Developing a Control and Monitoring System for a Vertical and Floating Wind Turbine for Deep Sea Deployment

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"Using the LabVIEW RIO platform for controlling I/O and the different nodes of the system, and WireQueue for secure transfer of data, we achieved a rugged, high performance, distributed control and monitoring system that gives us secure access to the data anywhere in the world."

- Daniel Ehrnberg, SeaTwirl AB

The Challenge:
Developing a control system for a vertical, floating wind turbine that can monitor the operating conditions of the turbine, control it to make sure it operates at its highest efficiency, gather and log data, and securely transfer the data to operators and developers anywhere in the world for analysis and continuous development.

The Solution:
Using the CompactRIO platform, LabVIEW software, and WireQueue to develop a rugged, high-performance, distributed control and monitoring system that can keep the wind turbine safe if any abnormality occurs, and allow access to the data from anywhere in the world.

Daniel Ehrnberg - SeaTwirl AB
Stefan Mattsson - WireFlow AB

Developing a Control and Monitoring System for a Vertical and Floating Wind Turbine for Deep Sea Deployment

Offshore wind power has great promise to help solve future energy demands through renewable energy. Offshore, the winds are stronger, blow more hours, and are more uniform. Increased depth and distance from land produces new challenges though. We cannot build turbines directly on the sea floor, and turbines must have a control system that can quickly shut down the generator in case we lose the connection to the onshore control rooms. Data must be easily and securely accessible to allow for future optimization and efficient maintenance strategies due to the practical difficulties of reaching the systems.

Innovative Design

SeaTwirl designs vertical and floating wind turbines for the ocean. Our wind turbines are easier to build, easier to install, and require less maintenance than traditional offshore wind turbines. We want to deliver the most cost-effective product for the production of renewable energy. The SeaTwirl wind turbine features a simple robust design, few moving parts, and can be placed at deeper waters with good wind conditions. It is built for the ocean. The underwater structure contains a buoyancy part and the weight distribution makes the structure stable. The full body, from the wind turbine on the top to the lowest underwater weight part, rotates as one piece and all its weight is carried up by the water

Figure 1: The full body, from the wind turbine in the top to the lowest underwater weight part, rotates as one piece and all its weight is carried up by the water. To translate the kinetic energy into electrical energy a generator is placed around the rotating tower.

We placed a generator around the rotating tower to translate the kinetic energy into electrical energy. We placed it above the sea level and anchored it to the bottom of the sea to hold it in place. We can use the anchoring method to place the generator in deep waters. We can place these floating wind turbines in new areas of the world with deep waters that were limited from previous wind power turbines.

A vertical wind turbine can absorb wind energy independent of wind direction. We do not need any yaw or pitch mechanism to face the blades to or from the wind. Scientific reportsshow that vertical axis wind turbines have a high structural limit and can be built larger than horizontal axis wind turbines, reaching a new limit of cost effectiveness. Fewer moving parts also helps keep maintenance costs lower than conventional wind turbines and minimizes downtime.

Need for Advanced Control and Monitoring

Even though the design itself has advantages compared to conventional turbines, our turbines still require a robust and powerful control system that continuously measures the wind and controls the rotational speed according to an algorithm that makes the power generation efficiency optimal. They also require continuous status monitoring, the capability to stop the rotation in case we discover any abnormalities, and the ability to take the system into a failsafe mode. Since the high-power frequency inverter is onshore, we had to distribute our control system with nodes that can interact with various kinds of sensors and machinery, both onshore and offshore, and it had to be very robust and reliable.

We planned to install our 30 kW prototype outside of Lysekil on the west coast of Sweden. We had to develop a control and monitoring system that could record a huge amount of measurement data. We would use this data to analyze the functionality and performance of the wind turbine. Our personnel would also use this data to monitor the operations from our control room in Gothenburg, more than 70 km away. We needed a secure remote monitoring link, but could not guarantee fixed internet services at the location.

Choosing a Development Partner for the Control System

We have expertise in energy technology, fluid dynamics, and mechanical design, but we needed a development partner with proven expertise in designing customized distributed control systems to help us design a powerful control and measurement system for the wind turbine. We decided to team up with NI Alliance Partner WireFlow from Gothenburg, Sweden. The company has experience creating control systems and an Internet of Things (IoT) product called WireQueue that delivers secure communication over the Internet. This experience made us certain that WireFlow is the right development partner for the control system.

The Tasks of the Control and Measurement System

The wind in conjunction with three electric generators located in the wind turbine control the rotational speed. Cables on the bottom of the sea connect the generators to a high-power frequency inverter located in the equipment building onshore. When starting up the rotation of the turbine, the frequency inverter controls the three electric generators that now act as motors to rotate the turbine to a specified speed. When the wind pushes the turbine blades, the motors break the rotation to the speed set by the frequency inverter. This makes the motors act as generators and energy flows from the wind turbine to the frequency inverter and in to the power grid.

There is a relationship between wind speed and the rotational speed where the wind turbine power generation efficiency is optimal. The main task for the control system is to continuously measure the wind and control the rotational speed through the frequency inverter. Besides doing this, the control system must also monitor status, and in case of any abnormalities, stop the rotational speed and take the system into a failsafe mode. The control system should monitor various status parameters such as:

  • The status of the frequency inverter and the generators
  • Status of the mechanical breaks
  • Temperature, wind speed, and other environmental parameters
  • Mechanical forces that affect the wind turbine by measuring vibrations, inclination, and torque

Maintenance personnel should be able to monitor the status of the wind turbine from remote locations over the Internet. Any alarms should trigger a notification in the monitoring computer or smartphone, but all measurement data should be continuously logged onto a large disc. SeaTwirl engineers can use this date for analysis to gain insight into how the wind turbine behaves in its real environment to facilitate future development and maintenance planning. The security of this data is very important. It must be transferred correctly, and unauthorized people must not access it.

Figure 2: An authorized operator can connect to an operator panel for the control system. The operator panel displays system status and can be used to control the turbine manually. The graphs show vibrations and movements in the x, y and z axis and the operator

An authorized operator should be able to connect to the control system with a PC running a program that acts as an operator panel for the control system. This operator panel should display system status, and it should be possible to control the turbine manually using the operator panel. The operator panel should provide a graph that shows vibrations and movements in the x, y, and z axis. The operator can use a chart to select which signals he wants to display.

Reliability is crucial

Because of the harsh conditions out at sea, we had to take great care with the reliability of the control system and ensure it would be responsive and reliable if the system needed to be shut down. We also need to make sure it could read and write to the variety of different sensors and peripheral units in the system. We chose to use the CompactRIO hardware platform since it provides the possibility to quickly design a robust and predictable control system using off-the-shelf hardware. We installed the CompactRIO in the onshore equipment building with the frequency inverter. It comes with 4–20 mA analog I/O modules and 0–24 V digital I/O modules that control the frequency inverter and the mechanical breaks located in the wind turbine. The modules also measure wind, temperature, and other types of environmental parameters. Using the CompactRIO platform, we could also put I/O modules in a reconfigurable I/O (RIO) expansion chassis inside the turbine itself.

Figure 3: The generators are connected with cables on the bottom of the sea to a high power frequency inverter located in the equipment building onshore. A CompactRIO connects a network attached storage, a RIO expansion unit and the PC operator panel, and WireQueue makes it possible to securely operate the turbine and access all gathered data remotely.

Using LabVIEW we could, with a short development time, design and implement a networked system that shares the collected data between the CompactRIO and the other parts of the control system: a network-attached storage, the RIO expansion unit, and the PC operator panel. By deploying a WireQueue Toolkit on the CompactRIO, we could then easily set up an IoT server for secure communication over the Internet that we can monitor from any web browser or through the WireQueue apps available on Android and iOS. Engineers can monitor the turbine in real time or access the data for offline analysis, a functionality that otherwise would have taken months to implement and would have required internal support and maintenance.


We used the LabVIEW RIO platform to control I/O and the different nodes of the system, and WireQueue for secure data transfer to achieve a rugged, high-performance, distributed control and monitoring system. This system can keep the wind turbine working at its highest efficiency and keep it safe in case of quick shifts in the working environment or other unforeseen circumstances. It can continuously log data and give us secure access to the data anywhere in the world, which is vital in the continuous development of our wind turbines, as we scale them up from 30 kW to the MW range. 

Author Information:
Daniel Ehrnberg
SeaTwirl AB

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