A modular multilevel converter demonstration device and a demonstration method thereof

Abstract

The application discloses a modular multilevel converter demonstration device and a demonstration method thereof, and the demonstration device comprises a controller and a display control panel, wherein the display control panel is divided into a function control area, a waveform display area and a topology circuit selection area; the function control area, the waveform display area and the topology circuit selection area are electrically connected with the controller; the controller executes corresponding sub-module on-off programs, waveform display programs and level demonstration programs according to start buttons of the function control area; and the teaching demonstration of the modular multilevel converter is performed through the execution of the above programs. The application has the functions of sequential demonstration, sub-module on-off and level demonstration, can visually and intuitively display the working principle of the modular multilevel converter, and is convenient for students or trainees to more deeply understand and master the complex and abstract basic working principle of the modular multilevel converter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible direct current transmission, in particular to a modular multilevel converter demonstration device and a demonstration method thereof. BACKGROUND

[0002] In a new power system mainly composed of new energy, new energy generation such as wind power generation and solar power generation has randomness, volatility and intermittency. Large-scale new energy access will increase the difficulty of grid peak regulation, frequency regulation and voltage control, and increase the risk of safe and stable operation of the power grid. Flexible direct current transmission can realize decoupling control of active power and reactive power, improve the voltage stability of the system, and is an effective way for the power grid to cope with the challenges brought by large-scale new energy access. At present, the converter used in domestic flexible direct current transmission projects is a modular multilevel converter, so it is necessary to study and teach the modular multilevel converter.

[0003] However, there are the following difficulties in studying and teaching the modular multilevel converter: first, the working principle of the modular multilevel converter is relatively abstract, and students or trainees have difficulty or do not fully understand the abstract text description and formula derivation in the book; second, configuring a set of modular multilevel converters in the laboratory or training room is not only expensive, but also the converter is packaged inside the shell, so students or trainees cannot clearly and intuitively see the process of each sub-module being put into operation and withdrawn from operation, and it is also difficult to understand and imagine the corresponding relationship between the different sub-modules and the generated staircase sine wave. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a modular multilevel converter demonstration device and a demonstration method thereof. Through the demonstration device, the working principle of the modular multilevel converter can be visually and intuitively demonstrated. Based on the demonstration method, students or trainees can more deeply understand and master the complex and abstract basic working principle of the modular multilevel converter.

[0005] To achieve the above object, one or more embodiments of the present application provide the following technical solutions:

[0006] The present application provides a modular multilevel converter demonstration device.

[0007] A modular multilevel converter demonstration device includes a controller and a display control panel, the display control panel is divided into a function control area, a waveform display area and a topology circuit selection area.

[0008] The topology circuit selection area comprises four upper bridge arm sub-modules, four lower bridge arm sub-modules, and a switching-on and switching-off switch corresponding to each sub-module, the switching-on and switching-off switch being electrically connected with the controller, and being used for controlling switching-on and switching-off operation of the corresponding sub-module.

[0009] The waveform display area displays a stepped sine wave comprising nine time periods and five levels, each time period corresponding to a level, and each level being electrically connected with the controller.

[0010] The function control area comprises a sequential demonstration button, a sub-module switching-on and switching-off button, a level demonstration button, and five level buttons, each button being electrically connected with the controller.

[0011] The controller is used for executing a sub-module switching-on and switching-off program, a waveform display program, and a level demonstration program according to the buttons of the function control area.

[0012] In a further technical solution, each upper bridge arm sub-module and each lower bridge arm sub-module is an LED display screen, and is inlaid in the topology circuit selection area of the display control panel in sequence and is electrically connected with the controller.

[0013] In a further technical solution, the LED display screen displays a capacitor icon or a short-circuit icon according to the state of the switching-on and switching-off switch, and preferably, a level type is marked beside the icon.

[0014] In a further technical solution, each level corresponding to each time period in the waveform display area is a light-emitting diode light belt, and is inlaid in the waveform display area of the display control panel, and is used for displaying stepped waves of different levels at different times.

[0015] In a further technical solution, the sequential demonstration button is used for starting a formation process of the stepped sine wave, and the sequential demonstration button corresponds to 9 time sequences, each time sequence corresponding to a level of the nine time periods displayed by the waveform display area.

[0016] In a further technical solution, the level demonstration button is used for starting a level demonstration function, and the five level buttons are respectively a 0 level button, a +U d / 2 level button, a -U d / 2 level button, a +U d level button, and a -U d level button, and are used for testing whether a student or a trainee can select appropriate sub-module switching-on and switching-off according to a given corresponding level waveform.

[0017] In a further technical solution, the sub-module switching-on and switching-off button is used for starting a sub-module switching-on and switching-off function.

[0018] The second aspect of the present application provides a demonstration method of a modular multilevel converter demonstration device, which uses the modular multilevel converter demonstration device for demonstration, comprising:

[0019] When the sequence display button is started, the controller executes the sequence display waveform program, controls the state of each sub-module in the topology circuit selection area according to the time sequence corresponding to the sequence display button, and displays the level in the waveform display area corresponding to the time period.

[0020] Further technical solutions also include:

[0021] When the level demonstration button is started, the five level buttons are in a standby state, and when any level button is started again, the controller executes the corresponding level demonstration program according to the started level button, controls the waveform display area to display the corresponding level according to the started level button, and judges whether the sub-module selected by the tester according to the displayed level waveform is correct according to the judgment rule.

[0022] The judgment rule refers to that different levels correspond to the start of different upper bridge arm sub-modules and lower bridge arm sub-modules, and specifically includes: 0 level corresponds to the start of any 2 upper bridge arm sub-modules and any 2 lower bridge arm sub-modules; +U d / 2 level corresponds to the start of any 1 upper bridge arm sub-module and any 3 lower bridge arm sub-modules; -U d / 2 level corresponds to the start of any 3 upper bridge arm sub-modules and any 1 lower bridge arm sub-module; +U d level corresponds to the start of 4 lower bridge arm sub-modules; -U d level corresponds to the start of 4 upper bridge arm sub-modules.

[0023] Further technical solutions also include:

[0024] When the sub-module on-off button is started, the controller executes the sub-module on-off program, and the state of each sub-module changes according to the change of the on-off switch state corresponding to the sub-module.

[0025] The above one or more technical solutions have the following beneficial effects:

[0026] (1) The present application proposes a modular multilevel converter demonstration device and a demonstration method thereof, which can visually and intuitively demonstrate the working principle of the modular multilevel converter, and based on the demonstration method, students or trainees can more deeply understand and master the complex and abstract basic working principle of the modular multilevel converter.

[0027] (2) This invention has sequential demonstration function, sub-module enable / disable function and level demonstration function. Through the sequential demonstration function, the formation process of the stepped sine wave can be vividly and clearly demonstrated, which is convenient for students or trainees to understand and master. Through the sub-module enable / disable function, the equivalent circuit of the sub-module and the corresponding output level can be clearly and clearly explained. Through the level demonstration function, it is possible to test whether students or trainees have mastered the basic principles of modular multilevel converter, which is beneficial to the teaching of modular multilevel converter. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0029] Figure 1 This is a schematic diagram of the modular multilevel converter demonstration device according to Embodiment 1 of the present invention;

[0030] Figure 2 This is a circuit connection diagram of the modular multilevel converter demonstration device according to Embodiment 1 of the present invention;

[0031] Figure 3 This is a schematic diagram of the capacitor icon in the modular multilevel converter demonstration device described in Embodiment 1 of the present invention;

[0032] Figure 4 This is a schematic diagram of a short-circuit icon in the modular multilevel converter demonstration device described in Embodiment 1 of the present invention.

[0033] Among them, 1-1, base plate; 1-2, casters; 1-3, lifting rod; 1-4, display and control area frame; 2, display control panel; 3-1, upper boom sub-module SM1; 3-2, upper boom sub-module SM2; 3-3, upper boom sub-module SM3; 3-4, upper boom sub-module SM4; 4-1, upper boom sub-module SM1's engagement / disengagement switch; 4-2, upper boom sub-module SM2's engagement / disengagement switch; 4-3, upper boom sub-module SM3's engagement / disengagement switch; 4-4, upper boom sub-module S... M4's enable / disable switch; 5-1, lower bridge arm submodule SM1; 5-2, lower bridge arm submodule SM2; 5-3, lower bridge arm submodule SM3; 5-4, lower bridge arm module SM4; 6-1, enable / disable switch of lower bridge arm module SM1; 6-2, enable / disable switch of lower bridge arm module SM2; 6-3, enable / disable switch of lower bridge arm module SM3; 6-4, enable / disable switch of lower bridge arm module SM4; 7-1, the 0 level output corresponding to time period t1; 7-2, the U level output corresponding to time period t2. d / 2 level, the output U corresponding to the time periods 7-3 and t3. d Level, the output U corresponding to the time intervals 7-4 and t4d / 2 level, 0 level corresponding to time periods 7-5 and t5, -U level corresponding to time periods 7-6 and t6. d / 2 level, the -U output corresponding to the 7-7 and t7 time periods. d Level, the -U output corresponding to the time periods 7-8 and t8. d / 2 level, 7-9, t9 time period corresponding to the output 0 level, 8, sequence demonstration button, 9, submodule enable / disable button, 10-1, level demonstration button, 10-2, 0 level button, 10-3, +U d / 2 level button, 10-4, -U d / 2 Level button, 10-5, +U d Level button, 10-6, -U d 11. Level button, 12. Power switch, 13. Power plug. Detailed Implementation

[0034] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] Example 1

[0037] This embodiment provides a modular multilevel converter demonstration device, as follows: Figure 1 and Figure 2 As shown, it includes a controller and a display control panel 2, which is divided into a function control area, a waveform display area and a topology circuit selection area.

[0038] The topology circuit selection area includes four upper bridge arm sub-modules, four lower bridge arm sub-modules, and an activation / deactivation switch corresponding to each sub-module. The activation / deactivation switch is electrically connected to the controller and is used to control the activation and deactivation of the corresponding sub-module.

[0039] The waveform display area displays a stepped sine wave comprising nine time segments and five voltage levels, with each time segment corresponding to one voltage level, and the voltage levels are electrically connected to the controller.

[0040] The function control area comprises a sequential demonstration button, a sub-module on-off button, a level demonstration button and five level buttons, each of which is electrically connected with the controller;

[0041] The controller is used for executing a sub-module on-off program, a waveform display program and a level demonstration program according to the buttons of the function control area.

[0042] Specifically, in the embodiment, the topology circuit selection area comprises an upper bridge arm sub-module SM1 3-1, an upper bridge arm sub-module SM2 3-2, an upper bridge arm sub-module SM3 3-3 and an upper bridge arm sub-module SM4 3-4, each of which is provided with an on-off switch, i.e. an on-off switch 4-1 of the upper bridge arm sub-module SM1, an on-off switch 4-2 of the upper bridge arm sub-module SM2, an on-off switch 4-3 of the upper bridge arm sub-module SM3 and an on-off switch 4-4 of the upper bridge arm sub-module SM4, each of which is used for controlling the on and off operation of the corresponding sub-module.

[0043] The topology circuit selection area further comprises a lower bridge arm sub-module SM1 5-1, a lower bridge arm sub-module SM2 5-2, a lower bridge arm sub-module SM3 5-3 and a lower bridge arm sub-module SM4 5-4, each of which is provided with an on-off switch, i.e. an on-off switch 6-1 of the lower bridge arm sub-module SM1, an on-off switch 6-2 of the lower bridge arm sub-module SM2, an on-off switch 6-3 of the lower bridge arm sub-module SM3 and an on-off switch 6-4 of the lower bridge arm sub-module SM4, each of which is used for controlling the on and off operation of the corresponding sub-module.

[0044] Further, each of the upper bridge arm sub-modules and the lower bridge arm sub-modules is an LED display screen, which is inlaid in the corresponding position of the upper bridge arm and the lower bridge arm of the topology circuit selection area of the display control panel 2 and is electrically connected with the controller on the back of the display control panel 2. In the embodiment, a PLC chip (Programmable Logic Controller) is selected as the control chip, and each of the upper bridge arm sub-modules and the lower bridge arm sub-modules is connected with the corresponding pin of the PLC chip on the back thereof. The LED display screen displays a capacitor icon or a short-circuit icon according to the state of the on-off switch, and further, the level type is marked beside the icon and is displayed in red highlight. The PLC chip installed on the back of the display control panel 2 is used for program logic control. Each of the on-off switches corresponding to the sub-modules is arranged beside the corresponding sub-module and is connected with the corresponding pin of the PLC chip on the back of the display control panel 2, and is used for controlling the on and off operation of the corresponding sub-module.

[0045] Specifically, the upper bridge arm sub-modules SM1 3-1, SM2 3-2, SM3 3-3 and SM4 3-4 are all LED display screens, which are inlaid in the corresponding positions of the upper bridge arm of the topology circuit selection area on the display control panel 2 and connected with the corresponding pins of the PLC chip on the back thereof. The on-off switches 4-1, 4-2, 4-3 and 4-4 of the upper bridge arm sub-modules SM1, SM2, SM3 and SM4 are respectively installed beside the sub-modules SM1, SM2, SM3 and SM4 and connected with the corresponding pins of the PLC chip on the back of the display control panel 2, for controlling the on and off operation of the corresponding sub-modules.

[0046] The lower bridge arm sub-modules SM1 5-1, SM2 5-2, SM3 5-3 and SM4 5-4 are all LED display screens, which are inlaid in the corresponding positions of the lower bridge arm of the topology circuit selection area on the display control panel 2 and connected with the corresponding pins of the PLC chip on the back thereof. The on-off switches 6-1, 6-2, 6-3 and 6-4 of the lower bridge arm sub-modules SM1, SM2, SM3 and SM4 are respectively installed beside the sub-modules SM1, SM2, SM3 and SM4 and connected with the corresponding pins of the PLC chip on the back of the display control panel 2, for controlling the on and off operation of the corresponding sub-modules.

[0047] The waveform display area displays a stepped sine wave including nine time periods and five levels, each time period corresponding to a level, and each level being a light-emitting diode light belt, which is inlaid in the corresponding position of the waveform display area of the display control panel 2 and electrically connected with the controller on the back thereof, i.e. connected with the corresponding pins of the PLC chip, for displaying stepped waves of different levels at different times.

[0048] In the present embodiment, the t1 time period corresponds to the output of 0 level, the t2 time period corresponds to the output of U d / 2 level, the t3 time period corresponds to the output of U d level, the t4 time period corresponds to the output of U d / 2 level, the t5 time period corresponds to the output of 0 level, the t6 time period corresponds to the output of -U d / 2 level, the t7 time period corresponds to the output of -U d level, the t8 time period corresponds to the output of -U d / 2 level, and the t9 time period corresponds to the output of 0 level.

[0049] Specifically, the t1 time period corresponds to the output of 0 level 7-1, the t2 time period corresponds to the output of U d level 7-2, the t3 time period corresponds to the output of U d level 7-3, the t4 time period corresponds to the output of U d level 7-4, the t5 time period corresponds to the output of 0 level 7-5, the t6 time period corresponds to the output of -U d level 7-6, the t7 time period corresponds to the output of -U d level 7-7, the t8 time period corresponds to the output of -U d level 7-8, the t9 time period corresponds to the output of 0 level 7-9, each level is a light-emitting diode lamp strip, inlaid in the corresponding position of the waveform display area of the display control panel 2, and connected with the corresponding pin of the PLC chip on the back thereof, for displaying different levels of step waves at different times.

[0050] The function control area includes a sequential demonstration button 8, a sub-module on-off button 9, a level demonstration button 10-1 and five level buttons. The five level buttons are respectively a 0 level button 10-2, a +U d / 2 level button 10-3, a -U d / 2 level button 10-4, a +U d level button 10-5, and a -U d level button 10-6. All the above buttons are respectively electrically connected with the controller.

[0051] Specifically, the sequential demonstration button 8 is installed on the upper part of the function control area of the display control panel 2 and connected with the corresponding pin of the PLC chip on the back thereof, for starting the formation process of the demonstration step sine wave. The sequential demonstration button 8 corresponds to 9 time sequences, and each time sequence corresponds to the level of the corresponding time period displayed by the nine time period display areas. The sub-module on-off button 9 is installed in the middle part of the function control area of the display control panel 2 and connected with the corresponding pin of the PLC chip on the back thereof, for starting the sub-module on-off function. The level demonstration button 10-1 is installed on the lower part of the function control area of the display control panel 2 and connected with the corresponding pin of the PLC chip on the back thereof, for starting the level demonstration function. The five level buttons are installed on the lower part of the function control area of the display control panel 2 and connected with the corresponding pin of the PLC chip on the back thereof, for testing whether the students or trainees can select the appropriate sub-module on-off according to the given corresponding level waveform.

[0052] Among the above five level buttons, the 0 level button 10-2 is installed on the lower part of the function control area of the display control panel 2 and connected with the corresponding pin of the PLC chip on the back thereof, for testing whether the students or trainees can select the appropriate sub-module on-off according to the given 0 level waveform. The +U dThe +U level button 10-3 is installed at the lower part of the function control area of the display control panel 2 and is connected with the corresponding pin of the PLC chip at the back thereof, and is used for testing whether the students or trainees can select the appropriate sub-module according to the given +U d level waveform, and select the appropriate sub-module to be put in or taken out. d The -U level button 10-4 is installed at the lower part of the function control area of the display control panel 2 and is connected with the corresponding pin of the PLC chip at the back thereof, and is used for testing whether the students or trainees can select the appropriate sub-module according to the given -U d level waveform, and select the appropriate sub-module to be put in or taken out. d The +U level button 10-5 is installed at the lower part of the function control area of the display control panel 2 and is connected with the corresponding pin of the PLC chip at the back thereof, and is used for testing whether the students or trainees can select the appropriate sub-module according to the given +U d level waveform, and select the appropriate sub-module to be put in or taken out. d The -U level button 10-6 is installed at the lower part of the function control area of the display control panel 2 and is connected with the corresponding pin of the PLC chip at the back thereof, and is used for testing whether the students or trainees can select the appropriate sub-module according to the given -U d level waveform, and select the appropriate sub-module to be put in or taken out.

[0053] The function control area further comprises a power switch 11 and a power plug 12, which are installed at the bottom of the function control area of the display control panel 2 and are used for power supply. The power plug 12 can be connected with 220V AC power, and when the power switch 11 is pointed to the direction of 1, i.e. the power switch is turned on, the device is powered.

[0054] The device of the embodiment further comprises a voice broadcast device, which is selected from a voice speaker (not shown in the figure) and is electrically connected with the controller and is used for issuing voice prompts. When the students or trainees are tested according to the given level waveform to select the appropriate sub-module to be put in or taken out, according to the selection results of the students or trainees, the voice prompts of “correct” or “incorrect” are issued.

[0055] In addition, the embodiment further comprises a bottom plate 1-1, universal wheels 1-2, lifting rods 1-3 and a display and control area frame 1-4.

[0056] The bottom plate 1-1 is a 10mm thick steel plate material, and a universal wheel 1-2 is arranged below the bottom plate 1-1 to facilitate moving the demonstration device as required; the lifting rod 1-3 is fixedly installed above the bottom plate 1-1 and is made of a 10mm thick steel plate material; the display and control area frame 1-4 is installed above the lifting rod 1-3 and is made of a 10mm thick steel plate material; the display control panel 2 is installed inside the display and control area frame 1-4, and the front of the display control panel 2 is printed with the words “topology circuit diagram”, “waveform display area” and “function control area”; meanwhile, the “topology circuit diagram” part is drawn with a modular multilevel converter diagram composed of eight sub-modules, and the “waveform display area” part is drawn with a stepped sinusoidal wave with nine time periods and five levels; the back of the display control panel 2 is provided with a controller, i.e., a PLC chip, for program logic control to execute a sub-module on-off program, a waveform display program and a level demonstration program.

[0057] Embodiment Two

[0058] The embodiment provides a demonstration method of a modular multilevel converter demonstration device, which is demonstrated by using the modular multilevel converter demonstration device in the embodiment one, and the method comprises the following steps:

[0059] When the sub-module on-off button is started, the controller executes the sub-module on-off program, and the state of each sub-module is changed according to the change of the on-off switch state corresponding to the sub-module. In the embodiment, each upper bridge arm sub-module and lower bridge arm sub-module is an LED display screen, which displays a capacitor icon or a short circuit icon according to the on-off state of the on-off switch.

[0060] Specifically, when the sub-module on-off button 9 is started, the sub-module on-off program in the PLC chip at the back of the display control panel 2 is executed. At this time, the on-off switch 4-1 of the upper bridge arm sub-module SM1, the on-off switch 4-2 of the upper bridge arm sub-module SM2, the on-off switch 4-3 of the upper bridge arm sub-module SM3, the on-off switch 4-4 of the upper bridge arm sub-module SM4, the on-off switch 6-1 of the lower bridge arm sub-module SM1, the on-off switch 6-2 of the lower bridge arm sub-module SM2, the on-off switch 6-3 of the lower bridge arm sub-module SM3 and the on-off switch 6-4 of the lower bridge arm sub-module SM4 can work. When the on-off switch is pressed to the 1 direction, it indicates that the sub-module is turned on, at this time, since the sub-module is an LED display screen, the LED display screen display pattern becomes the capacitor icon shown in the drawing, and the U / 2 is marked beside the capacitor icon, and the red highlight is displayed; when the on-off switch is pressed to the 0 direction, the sub-module is turned off, and the sub-module LED display screen display pattern becomes the short circuit icon shown in the drawing, and the 0 is marked beside the short circuit icon, and the red highlight is displayed. Figure 3 d Figure 4

[0061] ​​​It also includes: when the sequential display button is activated, the controller executes the sequential display waveform program, controls the state of each sub-module in the topology circuit selection area according to the timing corresponding to the sequential display button, and displays the level of the corresponding time period in the waveform display area.

[0062] When the pointer of the sequential display button 8 points to 1, the PLC chip program on the back of the display control panel 2 controls the display to change the graphics of the upper bridge arm submodules SM3 3-3, SM4 3-4, SM1 5-1, and SM2 5-2 into... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of the upper bridge arm submodules SM13-1, SM2 3-2, SM3 5-3, and SM4 5-4 are transformed into... Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the output level 0 (7-1) corresponding to time period t1 in the waveform display area is highlighted in green.

[0063] When the pointer of the sequential display button 8 points to 2, the PLC chip program on the back of the display control panel 2 controls the display to change the graphics of the upper bridge arm submodule SM4 3-4, lower bridge arm submodules SM1 5-1, SM2 5-2, and SM3 5-3 into... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of the upper bridge arm submodules SM13-1, SM2 3-2, SM3 3-3, and lower bridge arm module SM4 5-4 are changed to Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the output U corresponding to time period t2 in the waveform display area... d / 2 level 7-2 green highlight display.

[0064] When the pointer of the sequential display button 8 points to 3, the PLC chip program on the back of the display control panel 2 controls the display to change the graphics of the lower bridge arm submodules SM1 5-1, SM2 5-2, SM3 5-3, and SM4 5-4 into... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of upper bridge arm submodules SM13-1, SM2 3-2, SM3 3-3, and SM4 3-4 are transformed into... Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the output U corresponds to the time period t3 in the waveform display area. dLevel 7-3 is highlighted in green.

[0065] When the pointer of the sequential display button 8 points to 4, the PLC chip program on the back of the display control panel 2 controls the display to change the graphics of the upper bridge arm submodule SM4 3-4, lower bridge arm submodules SM1 5-1, SM2 5-2, and SM3 5-3 into... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of the upper bridge arm submodules SM13-1, SM2 3-2, SM3 3-3, and lower bridge arm module SM4 5-4 are transformed into... Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the output U corresponding to the time interval t4 in the waveform display area... d / 2 level 7-4 green highlight display.

[0066] When the pointer of the sequential display button 8 points to 5, the PLC chip program on the back of the display control panel 2 controls the display to change the graphics of the upper bridge arm submodules SM3 3-3, SM4 3-4, SM1 5-1, and SM2 5-2 into... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of the upper bridge arm submodules SM13-1, SM2 3-2, SM3 5-3, and SM4 5-4 are transformed into... Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the output level 0 (7-5) corresponding to the time interval t5 in the waveform display area is highlighted in green.

[0067] When the pointer of the sequential display button 8 points to 6, the PLC chip program on the back of the display control panel 2 controls the display to change the graphics of the upper bridge arm submodules SM2 3-2, SM3 3-3, SM4 3-4, and the lower bridge arm submodule SM15-1 to... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of the upper bridge arm submodule SM13-1, lower bridge arm submodule SM2 5-2, lower bridge arm module SM3 5-3, and lower bridge arm module SM4 5-4 are transformed into Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the waveform display area shows the output -U corresponding to time period t6. d / 2 level 7-6 green highlight display.

[0068] When the sequential display button pointer points to 7, the PLC chip program on the back of control panel 2 controls the display to change the graphics of upper bridge arm submodules SM1 3-1, SM2 3-2, SM3 3-3, and SM4 3-4 into... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of the lower bridge arm submodules SM1 5-1, SM2 5-2, SM3 5-3, and SM4 5-4 are transformed into Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the waveform display area shows the output -U corresponding to time period t7. d Level 7-7 is highlighted in green.

[0069] When the pointer of the sequential display button 8 points to 8, the PLC chip program on the back of the display control panel 2 controls the display to change the graphics of the upper bridge arm submodules SM2 3-2, SM3 3-3, SM4 3-4, and the lower bridge arm submodule SM15-1 to... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of the upper bridge arm submodule SM13-1, lower bridge arm submodule SM2 5-2, lower bridge arm module SM3 5-3, and lower bridge arm module SM4 5-4 are transformed into Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the output corresponding to the t8 time period in the waveform display area is -U. d / 2 level 7-8 green highlight display.

[0070] When the pointer of the sequential display button 8 points to 9, the PLC chip program on the back of the display control panel 2 controls the display to change the graphics of the upper bridge arm submodules SM3 3-3, SM4 3-4, SM1 5-1, and SM2 5-2 into... Figure 3 The capacitor icon shown is labeled U. d / 2, and highlighted in red; the graphics of the upper bridge arm submodules SM13-1, SM2 3-2, SM3 5-3, and SM4 5-4 are transformed into... Figure 4 The short-circuit icon shown is marked with 0 and highlighted in red. Simultaneously, the output level 0 during the t9 time period in the waveform display area is highlighted in green.

[0071] Further comprising: when the level demonstration button is started, the five level buttons are in a standby state, and when any level button is started again, the controller executes a corresponding level demonstration program according to the started level button, controls the wave display area to display a corresponding level according to the started level button, and judges whether the sub-modules selected by the tester according to the displayed level wave are correct according to a judgment rule.

[0072] The judgment rule is that different levels correspond to starting different upper bridge arm sub-modules and lower bridge arm sub-modules, specifically, 0 level corresponds to starting any 2 upper bridge arm sub-modules and any 2 lower bridge arm sub-modules; +U d / 2 level corresponds to starting any 1 upper bridge arm sub-module and any 3 lower bridge arm sub-modules; -U d / 2 level corresponds to starting any 3 upper bridge arm sub-modules and any 1 lower bridge arm sub-module; +U d level corresponds to starting 4 lower bridge arm sub-modules; -U d level corresponds to starting 4 upper bridge arm sub-modules.

[0073] In the embodiment, when the level demonstration button 10-1 is started, the level demonstration program in the PLC chip on the back of the control panel 2 is executed. At this time, the 0 level button 10-2, the +U d / 2 level button 10-3, the -U d / 2 level button 10-4, the +U d level button 10-5, and the -U d level button 10-6 can work. At the same time, the on-off switch 4-1 of the upper bridge arm sub-module SM1, the on-off switch 4-2 of the upper bridge arm sub-module SM2, the on-off switch 4-3 of the upper bridge arm sub-module SM3, the on-off switch 4-4 of the upper bridge arm sub-module SM4, the on-off switch 6-1 of the lower bridge arm sub-module SM1, the on-off switch 6-2 of the lower bridge arm sub-module SM2, the on-off switch 6-3 of the lower bridge arm sub-module SM3, and the on-off switch 6-4 of the lower bridge arm sub-module SM4 work.

[0074] When the 0 level button 10-2 is started, the PLC chip program on the back of the control panel 2 is controlled to display, the wave display area t1 time period corresponds to the output 0 level 7-1, the t5 time period corresponds to the output 0 level 7-5, and the t9 time period corresponds to the output 0 level 7-9, and the yellow color flashes. At this time, if the on-off switches beside any 2 sub-modules in the upper bridge arm are pressed to the 1 direction, the on-off switches beside the other 2 sub-modules are pressed to the 0 direction, and the on-off switches beside any 2 sub-modules in the lower bridge arm are pressed to the 1 direction, the on-off switches beside the other 2 sub-modules are pressed to the 0 direction, the voice prompts: correct, and the voice prompts: error in other cases.

[0075] When the +U dWhen the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area

[0076] When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area

[0077] When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area

[0078] When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area d When the -U level button 10-2 is pressed, the PLC chip program control on the back of the display control panel 2 displays the -U output corresponding to the t2 time period in the waveform display area

[0079] Through the demonstration method of the modular multilevel converter demonstration device, the modular multilevel converter theory is visually and intuitively demonstrated, so that students or trainees can easily master the complex and abstract basic working principle of the modular multilevel converter. Specifically, through the sequential demonstration function, the formation process of the stepped sine wave can be vividly and clearly demonstrated, which is convenient for students or trainees to understand and master; through the sub-module on-off function, the equivalent circuit of the sub-module and the corresponding output level can be clearly and clearly described; through the level demonstration function, it can be tested whether the students or trainees have mastered the basic principle of the modular multilevel converter, which is conducive to the teaching of the modular multilevel converter.

[0080] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0081] Although the specific embodiments of the present application are described above in combination with the drawings, it is not intended to limit the protection scope of the present application. Those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

[0082] Although the specific embodiments of the present application are described above in combination with the drawings, it is not intended to limit the protection scope of the present application. Those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A modular multilevel converter demonstration device, characterized by The display control panel is divided into a function control area, a waveform display area and a topology circuit selection area; The topology circuit selection area includes four upper bridge arm sub-modules, four lower bridge arm sub-modules and a switching-on and switching-off switch corresponding to each sub-module, the switching-on and switching-off switch is electrically connected with the controller and is used for controlling the switching-on and switching-off of the corresponding sub-module; each upper bridge arm sub-module and each lower bridge arm sub-module is an LED display screen and is inlaid in the topology circuit selection area of the display control panel in sequence and is electrically connected with the controller respectively; The waveform display area displays a stepped sine wave including nine time periods and five levels, each time period corresponds to a level, and each level is electrically connected with the controller respectively; The function control area includes a sequential demonstration button, a sub-module switching-on and switching-off button, a level demonstration button and five level buttons, each button is electrically connected with the controller respectively; The controller is used for executing a sub-module switching-on and switching-off program, a waveform display program and a level demonstration program according to the buttons of the function control area.

2. The modular multilevel converter demonstration device of claim 1, characterized in that The LED display screen displays a capacitor icon or a short-circuit icon according to the state of the switching-on and switching-off switch, and the level type is marked beside the icon.

3. The modular multilevel converter demonstration device of claim 1, wherein the plurality of submodules are arranged in a plurality of strings, each string comprising a plurality of submodules connected in series. Each level corresponding to each time period in the waveform display area is a light-emitting diode lamp strip and is inlaid in the waveform display area of the display control panel and is used for displaying the stepped wave of different levels at different times.

4. The modular multilevel converter demonstration device of claim 1, wherein the plurality of submodules are arranged in a plurality of strings, each string comprising a plurality of submodules connected in series. The sequential demonstration button is used for starting the formation process of the stepped sine wave, and the sequential demonstration button corresponds to 9 time sequences, and each time sequence corresponds to the level of the corresponding time period in the waveform display area.

5. The modular multilevel converter demonstration device of claim 1, wherein the plurality of submodules are arranged in a plurality of strings, each string comprising a plurality of submodules connected in series. The level demonstration button is used to start the level demonstration function; the five level buttons are respectively 0 level button, + U d / 2 level button, - U d / 2 level button, + U d level button and - U d level button, which are used to test whether the students or trainees can select the appropriate sub-modules according to the given corresponding level waveforms.

6. The modular multilevel converter demonstration device of claim 1, wherein the plurality of submodules are arranged in a plurality of strings, each string comprising a plurality of submodules connected in series. The sub-module switching-on and switching-off button is used for starting the sub-module switching-on and switching-off function.

7. A demonstration method of a modular multilevel converter demonstration device, characterized by, The modular multilevel converter demonstration device is used for demonstration, including: When the sequential display button is started, the controller executes a sequential display waveform program, controls the state of each sub-module in the topology circuit selection area according to the time sequence corresponding to the sequential display button and displays the level of the corresponding time period in the waveform display area.

8. The demonstration method of the modular multilevel converter demonstration apparatus according to claim 7, characterized by, Further including: When the level demonstration button is started, the five level buttons are in a standby state, and when any level button is started again, the controller executes a corresponding level demonstration program according to the started level button, controls the waveform display area to display the corresponding level according to the started level button and judges whether the sub-module selected by the tester according to the displayed level waveform is correct according to a judgment rule. The judgment rule is that different levels correspond to starting different upper bridge arm and lower bridge arm sub-modules, and specifically includes: 0 level corresponds to starting any 2 upper bridge arm sub-modules and any 2 lower bridge arm sub-modules; U d / 2 level corresponds to starting any 1 upper bridge arm sub-module and any 3 lower bridge arm sub-modules; U d / 2 level corresponds to starting any 3 upper bridge arm sub-modules and any 1 lower bridge arm sub-module; U d level corresponds to starting 4 lower bridge arm sub-modules; U d level corresponds to starting 4 upper bridge arm sub-modules.

9. The demonstration method of the modular multilevel converter demonstration apparatus according to claim 7, further comprising Including: When the sub-module switching-on and switching-off button is started, the controller executes a sub-module switching-on and switching-off program, and the state of each sub-module is changed according to the change of the state of the switching-on and switching-off switch corresponding to the sub-module.

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