Integrated Turbine Protection System

The Integrated Turbine Protection system (ITP) is a stand-alone solid state controller designed to provide optimum reliability and flexible testing of turbine mounted protective system components. The system is microprocessor-based and replaces the antiquated protective devices and relay-based protective functions of existing turbine control systems while providing enhanced data logging and communication capabilities.

The use of solid state components in the ITP system increases both reliability and availability by reducing unit trips associated with component failures. Recording the sequence of events and enhanced test features help determine the cause of unnecessary turbine trips and assist in diagnosing malfunctions in equipment such as pressure switches.

System Architecture:

The ITP system is comprised of three primary sub-systems:

• A high-speed data logger
• A PLC/Hardwired or optional Redundant PLC Operating System
• A CPU for display, operator interface, and communications

The system has been designed to insure fail-safe operation. Redundant activation paths are used for all critical signals, and all individual components. Signal paths are fully testable. All system faults are enunciated and, wherever necessary, bypass routing of critical signals is automatically initiated by the system.

Power System:

The ITP's power system is redundant and is designed to meet the necessary power requirements of all turbine mounted components and the system itself. Input power is drawn from two independent 115 volt AC sources (one of which should be uninterruptible or vital AC from the station inverters.) The system's DC voltages are generated by redundant switching power supplies that are used in a load sharing configuration to insure maximum useful life. Where 115 volt AC output is necessary for non-critical solenoid operation, it is provided by regulating transformers from the input power sources.

Redundant Trip Activation:

To maintain the highest level of system integrity as well as insuring maximum unit availability all inputs/outputs to turbine mounted equipment employ redundant isolated activation paths. A combination of hardwired optical isolation and a PLC operating system or optional redundant PLC operating systems are employed to activate all tripping functions. No single point failure will cause the loss of a turbine trip function. The trip push buttons on the operator interface panel, which send trip signals directly to the turbine mounted devices, do not use signal isolation.

Programmable Logic:

Industry standard PLC Relay Ladder Logic is used in one or both of the tripping paths as well as for all testing functions. Non-volatile memory is custom coded to meet unit specific needs. Self test and diagnostic routines are employed to eliminate the possibility that a turbine trip will result from a malfunction in an on-line test. Please note that all logic is fully configurable and maintainable by plant personnel.

Sequence of Events Recording:

The ITP's high speed data logging capabilities and sequence of events recording is accomplished by a Pan-Alarm Core 2000 data logging system. Sequences are automatically written to a hard disk and stored in non-volatile memory. Sequence retrieval is made through use of an operating panel CPU. Data retrieval is password protected and all data logging functions can be programmed through use of the operating panel CPU or a user-provided IBM compatible computer.

Operating Panel CPU:

The ITP's Operating Panel CPU is a Pentium based single board computer with integral display and is responsible for the following functions:

• Sequence of events printing.
• Sequence of events storage and retrieval.
• Communication with data logging hardware.
• Communication with balance of plant equipment.
• Display generation for the Operator Interface panel.

Communications are handled through standard RS232 and RS422 serial links; internal communications protocols are fixed. Communications protocols for the interfaces to plant equipment such as a DCS are custom programmed to meet receiving system requirements and can be user re-configured as necessary to accommodate subsequent upgrades.

Hardware:

All ITP System hardware is designed to meet or exceed applicable IEEE and NSI standards. Custom modifications can be made where required.

Cabinet:

The ITP cabinet is a stand-alone unit, based on standard 19" rack-mount hardware. The microprocessor, power system and interface rack access is from the front of the cabinet. Interconnections are made in the back of the cabinet. Incoming cables can enter the cabinet from either the top or the bottom through the removable access panel. The cabinet is designed to be mounted in any environmentally controlled location. Cabinet cooling is not necessary but can be provided for special applications.

Trip Signal Inputs:

Trip signal inputs are taken from turbine mounted equipment modified to optimize use of the existing protective system components while replacing antiquated components with modern equivalents. The ITP system employs a fully testable input translator for all two-out-of-three logic inputs. Where trip signals are presently derived from single inputs it is suggested that the turbine mounted equipment be modified to accommodate a two-out-of-three logic configuration. Necessary modifications, which substantially increase system reliability, are available as a system option. All standard types of inputs from the balance of plant equipment for cross tripping are supported.

Operator Interface:

The ITP Operator Interface is based on a flat panel touch screen. Communication through the operating panel CPU can be utilized to control the system from a DCS operating station if desired. As with all protective systems, direct trip push buttons are mounted on the operator interface panel. For maximum reliability these push buttons send redundant parallel trip signals directly to the trip hardware mounted on the turbine. Back-up push buttons are also provided for critical test functions in the event of a CPU failure. In all cases, the operator interface panel can, within certain size restraints, be custom configured.

Turbine Control Interface:

In all cases the ITP system will have to interface to the primary turbine control system to transfer turbine protective system status to the valve operating circuitry. The extent of this interface will vary with the system in question, but the basic interface provided is a redundant parallel signal transfer powered by the turbine control system. Custom interface requirements will be accommodated as necessary.

For more information on MD&A Control Systems' products and services, please call (970) 224-2223 Ext. 140 or email: amcneill@mdaturbines.com