A website about wind farm construction: not only turbine erection but also balance of plant – access roads, crane pads, turbine foundations, power collection network, substation, meteorological mast and the economics behind it.
The IEC (acronym of International Electrotechnical Commission) has just released a new design code. More precisely it is a new section of an existing code, the IEC61400.
The IEC is an international organization that prepares and publishes international standards for all electrical, electronic and related technologies, including energy production and distribution devices.
The IEC 61400 is a set of design requirements developed specifically for wind turbines – to be sure that they are appropriately engineered against damage from different type of hazards within the planned lifetime (currently, 20 to 30 years). If you are familiar with the wind business you will probably know that this is one of the key international standards.
The IEC 61400 has several sections.
Section 1 deals with the wind turbine loads (more precisely, “design requirements”) in most of the world. A relevant exception would be Germany and some of neighbouring countries, where DIBT is used.
The new section released is the IEC 61400-6:2020 Tower and foundation design requirements.
If you are a wind turbine foundation designer, you are already aware that there is not really and internationally accepted design reference for wind turbines: there are some national references (such as the French CFMS Recommendation, or the Chinese FD 003-2007), some guidelines from certification bodies (such as the DNV guidelines), and recommendations from associations (AWEA for example has a recommendation for foundation design, but not a specific code for wind turbine foundation).
If we assume a similar applicability of this code as the one from the IEC61400:1 my opinion is that this is going to be one the more relevant technical reference (if not the most important) in the market for the next few years.
I am not going to enter deep into the technical detail of this standards, but there are a few points I would like highlight:
The new standard specify that foundation gapping does not need to be the limiting factors for foundations in all the cases. This opens the option to reduce the foundation size importantly when the soil is good enough.
Specifies the applicable codes for concrete design and provide guidance in how to perform some calculations (for instance cracking, dynamic shear modulus, etc…)
Has a set of very interesting annexes providing specifics about seismic calculation, strut and tie modelling, rock anchors, etc…
Specifies that there should not be decompression of the tower flange under the extreme (un-factored) loads.
Provides guidance about how to apply the sub pressure and perform the equilibrium verifications (this may modify some existing practises in some countries).
There are several interesting sections in this code, and many about towers and concrete towers that I have not yet analysed deeply but it seems that we might see some changes in the way we design at the moment.
It looks somehow unusual that this code has been issues by an Electrotechnical Commission – given the subject, it looks more like a code that should have been created by an institution of civil/structural engineers.
However I also believe that this type of reference and guidance was much needed in the sector, so I am happy that the IEC had taken the initiative of releasing such code.
If you either work for a WTG manufacturer or any electric utility the situation in which you are asked to do a complete analyse of a project very quickly (like in 2 or 3 days) is very common.
You are usually asked to do this task for several reasons:
Preparation of a first rough layout with preliminary quantities.
To compare different alternative WTG layouts.
For a technical due diligences.
Until not so many years this type of assessments was done using the specialized design software: MDT, Civil 3D, Istram-Ispol, Clip, etc.
These programs are more focused on a detailed design and the processes are not easy to adapt to a different scenario, where quick results are required.
In the last years Infraworks has emerged as a powerful alternative.
It is a planning and design platform from Autodesk that has experienced an impressive development. It offers a bunch of very useful tools that can be easily adapted to the BoP design of a wind farm.
Some of the principal qualities are:
It allows engineers to quickly create a preliminary design in a realistic environment, making possible to position the point of view anywere in the wind fare and immediately be able to visualize the existing conditions.
The program supports data from multiple sources: GIS (shapefiles, geodatabases, etc), CAD, raster, and all kind of BIM-data. These data is integrated into an interactive 3D model.
Cloud technology is integrated through BIM 360. Different users from the same team can work dynamically on the same projects in remote - i.e. from any point in the planet, a feature especially useful in these "work from home" days.
Multiple alternatives called “Proposals” can be generated for the same project.
The program allows to extract quantities, create shadow analysis, analize conditions with style maps using “style rules”, etc.
It is that it is very user-friendly: it takes only a few days to learn the basics and start doing your own projects.
One of its major advantages included in the last releases is that it is possible to import detailed designs from other software such as 3Ds Max, Civil 3D or Revit.
What I like the most is the dynamic flow of work implemented in the most recent versions between Infraworks and Civil 3D. In this sense, I like to think about Infraworks as a good complement to Civil 3D. We can either:
Start the design in Civil 3D and export it to Infraworks.
Create the predesign directly in Infraworks feeding the model with data available in all kind of source formats: shapefiles, raster, etc.
The synchronization between both programs is not bidirectional: any change done in the Civil 3D model is automatically included in the Infraworks model but not the other way around.
Going more deeply in what the program can offer, here are some comments specific for the wind farm BoP items:
The software offers a quick way to obtain quantities for big construction areas such as crane hardstands.
The option “Land Areas & Grading Behaviours” allows the user to easily calculate quantities for gradings and landfills.
One point to improve is that currently there is no way to export this data to any other format: the information must be extracted "manually" to an external BoQ.
It works in a similar way as explained before with the hardstands.
For example, we can quickly model the foundation bottom pit and calculate the excavation volumes.
We can do it to analyse a certain position or, taking advantage from GIS format files and other formats, do an overall analysis of all the positions.
Infraworks has two typologies of roads, which will be used depending on the needs of both the designer and the project:
Planning roads: These are lightweight roads that use spline geometry. You can add planning roads to a model or import roadway data as planning roads. This format does not allow to extract quantities from the model.
Component roads: these are configurable roads in cross section, vertical and horizontal geometry. They provide a precise control of geometry and grades. This is the type of road we are interested in when creating a BoP design in a wind farm because they have available features such as the grading tool and the mass balance quantification.
The interesting thing about this tool is that we can have a full control of all the parameters from a 3D environment and we can export to quantities to a .csv file format.
Additionally, the intersections between roads are automatically created and very easy to handle and edit.
Hydraulics analysis and drainage calculations are hard to deliver in few hours - at least if you want to do a good job.
However, Infraworks offers a useful and easy module to deal with this matter. Some of the main available services are:
Watershed analysis: it includes point watershed creation, watershed analysis along roads and calculation of flows for a calculated watershed according to different methods (rational, regression, etc).
Culvert design analysis with automated culvert placement, culvert analysis and culvert reporting
Roadway inlet and pipe analysis, including automated inlet and pipe placement and inlet and pipe design analysis.
As a drawback, it is worth point out that drainage tools are only available in combination with a BIM 360 account.
Furthermore, depending on the kind of service required, we will need to have "cloud credits" available for certain processes such as culvert analysis.
In any case, it is difficult to find in the market a tool that gives such a powerful and interactive tool for preliminary drainage calculations.
Creation of realistic videos
Useful realistic videos or tours around the model can be created in a very easy way. They could not only look really fancy in a presentation but also are useful to assess whether there is a major mistake in the predesign. You ave an example at the beguinning of this article: the creation of this video took no more than 15 minutes from when the model was ready.
There is also the option to create advanced customized cross section profiles.
This could be of great use to model other elements linear elements such medium voltage electrical cable trench or high voltage lines.
Beyond all the great functionalities described so far, we must not lose the perspective: as it is now, Infraworks is not intended for a full detailed design. As a user you frequently feel that the program lacks "advanced capabilities" that would be highly appreciated.
Autodesk is aware that the software has a great potential and the company is working constantly to improve the product. To have a good idea of the expected developments in future releases I recommend to visit the webpage “Infraworks Public Roadmap”:
These new developments are based on the feedback given by the users. Suggestions and proposed new features are posted in the “Infraworks Idea Forum”. I have personally posted some of them myself.
I also include the link to the Youtube official channel which I consider a good audio-visual reference for those who want to crack on with the software:
In short, Infraworks is already a tool to take into consideration, not only in preliminary designs but also as a support for final designs.
It will be interesting to see whether future developments will transform in a main reference for designers - not only for wind farm projection, but also for all kind of civil works modelling.