C. Wind Farm Control Center
The control center represents the main control and protection functions. There are different devices include the meteorological server, windturbine controllers (WTC), condition monitoring system, human machine interface, circuit breaker control and metering servers. From the communication point of view, optical fibers are integrated with sub-marine power transmission cables. Wireless network or radio link may incorporate to increase the network reliability as a redundant or backup link.
We considered the Ormonde offshore wind power farm as a case study. The electric system consists of three main sub- systems: the wind turbines,internal grid and transmission system [13]. The wind farm covers an area of 7.8 Km2 in the Irish Sea. It has a total capacity of 150 MW (30 WTs each with 5MW). The numbers of rows/WTs are 2×8 WTs and 2×7 WTs as shown in Fig. 7. The distances between rows/WTs are 760m/560m. The turbine hub height is 100m while the rotor diameter is 126m. From the communication point of view, the authors in [14] considered the ZigBee Pro (31.25 KBytes/sec) for monitoring the overhead transmission line due to its low power consumption and ability to transmit data up to 1.5 Km in an open area. Therefore, in our network model we considered the ZigBee Pro for communication between neighbor wind turbines, where the distance between wind turbines is 560m. The advantages of this configuration is that, no need for protocol conversion between the sensor nodes, coordinator node and relay node because all nodes use the ZigBee technology.