Axial Momentum Theory

Across the disc caused by the rate of change of axial momentum as developed in Section 3.2.1 Equation 3.9 is additional to the pressure drop associated with the rotation of the wake and is uniform over the whole disc. If the wake did not expand as it slows down the rotational wake structure together with the rotational pressure gradient would not change as the wake develops whereas the pressure loss caused by the change of axial momentum will gradually reduce to zero in the fully-developed...

Wind farm and generator protection

Figure 10.20 shows a typical protection arrangement for a wind farm of fixed-speed wind turbines with generator voltages of 690 V and with a collection circuit voltage of 11 kV. The 11 kV circuit is fed from a 33 11 kV Delta Star wound transformer with the 11 kV neutral grounded either directly or through a resistor. The 11 0.69 kV transformers are also wound Delta Star and so the 690 V neutral points of each circuit may be directly grounded. The neutral point of the generators is not connected...

Connection charges deep and shallow

When a wind farm owner wishes to connect a project to the distribution network there are clearly costs associated with doing so and it is entirely reasonable that all the appropriate connection costs are borne by the wind farm. This is a similar situation to the connection of any large load. There are two main philosophies in charging for connection of either generation or load to a power system, i.e., 'Deep' or 'Shallow' charging. In deep charging the embedded wind-farm project will pay for...

Drivetrain Mounting Arrangement Options Lowspeed shaft mounting

The functions of the low-speed shaft are the transmission of drive torque from the rotor hub to the gearbox, and the transfer of all other rotor loadings to the nacelle structure. Traditionally the mounting of the low-speed shaft on fore and aft bearings has allowed these two functions to be catered for separately the gearbox is hung on the rear end of the shaft projecting beyond the rear bearing and the drive torque is resisted by a torque arm. The front bearing is positioned as close as...