Network integration of wind power - Wind Power Integration: Connection and System Operational Aspects - page 131

Figure 4.14 illustrates the 'over-reach' if the two paths are not of equal
impedance length.
As a result, system planners are likely to divide the circuit into two sections
using switchgear and locate the wind farm between the two plain feeders. Two or
three circuit breakers are required. Figure 4.15 shows a three circuit breaker
arrangement and Figure 4.16 a two-breaker arrangement.
This configuration may be preferred over an arrangement with the wind farm
positioned between two line breakers, because a failure in the wind farm connec-
tion does not remove the backbone circuit from service. Allowing for remote
operation, earthing, SCADA, battery chargers and security arrangements, an
expensive solution is likely to result. The transmission utility will probably seek to
retain, as far as possible, the security of its backbone circuit by ensuring that any
problem with the T-ed equipment is self-protected and leaves the backbone system
intact. Not every transmission circuit is of equal importance and some cost/benefit

Zone 2

Zone 1

Source

Figure 4.14 Distance protection with over-reach

Zone 2

Zone 1

Source

Figure 4.15 Distance protection - three circuit breaker arrangement