16-05-2012, 11:14 AM
Maine Mountain Power
5.1_Electrical_Power_Line_Report.pdf (Size: 134.69 KB / Downloads: 139)
Black Nubble Wind Farm
It is planned that 18 wind turbine units will occupy the Black Nubble site as
illustrated in Figure 2. Assuming the units will be V90-3.0 MW units capable of
3,000 kilowatts (3125 kVA @ .96 power factor), design load current is projected
to be a maximum of 52.3 amperes per unit at 34.5 kV.
Single String Approach
Based upon the turbine locations depicted in Figure 2, cable run distances were
estimated for a single string approach and are summarized in Table 3 below. Due
to the larger size of the units and a 600 amp limitation on the 34.5 kV connectors,
a single string design is not possible.
The multiple string approach employs a combination of 500 kcmil, 4/0 AWG and
1/0 AWG aluminum cable to provide the sufficient levels of ampacity from the
collector system as the unit connections multiply toward the medium voltage
transmission line. Except for Turbines 1, 5, 14 and 18, each wind turbine unit
will have two sets of collector system cables connected to the switchgear.
Turbines 1, 5, 14 and 18 will have only one set of collector cables since they are
located at the end of the series.
The medium voltage cable installation is assumed to be direct buried in a cable
trench 18 inches wide and 42 inches deep. The trench will be layered with 6
inches of sand prior to cable installation and the cable will have 36 inches of
cover after installation. In areas where the medium voltage cable is to pass under
roads or areas subject to heavy wheel loads, the cable shall be placed in steel
conduit or PVC conduit encased in concrete.