WIND ENERGY SYSTEMS - Cd3wd

Chapter 1—Introduction 1–10
TABLE 1.1 Specifications of ERDA and DOE
Two-Bladed Horizontal-Axis Wind Turbines
MOD-0 MOD-0A MOD-1 MOD-2
Rotor r/min 40 40 34.7 17.5
Generator output power (kW) 100 200 2000 2500
Rotor coefficient of performance, C p,max 0.375 0.375 0.375 0.382
Cut-in wind speed at hub height (m/s) 4.3 5.4 7.0 6.3
Rated wind speed at hub height (m/s) 7.7 9.7 14.6 12.4
Shutdown wind speed at hub height (m/s) 17.9 17.9 19.0 20.1
Maximum wind speed (m/s) 66 67 66 66
Rotor diameter (m) 37.5 37.5 61 91.5
Hub height (m) 30 30 46 61
Coning angle 7 o 7 o 12 o 0 o
Effective swept area (m 2 ) 1072 1140 2920 6560
Airfoil section, NACA- 23,000 23,000 44XX 230 XX
Weight of two blades (kg) 2090 2090 16,400 33,200
Generator voltage, line to line 480 480 4160 4160
The gearbox and generator were similar in design to those of the MOD-0A, except larger.
The tower was a steel, tubular truss design. The General Electric Company, Space Division, of
Philadelphia, Pennsylvania was the prime contractor for designing, fabricating, and installing
the MOD-1. The Boeing Engineering and Construction Company of Seattle, Washington,
manufactured the two steel blades.
As the MOD-1 design effort progressed, it became clear that the MOD-1 would be relatively
heavy and costly and could not lead to a cost competitive production unit. Weight and cost
were being determined by a number of factors, the most significant of which were the stiff tower
design criteria, the full span pitch control which required complicated, heavy mechanisms and
excessive space in the hub area, and a heavy bedplate supporting the weight on top of the
tower. A number of possible improvements in the design became evident too late to be
included in the actual construction. Only one machine was built because of the predicted
production costs. Like the MOD-0, it was operated as a test unit to help the designs of later
generation turbines.
One early problem with the MOD-1 was the production of subaudible vibrations which
would rattle the windows of nearby houses. The rotor would interact with the tower to produce
two pulses per revolution, which resulted in a vibration frequency of about 1.2 Hz. Techniques
used to reduce the annoyance included reducing the speed of rotation and replacing the steel
blades with fiberglass blades. Other operational problems, including a broken low speed shaft,
plus a reduction in federal funding, caused the MOD-1 to be disassembled in 1982.
The next machine in the series, the MOD-2, represented an effort to build a truly cost
competitive machine, incorporating all the information gained from the earlier machines. It
was a second generation machine with the Boeing Engineering and Construction Company
Wind Energy Systems by Dr. Gary L. Johnson November 20, 2001