Anti-islanding techniques for distributed power generation
First Claim
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1. An anti-islanding system for distributed power on a grid, comprising:
- a distributed power source operatively coupled to a grid and adapted with output current control, the distributed power source for providing power;
a voltage sensor connected to a node between the distributed power source and the grid, and adapted to monitor grid voltage;
a contactor operatively coupled between the distributed power source and the voltage sensor, and adapted for disconnecting the grid from the distributed power source; and
an anti-islanding protection controller operatively coupled to the distributed power source and the voltage sensor, the anti-islanding protection controller adapted to request the distributed power source to selectively output a current pulse in the power being provided so as to cause a voltage deflection in the grid voltage if an island condition exists, and to detect an island condition based on voltage deflection data provided by the voltage sensor wherein the current pulse is requested by the anti-islanding protection controller according to a pre-defined routine depending on the voltage deflection data provided by the voltage sensor.
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Abstract
Techniques for detecting an island in a system including a node that is operatively coupled to a primary power source (e.g., grid) and one or more distributed power generation sources are disclosed. In one embodiment, a current pulse is included in the output of a distributed power source. The grid voltage is monitored at the node to determine if a pulse-related disturbance occurs. If the grid is present, no pulse-related disturbance will manifest. If grid is down, then a pulse-related disturbance will manifest. Detection of the pulse-related disturbance is used to signal island detection.
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Citations
41 Claims
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1. An anti-islanding system for distributed power on a grid, comprising:
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a distributed power source operatively coupled to a grid and adapted with output current control, the distributed power source for providing power; a voltage sensor connected to a node between the distributed power source and the grid, and adapted to monitor grid voltage; a contactor operatively coupled between the distributed power source and the voltage sensor, and adapted for disconnecting the grid from the distributed power source; and an anti-islanding protection controller operatively coupled to the distributed power source and the voltage sensor, the anti-islanding protection controller adapted to request the distributed power source to selectively output a current pulse in the power being provided so as to cause a voltage deflection in the grid voltage if an island condition exists, and to detect an island condition based on voltage deflection data provided by the voltage sensor wherein the current pulse is requested by the anti-islanding protection controller according to a pre-defined routine depending on the voltage deflection data provided by the voltage sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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19. A method for detecting an island in a system including a node that is operatively coupled to a voltage sensor, a grid and one or more distributed power generation sources, the method comprising:
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selectively applying a current pulse from at least one of the distributed power generation sources onto the node wherein selectively applying the current pulse includes requesting the current pulse according to a pre-defined routine depending on the voltage deflection data measured at the node; monitoring the node with the voltage sensor for a disturbance related to the applied current pulse wherein in response to detecting the disturbance, at least one of disabling the at least one distributed power generation source and disconnecting the at least one distributed power generation source from the grid; and in response to detecting a disturbance, signaling an island detection.
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30. An apparatus for detecting an island in a system including a node that is operatively coupled to a grid and one or more distributed power generation sources, the apparatus comprising:
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a pulse request module adapted to generate a pulse request that causes a distributed power generation source to include a current pulse in its output signal so that a pulse-related disturbance will manifest on the node if an island is present; an island detection module adapted to generate an island detect signal in response to a pulse-related disturbance being detected on the node; and an island detect accumulator adapted to receive island detect signals from the island detection module, and to perform filtering and hysteresis of received island detect signals so as to reduce nuisance trips. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. An apparatus for detecting an island in a system including a node that is operatively coupled to a primary power source and one or more distributed power generation sources, the apparatus comprising:
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a disturbance request module adapted to cause a distributed power generation source to modify its output so that a disturbance-related to the modified output will manifest on the node if an island is present; an island detection module adapted to generate an island detect signal in response to a disturbance-related to the modified output being detected on the node; and an island detect accumulator adapted to receive island detect signals from the island detection module, and to perform filtering and hysteresis of received island detect signals so as to reduce nuisance trips.
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Specification