Westinghouse Electric Corporation

Leonard H Burrows

Jack R Smith

Robert A Yannone

James J Shields

John F Reuther

Richard S Heiser

Richard J Hertz

Joseph A Pesavento

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 predetermined time delay of speed setpoint ramping of a gas turbine is imposed at ignition in its primary control system or local maintenance controller in order to compensate for the fixed energy input at ignition which might otherwise greatly increase the possibility of flameout. The imposed time delay results in the increase of an initial turbine speed tracking mode time period for the duration of the time delay. During the time delay period, fuel flow is maintained at a fixed fuel valve setting and pressure. At the termination of the time delay period, ramping of a speed setpoint at a selected rate is begun and the turbine speed is thereby increased towards synchronization speed whereat synchronization is effected.

Delayed ramping in the primary control system or local maintenance

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 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.

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Gibsonia, PA, United States of America

Leonard H Burrows