505XT Digital Control for Steam Turbines

Applicatons

The 505XT controller is designed to operate single valve, or single extraction/admission industrial steam turbines of all sizes and applications. This steam turbine controller includes specifically designed algorithms and logic to start, stop, control, and protect industrial steam turbines or turbo- expanders, driving generators, compressors, pumps, or industrial fans.

The 505XT control’s unique PID structure makes it ideal for applications where it is required to control steam plant parameters like turbine speed, turbine load, turbine extraction header pressure, turbine inlet header pressure, exhaust header pressure, or tie-line power.

The control’s special PID-to-PID logic allows stable control during normal turbine operation and bumpless control mode transfers during plant upsets, minimizing process over or undershoot conditions. The 505XT controller senses turbine speed via passive or active speed probes and controls the steam turbine through one or two (split-range) actuators connected to the turbine inlet steam valves.

When configured to control single extraction and or admission based steam turbines, Woodward’s field-proven ratio-limiter function ensures that interaction between the two controlled parameters (i.e., speed & extraction or inlet header & extraction) is correctly decoupled. Simply by entering maximum levels and three points from the turbine’s steam map (operating envelope), the 505 automatically calculates all the PID-to-valve ratios and all turbine operation and protection limits.

The 505XT controller also includes the following turbine protection functions to ensure that the turbine or its driven load (compressor, pump, generator) is not operated outside of its designed limits:

• 3 Critical speed avoidance bands
• Overspeed anticipation and shutdown protection
• Configurable under- or over-pressure shutdown logic
• Minimum and maximum speed and load settings
• Maximum low pressure stage overpressure limits
• Minimum high pressure stage flow limits

Ethernet and serial communications allow users to easily connect the 505XT into the plant or process control system. All controller inputs, outputs, and statuses can be monitored and all start/stop or enable/disable commands can be given through industry standard Modbus ® * TCP or OPC protocols. The 505XT uses SNTP (synchronized network time protocol) over Ethernet to allow users to synchronize the 505XT’s real-time clock to the plant distributed control system.

Description

The 505XT control is packaged in an industrial hardened enclosure designed to be mounted within a system control panel located in a plant control room or next to the turbine. The control’s front panel serves as both a programming station and operator control panel (OCP). This user-friendly front panel allows engineers to access and program the unit to the specific plant’s requirements, and plant operators to easily start/stop the turbine and enable/disable any control mode. Password security is used to protect all unit program mode settings. The controller’s 8-inch (20 cm) graphical display allows operators to view actual and setpoint values from the same screen, simplifying turbine operation.

Turbine interface input and output wiring access is located on the controller’s lower back panel. Un-pluggable terminal blocks allow for easy system installation, troubleshooting, and replacement. Optionally, users can increase the number of input and output signals to/from the 505 by connecting pre- programmed LINKnet HT™ distributed I/O nodes to the 505XT’s CAN communication ports. These special distributed I/O modules are designed to allow for the flexibility of mounting by the turbine or by the controller, depending on customer’s preference. The following additional I/O signals can be connected to the 505XT via CAN communications:

• 16 4–20 mA input channels and 4 4–20 mA output channels (via 2 LINKnet HT AIO modules)
• 8 RTD signals (via 1 LINKnet HT RTD module)
• 16 Discrete inputs (via 1 LINKnet HT DI module)
• 16 Relay output drivers (via 1 LINKnet HT DO module)

Designed for steam turbine control, the 505XT control includes five PID controllers (Speed, Ext/Adm, Cascade, Aux-1 Aux-2) multiple start-up routines (manual, semi-auto, automatic, remote control), and multiple protection functions (overspeed, critical speed range, max power, etc.) which can be configured by a user depending on the specific turbine application’s requirements. Users can configure the 505XT’s different PID controllers, start routines, and protection levels themselves without the need for a special control engineer.

Once configured, the 505XT performs a configuration check routine to ensure that the programmer did not make any basic configuration mistakes.

Optionally, users can utilize Woodward’s RemoteView software program with the 505XT to function as a remote operator control panel and/or engineering station. Once loaded onto a remote computer or touch panel, this software program allows the computer or touch panel to perform all of the 505XT front panel display functions (monitor, operate, tune, and configure). Password-based login level security allows users to manage which functions they want the remote panel user to have. Refer to product specification 03424 for more information on RemoteView’s capabilities.

The 505XT also includes a suite of service tools to allow users to perform the following functions:

• Download configuration settings files to the 505XT
• Upload configuration settings files from the 505XT to save on another device
• Upload Alarm and Shutdown event log files
• Upload datalog trend information from the 505XT to view and save on another device
• Download different language files into the 505XT
• View real-time or saved trend files