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AssigneeGeneral Electric Company
InventorsFred W. Kelley, Jr., Georges R. E. Lezan
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In an alternating current electric power system subject to rapid load voltage regulation as a result of variations in reactive load current, reactive load current compensation is provided by fixed capacitors and inductors in parallel with the load, the inductors being in series with static switches which are phase controlled to continuously maintain the net reactive compensating current substantially equal and opposite to the reactive component of load current. Compensation control determines firing time of the static switches in accordance with the magnitude of reactive load current and regulating means additionally controls firing time to maintain line current and voltage at a selected line location substantially in phase coincidence.
Reactive current compensating apparatus for a multiphase alternating current electric power circuit having load terminals and supply conductors and subject to varying reactive current demand at said load terminals comprising, fixed multiphase capacitor means connected in said power circuit, fixed multiphase inductor means, alternating current static switching means connected in series with each phase of said inductor means, means connecting the series combination of said inductor means and switching means in parallel circuit relation with said capacitor means, each said switching means including gating means for varying the conduction angle of said switching means thereby to control the magnitude of reactive current traversing one phase of said inductor means, means for generating a group of individual signals representative in each half cycle of power circuit frequency of the reactive component of current in each phase of an electrical load connected to said load terminals, and means individually responsive to each said signal for so controlling said gating means in the associated phase that the net effective reactive impedance of said fixed capacitor means and said fixed inductor means in each phase is substantially equal and opposite to reactive current demand at the load terminal of each phase.
Reactive current supply apparatus for an alternating current electric power circuit including a critical voltage supply bus electrically separated by series impedance from load terminals which are adapted for connection to a major load subject to rapid oscillatory variation of reactive current demand comprising, fixed capacitor means connected across said load terminals, fixed inductor means connected across said load terminals in series circuit relation with static switching means, said static switching means including gating means for phase controlling the conduction angle of said switching means thereby to control the magnitude of reactive current traversing said inductor means, means for generating a unidirectional electrical signal representative in direction of the phase relation of the reactive component of load current at said load terminals and proportional in magnitude to the magnitude of said reactive component of load current, and means responsive to said electric signal for so controlling said gating means that the sum of the reactive currents traversing said fixed capacitor means and said fixed inductor means is substantially equal and opposite to said reactive component of load current.
Reactive current supply apparatus for an alternating current electric power circuit including a critical voltage supply bus electrically separated by series impedance from load terminals which are adapted for connection to a major load subject to rapid oscillatory variation of reactive current demand comprising, fixed capacitor means connected across said load terminals, fixed inductor means connected across said load terminals in series circuit relation with static switching means, said static switching means including gating means for phase controlling the conduction angle of said switching means thereby to control the magnitude of reactive current traversing said inductor means, means for generating a first unidirectional electric signal representative in magnitude and direction respectively of the magnitude and direction of the phase angle between voltage and line current at said critical voltage supply bus, means for generating a second unidirectional electric signal representative in direction of the phase relation of the reactive component of load current at said load terminals and proportional in magnitude to the magnitude of said reactive component of load current, summing means responsive to said first and second unidirectional electric signals to generate an error signal, and means responsive to said error signal for regulating said gating means to maintain said phase angle substantially constant over time intervals sufficient to eliminate objectionable voltage flicker at said critical voltage supply bus.
Reactive current compensating apparatus for a three phase alternating current electric power circuit having load terminals and supply conductors and subject to rapidly varying reactive current demand at said load terminals comprising, fixed three phase reactor means connected across said supply conductors, three phase alternating current static switching means connected to control current in each phase of said reactor means, said switching means including gating means for phase controlling the conduction angle of said switching means and thereby controlling the apparent reactance of said reactor means, means for generating unidirectional electric signals proportional in magnitude to the magnitude of the reactive components of load current in each phase of an electric load connected to said load terminals, each said signal having a polarity representative of leading or lagging phase relation of said reactive current components, and means utilizing all said signals for separately controlling the gating means of each phase of said switching means to establish in each said supply conductor a compensating reactive current component substantially equal and opposite to the reactive component of load current in said conductor.
The method of compensating reactive components of load current (I.sub.LX) in the three lines (1-2-3-) of a three phase alternating current electric power circuit which comprises, developing three separate unidirectional electric signals having magnitudes proportional to the reactive load current components in the respective power circuit lines, connecting reactive impedances in delta circuit relation across said lines, and individually varying the effective capacitive reactance (X.sub.c) of said impedances as lagging reactive load current varies and in accordance with the formulae:
Reactive current compensating apparatus for a multiphase alternating current electric power circuit having load terminals and supply conductors and subject to varying reactive current demand at said load terminals comprising, fixed multiphase capacitor means connected in said power circuit, fixed multiphase inductor means, alternating current static switching means connected in series with each phase of said inductor means, means connecting the series combination of said inductor means and switching means in parallel circuit relation with said capacitor means, each said static switching means including gating means for varying the conduction angle of said switching means thereby to control the magnitude of reactive current traversing one phase of said inductor means, means for generating individual gating signals representative in each half cycle of power circuit frequency of the phase angle between current and voltage in each phase of said power circuit at a selected point on said supply conductors, means individually responsive to each said gating signal for controlling said gating means in the associated phase to vary its conduction angle as necessary to maintain said phase angles substantially constant at said selected point, and negative feed-back means responsive to the magnitude of each said gating signal and operable to limit magnitude of said signals in a sense to limit the maximum amount of reactive compensating current traversing said power circuit.
Dependencies are inferred from the claim text.