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Wind Farm Collector Systems
Unlike traditional power generating plants which are built around a few generating units with very high rating in a single location, wind-farms derive their power from a multiplicity of small generators spread out over a large area. The energy generated by each unit must be collected and channeled to a substation by means of an underground network of medium-voltage (25–46 kV) cables called a collector system. Owing to the relatively large separation between the wind-powered generating units and the very large area covered by wind-farm installations, typical underground cable collector systems may measure over 100 three-phase circuit miles (161 kms).
Consequently, the reliability of the entire wind power plant is strongly impacted by the reliability of the underground cable system.
Wind farm collector systems can be structured in different configurations depending upon the desired level of system reliability. Typical configurations are as follows:
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Loop System
This system provides a redundant path for the wind generator output for each turbine by establishing a looped circuit between them. In the event of a cable failure, the loop can be opened and the full output of the wind farm can be maintained.
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Single String
This system places all of the wind turbines on a single series circuit. In the event of a cable failure, the wind turbines located beyond the faulted cable would not be available until the cable is repaired.
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Multiple String
This system distributes the wind turbines over several series circuits and permits the use of lower rated equipment. Similar to the Single String Configuration, in the event of a cable failure, the wind turbines beyond the faulted cable will not be available until the cable is repaired.
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The wind power plant collection system is a necessary, but often under-appreciated part of the wind plant. Optimizing the collector system can yield an incremental R0I greater than the overall wind plant R0I.
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