Method and apparatus for determining a corrected monitoring voltage

• US 9,509,142 B2
• Filed: 03/04/2014
• Issued: 11/29/2016
• Est. Priority Date: 02/05/2009
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Enphase Energy Incorporated
• Inventors: Fornage, Martin, Dargatz, Marv
• Primary Examiner(s): KASENGE, CHARLES R
• Application Number:
  US14/197,087
• Publication Number:
  US 20140185344A1
• Time in Patent Office: 1,001 Days
• Field of Search: 700/286, 700/295, 700/297, 700/298, 702/57, 702/61, 702/64, 363/55, 363/95, 323/371, 324/120, 361/18
• US Class Current: 1/1
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• 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 7/44 by static converters
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects

Abstract

A method and apparatus for correcting a locally measured inverter voltage. In one embodiment, the method comprises determining a voltage compensation to compensate for a voltage drop along an AC bus between an inverter and a remotely located point on the AC bus; obtaining a voltage measurement at the inverter; applying the voltage compensation to the voltage measurement to determine a corrected voltage measurement; comparing the corrected voltage measurement to a voltage requirement; and performing a corrective action at the inverter when the corrected voltage measurement does not meet the voltage requirement.

Claims

1. A method for correcting a locally measured inverter voltage, comprising:

determining a voltage compensation to compensate for a voltage drop that occurs along an AC bus based on the distance between an inverter and a remotely located point on the AC bus;

obtaining a voltage measurement at the inverter;

applying the voltage compensation to the voltage measurement to determine a corrected voltage measurement;

comparing the corrected voltage measurement to a voltage requirement; and

performing a corrective action at the inverter when the corrected voltage measurement does not meet the voltage requirement.

2. The method of claim 1, wherein the corrective action is one of (i) deactivating the inverter or (ii) performing AC voltage regulation.

3. The method of claim 1, wherein the voltage compensation is determined based on an initial power from the inverter, a subsequent power from the inverter, and a correction coefficient.

4. The method of claim 3, wherein the correction coefficient is equal to a ratio of a voltage measurement obtained at the remotely located point and an initial voltage measurement at the inverter.

5. The method of claim 4, wherein the initial voltage measurement is used to determine the initial power.

6. The method of claim 1, wherein the remotely located point is a point of common coupling (PCC) between a commercial AC power grid and a distributed generator (DG) that comprises the inverter.

7. The method of claim 6, wherein the DG is a photovoltaic (PV) system.

8. An apparatus for correcting a locally measured inverter voltage, comprising:

a voltage monitoring module comprising a central processing unit for;

determining a voltage compensation to compensate for a voltage drop that occurs along an AC bus based on the distance between an inverter and a remotely located point on the AC bus;

obtaining a voltage measurement at the inverter;

applying the voltage compensation to the voltage measurement to determine a corrected voltage measurement;

comparing the corrected voltage measurement to a voltage requirement; and

performing a corrective action at the inverter when the corrected voltage measurement does not meet the voltage requirement.

9. The apparatus of claim 8, wherein the corrective action is one of (i) deactivating the inverter or (ii) performing AC voltage regulation.

10. The apparatus of claim 8, wherein the voltage compensation is determined based on an initial power from the inverter, a subsequent power from the inverter, and a correction coefficient.

11. The apparatus of claim 10, wherein the correction coefficient is equal to a ratio of a voltage measurement obtained at the remotely located point and an initial voltage measurement at the inverter.

12. The apparatus of claim 11, wherein the initial voltage measurement is used to determine the initial power.

13. The apparatus of claim 8, wherein the remotely located point is a point of common coupling (PCC) between a commercial AC power grid and a distributed generator (DG) that comprises the inverter.

14. The apparatus of claim 13, wherein the DG is a photovoltaic (PV) system.

15. A system for correcting a locally measured inverter voltage, comprising:

a plurality of photovoltaic (PV) modules; and

a plurality of inverters coupled to the plurality of PV modules in a one-to-one correspondence, wherein each inverter of the plurality of inverters (i) determines a voltage compensation to compensate for a voltage drop along an AC bus between the inverter and a remotely located point on the AC bus;

(ii) obtains a local voltage measurement;

(iii) applies the voltage compensation to the local voltage measurement to determine a corrected voltage measurement;

(iv) compares the corrected voltage measurement to a voltage requirement; and

(v) performs a corrective action when the corrected voltage measurement does not meet the voltage requirement.

16. The system of claim 15, wherein the corrective action is one of (i) deactivating the inverter or (ii) performing AC voltage regulation.

17. The system of claim 15, wherein the voltage compensation is determined based on an initial power from the inverter, a subsequent power from the inverter, and a correction coefficient.

18. The system of claim 17, wherein the correction coefficient is equal to a ratio of a voltage measurement obtained at the remotely located point and an initial voltage measurement at the inverter.

19. The system of claim 18, wherein the initial voltage measurement is used to determine the initial power.

20. The system of claim 18, wherein the remotely located point is a point of common coupling (PCC) between a commercial AC power grid and a distributed generator (DG) that comprises the plurality of PV modules and the plurality of inverters.