W) (W) (Nm) (V) (V) -1 (sec. )
-2-1. INTRODUCTION
In report R 469 D ("Performance measurements on the 2 kW Dunlite wind generator") it was recommended to measure the torque vs. speed and power vs. speed characteristics of generator and transmission, on a laboratory test stand. The Laboratory of Electromechanics granted permission to use one of their generator test stands. Wasser mounted the generator on the test stand. Pieterse, Wasser and Wijnands carried out the measurements on February 2nd and 15th, 1981.
The assistance of van Gils and van der Veen, of the Laboratory of Electromechanics, is gratefully acknowledged.
2. DESCRIPTION OF TEST STAND
Via its transmission (I : 5) the Dunlite generator was driven by a dynamo for brake test, used as motor. The housing of this dynamo was fixed to the surroundings via a force meter; in this way the torque required to drive the generator could easily be measured.
The rotational speed of the dynamo was measured electrically, in rpm. The Dunlite generator was loaded with a variable resistance.
In series I the field current could be adjusted by a variable resistance; in series II the Dunlite's voltage regulator was used.
The experimental set-up is given in figure 1.
3. MEASUREMENTS
In series I the torque, rotational speed, generator voltage and generator current were measured for different values of the field current, i.e. If = 125; 150; 175; 225 and 300 mA, the resistive load in all cases
being 10
n.
These measurements are given in Table I. The resultingpower vs. speed and torque vs. speed curves are given in figures 2 and 3. In series II the torque, rotational speed, generator current and field current were measured for two values of the regulator voltage.
These measurements are given in Table II. Both Table I and II also state the efficiency of generator and transmission: electric output divided by mechanical input. The electric power needed for field excitation, has been neglected in calculating the efficiency.
-3-4. DISCUSSION
Efficiency of generator-transmission combination appears to be fairly good.
- Theory: P - n3, and T - n2 for this type of generator. See fig, 2 and 3. Power-speed and torque-speed curves seem to be rather good for coupling to a generator.
- Series II: cubicle + resistive load + output power determined by voltage setting and value of resistive load. (V
G does not remain constant, this might be due to the fact that the generator is only loaded with a resistor, not with batteries),
From figure 4 and 5 appears the strong dependence of the required power on the value of the resistive load (thus in normal operation: on the charge state of the batteries),
- For lower speeds
«
approx. 200 rpm), the required field current and so the torque increase rapidly. This implies that the cut-in speed of the system (the rpm when the windmill starts delivering power) will be above 200 rpm. The measured tip speed ratio (A=
3 to 4) istoo low for moderate wind regimes.
5. CONCLUSION
The generator shows good characteristics; as was anticipated in report R 469 D the improper matching of the rotor to the generator is one of the reasons for the low efficiencies of the Dunlite wind generator.
The generator mostly operates below 200 rpm instead of above that value. The rotor should operate at a higher tip speed ratio. say A = 8 instead of A = 4. For proper matching ~n a moderate wind regime (such as in Eindhoven) the rotor should also have a larger diameter and probably the transmission ratio should have to be reconsidered.
Ward-Leonar + d
...,
I I I I I I I J G F + G G F-4-~
Dunlite -generator-
GI
I-
F.
I
dynamo forbrake test, transmission 1 : 5
used as motor Series I
- - - -
---, + L+I
G GI
RG(;)
F L I L _ _ _ _ _ _ -J regulator cubicle Series II"T-i
--~--+--~~~
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:l
-9-TABLE-I: measurements of series I
n w Q P
mech VG IG RG Pel If n
(rpm) (rads/sec) (Nm) (W) (V) (A) (Q)
(W)
(mA) (%)146 15.3 16 245 40 4.1 9.8 164 125 66.9 170 17.8 22.5 401 53 5.4 9.8 286 125 71.4 197 20.6 30 619 67 6.8 9.8 456 125 73.4 223 23.4 38 887 81 8.2 9.8 664 125 74.9 245 25.7 44.5 1142 93 9.5 9.8 884 125 77 .4 275 28.8 51.5 1483 106 10.9 9.8 1155 125 77 .9 140 14.7 22 323 47 4.7 9.8 221 150 68.3 164 17.2 30.5 525 61 6.2 9.8 378 150 71.8 179 18.7 36.S 684 70 7.2 9.8 504 ]50 73.3 193 20.2 42.5 859 80 8.2 9.8 656 150 76.0 222 23.3 55 1279 99 10 9.8 990 150 77 .0 230 24.1 59 1421 106 10.6 9.8 ] 124 150 78.6 248 26.0 66 1714 116 11.8 9.8 1369 150 79.4 269 28.2 72 2028 126 12.8 9.8 1613 150 79. I 280 29.3 78 2287 134 13.6 9.8 1822 150 79.3 147 15.4 30 462 58 5.8 9.8 336 175 72.8 156 16.3 35 572 64 6.4 9.8 410 175 71.6 180 18.9 46 867 80 8.2 9.8 656 175 75.7 205 21.5 59 1267 98 10.0 9.8 980 175 77 .3 212 22.2 60 1332 102 10.3 9.8 1051 ]75 78.8 227 23.8 69 1641 I 13 11.5 9.8 1300 175 79.2 165 17.3 59 1020 87 8.9 9.8 774 225 75.9 183 19.2 72 1380 102 10.4 9.8 1061 225 76.7 204 21.4 86 1837 120 12.2 9.8 1464 225 79.7 228 23.9 104 2484 140 14.2 9.8 1988 225 80.0 145 15.2 55 835 78 8.0 9.8 624 250 74.7 164 17.2 71.5 1228 96 9.8 9.8 941 250 76.6 149 15.6 79.5 1240 97 9.8 9.8 951 300 76.7 154 16. 1 85 1371 102 10.4 9.8 1061 300 77 .4 163 I 7. I 95 1621 1 I I 11.3 9.8 1254 300 77.4 170 17.8 102 1816 I 17 12.0 9.8 1404 300 77.3 178 18.6 110 2050 126 12.8 9.8 1613 300 78.7 194 20.3 126 2560 142 14.4 9.8 2045 300 79.9
-10-TABLE-IIa: measurements of series II; V at maximum reg.
n w Q p
mech VG IG RG P el. If n
(rpm) (rads/sec) (Nm) (W) (V) (A) (n) (W) (rnA) (%)
300 31.4 76.5 2402 136 13.8 9.8 1877 116 78 277 29.0 77 .5 2248 133 13.5 9.8 1796 137 80 247 25.9 82 2124 128 13 9.8 1664 155 78 227 23.8 86 2047 126 12.9 9.8 1625 175 79 204 21.4 94 2012 125 12.8 9.8 1600 208 80 306 32.0 101 3232 131 19.6 6.7 2568 145 79 278 29.1 I I I 3230 128 20.2 6.3 2586 170 80 250 26.2 120 3144 126 19.8 6.4 2495 200 79 222 23.2 116 2691 124 17.5 7.1 2170 225 81 296 31.0 6.5 202 140 00 75 275 28.8 7 202 137 00 82 251 26.3 7.5 197 136 00 90 225 23.6 8 189 134 ClO 105 204 21.4 9 193 132 ClO 125 178 18.6 10 186 130 ClO 165 147 15.4 14 216 126 ClO 290
-11-TABLE-lIb: measurements of series II; V at minimum
reg.
n w Q p
mech
Ve
Ie
Re
p el. If n(rpm) (rads/sec) (Nm) (W) (V) (A) (rt) (VI)
{mAl
(%)
298 31.2 33 1030 87
