Closed loop power factor control for drilling rigs
First Claim
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1. In a drilling rig wherein one or more engine-generator sets form an alternating current power supply system for operating the rig'"'"'s electrical equipment and machinery, a method of controlling the system power factor comprising:
- sensing the instantaneous system power factor;
comparing the sensed instantaneous power factor to a prescribed power factor;
forming a power factor control signal indicative of the difference between the sensed power factor and the prescribed power factor;
providing a field excitation signal to an unloaded, over-excited generator operated in the motor mode in proportion to said power factor control signal to cause the over-excited generator to generate the requisite reactive power to correct the rig'"'"'s power factor to the prescribed power factor; and
coupling the output of the over-excited generator to the rig power system.
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Abstract
A power factor controller for alternating current/direct current drilling rigs is provided which utilizes a uniquely controlled, unloaded, over-excited generator to provide reactive power to maintain the rig'"'"'s power factor within prescribed limits during peak demand operations.
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Citations
20 Claims
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1. In a drilling rig wherein one or more engine-generator sets form an alternating current power supply system for operating the rig'"'"'s electrical equipment and machinery, a method of controlling the system power factor comprising:
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sensing the instantaneous system power factor; comparing the sensed instantaneous power factor to a prescribed power factor; forming a power factor control signal indicative of the difference between the sensed power factor and the prescribed power factor; providing a field excitation signal to an unloaded, over-excited generator operated in the motor mode in proportion to said power factor control signal to cause the over-excited generator to generate the requisite reactive power to correct the rig'"'"'s power factor to the prescribed power factor; and coupling the output of the over-excited generator to the rig power system. - View Dependent Claims (2, 3)
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4. In a drilling rig having a plurality of engine-generator sets which form an alternating current power supply system for operating the rig'"'"'s electrical equipment and machinery, a method for controlling the system power factor comprising:
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sensing the instantaneous power factor of each engine-generator set; comparing the sensed power factor from each engine-generator set to a prescribed power factor; forming a power factor control signal for each engine-generator set indicative of the difference between the sensed instantaneous power factors and the prescribed power factor; providing a field excitation signal to a reactive power generator proportionate to the power factor control signal which is indicative of the largest differential between sensed power factor and prescribed power factor; coupling the output of the reactive power generator to the rig power system; whereby the rig'"'"'s power factor is corrected by providing reactive power to the system which is required to correct the individual engine-generator set operating at the worst power factor. - View Dependent Claims (5, 6)
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7. In a drilling rig having one or more engine-generator sets forming an alternating current power supply system to operate the rig'"'"'s electrical equipment and machinery, an apparatus for controlling the system power factor comprising:
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means for sensing the instantaneous system power factor; means for setting a prescribed system power factor; means for forming a power factor control signal indicative of the difference between the sensed power factor and the prescribed power factor; means for generating reactive power in response to the power factor control signal, said generating means comprising an unloaded, over-excited generator operated in the motor mode provided with field excitation current proportional to the power factor control signal; and means for providing the generated reactive power to the rig system to maintain the rig power factor within the prescribed limits. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. In a drilling rig having a plurality of engine-generator sets forming an alternating current power supply system to operate the rig'"'"'s electrical equipment and machinery, an apparatus for controlling the system power factor comprising:
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means for sensing the instantaneous power factors of each of the engine-generator sets; means for setting a prescribed power factor for each of the engine-generator sets; means for forming a power factor control signal for each of the engine-generator sets indicative of the difference between the sensed power factor and the prescribed power factor for the particular engine-generator set; means for selecting the power factor signal indicative of the largest differential between sensed power factor and prescribed power factor; means for generating reactive power in response to the selected power factor control signal; and means for providing the generated reactive power to the rig power system to correct the rig power factor.
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20. In a drilling rig wherein one or more engine-generator sets form an alternating current power supply system for operating the rig'"'"'s electrical equipment and machinery, a method of controlling the system power factor comprising:
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sensing instantaneous power factors of one or more engine-generator sets; deriving a composite power factor by vectorially summing the sensed instantaneous individual power factors; comparing the composite instantaneous power factor to a prescribed power factor; forming a power factor control signal indicative of the difference between the sensed composite power factor and the prescribed power factor; providing a field excitation signal to a reactive power generator in proportion to the power factor control signal to cause the reactive power generator to generate the requisite reactive power to correct the rig'"'"'s power factor to the prescribed power factor; and
,coupling the output of the reactive power generator to the rig power system.
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Specification