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US 2009/0021877 A1Published application
Method and apparatus for anti-islanding of distributed power generation systems
AssigneeEnphase Energy, Inc.
InventorsMartin Fornage, Mudhafar Hassan-Ali, Tibor Bolfan
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Abstract
A method and apparatus for anti-islanding of distributed power generation systems having an inverter comprising a phase locked loop (PLL), a phase shift generator for injecting a phase shift into the PLL during at least one sample period, and a phase error signature monitor for monitoring at least one phase error response of the PLL during the at least one sample period.
Claims21
Apparatus for converting DC power to AC power, comprising:
- a phase locked loop (PLL);
- a phase shift generator for injecting a phase shift into the PLL during at least one sample period;
- and
- a phase error signature monitor for monitoring at least one phase error response of the PLL during the at least one sample period.
1 more element
A system, comprising:
- a plurality of inverters, wherein each inverter of the plurality of inverters comprises a phase locked loop (PLL), a phase shift generator for injecting a phase shift into the PLL during at least one sample period, and a phase error signature monitor for monitoring at least one phase error response of the PLL during the at least one sample period;
- and
- a controller coupled to the plurality of inverters, wherein the controller communicates a message to the plurality of inverters that causes the phase shift generator of each of the inverters of the plurality of inverters to inject the phase shift simultaneously into the plurality of inverters.
A method, comprising:
- injecting a phase shift into a phase locked loop (PLL) of an inverter, wherein the phase shift is injected during at least one sample period;
- integrating at least one phase error response of the PLL over at least one integration period to obtain at least one integrated phase error response;
- comparing the at least one integrated phase error response to at least one threshold;
- and
- flagging the at least one sample period as indicative of a possible islanding state when the at least one integrated phase error response satisfies the at least one threshold.
2 more elements
Dependencies are inferred from the claim text.