REMOTE POWER UNIT, DIRECT CURRENT POWER SYSTEM AND DIRECT CURRENT POWER SYSTEM FAULT DETECTION METHOD

• US 20200136428A1
• Filed: 12/27/2019
• Published: 04/30/2020
• Est. Priority Date: 06/29/2017
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: ZHANG, Guoqing, STIEDL, Andreas, XIAO, Zhiming, TABAKOV, Michael
• Granted Patent: US 11,374,395 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 31/50 Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections testing of sparking plugs H01T13/58
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H02H 1/0007 concerning the detecting means in general G01R or other subclasses of G01; reed switches H01H71/2445
• CPC Class Codes: H02H 11/005 in case of too low isolation resistance, too high load, short-circuit; earth fault
• CPC Class Codes: H02H 3/16 responsive to fault current to earth, frame or mass with balanced or differential arrangement H02H3/26 ; monitoring earth connection H02H5/105
• CPC Class Codes: H02H 5/12 responsive to undesired approach to, or touching of, live parts by living beings
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 13/0004 involved in a protection system

Abstract

A remote power unit for providing direct current power to a remote power receiver in a direct current power system is provided. A residual current protection circuit comprises a first switch, which opens a positive voltage rail, and a second switch, which open a negative voltage rail. A first current sensor measures a first residual current between the first switch and the remote power receiver, while the first switch is closed and the second switch is opened. A second current sensor measures a second residual current between the second switch and the remote power receiver, while the second switch is closed and the first switch is open. A controller detects a residual current event, if the first residual current and/or the second residual current are above a residual current threshold.

Claims

1. A remote power unit for providing direct current power to a remote power receiver in a direct current power system, wherein the remote power unit comprises:

a residual current protection circuit, comprising;

a power supply interface, configured to receive direct current power from a power supply;

a direct current interface, configured to connect the remote power unit to the remote power receiver via a positive voltage line and a negative voltage line;

a first switch, configured to open a positive voltage rail between the power supply interface and the direct current interface;

a second switch, configured to open a negative voltage rail between the power supply interface and the direct current interface;

a first current sensor, configured to measure a first residual current between the first switch and the direct current interface, while the first switch is closed and the second switch is open;

a second current sensor, configured to measure a second residual current between the second switch and the direct current interface, while the second switch is closed and the first switch is open; and

a controller, configured to detect a residual current event, if at least one of the first residual current and the second residual current are above a residual current threshold.

2. The remote power unit of claim 1, wherein the controller is configured to control the operation of the first switch and the second switch in a periodical and alternating manner.

3. The remote power unit of claim 1, wherein the controller is further configured to perform at least one of:

close the first switch and the second switch;

open the first switch and close the second switch; and

close the first switch and open the second switch.

4. The remote power unit of claim 1, wherein the controller is further configured to set at least one of:

an opening time of the first switch and an opening time of the second switch to 1 ms to 100 ms, preferably 5 ms to 20 ms; and

a closed time of the first switch and a closed time of the second switch to 10 ms to 1000 ms, preferably 50 ms to 200 ms.

5. The remote power unit of claim 1, wherein the controller is further configured to switch the first switch and the second switch to open, if a residual current event is detected.

6. The remote power unit of claim 1, wherein the controller is further configured to switch the first switch and the second switch to open, if at least two consecutive residual current events are detected.

7. The remote power unit of claim 1, wherein the remote power unit further comprises an insulation monitor configured to detect if at least one of the positive voltage rail and the negative voltage rail has an insulation defect.

8. The remote power unit of claim 7, wherein the residual current protection circuit is configured to operate only if the insulation monitor has detected that at least one of the positive voltage rail and the negative voltage rail has an insulation defect;

and

wherein the first switch and the second switch are closed, when the residual current protection circuit is not operating.

9. The remote power unit of claim 1, wherein the first switch and the second switch are transistors.

10. The remote power unit of claim 1, wherein the first current sensor and the second current sensor are shunt current sensors or magnetic current sensors.

11. The remote power unit of claim 1, wherein the remote power unit further comprises a power supply, configured to provide direct current power to the remote power unit through the power supply interface.

12. A direct current power system, comprising

a remote power unit for providing direct current power to a remote power receiver in a direct current power system, and

a remote power receiver,

wherein the remote power unit comprises:

a residual current protection circuit, comprising;

a power supply interface, configured to receive direct current power from a power supply;

a direct current interface, configured to connect the remote power unit to the remote power receiver via a positive voltage line and a negative voltage line;

a first switch, configured to open a positive voltage rail between the power supply interface and the direct current interface;

a second switch, configured to open a negative voltage rail between the power supply interface and the direct current interface;

a first current sensor, configured to measure a first residual current between the first switch and the direct current interface, while the first switch is closed and the second switch is open;

a second current sensor, configured to measure a second residual current between the second switch and the direct current interface, while the second switch is closed and the first switch is open; and

a controller, configured to detect a residual current event, if at least one of the first residual current and the second residual current are above a residual current threshold.

13. The direct current power system of claim 12, wherein the remote power receiver is connected to the remote power unit via a positive voltage line and a negative voltage line.

14. The direct current power system of claim 12, wherein the remote power receiver comprises an energy storage, configured to:

store energy while the first switch and the second switch are closed, and power is transmitted from the remote power unit to the remote power receiver; and

provide the stored energy while the first switch or the second switch are open, and no power is transmitted from the remote power unit to the remote power receiver.

15. A direct current power system fault detection method, wherein a remote power unit of the remote power system provides direct current power to a remote power receiver of a direct current power system,

wherein the method comprises the following steps:

generating direct current power by a power supply;

switching a first switch, arranged within a positive voltage rail of the remote power unit, on, and switching a second switch, arranged within a negative voltage rail of the remote power unit on;

switching the first switch off;

measuring a first residual current between the first switch and a direct current interface of the remote power unit and measuring second residual current between the second switch and the direct current interface;

determining, if at least one of the first residual current and the second residual current exceed a residual current threshold;

determining a residual current event, if at least one of the first residual current and the second residual current exceed a residual current threshold;

switching the first switch and the second switch on;

switching the second switch off;

measuring a first residual current between the first switch and a direct current interface of the remote power unit and measuring second residual current between the second switch and the direct current interface;

determining, if at least one of the first residual current and the second residual current exceed a residual current threshold;

determining a residual current event, if at least one of the first residual current and the second residual current exceed a residual current threshold; and

switching the first switch and the second switch off, if at least two residual current event are detected.

16. A residual current protection circuit, for use in a remote power unit providing direct current power to a remote power receiver, wherein the residual current protection circuit comprises:

a power supply interface, configured to receive direct current power from a power supply;

a direct current interface, configured to connect the remote power unit to the remote power receiver via a positive voltage line and a negative voltage line;

a first switch, configured to open a positive voltage rail between the power supply interface and the direct current interface;

a second switch, configured to open a negative voltage rail between the power supply interface and the direct current interface;

a first current sensor, configured to measure a first residual current between the first switch and the direct current interface, while the first switch is closed and the second switch is open;

a second current sensor, configured to measure a second residual current between the second switch and the direct current interface, while the second switch is closed and the first switch is open; and

a controller, configured to detect a residual current event, if the first residual current and/or the second residual current are above a residual current threshold.