Voltage-sensed system and method for anti-islanding protection of grid-connected inverters
First Claim
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1. A method for operating a power interface connected to a power source to provide power from the power source to an electric alternating current (AC) grid, the method comprising:
- generating a reference current waveform such that the reference current waveform is proportional to the product of a predetermined transfer function and a sensed output voltage waveform of the power interface, wherein (i) the predetermined transfer function includes a time delay and (ii) the product yields one of;
a stable and an unstable action;
controlling an output current waveform of the power interface to track the reference current waveform; and
discontinuing the output current waveform in response to the output voltage waveform being outside a predetermined waveform range.
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Abstract
A method is provided for preventing islanding of a power source connected to an electric AC grid via an interface. The method senses an output voltage waveform of the interface, controls an output current waveform of the interface to track a reference current waveform having a mathematical relationship with the sensed output voltage waveform, and discontinues the output current waveform when the output voltage waveform is sensed to be outside a predetermined waveform range.
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Citations
20 Claims
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1. A method for operating a power interface connected to a power source to provide power from the power source to an electric alternating current (AC) grid, the method comprising:
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generating a reference current waveform such that the reference current waveform is proportional to the product of a predetermined transfer function and a sensed output voltage waveform of the power interface, wherein (i) the predetermined transfer function includes a time delay and (ii) the product yields one of;
a stable and an unstable action;controlling an output current waveform of the power interface to track the reference current waveform; and discontinuing the output current waveform in response to the output voltage waveform being outside a predetermined waveform range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 19)
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9. A system for providing power to an alternating current (AC) grid, the system comprising:
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a power inverter electrically connectable between an energy source and the AC grid, the power inverter to supply an output voltage waveform to the AC grid; a control unit coupled to the power inverter and configured to (i) establish a reference current waveform proportional to the product of a predetermined transfer function and the output voltage waveform and (ii) control the inverter to generate an output current waveform that tracks the reference current waveform, wherein the predetermined transfer function includes a time delay, and the product yields one of;
a stable and an unstable action; anda discontinuing unit configured to discontinue the output current waveform in response to the output voltage waveform being outside a predetermined waveform range. - View Dependent Claims (10, 11, 12, 13, 20)
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14. A method for controlling a power inverter connected to an energy source to provide power to an electric alternating current (AC) grid, the method comprising:
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sensing an output voltage waveform of the power inverter; generating an output current waveform of the power inverter that tracks a reference current waveform such that the reference current waveform is proportional to the product of a predetermined transfer function and the sensed output voltage waveform, wherein (i) the predetermined transfer function includes a time delay and (ii) the product yields one of;
a stable and an unstable action; anddiscontinuing the output current waveform in response to the output voltage waveform being outside a predetermined waveform range. - View Dependent Claims (15, 16)
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17. A system for controlling a power inverter connected to an energy source to provide power to an electric alternating current (AC) grid, the system comprising:
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an input to receive an output voltage waveform of the power inverter; a processor programmed (i) to control the power inverter to generate an output current waveform that tracks a reference current waveform such that the reference current waveform is proportional to the product of a predetermined transfer function and the output voltage waveform and (ii) to discontinue the output the output current waveform in response to the output voltage waveform being outside a predetermined waveform range, wherein (i) the predetermined transfer function includes a time delay and (ii) the product yields one of;
a stable and an unstable action. - View Dependent Claims (18)
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Specification