Isolating apparatus for a photovoltaic string

Patent metadata

Field	Value
Publication number	US-2019181800-A1
Application number	US-201916277323-A
Country	US
Kind code	A1
Filing date	Feb 15, 2019
Priority date	Aug 17, 2016
Publication date	Jun 13, 2019
Grant date	—

Abstract

An apparatus for electrically disconnecting a first part from a second part of a photovoltaic string, which parts can be connected to a first terminal and a second terminal of the apparatus, respectively. The apparatus includes a switch coupled between the first terminal and the second terminal; and an actuation apparatus configured to open the switch when a voltage applied to at least one of the first and second terminals relative to a potential applied to a reference terminal is outside of a prescribed value range

First claim

1 . An apparatus for electrically disconnecting a first part from a second part of a photovoltaic string, which parts can be connected to a first terminal and a second terminal of the apparatus, respectively, wherein the apparatus comprises:
a switch coupled between the first terminal and the second terminal; and an actuation apparatus configured to open the switch when a voltage applied to at least one of the first and second terminals relative to a potential applied to a reference terminal is outside of a prescribed value range.

2 . The apparatus as claimed in claim 1 , wherein the switch comprises a series circuit composed of two semiconductor switches.

3 . The apparatus as claimed in claim 2 , wherein the first switch and the second switch are normally on type switches.

4 . The apparatus as claimed in claim 3 , wherein the first switch and the second switch comprise JFETs.

5 . The apparatus as claimed in claim 4 , wherein the first switch is a p-JFET and the second switch is an n-JFET.

6 . The apparatus as claimed in claim 1 , wherein a measurement impedance between one of the first and second terminals and the reference terminal is at least 10 kOhm.

7 . The apparatus as claimed in claim 1 , wherein the actuation apparatus is configured to generate a fault signal when the switch is opened.

8 . The apparatus as claimed in claim 1 , wherein the actuation apparatus is further configured to open the switch when an external signal is received.

9 . The apparatus as claimed in claim 1 , wherein the actuation apparatus is further configured to close the switch again after opening when at least one of the following criteria is met:
a magnitude of the difference between the ground potential and a mean voltage value at the first terminal and the second terminal is below a prescribed threshold value, a prescribed time period has passed since the opening of the switch, and an external signal for closing the switch is received.

10 . The apparatus as claimed in claim 1 , wherein the actuation apparatus is connected to an energy store for the purpose of electrical power supply, wherein the energy store is configured to charge from a voltage dropped across the switch.

11 . A photovoltaic energy generation installation, comprising:
a first inverter and a second inverter connected in series on an input side thereof, wherein a midpoint of the series circuit of the inverters is connected to an isolation monitoring circuit, at least one photovoltaic string connected to the series circuit of the inverters, and
an apparatus for electrically disconnecting a first part from a second part of one of the at least one photovoltaic string, which parts can be connected to a first terminal and a second terminal of the apparatus, respectively, wherein the apparatus comprises:
a switch coupled between the first terminal and the second terminal; and
an actuation apparatus configured to open the switch when a voltage applied to at least one of the first and second terminals relative to a potential applied to a reference terminal is outside of a prescribed value range.

12 . The photovoltaic energy generation installation as claimed in claim 11 , wherein the string has a maximum open circuit voltage of more than 1500 volts.

13 . The photovoltaic energy generation installation as claimed in claim 11 , further comprising a plurality of parallel-connected strings, wherein each string comprises an apparatus therein having the apparatus.

14 . The photovoltaic energy generation installation as claimed in claim 11 , wherein the reference terminal is connected to ground potential.

15 . The photovoltaic energy generation installation as claimed in claim 11 , wherein the apparatus is arranged in the string in such a way that the string is separated into two parts of the same length when the switch is opened.

16 . A photovoltaic energy generation installation, comprising:
an inverter, wherein a midpoint of a split input link circuit of the inverter is connected to an isolation monitoring circuit, at least one photovoltaic string having opposing first and second string ends, and an apparatus for electrically disconnecting a first part having the first string end from a second part having the second string end of one of the at least one photovoltaic string, which first and second sgtsring ends are connected to a first terminal and a second terminal of the apparatus, respectively, wherein the apparatus comprises:
a switch coupled between the first terminal and the second terminal; and
an actuation apparatus configured to open the switch when a voltage applied to at least one of the first and second terminals relative to a potential applied to a reference terminal is outside of a prescribed value range.

Assignees

• Sma Solar Technology Ag

Inventors

• Nesemann Karl

Classifications

• H02S40/32

  comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules · CPC title

• H02S50/00

  Monitoring or testing of PV systems, e.g. load balancing or fault identification · CPC title

• H02S40/36 Primary

  characterised by special electrical interconnection means between two or more PV modules, e.g. electrical module-to-module connection · CPC title

• H02S50/10

  Testing of PV devices, e.g. of PV modules or single PV cells (testing of semiconductor devices during manufacturing {H10P74/00}) · CPC title

• Y02E10/56

  Power conversion systems, e.g. maximum power point trackers · CPC title