Leeds & Northrup Company

General Signal Corporation

Charles W Ross

Frederick B Davis, 3rd

A method for optimizing combustion air flow to a furnace. As the air/fuel ratio changes or is periodically perturbated, the corresponding change in heat loss to the stack due to the change in the amount of combustibles in the flue gases is maintained equal to the change in heat loss to the stack due to changes in the amount of excess air in the flue gases. The control is carried out by continuously modifying the air/fuel ratio in the appropriate direction to maintain that equality.

Optimizing combustion air flow

A control system is provided for controlling the distribution of load among a plurality of generators with some of those generators responding quickly to control and some being slow in response. The area control error signal is divided into portions to provide a unit error signal assigned to each generator. A control is utilized which responds to the unit error signal to reposition the governor motor until the error signal is reduced to zero. Applying that control to slow responding units requires anticipation of the generation changes to be expected after full response. Control of the governor motor position so as to modify generation is from the unit error signal as modified in accordance with the difference between the desired generation for the units as required for economic considerations and the actual generation with that difference being modified by a signal which is a function of the anticipated generation. That function is expressable in one form by the equation ##EQU1## where: K is a constant

Unit controller for multiple-unit dispatch control

A method for correlating in a digital data acquisition system the time sequence of a group of events at locations remote from the master station. The method corrects the time tags on the events record for the signal transmission time between the master and remote stations and also takes into account the turnaround time at the remote station. In addition, compensation is made for the drift of the remote clocks with reference to the master clock.

Remote correlation of sequence of events

A control system is provided for controlling the distribution of load among a plurality of generators when some of those generators respond quickly to control and some do not. The area control error signal is divided into portions to provide a unit error signal assigned to each generator. A control is utilized which responds to the unit error signal to reposition the governor motor until the error signal is reduced to zero. Applying that control to slow responding units requires anticipation of the generation changes to be expected after full response. Control from the unit error signal is modified in accordance with the difference between the desired generation for the units as required for economic considerations and the actual generation with that difference being modified by a signal which is a function of the actual generation. That function is expressable by the Laplace transform ##EQU1## .

A method for modifying an area control error signal for controlling the generation in each area of a multiple-area interconnected electric power system using net-interchange tie-line bias control where the area control error is calculated in accordance with the equation

Time deviation and inadvertent interchange correction for automatic

A control system is provided for turbines in the utility part of an industrial plant using cogeneration so that control is maintained over the relative quantities of steam supplied to a common steam header from both the back pressure and the extraction turbines where the header supplies process steam at a predetermined pressure. The steam flow from a stage of the extraction turbine is controlled to maintain the header pressure at its desired value. The steam flow thus controlled is measured and a control means is provided to control the steam flow from a back pressure turbine supplying the same header so as to maintain a predetermined relationship between the two steam flows while maintaining electrical generation from the generators driven by the turbine at a maximum consistent with maintenance of an adequate control range for the header pressure control.

Control of parallel operated turbines in cogeneration

In a power distribution system comprising interconnected distribution areas which includes a jointly owned unit, that jointly owned unit is controlled to allocate regulating outputs for the areas participating in the joint ownership in accordance with the percentage of ownership, the amount and direction of change in generation requested by the participating areas and the rate limited capability of the unit.

Method and apparatus for controlling an interconnected distribution

There is disclosed a method and means for continuously controlling the consumption of power by an industrial customer wherein the control is accomplished by controlling the generation of the customer's own power source and/or his load in response to a signal representing the change necessary to make the energy consumed equal the demand limit. The gain of the control response is modified so that it is increased with increases in the difference between the energy actually consumed and the desired consumption.

Electric demand control system

Two controllers in a cascade control system are decoupled to avoid interaction by modifying the error signal to the primary controller in response to changes in the error signal to the secondary controller. The response is developed by a network which models the primary process. A signal developed from the output of the primary controller is fed forward to modify the manipulated variable. The modifying network is a model of the reciprocal of the dynamics of the secondary process. Also, the adjustment performed by the primary controller on the set point of the secondary controller is delayed in accordance with the product of the secondary process model and the reciprocal feedforward model.

Decoupled cascade control system

A removable control signal is provided which varies as the product of a gain constant times the control error and has means for increasing the gain constant as a time integral of the error. The integral is reset to zero, thus making the gain constant zero, when the error crosses zero to avoid an excessive build-up of the value of the control signal as when the error fails to promptly correct itself.

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Lansdale, PA, United States of America

Charles W Ross