Method and apparatus for activation and de-activation of power conditioners in distributed resource island systems using low voltage AC
View Patent ↗Methods and apparatus for controlling power conditioners in a distributed resource island are provided herein. In one embodiment, an input of a power conditioner that is operating in a de-energized state and coupled to an islanded grid is compared to an input threshold. When the input exceeds the input threshold, the power conditioner is operated in a soft-grid mode to generate a touch-safe AC voltage that is coupled to the islanded grid. The power conditioner compares an impedance of the islanded grid to a grid impedance range and compares load demand of the power conditioner to an activate threshold; when the impedance is within the grid impedance range and the load demand exceeds the activate threshold, the power conditioner is activated to operate proximate its nominal output voltage.
1. A method for controlling power conditioners in a distributed resource island system (DRIS), comprising:
comparing, at a power conditioner operating in a de-energized state, an input of the power conditioner to an input threshold, wherein the power conditioner is coupled to an islanded grid;
operating the power conditioner, when the input exceeds the input threshold, in a soft-grid mode to generate a touch-safe AC voltage that is coupled to the islanded grid;
comparing, by the power conditioner, an impedance of the islanded grid to a grid impedance range;
comparing, by the power conditioner, load demand for the power conditioner to an activate threshold; and
activating the power conditioner, when the impedance is within the grid impedance range and the load demand exceeds the activate threshold, to operate proximate its nominal output voltage,
wherein the power conditioner is a DC-AC power conditioner.
2. The method of claim 1 , further comprising, subsequent to activating the power conditioner, comparing, by the power conditioner, the load demand to a standby threshold; and operating the power conditioner in a standby mode when the load demand is less than the standby threshold.
3. The method of claim 1 , further comprising, subsequent to activating the power conditioner, comparing, by the power conditioner, the impedance to the grid impedance range; and switching the power conditioner to a de-energized state when the impedance is outside of the grid impedance range.
4. The method of claim 2 , further comprising, subsequent to operating the power conditioner in the standby mode, comparing, by the power conditioner, the load demand to a re-activate threshold; and activating the power conditioner, when the load demand exceeds the re-activate threshold, to operate proximate the nominal output voltage.
5. The method of claim 2 , wherein comparing the load demand to the standby threshold comprises comparing a required output current of the power conditioner to the standby threshold.
6. The method of claim 1 , wherein the power conditioner is coupled to a photovoltaic (PV) module that provides the input.
7. An apparatus for controlling power conditioners in a distributed resource island system (DRIS), comprising: a power conditioner, coupled to an islanded grid, comprising a black-start module for (i) comparing, while the power conditioner is operating in a de-energized state, an input of the power conditioner to an input threshold; (ii) operating the power conditioner, when the input exceeds the input threshold, in a soft-grid mode to generate a touch-safe AC voltage that is coupled to the islanded grid; (iii) comparing an impedance of the islanded grid to a grid impedance range; (iv) comparing load demand for the power conditioner to an activate threshold; and (v) activating the power conditioner, when the impedance is within the grid impedance range and the load demand exceeds the activate threshold, to operate proximate its nominal output voltage,
wherein the power conditioner is a DC-AC power conditioner.
8. The apparatus of claim 7 , wherein the black-start module further compares, subsequent to activating the power conditioner, the load demand to a standby threshold; and switches the power conditioner to a standby mode when the load demand is less than the standby threshold.
9. The apparatus of claim 7 , wherein the black-start module further compares, subsequent to activating the power conditioner, the impedance to the grid impedance range; and switches the power conditioner to a to a de-energized state when the impedance is outside of the grid impedance range.
10. The apparatus of claim 8 , wherein the black-start module further compares, subsequent to switching the power conditioner in the standby mode, the load demand to a re-activate threshold; and activates the power conditioner, when the load demand exceeds the re-activate threshold, to operate proximate the nominal output voltage.
11. The apparatus of claim 8 , wherein comparing the load demand to the standby threshold comprises comparing a required output current of the power conditioner to the standby threshold.
12. The apparatus of claim 7 , wherein the power conditioner is coupled to a photovoltaic (PV) module that provides the input.
13. A system for controlling power conditioners in a distributed resource island system (DRIS), comprising:
a plurality of power sources; and
a plurality of power conditioners, coupled to the plurality of power sources in a one-to-one correspondence and coupled to an islanded grid, wherein each power conditioner of the plurality of power conditioners comprises a black-start module for (i) comparing, while the power conditioner is operating in a de-energized state, an input of the power conditioner to an input threshold; (ii) operating the power conditioner, when the input exceeds the input threshold, in a soft-grid mode to generate a touch-safe AC voltage that is coupled to the islanded grid; (iii) comparing an impedance of the islanded grid to a grid impedance range; (iv) comparing load demand for the power conditioner to an activate threshold; and (v) activating the power conditioner, when the impedance is within the grid impedance range and the load demand exceeds the activate threshold, to operate proximate its nominal output voltage,
wherein the plurality of power conditioners are DC-AC power conditioners.
14. The system of claim 13 , wherein the black-start module further compares, subsequent to activating the power conditioner, the load demand to a standby threshold; and switches the power conditioner to a standby mode when the load demand is less than the standby threshold.
15. The system of claim 13 , wherein the black-start module further compares, subsequent to activating the power conditioner, the impedance to the grid impedance range; and switches the power conditioner to a to a de-energized state when the impedance is outside of the grid impedance range.
16. The system of claim 14 , wherein the black-start module further compares, subsequent to de-activating the power conditioner, the load demand to a re-activate threshold; and activates the power conditioner, when the load demand exceeds the re-activate threshold, to operate proximate the nominal output voltage.
17. The system of claim 14 , wherein comparing the load demand to the standby threshold comprises comparing a required output current of the power conditioner to the standby threshold.
18. The system of claim 13 , wherein the plurality of power sources are photovoltaic (PV) modules.