Author: TBG

“This new system caters for the easy addition or removal of functionality from the system”

The plant comprises more than 450 data channels used for data acquisition and control. Plant control, data analysis and trending are performed by three different PCs: a master PC controls the plant’s hardware, and two remote PCs are used to view the data from all sensors within the plant, producing historical trends and data logs, which are required by the owner of the technology under test and also the Scottish Environmental Protection Agency (SEPA).

Using the original system as software specification, all of the necessary objects, logic and functionality in Lookout were redesigned using LabVIEW, ensuring the new software mimics the look and feel of the original Lookout system. The system is divided into nine sections such as water cooling, furnace ignition or coal transport, allowing the operator to easily switch between each of the different screens.

The main design challenge was to determine the functionality of the original system through analysis of the existing Lookout code. It emerged that understanding the code alone was not sufficient to ensure that the LabVIEW system would operate correctly. As a result it was necessary to obtain a thorough understanding of the mechanics of the system through the study of existing flowcharts, wiring diagrams and hardware schematics. This had the added benefit of allowing us to be more capable at finding faults during the commissioning of the system.

Doosan Babcock now use a system that has the same functionality, look and feel as its original Lookout system. It does, however, have the added advantage of fast and easy implementation of new software features that reflect any necessary hardware changes required to the furnace architecture to test future coal burning technologies.

“The prevention of oil theft will in turn prevent environmental damage from spilt oil.”

The system needed to be:

Reliable: able to distinguish between vibration events that are not attacks.
Covert: hard to detect with no visible signs of the installation that would attract attention and reveal the location of the system; preventing tampering or removal.
Wireless: providing independence so that the system is not reliant on a single link, which can be costly and unsecure.
Robust: requiring no servicing for many years while the system is operational.
The wireless (via satellite link) sensor nodes were positioned at 3km intervals along the pipeline. Expandability in design allow the system to be deployed across many hundreds of kilometres. Algorithms were developed that used vibration data to accurately pinpoint theft locations.

The finished design was successfully demonstrated across a 1km test loop in Scotland.

The successful implementation of this project would provide Nigeria with a strong method of preventing valuable oil theft and greatly reduce the environmental impact from spilt oil.

TBG Solutions delivered a reconfigurable, expandable and synchronised data logging network for full scale tidal turbine power train testing.

System Overview

The system consists of a hardware interface with various physical switches and knobs which connects to the TBG PCB housing via various inputs and outputs. This included potentiometer outputs and alarm signals. The PCB I/O is controlled via the NI 9403 module in the cDAQ-9174 chassis which then connects to the PCB. The hardware interface also connects to the NI 9239 module which provides an input for the transducers. The cDAQ-9174 is connected to the control PC which enables the system to continuously send and receive data. Figure 1 is a graph outlining the physical connections between the described components.

The software was developed in LabVIEW and uses various tools which are explained later in the case study. The software receives data from the coil transducers and the Hall Effect sensor and plots it onto graphs located on the main interface. Furthermore, the front panel controls provide an interface for controlling the physical components seen in Figure 2.

Implementation

We designed the software to continuously receive data from the analogue inputs whilst offering the ability to manage the inspection unit through various digital and analogue outputs – all from a centralised location.

We used LabVIEW’s Object-Oriented Programming (OOP) architecture as this was an ideal tool to encapsulate each I/O type and create additional instances that could be dynamically dispatched inside the code. Using the OOP architecture increased the ease of development allowing us to produce simulation classes. This provided an I/O testing platform (Figure 4) for validating functionality throughout the development process and also allowed us to highlight any bugs that had been introduced. Due to the nature of the project, it was not viable for TBG to have access to the inspection hardware. By implementing the simulation classes, we were able to produce and test the software off-site, lowering the development costs and resolving any issues without having to involve the client.

Another invaluable tool that LabVIEW OOP offers is a graphical class hierarchy view (Figure 5) which enabled us to easily develop a Hardware Abstraction Layer (HAL). This greatly benefited the solution and allowed us to program the software in a way that would match the modularity of the NI hardware setup. This allowed us to accommodate potential software and hardware changes as new child classes, modifying the functionality without having to explicitly change the overall software.

Operator PC Interface

We used a number of LabVIEW front panel elements to achieve the full functionality required by the client. LabVIEW’s front panel tools allowed for the complex interface to be organised quickly and professionally while not compromising the ease of use. The front panel was divided using a tab control, allowing the user to quickly switch between screens of neatly organised controls and indicators. Furthermore, the ability to customise controls made the program more intuitive and straight-forward in use as each button was personalised with a unique icon.

Producing this solution required both hardware and software capable of interfacing with a number of inspection units. Using NI LabVIEW, a cDAQ-9174 Chassis with 1 x NI 9239 and 2 x NI 9403 modules and a customised TBG PCB and wiring harness, TBG were able to create a flexible and expandable solution capable of accommodating future changes in our customers requirements. Our solution enabled the monitoring of drill pipes, identifying defects before failure and possible damage.

“TBG Solutions delivered a reconfigurable, expandable and synchronised data logging network for full scale tidal turbine power train testing.”

Cell Design

Due to the extreme dangers inherent in the testing of these devices, the safety features of the test cell were foremost in the design. The safety features were based around operator exclusion from the cell during operation with hardware interlocks on doors which cut cell supply voltages, automatic VSC discharge paths on cell entry to protect against errant charge and stringent operating procedures for cell entry and loading. This can be seen in Figure 1.

The test cell can be broken down into six major parts;

1.      Operators console- This housed the control PC and interface and primary interlock key control.

2.      Test Cell- This is the walled exclusion zone that prevented contact with hazards through the use of 8 foot walls, flash proof filtered windows and an interlocked door.

3.      48U 19” power rack- This contained 2 MPE TS Series 4 3KV DC power supplies.

4.      48U 19” control rack- This housed the PXI chassis with associated signal conditioning and switching and communications interfaces for control and measurement.

This included;

a.      PXI-1044 14 slot chassis.

b.      PXI-PCI 8336 MXI-4 link.

c.      PXI-8231 Gigabit Ethernet Interface.

d.      PXI-8432/2 RS232 Interface.

e.      PXI-4071 6.5 Digit DMM

f.       PXI-5105 60MS/s 12 Bit 8 Channel Digitiser/Oscilloscope 128mb

g.      PXI-6514 Industrial IO Card

h.      PXI-2571 66 Channel, 1A SPDT Relay Module

i.        PXI-6224 M-Series Multifunction DAQ Card.

5.      UUT interface- This was a freestanding structure which housed the pneumatics, cooling interface, bus bars and high voltage switching. The UUTs also plugged into this.

6.      Cooling plant– This had a temperature controlled closed loop water cooling system that used deionised water.

The Test cell can be seen in figure 2

The system has two test bays; one for each UUT. The UUTs are brought into the system on trolleys as seen in Figure 3.

The UUTs are connected to the test cell via hydraulics once all operators vacate the test area and the doors are closed. Once the UUT Interface is connected, the tests can begin.

National Instruments Components-Hardware

One of the key safety concerns was a conductive path between the operator and the UUT. Thanks to NI this was easily overcome by using their fibre optic Ethernet link between the PXI chassis and the PC. This gave the added benefit that the PXI chassis did not require a controller, making the integrated cards appear as part of the PCI backplane. Another key feature of the NI hardware that accelerated development were the soft front panels, which shipped with the hardware and allowed direct control over instruments out of the box. This allowed commissioning of the very complex hardware independent of TestStand, giving us confidence in the test cell before we ran the automated test sequences.

National Instruments Components – Software

The software architecture was made up of several interfaces and engines which worked interactively to create a simple unified interface. This allowed an operator to automatically control a large and complex system. This particular system included complex control, data acquisition, cooling, critical safety monitoring and complex test and was also able to provide detailed debug and manual control capabilities. This can be seen in Figure 4.

The primary interface is a modified version of the shipped TestStand Operator Interface as seen in Figure 5 .

The interface is used by the Operators to run the test sequences and gives them live feedback on the status and progress of the UUTs. Another key modification to the interface was the ability to terminate a sequence in accordance with the safe practices required, when dealing with a high power system.

The second interface is the UUT Communications and Control interface as seen in Figure 6.

The VSC constantly streams a status message over RS232. This is then processed by the interface into a usable format and made available to the TestStand sequences using a shared variable library. Commands are also sent to the VSM via this interface. During testing this runs in the background and requires no user interaction, but was very useful during commissioning and debug.

The third and final interface as seen by the operator is the Data Acquisition and Control Interface as seen in Figure 7.

The Data Acquisition and Control Interface acts as an engine for the continuous data acquisition from the AI and DIO that required constant monitoring. It also included the software that controlled and monitored the cooling plant

Conclusion

TBG Solutions provided a high throughput, safe and reliable test system for a very demanding and high-tech requirement. The soft front panel tools, hardware abstraction layer and easy integration of a variety of instruments allowed rapid development and verification.

“The data logging system TBG supplied ensures that we know when a drop occurs helping us prevent damage to the Fuel Plugging Unit.”

The system was developed using National Instruments Compact FieldPoint consisting of a Real Time controller (cFP-2120), a digital output module (cFP-DO-400), a high-speed analogue input module (cFP-AIO-600) and a digital output module (cFP-DI-330).

Data from the load sensors attached to the winches is analysed and compared against set ‘Load Band’ parameters. If the readings go above these parameters the system waits a defined period of time for the load to stabilise. Following this wait period, the data is once again analysed against a set of steady state parameters and if the load is within these parameters a drop has occurred and the alarm is raised. The load profile for the detected NSP drop is stored to file and the system will continue to monitor the load on all three of the winches. The alarm can be cancelled via an external ‘Cancel’ button within the site facility. Provision was also given for a suite of test profiles to be sent to the Data Logger system should verification of the system be required.

The test system for the data logger is based on MXI-4 technology. Utilising a fibre optic link (PXI-PCI8336) to a PXI chassis (PXI-1031). A data acquisition card (PXI-6221) is used to send test signals to the data logger via a conditioning box (SCC-2345) containing a voltage to current converter (SCC-CO20). The tester can be connected to any of the three winch channels (via test sockets on the enclosure) to verify its operation. This allows site personnel to input the required test profile and view the received waveform on the Web interface Screen.

Prior to TBG Solutions developing this system our Customer had to assess how much damage an FPU had sustained due to an NSP drop, by carrying out extensive non-destructive testing of the FPU welds. Our system allows the size of the drop to be cross-referenced to the damage caused to the FPU. Site personnel will, in time, be able to look at any given drop and decide whether the FPU needs to be taken out of service for maintenance or left in service, thus preventing lost generation with a consequent loss of revenue.