Method and apparatus for detection and control of dc arc faults

• US 8,179,147 B2
• Filed: 07/23/2010
• Issued: 05/15/2012
• Est. Priority Date: 07/23/2009
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Enphase Energy Incorporated
• Inventors: Dargatz, Marv, Fornage, Martin
• Primary Examiner(s): He, Amy
• Application Number:
  US12/804,541
• Publication Number:
  US 20110019444A1
• Time in Patent Office: 662 Days
• Field of Search: 324/536, 361/42
• US Class Current: 324/536
• CPC Class Codes: H01H 9/50 Means for detecting the presence of an arc or discharge
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 3/00 Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems H02H7/00; systems for change-over to standby supply H02J9/00 ; integrated protection for motors H02H7/0822
• CPC Class Codes: H02H 3/445 of DC quantities
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A method and apparatus for managing DC arc faults. At least a portion of the method is performed by a controller comprising at least one processor. In one embodiment, the method comprises analyzing a signature of a signal of a power converter and determining, based on analysis of the signature, whether an arc fault exists.

Claims

1. A method for managing arc faults, at least a portion of the method being performed by a controller comprising at least one processor, the method comprising:

analyzing a signature of a signal of a power converter; and

determining, based on analysis of the signature, whether an arc fault exists, wherein analyzing the signature comprises (i) analyzing the signature to identify a potential arc fault, wherein the signature is based on a current of the power converter; and

(ii) comparing, upon identifying the potential arc fault, the signature with a second signature for determining an arc fault signature match that identifies the arc fault, wherein the second signature is based on a voltage of the power converter; and

determining polarity of a DC current of the power converter; and

differentiating between a series arc and a parallel arc based on the polarity.

2. The method of claim 1, further comprising inhibiting power production by the power converter upon determining that the arc fault exists.

3. The method of claim 1, further comprising applying a short circuit across DC input terminals of the power converter upon identifying the parallel arc.

4. The method of claim 3, further comprising analyzing the signature for current fluctuations, wherein a non-fluctuating current confirms the parallel arc.

5. The method of claim 4, further comprising removing the short circuit upon determining a fluctuating current.

6. The method of claim 1, wherein the series arc is identified when the polarity is positive and the parallel arc is identified when the polarity is negative.

7. The method of claim 1, wherein the signature is a DC current signature based on a DC current of the power converter and the second signature is a DC voltage signature based on a DC voltage of the power converter.

8. The method of claim 1, wherein determining whether the arc fault exists comprises distinguishing between irradiance-generated changes in the signature and arc-generated changes in the signature.

9. An apparatus for managing arc faults, comprising:

a waveform processing module, adapted for coupling to a power conversion circuit, for analyzing a signature of a signal of the power conversion circuit and determining, based on analysis of the signature, whether an arc fault exists, wherein analyzing the signature comprises (i) analyzing the signature to identify a potential arc fault, wherein the signature is based on a current of the power conversion circuit; and

(ii) comparing, upon identifying the potential arc fault, the signature with a second signature for determining an arc fault signature match that identifies the arc fault, wherein the second signature is based on a voltage of the power conversion circuit; and

wherein the waveform processing module further determines polarity of a DC current of the power conversion circuit; and

differentiates between a series arc and a parallel arc based on the polarity.

10. The apparatus of claim 9, wherein the waveform processing module inhibits power production by the power conversion circuit upon determining that the arc fault exists.

11. The apparatus of claim 9, further comprising a shorting mechanism for applying a short circuit across DC input terminals of the power conversion circuit upon the parallel arc being identified.

12. The apparatus of claim 11, wherein the waveform processing module further analyzes the signature for current fluctuations, wherein a non-fluctuating current confirms the parallel arc.

13. The apparatus of claim 12, wherein the short circuit is removed upon determining a fluctuating current.

14. The apparatus of claim 9, wherein the series arc is identified when the polarity is positive and the parallel arc is identified when the polarity is negative.

15. The apparatus of claim 9, wherein the signature is a DC current signature based on a DC current of the power conversion circuit and the second signature is a DC voltage signature based on a DC voltage of the power conversion circuit.

16. The apparatus of claim 9, wherein determining whether the arc fault exists comprises distinguishing between irradiance-generated changes in the signature and arc-generated changes in the signature.

17. A system for managing arc faults, comprising:

a photovoltaic (PV) module;

a power converter coupled to the PV module, wherein the power converter comprises a waveform processing module coupled to a power conversion circuit, for analyzing a signature of a signal of the power conversion circuit, the waveform processing module for analyzing a signature of a signal of the power converter and determining, based on analysis of the signature, whether an arc fault exists, wherein analyzing the signature comprises (i) analyzing the signature to identify a potential arc fault, wherein the signature is based on a current of the power conversion circuit; and

(ii) comparing, upon identifying the potential arc fault, the signature with a second signature for determining an arc fault signature match that identifies the arc fault, wherein the second signature is based on a voltage of the power conversion circuit; and

wherein the waveform processing module further determines polarity of a DC current of the power conversion circuit; and

differentiates between a series arc and a parallel arc based on the polarity.