Offshore Wind Farm Communication, stability starts with monitoring, control & predictability

The electric power generated by Wind Farms in addition to Solar Farms is the most proven green technology available to date. However, the power scale of wind turbine generators, in addition to the land footprint makes Wind Power even more attractive, especially when taken out of sight offshore. Like for every other critical asset, Offshore Wind Farm Communication is of great importance in order to know the exact state & condition of the asset. Figure 1 shows the typical elements in an offshore wind farm that almost every wind farm contains. 

The output power of a typical wind turbine generator (WTG) back in 2014 was around 3 – 5 MW, however this number for projects under execution is around 13 – 15 MW today and even 18 MW for projects under planning. This allows Wind Farms to easily enter the GW scale (1000 MW) and to be considered as a critical part of our society’s energy matrix. Such criticality together with the unmanned operation of these offshore assets calls for a certain stability and maturity level, which can only be guaranteed by innovative state-of-the-art automation & communication technologies to control & monitor the generation process and keep it safe and secure. This, together with cost saving approaches that wants to bring most of the footprint of the equipment onshroe rather than offshore, makes Offshore Wind Farm Communication a very critical topic in the planning, design, engineering and execution phase. Figure 2-a shows the electrical connection in a wind farm, while the same electrical cables also carry the fiber optic connections, as shown in Figure 2-b. 

Offshore Wind Farm Communication, Why Fiber Optics?

Stable and fast communication is a vital part of Offshore Wind Farm Communication Design and among the available options, fiber optics (FO) technology comes into the picture as the most reliable solution, but why? Here we list a number of features that make FO the most suitable option and later dive into the details.

• High Speed (Light Speed)
• High Bandwidth
• Availability, Simplicity, Maturity, and wide compatibility of technology
• Noise tolerance
• Cost reduction due to availability, simplicity & noise tolerance 

Fiber Optics are known for high-speed and high-bandwidth telecommunication applications. This together with simplicity and cost reduction in cable routing has allowed fiber optics to become a serious rival for copper in the field of wind farms and also other offshore applications. The technology has matured over the years and is widely compatible, standardized, and easy to be utilized among products of different vendors.  

Another unique characteristic of fiber optics in the Power sector is its ability to be fully functional while in high electrical noise environments. This has made this technology the most suitable and in some cases “the only applicable” communication technology in areas such as high electrical noise environments for electrical generator/turbine control, power conversion, and wind farm wide-area. This also allows the fiber cables to be packed in the same export power cables that are utilized to export produced electricity and save costs.

Where & How is it applied?

As in other offshore applications, FO cables are used both internally in the WTGs and also inside the offshore and onshore substations. In addition to that, the main backbone of the communication between the offshore & onshore is also happening through the FO cores inside the subsea cables (Figure 4). The robust subsea cables that are placed in the sea bottom (figure 3), allow for export of both electricity and data through the fiber cores that are pulled together with copper cores (Figure 4). The characteristics of the light allows for being exposed to high voltage in neighboring areas and still being fully functional without any affect by the noise and interference from neighboring high voltage AC or DC neighboring copper cores. 

References:

[1] Performance Evaluation of EPON-Based Communication Network Architectures for Large-Scale Offshore Wind Power Farms. URL:  https://www.researchgate.net/figure/a-Layout-of-wind-power-farm-b-Conventional-communication-network-of-wind-farm_fig1_236255782

[2] Complete Subsea Cable Systems from Nexan Norway, URL: https://www.offshore-technology.com/contractors/cables/nexans/

[3] Floating Substations: the next challenge on the path to commercial scale floating windfarms. URL: https://www.dnv.com/article/floating-substations-the-next-challenge-on-the-path-to-commercial-scale-floating-windfarms-199213