WEG´s operational experience with two medium-sized wind turbines

The Wind Energy Group has been responsible for the design, construction, commissioning and operation of two medium-sized wind-turbine generators. The first of these on Burgar Hill, Orkney, was commissioned in September 1983, and has since operated synchronously with the grid for more than 9700 h (as of January 1987). The machine has a 20 m diameter, 2-bladed horizontal-axis rotor and is rated at 250 kW. It was designed as a test bed in that its rotor can be operated with a teeter hinge, or locked solid with the main shaft, and at fixed or varying rotational speed. The 200 sensors on this machine include strain gauges, crack-detection systems, displacement transducers and accelerometers. They are connected via fibre-optic cable to a computer-based data-handling system. The second machine was commissioned at its site near Ilfracombe, in Devon, during December 1984. It differs substantially from the Orkney machine in that it has been designed to meet the market requirement with respect to cost and specification. It has a 25 m diameter, 3-bladed horizontal-axis rotor of wood-epoxy construction, rigidly mounted to the low-speed shaft. Twenty of these machines were installed in Altamont Pass, California, in December 1986. The paper gives brief specifications of the two wind turbines and describes the operational experience gained. Experimental data is presented and, where appropriate, compared with theoretical predictions resulting from the use of specially developed computer codes.