Westinghouse Electric Corporation

Jack R Smith

Terry J Reed

Leonard H Burrows

Robert A Yannone

Lyle F Martz

Roy W Kiscaden

James J Shields

Alan Martens

Theodore C Giras

John F Reuther

Guy E Davis

Richard S Heiser

Paul A Berman

Richard J Hertz

William E Mendez, Jr

Thomas J Radkevich

Robert A Putnam

Joseph A Pesavento

Francis A Lebonette

An electric power plant, including a fossil fired boiler and a steam turbine, is operated by a control system including a plant unit master. The control system includes a boiler control for determining the inputs of fuel, air and water, and a turbine control for determining the position of the throttle valves introducing steam from the boiler to the turbine. The plant unit master provides a load demand reference in parallel to the boiler control and to the turbine control, whereby the turbine and the boiler are operated in a coordinated manner. Measuring means provide indications of throttle pressure, power generated by the system and turbine rotor speed. Distinct controllers, each including a controller and responsive to one of the aforementioned indications and its corresponding reference, modify the load demand reference before it is applied to the turbine control or to the boiler control. The above-described control system including the plant unit master, boiler control and turbine control is implemented by a single digital computer.

Plant unit master control for fossil fired boiler implemented with a

A combined cycle electric power plant includes gas and steam turbines and steam generators and a digital/analog control system. In the automatic and manual modes of operation, the control system develops a fuel reference signal for the throttle valve position control by means of a speed/load control which functions on a feedforward speed control basis without speed feedback correction. An electrical overspeed protection control is directly coupled to the throttle valve position control to limit turbine speed to a first reference value when the breaker is closed and to limit turbine speed to a lower reference value when the breaker is open. Electrical and mechanical overspeed protection systems directly trip the turbine at higher speed references.

Combined cycle electric power plant and a gas turbine having an improved

A combined cycle electric power plant includes gas and steam turbines and steam generators and a digital/analog control system. A gas turbine megawatt load control system is included in the control and it includes a feedforward load control which generates a fuel reference equal to the sum of a megawatt load demand and an idle speed fuel demand. The megawatt load control also includes a feedback load trimmer which provides minor corrective action on the operation of the feedforward load control. Gas turbine and combined cycle plant operation results in the generation of megawatts equal to an input demand value.

Combined cycle electric power plant and a gas turbine having improved

A digital computer system provides automatic control for a steam turbine and two gas turbines in a combined cycle electric power plant during startup and load modes of operation. The gas turbine automatic control system provides speed, load and blade path temperature control functions in developing an output fuel control signal for application to each gas turbine fuel valve control. An analog control for each gas turbine selectively provides startup and temperature and load control functions as a backup for the automatic gas turbine control, and further provides gas turbine overspeed, surge and other limit controls continuously. An operator panel functions with the analog and digital controls to provide an operator interface with the plant, and an interface circuit ties the digital and analog controls together for bumpless transfer between manual and automatic modes of operation. A sequencer is provided for each gas turbine and it provides gas turbine startup sequence control, gas turbine trip protection and other functions in both the automatic and the backup modes of operation. A gas turbine monitor develops temperature and vibration signals for the sequencer and the fuel controls.

Combined cycle electric power plant having an improved digital/analog

A combined cycle power plant includes a gas turbine and an afterburner to which fuel is supplied for speed and load control. Water is injected into the turbine combustors by a controlled water injection system to control total NOx emissions from the turbine and the afterburner as a function of turbine load corrected for changes in inlet air temperature and inlet guide vane position.

Gas turbine and combined cycle power plant having reduced emission of

A combined cycle electric power generating plant includes gas and steam turbines and a heat recovery steam generator recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. The gas turbine includes a plurality of variably set guide vanes whose position may be set to determine the inlet flow to the gas turbine. Guide vane control apparatus is provided to limit the inlet guide vane position as a function of gas turbine compressor inlet temperature in accordance with a desired gas turbine exhaust flow, and to match the gas turbine exhaust flow to the steam requirements of the steam generator as in turn determined by the load placed upon its steam turbine. In addition, an afterburner is provided to supplementally heat the exhaust gas turbine gases before they are directed to the steam generator. During the startup, the afterburners are operated to supply supplemental heating to the gas turbine exhaust gases supplied to the steam generator whereby the temperature of the steam passed to the steam turbine is maintained at a minimum level. Further, the afterburners are fired to permit additional loading to be placed upon the steam turbine.

Control apparatus for controlling the operation of a gas turbine inlet

The electric power plant including a steam generator and a steam turbine is operated by a control system including two redundant digital computers. Switching circuitry is provided for coupling one of the computers through interface equipment to the steam generator and the turbine and a generator according to programmed computer control. A data link is established between the computers to transfer manual/automatic status and other needed data from the control computer to the standby computer. A system is provided for detecting when certain hardware and software malfunctions have occurred and for responsively transferring control to the standby computer. The standby computer is tracked to the control computer so that control computer transfer can be made reliably without disturbing the electric power generation process.

Electric power plant having a multiple computer system for redundant

In a primary or backup control system for operating a gas turbine, a blade path temperature limit signal is generated which acts as a check on a fuel scheduling signal to the turbine which might otherwise cause excursion of the blade path temperature beyond prescribed limits. The means for generating the blade path temperature limit signal is adapted however so that a preliminary error signal is conditioned to behave in one manner in response to a condition of increasing temperature and in another manner to a condition of decreasing temperature. This two-way response is achieved by utilizing a plurality of proportional signal limiters, each one of which is matched to or tuned in accordance with the characteristics of the gas turbine. Further, the response duality is automatic and subject to the particular condition of temperature change which obtains. In addition, means are provided for generating a temperature limit signal which is clamped to a fixed, predetermined percentage of the fuel scheduling signal. This signal is employed, under appropriate conditions, in place of the conditioned error signal to insure that the conditioned error signal does not otherwise set the fuel scheduling signal at less than the fixed percentage above its 100% value. Acting in concert, the means for conditioning the preliminary error signal and the means for generating the clamped temperature signal yield increased turbine protection, greater operating stability and more rapid control response where permissible.

Matching response of a blade path temperature limit signal to

A backup control system for a gas turbine power plant having a computer implemented primary control system is disclosed. Bumpless transfer between the two control systems is effected by tracking a plurality of control signals generated by each control system, the signals being functionally identical, but independent. After comparison of the functionally identical signals, transfer between the two control systems is permitted only if any tracking error does not exceed a permissible deadband margin. The presence of tracking error is also utilized to generate a signal which is employed to operate panel mounted signal means, which panel can thereby be used as a diagnostic tool in monitoring the health of both the primary and backup systems. Transfer reliability is thereby enhanced and turbine availability improved.

Bumpless transfer in shifting control command between the primary and

A combined cycle electric power plant includes gas and steam turbines and steam generators and a digital/analog control system. A surge protection system is included as part of the analog portion of the control system, and it functions in both automatic and manual modes of operation. A surge protection signal is generated to limit fuel demand as a function of speed during startup and as a function of combustor shell pressure during higher speed load operation.

Electric power plant having a gas turbine with an improved wide range

A local maintenance controller permits continued power generation during maintenance or failure of a primary gas turbine control system by manually for maintenance purposes or automatically for failure purposes assuming turbine control to thereby insure continued operation. The local maintenance controller set forth is particularly suitable for use in conjunction with a computer implemented gas turbine control system. Transfer between the local maintenance controller and the primary control system is effected in a bumpless manner so that load swings are absent. However, if the turbine was operating at system reserve at the time of transfer, the local maintenance controller reduces the load to peak value until primary control is resumed. Operation at any other load at the time of transfer is maintained by the controller. Transfer back to primary control is also effected in a bumpless manner. Pushbuttons provided on the controller and associated circuitry permit an operator to change loads as necessary within the limits of a peak performance curve. In addition, the turbine can be started, synchronized and loaded as necessary by the operator.

Local maintenance controller for gas turbine power plants having a

A combined cycle electric power plant includes gas and steam turbines and steam generators and a digital/analog control system. A backup control is included for each of the gas turbines with an outlet or preferably blade path temperature limit control which prevents the operator from causing the turbine to operate above a temperature limit reference. The temperature limit control further restricts the rate at which the operator can move the gas turbine operating or load level toward the temperature limit value. When the turbine is operating at a load below the temperature limit value, the operator can freely move the fuel reference until the blade path temperature approaches the temperature limit value.

A combined cycle electric power plant including gas and steam turbines, steam generators, afterburners and a digital/analog control system is provided with inlet guide vane control apparatus adapted to match gas turbine exhaust flow to the requirements of the steam generator with which it is associated. The guide vane control apparatus operates to limit the inlet guide vane position as a function of gas turbine compressor inlet temperature in accordance with a desired gas turbine exhaust flow at predetermined operating conditions.

Control apparatus for matching the exhaust flow of a gas turbine

A combined cycle electric power generating plant, which includes gas and steam turbines, inlet guide vane positioning means for the gas turbines, steam generators, afterburners and a digital/analog control system, is provided with inlet guide vane control apparatus adapted to modulate the position of the inlet guide vanes as a function of load or inlet blade path temperature. The inlet guide vane control apparatus is further adapted to operate in either an automatic or manual mode with additional provision for bumpless transfer therebetween incorporated in the control apparatus.

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Pittsburgh, PA, United States of America

Jack R Smith