WO2020032457A1

WO2020032457A1 - Submodule for mmc converter

Info

Publication number: WO2020032457A1
Application number: PCT/KR2019/009466
Authority: WO
Inventors: 박용희; 유현호; 정홍주; 이주연
Original assignee: 효성중공업 주식회사
Priority date: 2018-08-07
Filing date: 2019-07-30
Publication date: 2020-02-13
Also published as: KR20200016431A

Abstract

The present invention relates to a submodule for an MMC converter configured to supply power in a stable manner to a submodule controller for controlling the submodule for the MMC converter. A submodule for an MMC converter according to an embodiment of the present invention comprises: a charging unit for charging a voltage; a plurality of switching elements connected in parallel in a bridge form to the charging unit; and a submodule controller for controlling the switching of the plurality of switching elements, wherein the submodule controller is connected to a main controller by a power line and receives a voltage from the main controller through the power line.

Description

Submodule of MMC Converter

The present invention relates to a submodule of a modular multilevel converter (MMC), and more particularly to a submodule of an MMC converter configured to stably supply power to a submodule controller for controlling a submodule for an MMC converter.

As is well known, a Modular Multilevel Converter (MMC) converter may be linked to an HVDC system for power transmission and reactive power compensation. The MMC converter includes a plurality of submodules connected in series.

In the MMC converter, the submodule is a very important factor and is controlled by the submodule controller provided inside the submodule. Generally, the submodule is used as a power source of the submodule controller using the high voltage of the submodule.

In this case, in order to use the high voltage of the submodule as a power source of the submodule controller, a power supply device for converting the low voltage required for the submodule controller is required.

1 is a configuration diagram of a submodule of a conventional MMC converter. The submodule 10 includes a bridge circuit including a plurality of

switches

11 and 12 and a capacitor 13.

The submodule 10 is controlled by an internal submodule controller 16. The power supply of the submodule controller 16 uses the high voltage charged in the capacitor 13. That is, the high voltage of the submodule 10 is converted into the power of the submodule controller 16 by the DC-DC converter 15 to be supplied to the submodule controller 16. The submodule controller 16 switches the

switches

11 and 12.

In this way, the submodule 10 of the conventional MMC converter is required to supply the submodule controller 16 with a high voltage of several tens to several tens of volts stored in the submodule 10 to supply power to the submodule controller 16. A DC-DC converter 15 that converts to a low voltage of several tens of volts is necessary.

However, when an overvoltage occurs at a high voltage of several tens to several kilowatts, there is a problem that a failure occurs exceeding the input range of the DC-DC converter 15. In order to solve this problem, the input voltage specification of the DC-DC converter 15 needs to be increased, but in order to consider the overvoltage generation range, there is a problem in that the cost increases by applying the DC-DC converter 15 having a higher specification than necessary.

Accordingly, an object of the present invention is to provide a submodule of an MMC converter capable of stably supplying a voltage required for the operation of the submodule controller without providing a DC-DC converter in the submodule applied to the MMC converter.

In addition, the present invention has an additional object to provide a sub-module of the MMC converter to prevent a failure due to the internal overvoltage of the sub-module in supplying power to the controller of the sub-module applied to the MMC converter.

Sub-module of the MMC converter according to an embodiment of the present invention, the charging unit for charging a voltage; A plurality of switching elements connected in parallel to the charging unit in a bridge form; And a sub module controller for controlling switching of the plurality of switching elements, wherein the sub module controller is connected to a main controller with a power line and receives a voltage from the main controller through the power line.

In the present invention, it further comprises one or more charging cells connected to the sub module controller, the voltage charged in the charging cell is supplied to the sub module controller.

In an embodiment of the present invention, the apparatus may further include at least one charging cell connected to the sub module controller and a switch for electrically connecting the charging cell and the sub module controller, wherein the sub module controller detects a voltage supplied from the main controller. The sub-module controller further includes a voltage detector, and when the voltage detected by the voltage detector is less than a preset voltage, the sub-module controller turns on the switch to supply the charged voltage to the sub-module controller.

In addition, the sub-module of the MMC converter according to another embodiment of the present invention, the charging unit for charging a voltage; A plurality of switching elements connected in parallel to the charging unit in a bridge form; And a sub-module controller for controlling switching of the plurality of switching elements, wherein the sub-module controller is connected to a main controller by an optical fiber cable and uses a optical signal received from the main controller through the optical fiber cable to supply a voltage. Create

In the present invention, the sub-module controller, the light receiving unit for receiving an optical signal received from the main controller; And a photoelectric conversion unit generating a voltage by converting the optical signal received from the light receiving unit into an electrical signal.

In an embodiment of the present invention, the apparatus may further include at least one charging cell connected to the sub module controller, and a switch for electrically connecting the charging cell and the sub module controller, wherein the sub module controller detects a voltage supplied from the main controller. The sub-module controller further includes a voltage detector, and when the voltage detected by the voltage detector is less than a preset voltage, the sub-module controller turns on the switch to supply the charged voltage to the sub-module controller.

According to the present invention, a stable voltage can be supplied to the submodule controller even when the submodule of the MMC converter is not provided with a high specification DC-DC converter.

According to the present invention, since the submodule does not have a DC-DC converter, cost can be reduced and there is no problem in the operation of the submodule controller even when an overvoltage occurs in the internal high voltage.

According to the present invention, it is possible to operate the submodule controller without operating the submodule, so that the abnormal state of the submodule can be monitored in advance even when the submodule is not operated.

1 is a configuration diagram of a sub module of a conventional MMC converter.

2 is a configuration diagram of a sub module of an MMC converter according to an embodiment of the present invention.

3 to 7 are diagrams illustrating the configuration of a sub module of an MMC converter, according to another exemplary embodiment.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used to refer to the same components as much as possible, even if displayed on different drawings. In addition, in describing the embodiments of the present invention, when it is determined that a detailed description of a related well-known configuration or function disturbs the understanding of the embodiment of the present invention, the detailed description thereof will be omitted.

In addition, in describing the components of the embodiments of the present disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are only to distinguish the components from other components, and the nature, order, order, etc. of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected or connected to that other component, but there is another component between each component. It should be understood that may be "connected", "coupled" or "connected".

Referring to FIG. 2, the submodule 100 according to an exemplary embodiment includes a plurality of

switching devices

110 and 120, a charging unit 130, and a submodule controller 140.

The plurality of

switching devices

110 and 120 may switch the input voltage input to the sub module 100 to charge the charging unit 130. The plurality of

switching elements

110 and 120 may be preferably composed of two to six power semiconductor switches, and are connected to the charging unit 130 in a bridge form to control the switching operation by the sub-module controller 140. Although the figure shows a half bridge shape as an example, a full bridge shape is also possible.

The

switching elements

110 and 120 may include, for example, an IGBT, a FET, a transistor, and the like, and the charging unit 130 may be a capacitor, for example, a device that stores a DC voltage.

The submodule controller 140 receives the power required for operation from the outside to control the switching of the plurality of

switching elements

110 and 120. To this end, the submodule controller 140 receives power from an external main controller 150.

In an embodiment of the present disclosure, the submodule controller 140 may be selectively connected to the main controller 150, which is an upper controller, by a power line 160. Accordingly, the submodule controller 140 may perform power line communication with the main controller 150. The submodule controller 140 may communicate not only a voltage but also a control signal through the power line communication from the main controller 150.

As such, the sub-module controller 140 according to an embodiment of the present invention can receive power without a DC-DC converter necessarily provided in the prior art.

3 is a diagram illustrating a submodule configuration of an MMC converter according to another exemplary embodiment of the present invention.

In FIG. 3, only a portion P of the submodule controller 140 is illustrated in FIG. 2 for convenience of description. Other components of FIG. 2, that is, not illustrated in FIG. 3, that is, the configuration and operation of the plurality of

switching elements

110 and 120 and the charging unit 130 are the same. This also applies to FIGS. 4 to 7.

Referring to FIG. 3, one or more charging cells 170 may be connected to the submodule controller 140 in the submodule 100 according to another embodiment of the present invention. The charging cell 170 provides a constant voltage to the submodule controller 140 when the voltage applied to the submodule controller 140 is smaller than a preset reference voltage.

Specifically, the submodule controller 140 stores the voltage supplied from the main controller 150 in an energy storage unit (not shown). In order for the submodule controller 140 to operate, the voltage stored in the energy storage unit must be at least a voltage required for the operation of the submodule controller 140. However, if the voltage stored in the energy storage unit does not reach the operating voltage due to some cause, the sub-module controller 140 cannot operate so that the voltage of the charging cell 170 is supplied to the energy storage unit to prevent this. This is to ensure that the voltage stored is always the required operating voltage.

As such, even if the voltage supplied from the main controller 150 does not reach the operating voltage of the submodule controller 140, the voltage charged in the charging cell 170 is supplied to the submodule controller 140 so as to supply the submodule controller 140. ) To maintain a constant voltage required for operation.

4 is a diagram illustrating a submodule configuration of an MMC converter according to another embodiment of the present invention. Referring to FIG. 4, in the sub-module 100 according to another exemplary embodiment of the present disclosure, the sub-module controller 140 may further include a voltage detector 180 and the charging cell 170 and the sub-module controller 140. The switch 190 may be connected between.

The voltage detector 180 detects a voltage supplied from the main controller 150 to the submodule controller 140. Accordingly, when the voltage supplied from the main controller 150 is less than the voltage required for the submodule controller 140, the submodule controller 140 turns on the switch 190 connected to the charging cell 170 to the charging cell 170. The charged voltage is supplied to the submodule controller 140.

3 and 4, the voltage is continuously supplied from the charging cell 170 to the sub-module controller 140 in FIG. 3, but in FIG. 4, the supply voltage from the main controller 150 is smaller than the voltage required for operation. Only when the voltage of the charging cell 170 is to be supplied to the sub-module controller 140.

5 is a diagram illustrating a submodule configuration of an MMC converter according to another embodiment of the present invention. Referring to FIG. 5, in the submodule 100 according to another exemplary embodiment of the present disclosure, the submodule controller 140 may be selectively connected to the main controller 150 by an optical power cable 200. have. Such an optical power cable may include an optical fiber cable. The optical fiber cable serves to transmit the light emitted from the light source. In this configuration, the main controller 150 may include a light source for optical power transmission, and the light generated from the light source is transmitted to the submodule controller 140 through the optical fiber cable 200.

In this case, the sub-module controller 140 according to the present invention may include a light receiving unit 210 for receiving such light and a photoelectric conversion unit 220 for converting the light into power using the received light. The light receiver 210 may include a semiconductor light receiver such as a photodiode as a device for detecting light. The photoelectric conversion unit 220 may convert an optical signal into an electrical signal and may include, for example, a photoconductive sensor, a phototransistor, a photoconductive image sensor, and the like.

As described above, the submodule controller 140 may generate a voltage necessary for the operation of the submodule controller 140 using the optical signal received from the main controller 150 through the optical fiber cable 200. This allows the submodule controller 140 according to the present invention to be supplied with power without the DC-DC converter provided in the prior art.

6 and 7 are diagrams illustrating submodules of the MMC converter according to another exemplary embodiment of the present invention, respectively.

Referring to FIG. 6, one or more charging cells 170 may be connected to the submodule controller 140 in the submodule 100 according to another exemplary embodiment. The charging cell 170 may provide a constant voltage to the submodule controller 140 when the voltage generated by the photoelectric conversion unit 220 of the submodule controller 140 is smaller than the voltage required for the operation of the submodule controller 140. do.

In detail, the submodule controller 140 stores the voltage generated by the photoelectric conversion unit 220 in the energy storage unit (not shown). In order for the submodule controller 140 to operate, the voltage stored in the energy storage unit must be at least a voltage required for the operation of the submodule controller 140. However, if the voltage stored in the energy storage unit does not reach the operating voltage due to some cause, the sub-module controller 140 cannot operate so that the voltage of the charging cell 170 is supplied to the energy storage unit to prevent this. This is to ensure that the voltage stored is always a constant voltage required for operation.

As such, when the optical signal is transmitted from the main controller 150 to the submodule controller 140, the photoelectric conversion unit 220 charges the voltage generated from the optical signal even if it does not reach the operating voltage of the submodule controller 140. The voltage charged in the cell 170 is supplied to the submodule controller 140 so that the submodule controller 140 maintains a constant voltage.

Referring to FIG. 7, in the sub-module 100 according to another exemplary embodiment of the present disclosure, the sub-module controller 140 illustrated in FIG. 6 may further include a voltage detector 240 and may include a charging cell 170. The switch 250 may be connected between the submodule controllers 140.

The voltage detector 240 detects a voltage generated by the photoelectric converter 220. Accordingly, when the voltage detected by the voltage detector 240 is smaller than the voltage required for the operation of the submodule controller 140, the submodule controller 140 turns on the switch 250 connected to the charging cell 170 to charge the battery 170. ) Is supplied to the sub-module controller 140.

6 and 7, the voltage is continuously supplied from the charging cell 170 to the sub-module controller 140 in FIG. 6, but in FIG. 7, the voltage generated by the photoelectric conversion unit 240 is required for operation. Only when smaller, the voltage of the charging cell 170 is supplied to the submodule controller 140.

As described above, the submodule 100 of the MMC converter according to the present invention may supply a voltage required for the operation of the internal submodule controller 140 by using a voltage or an optical signal supplied from the main controller 150. Therefore, it is not necessary to provide a high-end DC-DC converter for the power supply of the submodule controller 140 as in the prior art. As a result, even when the voltage is not supplied to the submodule 100, the voltage can be applied to the submodule controller 140 so that the submodule 100 can be monitored even before the submodule 100 is operated. Even if an overvoltage occurs, it is irrelevant to the operation of the submodule controller 140.

Although the above-described present invention has been described in detail through the preferred embodiments, it should be understood that the present invention is not limited to the contents of these embodiments. Those skilled in the art to which the present invention pertains, although not shown in the examples, can be imitated or improved for various inventions within the scope of the appended claims, all of which fall within the technical scope of the present invention. Belonging will be too self-evident. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims

A charging unit for charging a voltage;

A plurality of switching elements connected in parallel to the charging unit in a bridge form; And

And a sub-module controller for controlling switching of the plurality of switching elements.

The submodule controller is connected to a main controller and a power line, and receives a voltage from the main controller through the power line.
The method of claim 1,

The sub module of the MMC converter further comprises one or more charging cells connected to the sub module controller, the voltage charged in the charging cell is supplied to the sub module controller.
The method of claim 1,

At least one charging cell connected to the sub module controller, and a switch for electrically connecting the charging cell and the sub module controller, wherein the sub module controller further includes a voltage detector configured to detect a voltage supplied from the main controller; And the sub-module controller turns on the switch to supply the voltage charged in the charging cell to the sub-module controller when the voltage detected by the voltage detector is less than a predetermined voltage.
A charging unit for charging a voltage;

A plurality of switching elements connected in parallel to the charging unit in a bridge form; And

And a sub-module controller for controlling switching of the plurality of switching elements.

The submodule controller is connected to a main controller and an optical fiber cable and generates a voltage using an optical signal received from the main controller through the optical fiber cable.
The method of claim 4, wherein the sub-module controller,

A light receiving unit receiving an optical signal received from the main controller; And

The sub-module of the MMC converter including a photoelectric conversion unit for generating a voltage by converting the optical signal received from the light receiving unit into an electrical signal.
The method of claim 5,

Submodule of the MMC converter further comprises one or more charging cells connected to the submodule controller, the voltage charged in the charging cell is supplied to the submodule controller.
The method of claim 5,

At least one charging cell connected to the sub module controller, and a switch for electrically connecting the charging cell and the sub module controller, wherein the sub module controller is configured to detect a voltage generated by the photoelectric conversion unit. The sub-module controller further includes a sub-module of the MMC converter that turns on the switch to supply the charged voltage to the sub-module controller when the voltage detected by the voltage detector is smaller than a predetermined voltage.