Grid load logic

Details Grid load logic Grid load logic

2001-07-03

2004-07-06

Toatley, Jr., Gregory J. (Department: 2836)

Electrical transmission or interconnection systems

Plural supply circuits or sources

One source floats across or compensates for other source

C307S052000

Reexamination Certificate

active

06759764

ABSTRACT:

SUMMARY OF THE INVENTION
The present invention is of a method of supplying supplemental power from a supplemental power source in addition to that from a primary power source in order to meet power demand of a load, comprising: setting a set point for power received from the primary power source; establishing a variable gain for the supplemental power source; and employing the variable gain, periodically adjusting power supplied by the supplemental power source based on deviations between power actually received from the primary power source and the set point. In the preferred embodiment, establishing comprises establishing a variable gain that is higher for negative deviations between power actually received from the power source and the set point than for positive deviations. Employing comprises adjusting via a variable gain reset—hold integrator and measuring power actually received from the primary power source via a digital meter. The digital meter communicates readings to a supervisory control and data acquisition system, and control personnel are permitted to change the set point and variable gain by command to the supervisory control and data acquisition system via a World Wide Web browser interface. The supplemental power source is preferably a turbine generator. The method results in load transients being absorbed by the primary power source rather than the supplemental power source. The size of the power adjustment in each period is based on the product of the variable gain and a size of the deviation between power actually received from the primary power source and the set point Adjustment is made only when deviations between power actually received from the primary power source and the set point are outside a tolerance band. The tolerance band is established at least in part based on operating limitations of the microturbine and/or on a desired insensitivity to small changes in the load. The set point is automatically reset to zero based on a turbine status bit related to an operating condition of the turbine, wherein the operating condition is chosen from the group that includes turbine speed, turbine inlet temperature, turbine exhaust temperature, fuel flow, and power output.
The invention is also of a method of maintaining a fixed flow offset between the primary flow source and the supplemental flow source in a system employing a primary flow source and a supplemental flow source to satisfy a demand, wherein the supplemental flow source supplies flow to meet at least a portion of the demand, comprising: creating an actual primary flow source measurement by measuring flow from the primary flow source to the demand; developing an error signal by establishing a difference between the fixed flow offset from the actual primary flow source flow measurement; establishing a gain; creating an input by multiplying the error signal by the gain; establishing a predetermined tolerance range; creating a supplemental flow source flow adjustment command based upon the input; and adjusting the flow output of the supplemental flow source based on the supplemental flow source flow adjustment command, thereby driving the error signal to within the predetermined tolerance range. In the preferred embodiment, the gain is a variable gain and creating a supplemental flow source flow adjustment command comprises integrating the input.
The invention is further of a method of maintaining a fixed power offset between the primary power source and the: supplemental power source in a system employing a primary power source and a supplemental power source to satisfy a power load, wherein the supplemental power source supplies power to meet at least a portion of the power load, comprising: creating an actual primary power source measurement by measuring power flow from the primary power source to the power load; developing an error signal by subtracting the fixed power offset from the actual primary power source power measurement; establishing a gain; creating an input by multiplying the error signal by the gain; establishing a predetermined tolerance range; creating a supplemental power source power adjustment command based upon the input; and adjusting the power output of the supplemental power source based on the supplemental power source power adjustment command, thereby driving the error signal to within the predetermined tolerance range. In the preferred embodiment, the gain is a variable gain and creating a supplemental flow source flow adjustment command comprises integrating the input.
The present invention is additionally of a method of maintaining a fixed power offset between the grid and the end-user's power load regardless of the load demanded up to the microturbine's predetermined maximum power output in a grid-connected application of a microturbine having an adjustable power output up to a predetermined maximum power output and wherein the microturbine supplies power to meet at least a portion of an end-user's power load, comprising: creating an actual grid power measurement by measuring power flow from the grid to the end-user's power load; developing an error signal by subtracting the fixed power offset from the actual grid power measurement; establishing a gain; creating an input by multiplying the error signal by the gain; establishing a predetermined tolerance range; creating a microturbine power adjustment command based upon the input; and adjusting the power output of the microturbine based on the microturbine power adjustment command, thereby driving the error signal to within the predetermined tolerance range. In the preferred embodiment, the gain is variable and preferably is higher for an error signal representing a negative deviation between the actual grid power measurement and the fixed power offset than for positive deviations. Creating a supplemental flow source flow adjustment command preferably comprises integrating the input. The tolerance range is established at least in part based on operating limitations of the microturbine and/or on a desired insensitivity to small changes in the end-user's power load. Creating an actual grid power measurement preferably comprises employing a digital meter which communicates readings to a supervisory control and data acquisition system. Control personnel are permitted to change the fixed power offset and gain by command to the supervisory control and data acquisition system via a World Wide Web browser interface. The method results in load transients being absorbed by the grid rather than the microturbine. The fixed power offset is automatically reset to zero based on a turbine status bit related to an operating condition of the turbine, wherein the operating condition is chosen from the group that includes turbine speed, turbine inlet temperature, turbine exhaust temperature, fuel flow, and power output.


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