Networked multi-inverter maximum power-point tracking

1. A method of controlling a group of power generating stations, each of the power generating stations comprising a DC power source supplying power to an inverter, the method comprising:

connecting a plurality of inverters to a communications network;

transmitting maximum power point (MPP) data over the network;

determining, from the MPP data, whether to operate any of the inverters as a slave inverter, and

upon assigning an inverter to operate as a slave inverter, setting or changing an operating point of the slave inverter responsive to the MPP data transmitted on the network.

2. The method of claim 1 , further comprising:

dynamically selecting one of said inverters to function as a master in accordance with predetermined criteria for a representative sample of similarly situated inverters; wherein

functioning as a master comprises MPP tracking.

3. The method of claim 2 , further comprising:

the inverters mapped according to said predetermined criteria;

in the case of the mapping resolving to a mapped cluster of said inverters that spans more than one allowable error margin, reducing the error margin to more clearly isolate the mapped cluster.

4. The method of claim 2 , further comprising

setting an operating point of at least one slave to the MPP tracked by the master.

5. The method of claim 1 , further comprising:

comparing MPP factors or MPP data from at least a subset of power generating stations to generate comparison data; and

adjusting the operating point of the inverter operating as a slave based on the comparison data.

6. The method of claim 5 , wherein:

the DC source comprises photovoltaic panels;

the MPP data comprises a bus-voltage setting that produces a maximum power output from an individual photovoltaic panel; and

adjusting the operating point compensates for variation in MPP factors.

7. The method of claim 1 , further comprising:

comparing MPP factors or MPP data from at least a subset of power generating stations to generate comparison data;

dynamically selecting a representative one of said power generating stations to function as a master based on the comparison data;

causing the master to execute an MPP tracking algorithm; and

setting the operating point of the slave inverter to the MPP tracked by the master.

8. The method of claim 7 , wherein:

photovoltaic panels comprise the DC source in at least a subset of the power generating stations;

the MPP data comprises an operating point that produces a maximum power output from an individual photovoltaic panel; and

the MPP tracking provides adjustments for variation in at least one MPP factor.

9. The method of claim 7 , wherein:

photovoltaic panels comprise the DC source in at least a subset of the power generating stations;

the MPP data comprises an operating point that produces a maximum power output from an individual photovoltaic panel; and

the MPP factor comprises irradiance near the photovoltaic panel.

10. The method of claim 1 , further comprising:

comparing MPP factors or MPP data from at least a subset of power stations to generate comparison data;

using photovoltaic panels as the DC source in at least a subset of the power generating stations;

using a bus-voltage setting that produces a maximum power output

from an individual photovoltaic panel as part of the MPP data;

storing at least one MPP factor;

retrieving the stored MPP factor;

measuring at least one real-time MPP factor;

using the stored MPP factor and the real-time MPP factor to perform maximum

power-point tracking (MPPT).

11. The method of claim 1 , further comprising:

comparing MPP factors or MPP data from at least a subset of power generating stations in the power network to generate comparison data;

using photovoltaic panels as the DC source in at least a subset of the power generating stations;

using a bus-voltage setting that produces a maximum power output from an individual photovoltaic panel as part of the MPP data;

storing at least one MPP factor;

retrieving the stored MPP factor; and

measuring at least one real-time MPP factor;

wherein using the stored MPP factor and the real-time MPP factor to perform maximum power-point tracking (MPPT) provides adjustments for variation in MPP factors over time.

12. The method of claim 1 , further comprising:

setting the operating point of one or more inverters associated with the power generating stations based on maximum power points (MPPs);

mapping the inverters in MPP-factor space;

selecting an optimal grouping of masters and slaves according to predetermined criteria; and

re-evaluating and, if appropriate, reassigning masters and slaves either at fixed intervals or when measured MPP factors change by more than a threshold amount.

13. The method of claim 1 , further comprising:

setting the operating point of one or more inverters associated with the power generating stations based on maximum power points (MPPs);

mapping the inverters in MPP-factor space;

selecting an optimal grouping of masters and slaves according to predetermined criteria, including a minimum number of masters; and

re-evaluating and, if appropriate, reassigning masters and slaves either at fixed intervals or when measured MPP factors change by more than a threshold amount.

14. The method of claim 13 , further comprising in the case of the mapping resolving to a mapped cluster of said inverters that spans more than one allowable error margin, reducing the error margin to more clearly isolate the mapped cluster.

15. The method of claim 1 , further comprising:

comparing MPP factors or MPP data from at least a subset of power generating stations to generate comparison data; and

using an operating-point setting that produces a maximum power output from an individual power generating station as part of the MPP data.

16. The method of claim 15 , further comprising:

performing maximum power-point tracking (MPPT) on inverter outputs of the power generating stations;

selecting the slave inverter to operate in response to a master inverter MPPT, and

selecting the master inverter from a group of inverters having MPP factors within a predetermined variance from the slave inverter .

17. The method of claim 1 , wherein the operating point is transmitted over the network from a central control unit.

18. The method of claim 1 , further comprising:

performing maximum power-point tracking (MPPT) on inverter outputs of the

power generating stations;

using a central control unit to adjust the operating point of the slave inverter

based on a result of the MPPT;

monitoring power produced by the slave inverter, and

in the event that the slave varies from a maximum power point (MPP)factor,

causing the slave inverter to override the control from the central control

unit and operate as a master.

19. The method of claim 1 , further comprising:

performing maximum power-point tracking (MPPT) on inverter outputs of the

power generating stations; and

using peer-to-peer control to change the operating point of the slave inverter

based on a result of the MPPT.

20. The method of claim 1 , further comprising:

performing maximum power-point tracking (MPPT) on inverter

outputs of the power generating stations; and

setting or changing the operating point of the slave inverter based on a predicted result of the MPPT.

21. The method of claim 1 , further comprising:

tracking at least one MPP factor for at least one power generating station;

setting an operating point for the power generating station;

monitoring at least one sensor associated with the station, the sensor detecting at

least one of power, irradiance, and temperature;

determining whether a reading from the sensor represent a change

from a previous reading; and

in the case of the reading changing from the previous reading, effecting an adjustment in the operating point.

22. A method of controlling a power generating station within a group of power generating stations, the method comprising:

tracking at least one MPP factor for the power generating station;

identifying a corresponding MPP factor for at least one neighbor power generating station;

comparing the MPP factors or MPP data of the power generating station and the neighbor power generating station;

based on the compared MPP factors or MPP data, operating the power generating station as a master or as a slave; wherein having

a master performs MPP tracking, and

a slave sets its operating point to the master's most recently tracked MPP.

23. The method of claim 22 , further comprising:

monitoring at least one sensor associated with the station, the sensor detecting at least one of power, irradiance, and temperature;

determining whether readings from the sensor represent a change from a previous reading; and

in the case of the reading changing from the previous reading, effecting an adjustment in the operating point.

24. The method of claim 22 , further comprising:

setting the operating point of one or more inverters associated with the power generating stations based on maximum power points (MPPs); and

re-evaluating and, if appropriate, reassigning masters and slaves either at fixed intervals or when measured MPP factors change by more than a threshold amount.

25. The method of claim 24 , further comprising:

setting the operating point of one or more inverters associated with the power generating stations based on maximum power points (MPPs);

mapping the inverters in MPP-factor space;

selecting an optimal grouping of masters and slaves according to predetermined criteria, including a minimum number of masters; and

re-evaluating and, if appropriate, reassigning masters and slaves either at fixed intervals or when measured MPP factors change by more than a threshold amount.

26. The method of claim 25 , further comprising in the case of the mapping resolving to a mapped cluster of said inverters spans more than one allowable error margin, reducing the error margin to more clearly isolate the mapped cluster.

27. A method of controlling a power generating station within a group of multiple power generating stations, the method comprising:

selecting MPP factors or MPP data ;

reading the selected MPP factors or MPP data;

searching a data-store for a previous reading of the selected MPP factors or MPP data;

upon finding a previous reading, computing a difference between the reading and the previous reading and comparing the difference with an allowed margin;

in the case of the difference exceeding the allowed margin, or finding no previous reading, searching for another power generating station with similar MPP factors or MPP data;

in the case of locating another power generating station with similar MPP factors or MPP data, establishing one of the power generating stations as a slave; and

in the case of not locating another power generating station with similar MPP factors or MPP data, establishing the power generating station as a master.

28. The method of claim 27 , wherein the readings comprise inverter maximum power point (MPP) readings.

29. Control apparatus for a group of power generating stations, comprising:

a circuit module capable of comparing MPP factors or MPP data from at least a subset of power stations to generate comparison data;

a circuit module capable of selecting a master inverter based on the comparison data and causing the master inverter to perform MPP tracking; and

a circuit module capable of adjusting an operating point of a slave inverter based on the MPP tracked by the master.

30. Control apparatus for a group of multiple power generating stations, comprising:

means for comparing MPP factors or MPP data from at least a subset of power stations to generate comparison data;

means for performing maximum power-point tracking (MPPT) based on the comparison data to provide MPPT data; and

adjustment means for performing MPPT adjustments based on the MPPT data.

31. The control apparatus of claim 30 , further comprising:

means for monitoring at least one MPP factor from a power station in the subset;

means for determining whether the monitored MPP factor results in an MPP variation greater than a margin threshold; and

means for causing the power station to override control from a central control unit and track its own MPP if the MPP variation is greater than the margin threshold.

32. A computer program product, comprising:

a non-transitory computer-readable medium comprising:

a first instruction for causing a computer to compare MPP factors or MPP data from at least a subset of power stations in a group to generate comparison data;

a second instruction for causing the computer to select one of the power stations to temporarily operate as a master, cause the master to perform maximum power-point tracking (MPPT), and collect resulting MPP data; and

a third instruction for causing the computer to determine whether efficiency of the group would improve by operating another power station as a slave to the master, and if so, adjusting an operating point of the slave based on the MPP data.

33. The computer program product of claim 32 , further comprising a fourth instruction for causing the computer to re-evaluate and, if appropriate, reassign masters and slaves either at fixed intervals or when measured maximum power point (MPP) factors change by more than a threshold amount.