System and method for establishing communication with an array of inverters

• US 9,160,408 B2
• Filed: 10/11/2010
• Issued: 10/13/2015
• Est. Priority Date: 10/11/2010
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Sunpower Corporation (Totalenergies Se)
• Inventors: Krohne, Edward, Kuhn, Brian T.
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): Mourad, Rasem
• Application Number:
  US12/902,046
• Publication Number:
  US 20120089260A1
• Time in Patent Office: 1,828 Days
• Field of Search: 307/1, 307 3- 4, 307/82, 700/286, 363/71, 363/95
• US Class Current: 1/1
• CPC Class Codes: H02J 13/00007 using the power network as support for the transmission
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02M 7/42 Conversion of dc power input into ac power output without possibility of reversal
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04B 3/544 Setting up communications; Call and signalling arrangements
• CPC Class Codes: H04B 3/548 the power on the line being DC arrangements for feeding power H04L12/10; extracting feeding power from signals H04L25/02
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 40/70 Smart grids as climate change mitigation technology in the energy generation sector
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/123 the energy generation units being or involving renewable energy sources
• CPC Class Codes: Y04S 40/121 using the power network as support for the transmission

Abstract

A system and method for establishing communication between a controller and a plurality of inverters comprises determining a response time window length and broadcasting a response request to the array of inverters that includes the response time window length. Each inverter, in response to receiving the response requests, transmits a response to the controller at a randomly determined response time within the response time window. In response to receiving an acknowledgement from the controller, the responding inverter may ignore subsequent response requests. The controller may adjust the response time window and broadcasts the new response time window until no inverter response is received for a pre-determined number of response time windows.

Claims

1. A method for establishing communication with a plurality of inverters, each of the inverters being configured to convert direct current (DC) power generated from an alternative source to alternating current (AC) power, the method comprising:

determining an initial length of a response time window;

broadcasting the initial length of the response time window to each inverter of the plurality of inverters to prompt each inverter to respond with corresponding identification data;

in response to receiving a response from at least one inverter during the response time window, (i) recording the identification data of the at least one inverter and (ii) transmitting an acknowledgement to the at least one inverter using the identification data; and

in response to the response time window expiring, (i) adjusting the length of the response time window and (ii) broadcasting the adjusted length of the response time window to each inverter of the plurality of inverters.

2. The method of claim 1, wherein determining the initial length of the response time window comprises determining the initial length based on a predetermined length of time required by an inverter of the plurality of inverters to transmit a response to the broadcast.

3. The method of claim 2, wherein determining the initial length of the response time window comprises determining an initial length of the response time window that is a multiple of the predetermined length of time required by the inverter to transmit the response to the broadcast.

4. The method of claim 1, wherein broadcasting the initial length comprises broadcasting the initial length over an AC power line using a power line communication protocol.

5. The method of claim 1, wherein receiving a response from the at least one inverter comprises receiving a response that includes an identification number that uniquely identifies the responding inverter from the other inverters of the plurality of inverters and facilitates directed communication with the responding inverter using the identification number.

6. The method of claim 1, wherein transmitting the acknowledgement to the at least one inverter comprises transmitting the acknowledgement after expiration of the time window.

7. The method of claim 1, wherein adjusting the length of the response time window comprises decreasing the length of the response time window by a multiple of a predetermined length of time required by an inverter of the plurality of inverters to transmit a response to the broadcast.

8. The method of claim 1, wherein adjusting the length of the response time window comprises increasing the length of the response time window in response to a number of communication collisions during the response time window being greater than a predetermined value.

9. The method of claim 1, further comprising:

incrementing a counter in response to not receiving a response from at least one inverter of the plurality of inverters during the response time window, and

wherein broadcasting the adjusted length comprises broadcasting the adjusted length in response to the counter being less than a maximum threshold value.

10. The method of claim 9 further comprising stopping the broadcast of adjusted lengths in response to the counter being equal to a maximum threshold value.

11. The method of claim 1, further comprising:

incrementing a counter in response to not receiving a response from at least one inverter of the plurality of inverters during the time window, and

repeating the adjusting step, the broadcasting the adjusted length step, and the incrementing step until the counter equals a predetermined threshold value.

12. A controller for communicating with a plurality of inverters over an alternating current (AC) power line, the inverters configured to convert direct current (DC) power from an alternative energy source to AC power, the controller comprising:

a communication circuit to communicate with the plurality of inverters over the AC power line using a power line communication protocol;

a processor communicatively coupled to the communication circuit; and

a memory communicatively coupled to the processor, the memory having stored therein a plurality of instructions, which when executed by the processor, result in the processor;

determining an initial length of a response time window,

broadcasting, using the communication circuit, the initial length of the response time window to each inverter of the plurality of inverters to prompt each inverter to respond with corresponding identification data,

in response to receiving a response from at least one inverter during the response time window, (i) storing the identification data of the at least one inverter in the memory and (ii) transmitting an acknowledgement, using the communication circuit, to the at least one inverter using the identification data, and

in response to the response time window expiring, (i) adjusting the length of the response time window and (ii) broadcasting, using the communication circuit, the adjusted length of the response time window to each inverter of the plurality of inverters.

13. The controller of claim 12, wherein determining the initial length of the response time window comprises determining the initial length based on a predetermined length of time required by an inverter of the plurality of inverters to transmit a response to the broadcast.

14. The controller of claim 12, wherein adjusting the length of the response time window comprises decreasing the length of the response time window by a multiple of a predetermined length of time required by an inverter of the plurality of inverters to transmit a response to the broadcast.

15. The controller of claim 12, wherein the plurality of instructions further result in the processor:

incrementing a counter in response to not receiving a response from at least one inverter of the plurality of inverters during the response time window, and

wherein broadcasting the adjusted length comprises broadcasting the adjusted length in response to the counter being less than a maximum threshold value.

16. The controller of claim 15, wherein the plurality of instructions further result in the processor stopping the broadcast of adjusted lengths in response to the counter being equal to a maximum threshold value.

17. The controller of claim 12, wherein the plurality of instructions further result in the processor:

incrementing a counter in response to not receiving a response from at least one inverter of the plurality of inverters during the time window, and

repeating the adjusting step, the broadcasting the adjusted length step, and the incrementing step until the counter equals a predetermined threshold value.

18. The controller of claim 12, wherein the identification data includes an identification number that uniquely identifies the responding inverter from the other inverters of the plurality of inverters and facilitates directed communication with the responding inverter using the identification number.

19. The controller of claim 12, wherein transmitting the acknowledgement to the at least one inverter comprises transmitting the acknowledgement after expiration of the response time window.

20. The controller of claim 12, wherein adjusting the length of the response time window comprises increasing the length of the response time window in response to a number of communication collisions during the response time window being greater than a predetermined value.

21. One or more non-transitory, machine-readable media comprising a plurality of instructions, which in response to execution by a controller communicatively coupled to a plurality of AC-to-DC inverters over an AC power line, cause the controller to:

determine an initial length of a response time window;

broadcast the initial length of the response time window to each inverter of the plurality of inverters to prompt each inverter to respond with corresponding identification data;

in response to receipt a response from at least one inverter during the response time window, (i) record the identification data of the at least one inverter and (ii) transmit an acknowledgement to the at least one inverter using the identification data; and

in response to expiration of the response time window, (i) adjust the length of the response time window and (ii) broadcast the adjusted length of the response time window to each inverter of the plurality of inverters.

22. The one or more non-transitory, machine-readable media of claim 21, wherein to determine the initial length of the response time window comprises to determine the initial length based on a predetermined length of time required by an inverter of the plurality of inverters to transmit a response to the broadcast.

23. The one or more non-transitory, machine-readable media of claim 22, wherein to determine the initial length of the response time window comprises to determine an initial length of the response time window that is a multiple of the predetermined length of time required by the inverter to transmit the response to the broadcast.

24. The one or more non-transitory, machine-readable media of claim 22, wherein the identification data includes an identification number that uniquely identifies the responding inverter from the other inverters of the plurality of inverters and facilitates directed communication with the responding inverter using the identification number.

25. The one or more non-transitory, machine-readable media of claim 22, wherein to transmit the acknowledgement to the at least one inverter comprises to transmit the acknowledgement after expiration of the time window.

26. The one or more non-transitory, machine-readable media of claim 22, wherein to adjust the length of the response time window comprises to decrease the length of the response time window by a multiple of a predetermined length of time required by an inverter of the plurality of inverters to transmit a response to the broadcast.

27. The one or more non-transitory, machine-readable media of claim 22, wherein to adjust the length of the response time window comprises to increase the length of the response time window in response to a number of communication collisions during the response time window being greater than a predetermined value.

28. The one or more non-transitory, machine-readable media of claim 22, wherein the plurality of instructions further cause the controller to increment a counter in response to not receiving a response from at least one inverter of the plurality of inverters during the response time window, and

wherein to broadcast the adjusted length comprises to broadcast the adjusted length in response to the counter being less than a maximum threshold value.

29. The one or more non-transitory, machine-readable media of claim 28, wherein the plurality of instructions further cause the controller to stop the broadcast of adjusted lengths in response to the counter being equal to a maximum threshold value.

30. The one or more non-transitory, machine-readable media of claim 22, wherein the plurality of instructions further cause the controller to:

increment a counter in response to not receiving a response from at least one inverter of the plurality of inverters during the time window, and

repeat the adjustment step, the broadcast of the adjusted length step, and the increment step until the counter equals a predetermined threshold value.