Mmc type power grid simulation device

Abstract

This application discloses an MMC-type power grid simulation device, comprising multiple power cabinets, each power cabinet constituting at least one grid-side bridge arm or at least one machine-side bridge arm. Each grid-side or machine-side bridge arm includes an upper bridge arm and a lower bridge arm, and each upper or lower bridge arm includes at least one power unit and a reactor. The power unit includes at least one single-board-level power module. The single-board-level power module includes a bridge circuit composed of power switching transistors, a discharge resistor connected to the DC side of the bridge circuit, and a bus capacitor. The single-board-level power module also includes at least one of the following: a drive circuit for driving the power switching transistors, a detection circuit for detection, a protection circuit for protection, a bypass circuit for bypassing, a control circuit for control, and a power supply circuit for providing power. This application can eliminate the dependence of traditional power grid simulation devices on transformer equipment, and at the same time avoid the technical and cost risks associated with directly developing large-capacity equipment.

Description

Technical Field

[0001] This application relates to the field of power grid simulation technology, and in particular to an MMC-type power grid simulation device. Background Technology

[0002] With the rapid development of distributed generation systems (DPS), their impact on grid stability is increasing, while grid stability, in turn, affects the normal operation of DPS. DPS systems should possess strong capabilities to cope with grid faults, remaining connected to the grid even during faults and maintaining grid stability by outputting active or reactive power. Due to the randomness and uncontrollability of grid faults, it is difficult to reproduce various grid faults in practice. To meet the requirements for grid adaptability testing of DPS systems, it is necessary to research specialized grid simulation devices to simulate various grid operating conditions.

[0003] The MMC (Modular Multilevel Converter) topology supports high-voltage and high-capacity applications. Due to its modular design, capacity and voltage levels can be expanded by increasing the number of power modules, making it excellent in high-voltage, high-power transmission systems. While the MMC topology eliminates the need for transformers in high-voltage, high-capacity applications, current research on MMC-type grid simulation devices is limited and the technology is immature. Directly developing large-capacity grid simulation devices could lead to resource waste. Utility Model Content

[0004] This application provides an MMC-type power grid simulation device to eliminate the dependence of traditional power grid simulation devices on transformer equipment, while avoiding the technical and cost risks of directly developing large-capacity equipment.

[0005] This application provides an MMC-type power grid simulation device, which includes multiple power cabinets. Each power cabinet constitutes at least one grid-side bridge arm or at least one machine-side bridge arm. The grid-side bridge arm or the machine-side bridge arm includes an upper bridge arm and a lower bridge arm. The upper bridge arm or the lower bridge arm includes at least one power unit and a reactor. The power unit includes at least one single-board-level power module.

[0006] The single-board power module includes a bridge circuit composed of power switching transistors, a discharge resistor and a bus capacitor connected to the DC side of the bridge circuit.

[0007] The single-board-level power module also includes at least one of the following:

[0008] The circuit includes a drive circuit for driving the power switch, a detection circuit for detection, a protection circuit for protection, a bypass circuit for bypassing, a control circuit for control, and a power supply circuit for providing power.

[0009] In one example, the bridge circuit consists of four of the aforementioned power switching transistors.

[0010] In one example, the power switch consists of a fully controlled device and an anti-parallel diode, wherein the fully controlled device includes at least one of MOSFET, IGBT, and IGCT.

[0011] In one example, the network-side bridge arm or the machine-side bridge arm both include an upper bridge arm controller for controlling the upper bridge arm and a lower bridge arm controller for controlling the lower bridge arm, and the single-board-level power module is communicatively connected to the corresponding upper bridge arm controller or lower bridge arm controller.

[0012] In one example, the power unit in the upper bridge arm is arranged on one side of the power cabinet, and the reactor in the upper bridge arm, the reactor in the lower bridge arm, and the power unit in the lower bridge arm are all arranged on the other side of the power cabinet.

[0013] In one example, the MMC-type power grid simulation device further includes a control cabinet for controlling the plurality of power cabinets, the control cabinet including a grid-side main controller and a machine-side main controller communicatively connected to the grid-side main controller.

[0014] In one example, the grid-side bridge arm or the machine-side bridge arm both include an upper bridge arm controller for controlling the upper bridge arm and a lower bridge arm controller for controlling the lower bridge arm, and the upper bridge arm controller and / or the lower bridge arm controller are communicatively connected to the corresponding grid-side main controller or machine-side main controller.

[0015] In one example, the control cabinet also includes at least one of the following:

[0016] A reset button for resetting the network-side main controller and / or the machine-side main controller;

[0017] Indicator unit used to display operating status;

[0018] A sampling unit for voltage and / or current sampling on the sampling machine side and / or grid side.

[0019] In one example, the number of power cabinets is seven, of which three power cabinets constitute three grid-side bridge arms and the other four power cabinets constitute four machine-side bridge arms, with the output of one of the machine-side bridge arms serving as a neutral reference point for three-phase output control.

[0020] The MMC-type power grid simulation device provided in this application uses a single-board-level power module instead of a conventional power module to build a prototype to verify the function of the MMC-type power grid simulation device. This can get rid of the dependence of traditional power grid simulation devices on transformer equipment, and at the same time avoid the technical and cost risks of directly developing large-capacity equipment. Attached Figure Description

[0021] Figure 1 A schematic diagram of the control cabinet of the MMC-type power grid simulation device provided in the embodiments of this application;

[0022] Figure 2 A front view schematic diagram of the power cabinet of the MMC-type power grid simulation device provided in the embodiments of this application;

[0023] Figure 3 A rear view schematic diagram of the power cabinet of the MMC-type power grid simulation device provided in the embodiments of this application;

[0024] Figure 4 A schematic diagram of a single-board-level power module for an MMC-type power grid simulation device provided in this application embodiment;

[0025] Figure 5 A schematic diagram of the specific circuit of the MMC-type power grid simulation device provided in the embodiments of this application.

[0026] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer and more understandable, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application.

[0028] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] like Figures 1-4 As shown in the figure, this application provides an MMC type power grid simulation device, including multiple power cabinets, each power cabinet constituting at least one grid-side bridge arm or at least one machine-side bridge arm. The grid-side bridge arm or the machine-side bridge arm includes an upper bridge arm and a lower bridge arm. The upper bridge arm or the lower bridge arm includes at least one power unit and a reactor. The power unit includes at least one single-board level power module. The single-board level power module refers to a power module consisting of a single board (PCB) and its integrated multiple components.

[0030] Specifically, the single-board power module includes a bridge circuit composed of power switching transistors, a discharge resistor (R1 in the figure) and a bus capacitor (C1 in the figure) connected to the DC side of the bridge circuit.

[0031] The single-board-level power module also includes at least one of the following:

[0032] The circuit includes a drive circuit for driving the power switch, a detection circuit for detection, a protection circuit for protection, a bypass circuit for bypassing, a control circuit for control, and a power supply circuit for providing power.

[0033] The above-described MMC-type power grid simulation device uses single-board-level power modules instead of conventional power modules to build a prototype for verifying the functionality of the MMC-type power grid simulation device. This prototype can meet all or most of the current functions of power grid simulation devices. By modifying the wiring, the power grid simulation device can also be used to verify the functions of other equipment, such as expanding to verify controller schemes for other cascaded topology devices. This MMC-type power grid simulation device eliminates the dependence on transformer equipment in traditional power grid simulation devices, allowing it to verify the software code of large-capacity machines. It also avoids the technical and cost risks associated with directly developing large-capacity equipment; that is, the functionality of the MMC-type power grid simulation device can be verified without developing a large-capacity machine, saving costs and mitigating technical risks.

[0034] In one example, the bridge circuit consists of four power switching transistors. Two of the power switching transistors form a series branch, and the two series branches are connected in parallel. The discharge resistor and the bus capacitor are also connected in parallel with the series branches. The circuit can be used as a half-bridge or a full-bridge; specifically, the conversion between half-bridge and full-bridge can be achieved by changing the wiring method.

[0035] In one example, the power switch consists of a fully controlled device and an anti-parallel diode. The fully controlled device includes at least one of MOSFET, IGBT, and IGCT. For example, using a MOSFET, along with supporting driving, detection, control, and protection circuits, to form a single-board-level power module can replace a conventional power module, achieving all the functions of a conventional power module.

[0036] In one example, both the network-side bridge arm and the machine-side bridge arm include an upper bridge arm controller for controlling the upper bridge arm and a lower bridge arm controller for controlling the lower bridge arm. The single-board-level power module is communicatively connected to the corresponding upper bridge arm controller or lower bridge arm controller. For example, the single-board-level power module is communicatively connected to the corresponding upper bridge arm controller or lower bridge arm controller via optical fiber, thereby realizing the control of the single-board-level power module.

[0037] In one example, the power unit in the upper bridge arm is arranged on one side of the power cabinet, and the reactor in the upper bridge arm, the reactor in the lower bridge arm, and the power unit in the lower bridge arm are all arranged on the other side of the power cabinet.

[0038] For example, the power unit and upper bridge arm controller in the upper bridge arm are arranged on the front side of the power cabinet, while the reactor in the upper bridge arm, the reactor in the lower bridge arm, the power unit in the lower bridge arm, and the lower bridge arm controller are arranged on the rear side of the power cabinet.

[0039] It is understandable that the power cabinet may also include current sampling and other circuits as shown in the figure, fans arranged on the cabinet, etc.

[0040] In one example, the MMC-type power grid simulation device further includes a control cabinet for controlling the plurality of power cabinets, the control cabinet including a grid-side main controller and a machine-side main controller communicatively connected to the grid-side main controller.

[0041] In one example, the upper arm controller and / or the lower arm controller are communicatively connected to the corresponding network-side main controller or the machine-side main controller. For instance, the upper arm controller and / or the lower arm controller are communicatively connected to the corresponding network-side main controller or the machine-side main controller via optical fiber. The network-side main controller and the machine-side main controller can have the same hardware structure, controlling the machine-side power cabinet and the network-side power cabinet respectively.

[0042] In one example, the control cabinet also includes at least one of the following:

[0043] A reset button for resetting the network-side main controller and / or the machine-side main controller;

[0044] An indicator unit used to display the operating status, such as an indicator light; the operating status may be, for example, running, alarm, fault, or other status information;

[0045] A sampling unit for voltage and / or current sampling on the sampling machine side and / or grid side.

[0046] It is understandable that the control cabinet may also include auxiliary power supply, auxiliary wiring and other circuits, soft start circuit, etc., as shown in the figure.

[0047] In one example, the number of power cabinets is seven, of which three power cabinets constitute three grid-side bridge arms and the other four power cabinets constitute four machine-side bridge arms, with the output of one of the machine-side bridge arms serving as a neutral reference point for three-phase output control.

[0048] Specifically, the grid side consists of three arms formed by an MMC topology, and the generator side adds a fourth arm to the existing three arms of the MMC topology. The output of the fourth arm serves as the neutral reference point for three-phase output control. In this way, while meeting the topology and stage specifications, high-capacity equipment is de-capacitated and its voltage reduced, using single-board-level power modules instead of conventional power modules to build a prototype and verify the functionality of the MMC-type power grid simulation device.

[0049] In this example, the power grid simulation device consists of a control cabinet and seven power cabinets, forming a three-phase four-arm system. The seven power cabinets are structurally identical, divided into grid-side power cabinets and generator-side power cabinets, connected via a DC bus. The grid-side and generator-side arms are structurally identical, with the three grid-side arms and four generator-side arms connected via a common DC bus. The control cabinet includes a grid-side main controller and a generator-side main controller, which communicate with each other to control the three grid-side arms and four generator-side arms respectively. Each power cabinet includes several power units, arm controllers, and arm inductors, forming a single-phase arm. The arm controller communicates with the corresponding grid-side main controller and / or generator-side main controller.

[0050] The control system of the power grid simulation device is divided into a grid-side main controller, a machine-side main controller, and upper and lower bridge arm controllers for each bridge arm. The grid-side main controller and the machine-side main controller control the corresponding bridge arm controllers, and each bridge arm controller controls the corresponding power module.

[0051] by Figure 5 For example, the MMC-type power grid simulation device consists of seven identical bridge arms. Each bridge arm contains multiple series-connected power modules and a reactor. The number of power modules can be adjusted as needed. There are three bridge arms on the grid side and four bridge arms on the generator side. The three grid-side bridge arms are connected to the three-phase power grid, and the four generator-side bridge arms are connected to the device under test. The single-phase output function is planned to be implemented through the fourth bridge arm added on the generator side. The output of the fourth bridge arm serves as the neutral reference point for three-phase output control. Based on the zero-sequence voltage control method, the operating mode of the fourth bridge arm can be defined according to two logics.

[0052] Method 1: The fourth bridge arm output is only used to output the midpoint of the total DC bus, and the zero-sequence voltage is controlled by the output of the three phase bridge arms; Method 2: The fourth bridge arm is responsible for the output control of the zero-sequence voltage, and the three phase bridge arms are responsible for the output of the positive and negative sequence voltages.

[0053] In one possible implementation, the fourth bridge arm output is only used to output the midpoint of the total DC bus. The zero-sequence voltage is controlled by the output of the three phase bridge arms. At this time, the upper and lower bridge arms of the fourth bridge arm each bear half of the DC side voltage, so at least half of the number of phase bridge arm power modules is required.

[0054] In one possible implementation, the fourth bridge arm is responsible for the output control of the zero-sequence voltage, while the three phase bridge arms are responsible for the positive-sequence and negative-sequence voltage outputs. The most severe operating condition when outputting zero-sequence voltage is a two-phase short circuit to ground. In this case, the magnitude of the zero-sequence voltage output by the fourth bridge arm is 1 / 3 (U... A +U B +U C The smallest series is

[0055]

[0056] The preferred embodiments of this application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and spirit of this application shall be within the scope of the claims.

Claims

1. An MMC type power grid simulation device, characterized by, The MMC-type power grid simulation device includes multiple power cabinets, each power cabinet forming at least one grid-side bridge arm or at least one machine-side bridge arm. The grid-side bridge arm or the machine-side bridge arm includes an upper bridge arm and a lower bridge arm. The upper bridge arm or the lower bridge arm includes at least one power unit and a reactor. The power unit includes at least one single-board-level power module. The single-board power module includes a bridge circuit composed of power switching transistors, a discharge resistor and a bus capacitor connected to the DC side of the bridge circuit. The single-board-level power module also includes at least one of the following: The circuit includes a drive circuit for driving the power switch, a detection circuit for detection, a protection circuit for protection, a bypass circuit for bypassing, a control circuit for control, and a power supply circuit for providing power.

2. The MMC-type power grid simulation device according to claim 1, characterized in that The bridge circuit consists of four power switching transistors.

3. The MMC-type power grid simulation device according to claim 1, characterized in that, The power switch consists of a fully controlled device and an anti-parallel diode. The fully controlled device includes at least one of MOSFET, IGBT, and IGCT.

4. The MMC-type power grid simulation apparatus according to claim 1, characterized in that, Both the network-side bridge arm and the machine-side bridge arm include an upper bridge arm controller for controlling the upper bridge arm and a lower bridge arm controller for controlling the lower bridge arm. The single-board-level power module is communicatively connected to the corresponding upper bridge arm controller or lower bridge arm controller.

5. The MMC-type power grid simulation device according to claim 1, characterized in that, The power unit in the upper bridge arm is arranged on one side of the power cabinet, and the reactor in the upper bridge arm, the reactor in the lower bridge arm, and the power unit in the lower bridge arm are all arranged on the other side of the power cabinet.

6. The MMC-type power grid simulation apparatus according to claim 1, characterized by The MMC-type power grid simulation device also includes a control cabinet for controlling the multiple power cabinets. The control cabinet includes a grid-side main controller and a machine-side main controller that is communicatively connected to the grid-side main controller.

7. The MMC-type power grid simulation device according to claim 6, characterized in that The grid-side bridge arm or the machine-side bridge arm each includes an upper bridge arm controller for controlling the upper bridge arm and a lower bridge arm controller for controlling the lower bridge arm. The upper bridge arm controller and / or the lower bridge arm controller are communicatively connected to the corresponding grid-side main controller or machine-side main controller.

8. The MMC-type power grid simulation apparatus according to claim 1, characterized by, The control cabinet also includes at least one of the following: A reset button for resetting the network-side main controller and / or the machine-side main controller; Indicator unit used to display operating status; A sampling unit for voltage and / or current sampling on the sampling machine side and / or grid side.

9. The MMC-type power grid simulation apparatus according to claim 1, characterized by, The number of power cabinets is seven, of which three power cabinets constitute three grid-side bridge arms, and the other four power cabinets constitute four machine-side bridge arms, with the output of one of the machine-side bridge arms serving as the neutral reference point for three-phase output control.

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