DC current sampling device, method and modular multi-level converter system

Abstract

The embodiment of the present invention discloses a DC current sampling device, method and modular multi-level converter system. The device includes: a current detection unit and a conversion unit; the current detection unit includes multiple current detection sub-units connected in parallel, and the multiple current detection sub-units are respectively used to detect the current flowing through part of the high-voltage busbar; the conversion unit is respectively connected to the multiple current detection sub-units and the valve control device, and is used to provide working voltage for the multiple current detection sub-units, and convert the current signals detected by the multiple current detection sub-units into voltage signals, and accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device. The DC current sampling device, method and modular multi-level converter system provided by the embodiment of the present invention, the multiple current detection sub-units respectively detect the current flowing through part of the high-voltage busbar, and can sample the current in real time.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a direct current sampling device, method and a modular multi-level converter system. Background Art

[0002] At present, the current sampling of the bridge arm of the Modular Multilevel Converter (MMC) system mainly uses Hall current sensors to sample the current of the high-voltage cable busbar or the high-voltage copper busbar, so as to improve the current sampling accuracy and save costs.

[0003] As the power level and capacity of valve-controlled equipment become larger and larger, the outer diameter of high-voltage cables and the insulating shed of cable heads become larger and larger, and the width and thickness of high-voltage copper busbars become larger and larger. However, the inner diameter of the Hall current sensor is relatively small, resulting in the high-voltage cable busbar or the high-voltage copper busbar being unable to pass through the Hall current sensor, and thus unable to achieve real-time sampling of current. Summary of the invention

[0004] The embodiments of the present invention provide a direct current sampling device, method and modular multi-level converter system, which can perform real-time current sampling.

[0005] In one aspect, an embodiment of the present invention provides a direct current sampling device, the device comprising: a current detection unit and a conversion unit;

[0006] The current detection unit includes a plurality of current detection sub-units connected in parallel, and the plurality of current detection sub-units are respectively used to detect the current flowing through a portion of the high-voltage busbar; wherein the high-voltage busbar as a whole is composed of a plurality of portions of the high-voltage busbars connected in parallel;

[0007] The conversion unit is connected to multiple current detection sub-units and valve control devices respectively, and is used to provide working voltage for the multiple current detection sub-units, and convert the current signals detected by the multiple current detection sub-units into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device.

[0008] In one embodiment of the present invention, the high-voltage busbar includes: a high-voltage cable busbar or a high-voltage copper busbar.

[0009] In one embodiment of the present invention, the high-voltage busbar comprises: a high-voltage cable busbar;

[0010] The conversion unit includes: a switching power supply and a Hall current acquisition board;

[0011] The Hall current acquisition board is respectively connected to the switching power supply, multiple current detection sub-units and the valve control device, and is used to provide the voltage output by the switching power supply to the multiple current detection sub-units and convert the current signals detected by the multiple current detection sub-units into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device.

[0012] In one embodiment of the present invention, the high-voltage busbar includes: a high-voltage copper busbar;

[0013] The conversion unit includes: a power supply unit, an isolation transformer, a switching power supply and a Hall current acquisition board;

[0014] The input end of the isolation transformer is connected to the power supply unit, and the output end of the isolation transformer is connected to the switching power supply, so as to input an isolated voltage to the switching power supply;

[0015] The Hall current acquisition board is respectively connected to the switching power supply, multiple current detection sub-units and the valve control device, and is used to provide the voltage output by the switching power supply to the multiple current detection sub-units and convert the current signals detected by the multiple current detection sub-units into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device.

[0016] In one embodiment of the present invention, the Hall current acquisition board includes: a voltage output subunit, a plurality of current-to-voltage conversion subunits, and a voltage accumulation subunit;

[0017] The voltage output subunit is connected to the switching power supply and the multiple current detection subunits respectively, and is used to provide the voltage output by the switching power supply to the multiple current detection subunits;

[0018] Each current-to-voltage conversion subunit in the plurality of current-to-voltage conversion subunits is respectively connected to each current detection subunit and the voltage accumulation subunit in the plurality of current detection subunits, and is used to convert the current signal collected by the current detection subunit connected thereto into a voltage signal, and send the voltage signal to the voltage accumulation subunit;

[0019] The voltage accumulation subunit is also connected to the valve control device, and is used to accumulate the voltage signal and transmit the accumulated voltage signal to the valve control device.

[0020] In one embodiment of the present invention, the Hall current collection board further includes: an electro-optical conversion subunit;

[0021] The electro-optical conversion sub-unit is connected to the voltage accumulation sub-unit and the valve control device respectively, and is used for converting the accumulated voltage signal into an optical signal and transmitting it to the valve control device.

[0022] In one embodiment of the present invention, the conversion unit is connected to the valve control device via an optical fiber, and is also used to convert the accumulated voltage signal into an optical signal and transmit it to the valve control device.

[0023] In one embodiment of the present invention, the current detection subunit includes: a Hall current sensor.

[0024] On the other hand, an embodiment of the present invention provides a modular multilevel converter system. The modular multilevel converter system includes the direct current sampling device provided by an embodiment of the present invention.

[0025] On the other hand, an embodiment of the present invention provides a direct current sampling method, the direct current sampling method comprising:

[0026] The multiple current detection sub-units connected in parallel respectively detect the current flowing through the part of the high-voltage busbar, and send the detected current signal to the conversion unit; wherein the high-voltage busbar as a whole is composed of multiple parts of the high-voltage busbars connected in parallel;

[0027] The conversion unit converts the current signals detected by the multiple current detection sub-units connected in parallel into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device to complete the sampling of the high-voltage busbar current.

[0028] In one embodiment of the present invention, the conversion unit converts the current signals detected by the multiple current detection sub-units connected in parallel into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device, including:

[0029] The Hall current acquisition board included in the conversion unit converts the current signals detected by the multiple current detection sub-units into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device.

[0030] In one embodiment of the present invention, the Hall current acquisition board included in the conversion unit converts the current signals detected by the multiple current detection sub-units into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device, including:

[0031] The multiple current-to-voltage conversion subunits included in the Hall current collection board respectively convert the current signals collected by the current detection subunits connected thereto into voltage signals, and send the voltage signals to the voltage accumulation subunit included in the Hall current collection board;

[0032] The voltage accumulation subunit accumulates the voltage signal and transmits the accumulated voltage signal to the valve control device.

[0033] In one embodiment of the present invention, the DC current sampling method further includes:

[0034] The electro-optical conversion subunit included in the Hall current acquisition board converts the accumulated voltage signal into an optical signal and transmits it to the valve control device.

[0035] In one embodiment of the present invention, the DC current sampling method further includes:

[0036] The conversion unit converts the accumulated voltage signal into an optical signal and transmits it to the valve control device.

[0037] The DC current sampling device, method and modular multi-level converter system provided by the embodiments of the present invention respectively detect the current flowing through part of the high-voltage busbar, and can sample the current in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following briefly introduces the drawings required for use in the embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 A first structural schematic diagram of a DC current sampling device provided by an embodiment of the present invention is shown;

[0040] Figure 2 A second structural schematic diagram of a DC current sampling device provided by an embodiment of the present invention is shown;

[0041] Figure 3 A third structural schematic diagram of the DC current sampling device provided by an embodiment of the present invention is shown;

[0042] Figure 4 A fourth structural schematic diagram of a DC current sampling device provided by an embodiment of the present invention is shown;

[0043] Figure 5 A fifth structural schematic diagram of the DC current sampling device provided by an embodiment of the present invention is shown;

[0044] Figure 6 A schematic flow chart of a DC current sampling method provided in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0045] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0046] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "bottom", "top" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0047] Figure 1 The first structural schematic diagram of the DC current sampling device provided by the embodiment of the present invention is shown. The current sampling device 10 comprises: a current detection unit 101 and a conversion unit 102 .

[0048] The current detection unit 101 includes a plurality of current detection sub-units 111 connected in parallel, and each of the plurality of current detection sub-units 111 is used to detect the current flowing through a portion of the high-voltage busbar.

[0049] The high-voltage busbar as a whole is composed of a plurality of partial high-voltage busbars connected in parallel.

[0050] The conversion unit 102 is respectively connected to multiple current detection sub-units 111 and the valve control device 11, and is used to provide working voltage for the multiple current detection sub-units 111, and convert the current signals detected by the multiple current detection sub-units 111 into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device 11.

[0051] In the current sampling device provided by the embodiment of the present invention, a plurality of current detection sub-units respectively detect the current flowing through a portion of the high-voltage busbar, and can perform real-time sampling of the current.

[0052] In one embodiment of the present invention, the conversion unit 102 and the valve control device 11 may be connected via an optical fiber, and the conversion unit 102 is further configured to convert the accumulated voltage signal into an optical signal and transmit it to the valve control device 11 .

[0053] In one embodiment of the present invention, the high-voltage busbar may include: a high-voltage cable busbar or a high-voltage copper busbar.

[0054] In one embodiment of the present invention, if the high-voltage busbar includes a high-voltage cable busbar, since the external insulation reliability of the high-voltage cable is high and can meet the requirements of electrical isolation, it is not necessary to use an isolated power supply method to provide the power required for the operation of the multiple current detection sub-units 111. Based on this, the conversion unit 102 includes: a switching power supply 121 and a Hall current acquisition board 122. Figure 2 As shown,

[0055] Figure 2 A second structural schematic diagram of a DC current sampling device provided in an embodiment of the present invention is shown.

[0056] The Hall current acquisition board 122 is respectively connected to the switching power supply 121, multiple current detection sub-units 111 and the valve control device 11, and is used to provide the voltage output by the switching power supply 121 to the multiple current detection sub-units 111 and convert the current signals detected by the multiple current detection sub-units 111 into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device 11.

[0057] In one embodiment of the present invention, if the high-voltage busbar includes a high-voltage copper busbar, since the voltage of the high-voltage copper busbar is relatively high and the external insulation reliability is relatively poor, it cannot meet the requirements of electrical isolation. Therefore, it is necessary to adopt an isolated power supply method to provide the power required for the operation of multiple current detection sub-units 111. Based on this, the conversion unit 102 includes: a switching power supply 121, a Hall current acquisition board 122, a power supply sub-unit 123 and an isolation transformer 124. Figure 3 As shown, Figure 3 A third structural schematic diagram of the DC current sampling device provided in an embodiment of the present invention is shown.

[0058] An input end of the isolation transformer 124 is connected to the power supply subunit 123 , and an output end of the isolation transformer 124 is connected to the switching power supply 121 , so as to input an isolated voltage to the switching power supply 121 .

[0059] The Hall current acquisition board 122 is respectively connected to the switching power supply 121, multiple current detection sub-units 111 and the valve control device 11, and is used to provide the voltage output by the switching power supply 121 to the multiple current detection sub-units 111 and convert the current signals detected by the multiple current detection sub-units 111 into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device 11.

[0060] Exemplarily, the power supply subunit 123 inputs a non-isolated voltage (e.g., 220 volts AC (VAC)) to the isolation transformer 124. The isolation transformer 124 outputs an isolated voltage (e.g., isolated 220VAC) to the switching power supply 121. At this time, the switching power supply 121 inputs an isolated voltage (isolated 220VAC), and the switching power supply 121 outputs an isolated voltage (e.g., isolated 15 volts DC (VDC)) to the Hall current acquisition board 122. The Hall current acquisition board 122 outputs the isolated voltage (isolated 15VDC) to the multiple current detection subunits 111. The multiple current detection subunits 111 start working after inputting the isolated voltage (isolated 15VDC).

[0061] The safety of the current sampling device can be improved by using an isolation transformer.

[0062] In one embodiment of the present invention, the Hall current acquisition board 122 may include: a voltage output subunit 1221, a plurality of current-to-voltage conversion subunits 1222, and a voltage accumulation subunit 1223. The following description is made by taking the high-voltage busbar as a high-voltage copper busbar as an example. Figure 4 As shown, Figure 4 A fourth structural schematic diagram of the direct current sampling device provided in an embodiment of the present invention is shown.

[0063] The voltage output subunit 1221 is respectively connected to the switching power supply 121 and the plurality of current detection subunits 111 , and is used to provide the voltage output by the switching power supply 121 to the plurality of current detection subunits 111 .

[0064] Each current-to-voltage conversion subunit 1222 among the multiple current-to-voltage conversion subunits 1222 is respectively connected to each current detection subunit 111 among the multiple current detection subunits 111 and the voltage accumulation subunit 1223, and is used to convert the current signal collected by the current detection subunit 111 connected thereto into a voltage signal, and send the voltage signal to the voltage accumulation subunit 1223.

[0065] The voltage accumulation subunit 1223 is also connected to the valve control device 11 , and is used for accumulating the voltage signal and transmitting the accumulated voltage signal to the valve control device 11 .

[0066] In one embodiment of the present invention, the Hall current collection board 122 may further include: an electro-optical conversion sub-unit 1224. The following description is also based on the example that the high-voltage busbar is a high-voltage copper busbar. Figure 5 As shown, Figure 5 A fifth structural schematic diagram of the direct current sampling device provided in an embodiment of the present invention is shown.

[0067] The electro-optical conversion subunit 1224 is connected to the voltage accumulation subunit 1223 and the valve control device 11 respectively, and is used to convert the accumulated voltage signal into an optical signal and transmit it to the valve control device 11 .

[0068] It can be understood that the electro-optical conversion subunit 1224 is connected to the valve control device 11 via an optical fiber.

[0069] In one embodiment of the present invention, the current detection subunit 111 may include: a Hall current sensor.

[0070] In the DC current sampling device provided by the embodiment of the present invention, each of the multiple Hall current sensors only detects the current flowing through a portion of the high-voltage busbar, so that a portion of the high-voltage busbar can pass through the Hall current sensor, and the current can be sampled in real time.

[0071] An embodiment of the present invention further provides a modular multilevel converter system. The modular multilevel converter system includes the direct current sampling device provided by the embodiment of the present invention.

[0072] A modular multilevel converter is composed of a plurality of cascaded sub-modules (SM) with the same structure. A system composed of modular multilevel converters is usually called a modular multilevel converter system.

[0073] Based on the above description, an embodiment of the present invention further provides a DC current sampling method. The DC current sampling method provided by the embodiment of the present invention utilizes the DC current sampling device provided by the embodiment of the present invention. Figure 6 As shown, Figure 6 The flow chart of the DC current sampling method provided by the embodiment of the present invention is shown. The DC current sampling method may include:

[0074] S601: The multiple current detection sub-units connected in parallel respectively detect the current flowing through a part of the high-voltage busbar, and send the detected current signal to the conversion unit.

[0075] The high-voltage busbar as a whole is composed of a plurality of partial high-voltage busbars connected in parallel.

[0076] S602: The conversion unit converts the current signals detected by the multiple current detection sub-units connected in parallel into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device to complete the sampling of the high-voltage busbar current.

[0077] In one embodiment of the present invention, a conversion unit converts current signals detected by a plurality of current detection sub-units connected in parallel into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to a valve control device, including:

[0078] The Hall current acquisition board included in the conversion unit converts the current signals detected by the multiple current detection sub-units into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device.

[0079] In one embodiment of the present invention, the Hall current acquisition board included in the conversion unit converts the current signals detected by the multiple current detection sub-units into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device, including:

[0080] The multiple current-to-voltage conversion subunits included in the Hall current acquisition board respectively convert the current signals collected by the current detection subunits connected thereto into voltage signals, and send the voltage signals to the voltage accumulation subunit included in the Hall current acquisition board;

[0081] The voltage accumulation subunit accumulates the voltage signal and transmits the accumulated voltage signal to the valve control device.

[0082] In one embodiment of the present invention, the DC current sampling method further includes:

[0083] The electro-optical conversion subunit included in the Hall current acquisition board converts the accumulated voltage signal into an optical signal and transmits it to the valve control device.

[0084] In one embodiment of the present invention, the DC current sampling method further includes:

[0085] The conversion unit converts the accumulated voltage signal into an optical signal and transmits it to the valve control device.

[0086] In the DC current sampling method provided by the embodiment of the present invention, a plurality of current detection sub-units respectively detect the current flowing through a portion of the high-voltage busbar, and can sample the current in real time.

[0087] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A DC current sampling device, characterized in that: The device comprises: a current detection unit and a conversion unit; The current detection unit includes a plurality of current detection sub-units connected in parallel, and the plurality of current detection sub-units are respectively used to detect the current flowing through a portion of the high-voltage busbar; wherein the high-voltage busbar as a whole is composed of a plurality of the plurality of the high-voltage busbars connected in parallel; The conversion unit is connected to the multiple current detection sub-units and the valve control device respectively, and is used to provide working voltage for the multiple current detection sub-units, and convert the current signals detected by the multiple current detection sub-units into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device.

2. The DC current sampling device according to claim 1, characterized in that: The high-voltage busbar includes: a high-voltage cable busbar or a high-voltage copper busbar.

3. The DC current sampling device according to claim 2, characterized in that: The high-voltage busbar includes: a high-voltage cable busbar; The conversion unit includes: a switching power supply and a Hall current acquisition board; The Hall current acquisition board is respectively connected to the switching power supply, the multiple current detection sub-units and the valve control device, and is used to provide the voltage output by the switching power supply to the multiple current detection sub-units and convert the current signals detected by the multiple current detection sub-units into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device.

4. The DC current sampling device according to claim 2, characterized in that: The high-voltage busbar includes: a high-voltage copper busbar; The conversion unit includes: a power supply unit, an isolation transformer, a switching power supply and a Hall current acquisition board; The input end of the isolation transformer is connected to the power supply subunit, and the output end of the isolation transformer is connected to the switching power supply, so as to input an isolated voltage to the switching power supply; The Hall current acquisition board is respectively connected to the switching power supply, the multiple current detection sub-units and the valve control device, and is used to provide the voltage output by the switching power supply to the multiple current detection sub-units and convert the current signals detected by the multiple current detection sub-units into voltage signals, accumulate the voltage signals, and transmit the accumulated voltage signals to the valve control device.

5. The DC current sampling device according to claim 3 or 4, characterized in that: The Hall current acquisition board comprises: a voltage output subunit, a plurality of current-to-voltage conversion subunits and a voltage accumulation subunit; The voltage output subunit is connected to the switching power supply and the multiple current detection subunits respectively, and is used to provide the voltage output by the switching power supply to the multiple current detection subunits; Each current-to-voltage conversion subunit of the plurality of current-to-voltage conversion subunits is respectively connected to each current detection subunit of the plurality of current detection subunits and the voltage accumulation subunit, and is used for converting the current signal collected by the current detection subunit connected thereto into a voltage signal, and sending the voltage signal to the voltage accumulation subunit; The voltage accumulation subunit is also connected to the valve control device, and is used to accumulate the voltage signal and transmit the accumulated voltage signal to the valve control device.

6. The DC current sampling device according to claim 5, characterized in that: The Hall current collection board also includes: an electro-optical conversion subunit; The electro-optical conversion subunit is connected to the voltage accumulation subunit and the valve control device respectively, and is used to convert the accumulated voltage signal into an optical signal and transmit it to the valve control device.

7. The DC current sampling device according to claim 1, characterized in that: The conversion unit is connected to the valve control device via an optical fiber, and is also used to convert the accumulated voltage signal into an optical signal and transmit it to the valve control device.

8. The DC current sampling device according to claim 1, characterized in that: The current detection subunit is a Hall current sensor.

9. A modular multilevel converter system, characterized in that: The modular multilevel converter system comprises the direct current sampling device according to any one of claims 1 to 8.

10. A DC current sampling method, characterized in that: The method comprises: The multiple current detection sub-units connected in parallel respectively detect the current flowing through the part of the high-voltage busbar, and send the detected current signal to the conversion unit; wherein the high-voltage busbar as a whole is composed of a plurality of the said parts of the high-voltage busbars connected in parallel; The conversion unit converts the current signals respectively detected by the multiple current detection sub-units connected in parallel into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device to complete the sampling of the high-voltage busbar current.

11. The DC current sampling method according to claim 10, characterized in that: The conversion unit converts the current signals detected by the multiple current detection sub-units connected in parallel into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device, including: The Hall current acquisition board included in the conversion unit converts the current signals detected by the multiple current detection sub-units into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device.

12. The DC current sampling method according to claim 11, characterized in that: The Hall current acquisition board included in the conversion unit converts the current signals detected by the multiple current detection sub-units into voltage signals, accumulates the voltage signals, and transmits the accumulated voltage signals to the valve control device, including: The multiple current-to-voltage conversion subunits included in the Hall current collection board respectively convert the current signals collected by the current detection subunits connected thereto into voltage signals, and send the voltage signals to the voltage accumulation subunit included in the Hall current collection board; The voltage accumulation subunit accumulates the voltage signal and transmits the accumulated voltage signal to the valve control device.

13. The DC current sampling method according to claim 12, characterized in that: The method further comprises: The electro-optical conversion subunit included in the Hall current collection board converts the accumulated voltage signal into an optical signal and transmits it to the valve control device.

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