GESPEEDTRONIC™ MARK V GAS TURBINE CONTROL SYSTEM

INTRODUCTION

The SPEEDTRONIC™ Mark V Gas Turbine

Control System is the latest derivative in the

highly successful SPEEDTRONIC™ series.

Preceding systems were based on automated turbine control, protection and sequencing techniques dating back to the late 1940s, and have

grown and developed with the available technology. Implementation of electronic turbine control, protection and sequencing originated with

the Mark I system in 1968. The Mark V system is

a digital implementation of the turbine automation techniques learned and refined in more

than 40 years of successful experience, over 80%

of which has been through the use of electronic

control technology.

The SPEEDTRONIC™ Mark V Gas Turbine

Control System employs current state-of-the-art

technology, including triple-redundant 16-bit

microprocessor controllers, two-out-of-three voting redundancy on critical control and protection parameters and Software-Implemented

Fault Tolerance (SIFT). Critical control and protection sensors are triple redundant and voted

by all three control processors. System output

signals are voted at the contact level for critical

solenoids, at the logic level for the remaining

contact outputs and at three coil servo valves for

analog control signals, thus maximizing both

protective and running reliability. An independent protective module provides triple redundant hardwired detection and shutdown on

overspeed along with detecting flame. This module also synchronizes the turbine generator to

the power system. Synchronization is backed up

by a check function in the three control processors.

The Mark V Control System is designed to fulfill all gas turbine control requirements. These

include control of liquid, gas or both fuels in

accordance with the requirements of the speed,

load control under part-load conditions, temperature control under maximum capability

conditions or during startup conditions. In addition, inlet guide vanes and water or steam injection are controlled to meet emissions and operating requirements. If emissions control uses

Dry Low NOx techniques, fuel staging and combustion mode are controlled by the Mark V system, which also monitors the process.

Sequencing of the auxiliaries to allow fully automated startup, shutdown and cooldown are also

handled by the Mark V Control System. Turbine

protection against adverse operating situations

and annunciation of abnormal conditions are

incorporated into the basic system. The operator interface consists of a color

graphic monitor and keyboard to provide feedback regarding current operating conditions.

Input commands from the operator are entered

using a cursor positioning device. An arm/execute sequence is used to prevent inadvertent turbine operation. Communication between the

operator interface and the turbine control is

through the Common Data Processor, or <C>, to

the three control processors called <R>, <S> and

<T>. The operator interface also handles communication functions with remote and external

devices. An optional arrangement, using a

redundant operator interface, is available for

those applications where integrity of the external data link is considered essential to continued plant operations. SIFT technology protects

against module failure and propagation of data

errors. A panel mounted back-up operator display, directly connected to the control processors, allows continued gas turbine operation in

the unlikely event of a failure of the primary

operator interface or the <C> module.

Built-in diagnostics for troubleshooting purposes are extensive and include “power-up,”

background and manually initiated diagnostic

routines capable of identifying both control

panel and sensor faults. These faults are identified down to the board level for the panel and

to the circuit level for the sensor or actuator

components. The ability for on-line replacement

of boards is built into the panel design and is

available for those turbine sensors where physical access and system isolation are feasible. Set

points, tuning parameters and control constants

are adjustable during operation using a security

password system to prevent unauthorized access.

Minor modifications to sequencing and the

addition of relatively simple algorithms can be

accomplished when the turbine is not operating.

They are also protected by a security password.

A printer is included in the control system

and is connected via the operator interface. The

printer is capable of copying any alpha-numeric

display shown on the monitor. One of these displays is an operator configurable demand display that can be automatically printed at a

selectable interval. It provides an easy means to

obtain periodic and shift logs. The printer automatically logs time-tagged alarms, as well as the

clearance of alarms. In addition, the printer will

print the historical trip log that is frozen in

memory in the unlikely event of a protective

trip. The log assists in identifying the cause of a

trip for trouble shooting purposes.

The statistical measures of reliability and availability for SPEEDTRONIC™ Mark V systems have

quickly established the effectiveness of the new

control because it builds on the highly successful SPEEDTRONIC™ Mark IV system.