A fluid flow control system for controlling the flow of fluid through a valve is disclosed. The control system controls the flow of fluid through the valve by varying the position of the valve. The control system performs this function in such a manner that the change in position of the valve at all times remains sufficiently bounded so as to ensure that the actual flow of fluid through the valve is substantially equal to the flow predicted by the static flow equation for the valve.

Fluid flow control system

An irrigation control system and a related method for controlling a large number of valves in accordance with a plurality of schedules of instructions provided by the user of the system. Schedules of instructions may be created or modified during normal operation of the system by utilizing a variety of command sequences on a keyboard and display device, and schedules may also be reviewed or monitored during operation. The control system includes apparatus for processing a plurality of digital inputs by means of which the conditions of sensing devices located in the field are monitored and can be used to condition execution of the schedules of instructions. The control system is disclosed for use with a two-wire irrigation system in which on/off control signals are encoded into a power signal for transmission along a pair of wires to which decoding units are connected. The control system includes an input/output service module which transmits on/off control signals to the decoding units repeatedly, as rapidly as the two-wire system will permit, to ensure that the valves remain switched in the manner intended.

Interactive irrigation control system

A diagnostic apparatus for diagnosising of a valve device in a turbine system comprises at least one of a pressure sensor for sensing hydraulic pressure in a hydraulic cylinder for driving a valve body of the valve device and a position sensor for sensing the displacement of the valve body, and a processing device for processing the output signal from the above-mentioned at least one sensor. The processing device has an offset computing device which receives a signal representing the actual operating state of the valve device obtained on the basis of the output signal from the at least one sensor and a signal corresponding to a reference value obtained under the normal operating state of the valve device. The offset computing device is operable to compute the offset between the signals received thereto. A judging device is provided for judging as to whether or not there is a symptom of a sticking in the valve device, in accordance with the output signal from the offset computing device.

Apparatus for making diagnosis of valve device in turbine system

The present invention relates to methods and systems for economically dispatching electrical power. The present invention utilizes real-time heat rates for a plurality of power generating units, e.g., steam turbines, and corresponding emission data for each unit, to dispatch electrical power at the lowest possible cost. The method of the present invention also compares the cost associated with generating power to the cost to purchase power from other electric utilities to achieve maximum cost savings associated with the dispatching of the electrical power.

System and method for economic dispatching of electrical power

A coin computing apparatus includes an input for converting coin values received to coin unit data for storage along with other data. This data is subsequently converted to unit data for controlling operation of the device or the dispensing of articles. The storage includes a temporary storage for storing play unit data as it is received and a permanent storage device for receiving data from the temporary storage device for updating purposes. A read/write control device is included for reading the permanent storage data to the temporary storage means following interruptions such as power failures.

Coin computing apparatus

An improvement in the operation of an electric power plant utilizing a steam turbine controlled, in an automatic mode, by means of a digital computer, is accomplished by simplifying the interaction between the programmed automatic process control and the manual backup control. The position setpoint for each of a plurality of valves in the system to be controlled is established as a direct digital holding function in a respective bistable relay register. In addition, a single valve control holding register is provided which is coupled to all of the valve position controls in parallel. Automatic operation is then possible in either single valve or programmed sequential valve modes, and the programmed interaction to accomplish switching from manual to automatic control is simplified by updating the automatic control status until the single valve holding register has a setting equal to the manual control representation before consummating the manual to automatic switching. The direct digital holding registers also improve total system operation in eliminating drift with respect to the valve positions represented so as to extend the period of reliable operation in the manual mode, and also make it possible to retain the last valid position setpoints held in the respective registers prior to a computer power failure.

Steam turbine system with digital computer position control having improved automatic-manual interaction

In a system and method for automatically starting, synchronizing and operating a steam turbine, proportional plus integral feedbck control utilizing digital computer systems is adapted to correspond to physical valve operation by applying integration limits. Useful for both speed and load control modes of operation, the demand signal is compared with prior values thereof, and the differential is both multiplied by a proportional gain factor, and integrated in the computer utilizing numerical integration techniques. The integrated total is kept within a desired range by applying upper and lower limits, and the limited integral is combined with the proportional factor, further limited, as desired, and appropriately scaled for use as a process variable.

System and method for operating a steam turbine with digital computer control having integrator limit

An electric power plant having dual turbine-generators connected to a steam source that includes a high temperature gas cooled nuclear reactor. Each turbine comprises a high pressure portion operated by superheat steam and an intermediate-low pressure portion operated by reheat steam; a bypass line is connected across each turbine portion to permit a desired minimum flow of steam from the source at times when the combined flow of steam through the turbine is less than the minimum. Coolant gas is propelled through the reactor by a circulator which is driven by an auxiliary turbine which uses steam exhausted from the high pressure portions and their bypass lines. The pressure of the reheat steam is controlled by a single proportional-plus-integral controller which governs the steam flow through the bypass lines associated with the intermediate-low pressure portions. At times when the controller is not in use its output signal is limited to a value that permits an unbiased response when pressure control is resumed, as in event of a turbine trip.

Dual turbine power plant and a reheat steam bypass flow control system for use therein

In a system and method for automatically starting, synchronizing and operating a steam turbine, turbine control including valve position limiting and means for generating a reference control signal representative of desired turbine operation, the reference control signal being limited corresponding to the valve position limit. The reference signal is limited by calculated valve position limits, such that the reference signal is not permitted to rise above such limits. Desired system changes result in reference signal changes which are more quickly reflected in valve position changes, thereby enabling improved system response.

System and method for operating a steam turbine with digital computer control having setpoint and valve position limiting

In a system and method for automatically starting, synchronizing and operating a steam turbine, control means for valve position limiting wherein such limit can be changed non-linearly. Means are provided whereby the system operator has the ability to manually select a minimum incremental change of the valve position limit as a keyboard-entered constant. If the operator enables a continuing change in the limit it is introduced arithmetically, permitting large swings in a reasonably short period of time.

Andrew S Braytenbah

Papers

Steam turbine system with digital computer position control having improved automatic-manual interaction

System and method for operating a steam turbine with digital computer control having integrator limit

Dual turbine power plant and a reheat steam bypass flow control system for use therein

System and method for operating a steam turbine with digital computer control having setpoint and valve position limiting

System and method for operating a steam turbine with digital computer control with accelerating setpoint change