A Reconfigurable, Expandable and Synchronised Data-Logging Network for Full-Scale Tidal Turbine Power Train Testing

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"LabVIEW object-oriented programming provided an elegant way to add new nodes and modules to the system while eliminating the need to change the surrounding software architecture. NI offers a variety of DAQ hardware platforms for nearly all eventualities."

- Lewis Gear, TBG Solutions

The Challenge:
Measuring a wide range of signal types using a variety of DAQ hardware for tidal turbine testing.

The Solution:
Using NI DAQ hardware to develop a data-logging network that utilises LabVIEW object-oriented programming to create a hardware abstraction layer, Precision Time Protocol for synchronization, and network streams for lossless data communication.

Author(s):
Lewis Gear - TBG Solutions

Global Nacelle Testing Needs

Tidal turbines are installed on the seabed in areas with fruitful tidal resources. It is imperative that the devices are efficient and reliable to maximize generated electricity.

As part of the Offshore Renewable Energy Catapult, The National Renewable Energy Centre is dedicated to advancing the development, demonstration, deployment and grid integration of renewable-energy and low-carbon generation technologies. In one of its world-class integrated test facilities, customers can test complete power train systems for marine turbines of up to 3 MW. The system, unique in the UK, can simulate tidal conditions, extreme events, and fatigue for manufacturers of these innovative and quickly maturing renewable energy devices.

The National Renewable Energy Centre needed a data acquisition software solution in all of its testing facilities. After competitive consideration that assessed both technical and financial merits, the Centre chose TBG Solutions, an NI Gold Alliance Partner, to provide the solution.

 

                        Figure 1.TBG Solutions and Offshore Renewable Energy Catapult Logos


Power Train Test System Overview

Using the complete power train testing system, customers can test tidal turbines from different manufacturers, with power outputs of up to 3 MW. Mechanical inputs to the power train are generated using a motor and a force application system (FAS), shown in Figure 2.

 

 Figure 2. Power Train Test System Overview

 

A variable-speed drive controls the torque and speed delivered by the motor (which simulates the torque generated by the tides flowing through the turbine’s blades), and the FAS simulates other loads imposed on the other axes by powerful marine currents.

 

Figure 3.Power Train Test System

 

Using this specialised test equipment (which is larger than a double-decker bus), the facility can accelerate the effects of a lifetime of service on the device being tested, in a controlled and highly monitored way. Measurement nodes are placed where required within the test nacelle and into auxiliary plant rooms, which can contain high-voltage power converters and switchgear. The measurement nodes are designed to be easily installed in the nacelle to keep signal cables as short as possible (due to the potentially electrically noisy environment), but this created a significant challenge to the synchronisation and centralised visualisation of data across the facility.

Data-Logging System Overview

The National Renewable Energy Centre specified an acquisition system flexible enough to cope with the wide variety of nacelles that could pass through the facility. It also needed to synchronise multiple measurement systems and present them on the same scale. This synchronisation had to be better than 1 ms throughout tests that might last many months. The result was a data-logging network consisting of one CompactDAQ device, two PXI devices, and two CompactRIO data acquisition nodes that can easily be expanded to accommodate more nodes. The CompactRIO modules are a powerful and compact solution for harsh environments, compared to the PXI and CompactDAQ devices that are more flexible by taking advantage of an NI-DAQmx driver. The PXI platform also boasts the highest levels of high-speed interchannel synchronisation. The nodes perform signal conditioning, acquisition, and processing before sending the data over the network or directly to a central server, as shown in Figure 4. The Centre can add a new type of node that would only require Ethernet connectivity to the central server; it could be another DAQ node, a bench top instrument or a PC. 

Figure 4.Data-Logging Architecture Overview

 

Depending on requirements, customers can configure a test by adding data acquisition nodes and setting the node’s module configuration.

The system uses LabVIEW object-oriented programming to create a hardware abstraction layer. New input modules and new node types can be added to the system with minimal change to system architecture. Using inheritance and dynamic dispatching, acquisition nodes are treated generically and code reuse is maximized, as shown in Figure 5, producing an expandable and highly reconfigurable system.

 

Figure 5.LabVIEW HAL Class Hierarchy

 

Using NI software-defined IEEE 1588 synchronisation, the data acquisition nodes synchronize to a global positioning system time source to within 1 ms without extra hardware or cabling.

Network streams transfer data from the networked nodes to the data server. Sending arbitrary data types over a lossless communication network without writing any code saved significant time. Once the data has reached the server, it is logged to disk and published to operator consoles. Operators can view live data and control the system, or analyze saved data using DIAdem.

Positive Impact of the Reconfigurable Data-Logging Network

TBG Solutions designed a system to suit the different test and measurement needs of the National Renewable Energy Centre and its customers. LabVIEW object-oriented programming provided an elegant way to add new nodes and modules to the system while eliminating the need to change the surrounding software architecture. Furthermore, NI offers a variety of DAQ hardware platforms for nearly all eventualities.

The successful partnership between TBG Solutions and the National Renewable Energy Centre resulted in a data-logging network for thorough nacelle testing. Customers can use the facility to test the latest and greatest marine turbine designs. TBG Solutions will continue to add support for new hardware and meet the Centre’s measurement needs in the future, including expanding into other world-class testing facilities.

Author Information:
Lewis Gear
TBG Solutions
3A Midland Court, Barlborough
Chesterfield
United Kingdom
lewis.gear@tbg-solutions.com

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