Method and apparatus for determining a corrected monitoring voltage

Patent metadata

Field	Value
Publication number	US-9509142-B2
Application number	US-201414197087-A
Country	US
Kind code	B2
Filing date	Mar 4, 2014
Priority date	Feb 5, 2009
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

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.

First claim

The invention claimed is:

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.

Assignees

• Enphase Energy Inc

Inventors

• Fornage Martin
• Dargatz Marv

Classifications

• H02M7/44

  by static converters · CPC title

• H02J2101/28

  Wind energy · CPC title

• H02J2101/24

  Photovoltaics · CPC title

• H02J2101/20

  Dispersed power generation using renewable energy sources · CPC title

• Y02E10/563

  Cross-Sectional Technologies · mapped topic