User Solutions
(Issue 1, 2004)

Control system combines off-the-shelf components with Terminator I/O for complex turbine
generator applications

by Ernesto Colon
Vice President and Start Up/Controls Engineer for TDS
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"TDS uses Automation Direct's Terminator I/O field I/O modules in their TurboNet DASH 1 system."

Turbine Diagnostic Services (TDS) is a power generation field service company that provides industrial, utility, independent power producers, and municipality power generation systems for turbine generator applications. The company's TurboNet DASH 1® Control System is a complete DCS-structured turbine generator control system, developed to meet the needs of customers looking for a stable, "crash-free" system for turbine control. "Our Linux and LYNX OS operating platforms make our system much more stable than Windows-based systems, and offers a reliable, real-time operating environment," says John Todd, TurboNet Programmer for TDS.

The system includes a complete control panel, an Human Machine Interface (HMI) station, an optional Engineering Work Station (EWS), and Historian systems, supplying balance of plant and turbine controls in one package. The system is easily adaptable to various size steam, mechanical drive, and gas turbine control applications, and, because of its compact design, is also suitable for retrofits and upgrades.

The TurboNet DASH 1 Control System hardware architecture incorporates off-the-shelf, readily available computer components (with the exception of three specialized I/O modules) to reduce ownership and maintenance costs. The power supplies are available in a redundant configuration using industry standard components, the control panel and HMI station are based on industry standard, x86 compatible microprocessors, and all monitors are industry standard LCD displays.

"The off-the-shelf-price of our components makes the TurboNet extremely cost effective for maintenance. The customer can afford to have a complete set of spare parts in stock," explains Brian Walsh, Senior Designer for TDS.

TDS uses Terminator field I/O modules from AutomationDirect, and has developed a protocol to communicate with redundant control processors via the Terminator I/O's Ethernet network interface. TDS uses all of the standard Terminator I/O modules and has developed low-density termination boards that, interposed between the I/O modules and the field I/O, provide suppression and fuse protection as required, as well as standard contact relays operated by the output modules. With three nodes of Terminator I/O modules, each individually powered and with separate Ethernet interfaces, the system is able to handle triple redundant field I/O. The hot-swappable I/O modules allow non-critical or critical redundant I/O to be changed online.

The control system scans the I/O and performs the control processing at a 20ms scan rate. The "hot standby" processor monitors the broadcast of the primary processor every 20ms and takes control after two failed primary broadcasts in 50ms, allowing it to be in service on the third scan. The control processors interface with the HMI via the main data highway to provide data for monitoring and alarming, and to receive operator initiated control commands.

To handle the complexity of turbine generator control, TDS developed three specialized I/O modules in cooperation with AutomationDirect and their technology partner HOST Engineering that seamlessly interface into the standard Terminator bases and Ethernet network interfaces. These specialized I/O modules (an overspeed module, servo loop control module and a vibration module) are used for the control and protection of the turbine generator interfacing with devices typical of turbine generator industry standards.

Utilizing a high-speed Internet connection, the TurboNet DASH 1 control system can be accessed for control and maintenance from remote locations. Operators can perform control operations and access any historical data collected. Engineers can implement program changes, as well as monitor and troubleshoot the system online.

www.turbinedoctor.com

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