Wind Turbine Generator Impacts to Marine Vessel Radar (2022) / Chapter Skim
Currently Skimming:
2 Impacts of Wind Turbine Generators on Marine Vessel Radar
2 Impacts of Wind Turbine Generators on Marine Vessel Radar
Pages 21-50
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 21... ...
Although areas of the waterways may be designated as shipping safety fairways and formal routing measures, which will prohibit the construction of wind turbines in certain locations, the presence of wind farms adjacent to these shipping safety fairways and navigational routing measures will still provide new risks for the mariner to consider while safely navigating. Of the many tools a mariner leverages for safe navigation, the marine vessel radar (MVR)
|
From page 22... ...
The plan should include the plotting of the intended route indicating all areas of danger, existing ships' routing and reporting systems, VTS, and any areas where marine environmental protection considerations apply. The main ele ments to ensure safety of life, safe and efficient navigation, and protection of the environ ment during the voyage should include but are not limited to • safe speed, considering the proximity of navigation hazards and the maneuvering characteristics of the vessel; • positions where a change of machinery status is required; • course alteration points, taking into account the vessel's turning circle and the effect of wind and currents; • the method and frequency of position fixing, including primary and secondary options, and the indication of areas where accuracy is critical and where maximum reliability must be obtained; • use of vessel routing and reporting systems and VTS; • considerations relating to the protection of the marine environment; and • contingency plans.
|
From page 23... ...
, may also be affected by wind turbines (e.g., Trockel et al., 2018a,b; Kirincich et al., 2019)
|
From page 24... ...
As such, the applicable excerpts from the International Navigation Rules are referenced throughout this chapter. In addition to the Navigation Rules, certain inspected vessels are required to carry and operate radar per U.S.
|
From page 25... ...
If the impacts of the WTGs prohibit the ability of the radar to accurately provide the range and relative motion of a target, and thus provides the mariner "scanty radar information," this valuable tool could be rendered ineffective in determining a risk of collision. Rule 8 further references use of MVR when taking action to avoid a collision: "Any alteration of course or speed to avoid collision shall, if the circumstances of the case admit, be large enough to be readily apparent to another vessel observing visually or by radar.12" The presence of WTGs could block an MVR's ability to properly track a smaller vessel operating within a wind farm.
|
From page 26... ...
Marine Vessel Radar Design The standard design for MVR uses a magnetron source as its transmitter. The front-end antenna is a slotted waveguide array, which comprises a linear array of slots cut along a metal waveguide.
|
From page 27... ...
More recently, multifunction displays have been introduced that can simultaneously display not only the PPI from an MVR but also information from Global Positioning System chartplotters, fishfinders, and other onboard sensors. Marine Vessel Radar Market and Recent Developments As of 2019, MVR constitutes about 40 percent of the $5 billion marine electronics market (Technavio, 2020)
|
From page 28... ...
Marine Vessel Radar Installation and Operation MVRs are typically mounted at high locations on vessels to achieve an unobstructed view of the surrounding scene, such as the top of the wheelhouse or on a mast. Instead of the theoretical maximum range of a radar supplied by the vendor (which depends on the transmit power and the antenna gain, among other parameters)
|
From page 29... ...
OFFSHORE WIND TURBINE GENERATOR CHARACTERISTICS AND DEPLOYMENT The standard design for offshore WTGs -- three-bladed, upwind, horizontal axis -- is the same as that for onshore WTGs. However, because offshore wind turbines do not have the same transportation infrastructure limitations of onshore wind turbines where blade size is limited (e.g., by the roads that trucks can take and the radius of the turns, and the capacity of the cranes used in construction)
|
From page 30... ...
The nacelle cover functions to protect these components from the elements and is typically constructed from a fiberglass composite to reduce the weight of the nacelle. There are also more novel offshore WTG designs being explored in the United States from vertical axis wind turbines (VAWTs)
|
From page 31... ...
Without terrain features that are present onshore, offshore wind farm developers can arrange the WTGs in a standard grid pattern. Data from BOEM show that a typical layout for a single offshore wind farm within the lease areas off the East Coast of the United States will include turbines spaced approximately 1 nmi × 1 nmi (BOEM, 2021)
|
From page 32... ...
and multi-rotor wind turbines are being researched and would require additional analysis from the marine vessel radar point of view if deployed in the marine environment. SOURCE: Sandia National Laboratories.
|
From page 33... ...
. The wind turbine blades are commonly composed of lightweight materials engineered to provide mechanical robustness while capturing wind energy efficiently.
|
From page 34... ...
34 FIGURE 2.6 Scaled representation of vessels common to the Coastal Virginia Offshore Project Area relative to wind turbine generator rotor diameter and 0.75 nautical mile spacing. (Figure 2.1-1 in the 2021 Construction and Operations Plan for the Coastal Virginia Offshore Wind Commercial Project)
|
From page 35... ...
The anticipated offshore wind facilities in the United States over the next 15 years are considerably larger than those at Fenner, New York, with tower heights ranging from 135 m to 158 m and blade lengths ranging from 105 m to 128 m. Therefore, it is natural to ask how the RCS of these larger turbines will scale and whether they may pose a greater challenge to the operation of MVRs.
|
From page 36... ...
. However, in scenarios where the MVR is operating sufficiently close to or even inside the wind farm, several research groups have argued that a taller tower may not give rise to the high level of RCS predicted under the standard far-field condition.
|
From page 37... ...
WIND TURBINE GENERATOR IMPACTS ON MARINE VESSEL RADAR The impact of WTGs on MVR performance is influenced by a number of factors, such as the following: • MVR design choices, including operating frequency, antenna characteristics, transmitter type, receive processing approach, and ARPA design. • Characteristics of the WTG deployment, including the RCS of the WTG's constituent components; size and separation of the WTGs; extent of the WTG farm; and blade size, composition, orientation, and tip speed.
|
From page 38... ...
This means that the radar display of returns over range and angle, referred to as the PPI, is cluttered with WTG returns in the absence of mitigating techniques. Figure 2.10 shows an illustrative example of a PPI for magnetron-based MVR operating in the vicinity of the Kentish Flats Offshore Wind Farm.
|
From page 39... ...
For this reason, the typical MVR design appears much more reliant on operator control of the threshold setting than, for example, radar systems used for air traffic control or military applications. Given the copious detections shown on the MVR display in Figure 2.10, a natural operator response is to adjust the detection threshold upward (reduce the receive gain)
|
From page 40... ...
FIGURE 2.11 Ducting allows the radar to see objects below the radar horizon, bringing wind turbine generators at far range into the radar field of view and complicating the operating picture. SOURCE: Colburn et al.
|
From page 41... ...
Distortion includes signal harmonics that degrade the radar scene with additional, spurious signals. FIGURE 2.12 Shadowing effects within the wind farm (color bar in decibels)
|
From page 42... ...
. The left-most panel in Figure 2.14 is shown for 1.5 GHz and the frontal incidence, so the response is relatively constant, whereas the right-most panel of Figure 2.14 is at 3.6 GHz and 137 degrees from frontal incidence, so that RCS varies substantially FIGURE 2.13 Multipath example within proximity of wind turbine generators.
|
From page 43... ...
In general, reliable detection requires an S/I of approximately 13 dB, so the region shown in blue in Figure 2.15 represents substantial degradation in detection capability, with expected detection rates of less than a few percent for returns from objects other than WTGs with RCS values less than 20 dBsm, and only ~25 percent for an object with RCS of approximately 30 dBsm. In the context of MVR, Figure 2.15 confirms that WTGs are significant sources of interference to detecting moving targets and smaller stationary objects, such as navigation buoys.
|
From page 44... ...
With the aforementioned in mind, the WTG impacts solid-state radar similarly to the magnetron-based radar systems, with the distinction that solid-state radar can separate objects by Doppler frequency. Stationary objects, such as the WTG tower or a buoy, appear at a fixed Doppler depending on the angle between the object location and the marine vessel direction of motion.
|
From page 45... ...
All other objects fall along the sinusoidal curve shown in Figure 2.17, as the Doppler is strictly given as twice the projection of the MVR's velocity vector onto a unit vector pointing toward the object of interest divided by the radar FIGURE 2.16 Wind turbine generator spectrogram (Doppler frequency versus time)
|
From page 46... ...
Δθ is defined as the change in angle measured starting 90 degrees to the portside and proceeding in a clockwise direction relative to the velocity vector (v) of the observer's shipboard marine vessel radar (MVR)
|
From page 47... ...
The impact of WTG on solid-state radar requires further assessment, as the majority of fielded radar, and hence collected data on WTG impacts, are magnetron-based. The well-known Kentish Flats Wind Farm results, for instance, correspond to a magnetron-based radar (Marico Marine, 2007)
|
From page 48... ...
Δθ is defined as the change in angle measured starting 90 degrees to the portside and proceeding in a clockwise direction relative to the velocity vector of the observer's shipboard marine vessel radar (MVR) , such that 90 degrees is the direction of travel.
|
From page 49... ...
2021. Lecture: Marine Turbine Generator Impacts to Marine Vessel Radar (Hensoldt UK)
|
From page 50... ...
. Presentation to the Committee on Wind Turbine Generator Impacts to Marine Vessel Radar, August 10, 2021.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.