CN111665411A - Modular multifunctional MMC topology universal experimental platform and method thereof - Google Patents

Abstract

The invention discloses a modular multifunctional MMC topology universal experimental platform and a method thereof, belonging to the technical field of power electronics. The experimental platform is composed of modular hardware. Wherein the bridge arm module can be converted into a shaping circuit and a conducting switch circuit; the power supply module comprises an auxiliary power module and an AC-DC side power supply port, can be connected with AC and DC sources, and can also be used for interconnecting a plurality of universal experiment platforms, so that the requirement of a multi-terminal cooperative control experiment is met; the control module comprises a master controller and a slave controller. The platform can meet various topological experiments such as MMC, HMMC, AAMC, HCMC, modular multilevel DC-DC converters and the like, and the aim of developing various topological experiments by utilizing one platform is fulfilled. The modular multifunctional MMC topology universal experimental platform provided by the invention has the advantages of simple operation, multiple functions, strong universality, strong expansibility, high safety and the like, and is beneficial to accelerating the conversion of scientific research achievements.

Description

Modular multifunctional MMC topology universal experimental platform and method thereof

Technical Field

The invention belongs to the technical field of power electronics, and particularly relates to a modular multifunctional MMC topology universal experimental platform and a method thereof.

Background

High Voltage Direct Current (HVDC) has the advantages of high transmission efficiency, large capacity, variable tidal current flow direction, easy incorporation of distributed power supplies, less large-scale energy storage equipment and the like, and gradually becomes a preferred scheme for long-distance, trans-regional and large-capacity power transmission. Modular Multilevel Converters (MMC) gradually become one of the most promising converters in HVDC systems due to their high degree of modularity, good quality of output waveforms, low switching frequency of devices, and the like. Because the full-bridge MMC has high cost, and the half-bridge MMC has no direct-current fault ride-through capability, on one hand, in order to have certain direct-current fault ride-through capability, an HMMC topology is provided; on the other hand, in order to save cost, the structural characteristics of the traditional two-level converter and the MMC are combined, and the HCMC and AAMC hybrid converter is provided. However, due to the problems of large direct-current side harmonic content, difficult capacitance-voltage balance and the like of the HMMC, the HCMC and the AAMC, only a small amount of MMC is put into use in HVDC engineering at present. With the deep research on a high-voltage direct-current power transmission system, a novel high-voltage direct-current power distribution system is gradually valued, and as the MMC has the advantages of high voltage level, modular design, multi-level output and the like, a scholars puts forward the topology of the modular multi-level DC-DC converter, and the field gradually becomes a large research hotspot of the high-voltage direct-current power distribution system in recent years.

In order to further deeply research the characteristics, advantages and disadvantages and applicable conditions of the MMC type topology and promote the application of the MMC type topology in practical engineering, a principle verification prototype is expected to be built, a simulation result is verified, and the experimental results of different MMC type topologies under the same conditions are compared. However, the establishment of the principle verification prototype has a plurality of difficulties: the current converter has a huge structure, a large number of modules and difficult circuit design, so that the hardware design difficulty is high; the software design difficulty is high due to the complex control structure, various signal types and huge data total amount. The difficulty makes the principle verification prototype difficult to set up and long in period. At present, some existing principle verification prototypes have the defects of single structure function, poor expansibility and insufficient flexibility, and only one kind of topological experiment can be carried out by one kind of experiment platform. Therefore, how to build a universal experiment platform for multi-functional MMC topologies, the multi-MMC topologies can be developed on the universal experiment platform for relevant verification experiments, the conversion of scientific research achievements is accelerated, and the problem which is not solved in the field of HVDC engineering is solved.

Disclosure of Invention

In view of the above, the invention provides a modular multifunctional MMC topology universal experimental platform and a method thereof by combining the common characteristics of MMC topologies and utilizing the thought of modular design, the universal experimental platform can carry out experiments related to MMC, HMMC, AAMC, HCMC and a modular multilevel DC-DC converter, a plurality of universal experimental platforms can also realize multi-port cooperative control experiments, the switching between topologies is convenient and fast, and the expansibility is strong.

In order to achieve the purpose, the invention adopts the following technical scheme:

a modular multifunctional MMC topology universal experimental platform comprises a cabinet and modular hardware installed in the cabinet, wherein the modular hardware comprises a bridge arm module, a sampling module, a power supply module, a control module, an inductance module, an isolation transformer and a protection module;

the bridge arm modules comprise an upper bridge arm module and a lower bridge arm module, and the input end of each phase of the upper bridge arm module is connected with the positive pole of the direct current side power port of the power module after being sampled by the current converter level current of the sampling module and protected by the direct current side of the protection module; the input end of the lower bridge arm module is connected with the negative electrode of the direct-current side power port of the power module; the output ends of the upper bridge arm module and the lower bridge arm module are sampled by a current converter stage of the sampling module and then are connected with the input end of the inductance module; the two output ends of each phase in the inductance module are connected, and are connected with the input end of the isolation transformer after being subjected to current converter level sampling of the sampling module and alternating current side protection of the protection module; the output end of the isolation transformer is connected with an alternating current side power supply port of the power supply module;

the sampling module is provided with a plurality of voltage detection ports and current detection ports, the voltage detection ports are arranged on an upper bridge arm module, a lower bridge arm module, an input end and an output end of an isolation transformer and a direct current side power supply port of a power supply module in parallel, and the current detection ports are arranged on a bridge arm side, an alternating current side and a direct current side of the converter; the working states of the bridge arm module, the sampling module, the power supply module, the inductance module, the isolation transformer and the protection module are all controlled by the control module.

Preferably, the control module comprises a master controller and slave controllers, the master controller is provided with a plurality of optical fiber communication interfaces and communicates with the slave controllers through optical fibers; the slave controller is integrated with a high performance DSP.

Preferably, a bridge arm module state display screen and a voltage and current display screen are arranged in the cabinet, the bridge arm module state display screen is connected with the main controller through a network cable, and the bridge arm module states capable of being displayed comprise a normal state, an operating state, an overvoltage state, an overcurrent state, an overtemperature state and a communication error; and the voltage and current display screen is connected with the power supply module and the sampling module.

Preferably, the sampling module is divided into converter-level sampling and full-bridge sub-module sampling, and the converter-level sampling comprises converter-level voltage and current sampling. The converter-level sampling is an independent unit with complete functions and is composed of a sampling plate and a slave controller. The full-bridge submodule sampling is composed of a miniaturized sampling plate and a slave controller, and can acquire capacitor voltage of the full-bridge submodule and current flowing through the full-bridge submodule.

Preferably, the protection module comprises a direct current side protection, an alternating current side protection and a full bridge sub-module protection, and the direct current side protection and the alternating current side protection comprise an air switch and a controllable circuit breaker which are connected in series.

Preferably, the bridge arm module is formed by connecting a plurality of full-bridge submodules in series, and each full-bridge submodule is an independent unit formed by sampling of the full-bridge submodule of the sampling module, and protection of the full-bridge submodule of the slave controller, the power board and the protection module.

Preferably, the full-bridge submodule in the bridge arm module can be converted into a conducting switch circuit and a shaping circuit formed by a full-bridge structure or a half-bridge structure after being controlled by the control module.

Preferably, the power supply module includes an auxiliary power module, an ac side power supply port, and a dc side power supply port.

Preferably, the inductance module is composed of 6 sets of inductance modules with adjustable inductance values.

Another objective of the present invention is to provide an experimental method for the above modular multifunctional MMC-like topology universal experimental platform, which includes the following steps:

step 1: determining the topology type and the number of full-bridge submodules required by a shaping circuit and a conducting switch circuit according to the experiment requirement, and controlling redundant full-bridge submodules to be in a cutting state if the required number is less than the number provided by a general experiment platform; if the quantity is equal to the quantity provided by the general experiment platform, the adjustment is not needed; if the number of the sub-modules is larger than that provided by the universal experiment platform, a plurality of additional full-bridge sub-modules are added in series;

step 2: the method is characterized in that a modular program is integrated in a control module of the test platform, the modular program comprises an MMC, an HMMC, an AAMC, an HCMH and a control and debugging program of a modular multilevel DC-DC converter, and a corresponding connection mode and a control and modulation program are selected according to a topology type:

scheme 1: MMC experiment

Selecting an MMC control and debugging program, controlling all the full-bridge sub-modules into shaping circuits, and operating in a full-bridge structure or a half-bridge structure state;

scheme 2: HMMC experiments

Selecting an HMMC control and debugging program, controlling all the full-bridge sub-modules into shaping circuits, and controlling the full-bridge sub-modules to be in a full-bridge structure state or a half-bridge structure state according to the number of the required full-bridge structures and half-bridge structures;

scheme 3: AAMC experiments

Selecting an AAMC control and debugging program, and controlling the full-bridge submodule to be in a state of conducting a switch circuit, a full-bridge structure or a half-bridge structure according to the AAMC topology;

scheme 4: HCMC assay

Selecting an HCMC control and debugging program, connecting the conduction switch circuits in series, connecting the shaping circuits in series, connecting the conduction switch circuits of the upper bridge arm module and the lower bridge arm module with the input port of the shaping circuit in common, and connecting the output port of the shaping circuit with the input port of the inductance module; then controlling the full-bridge submodule to be in a state of conducting the switch circuit or the full-bridge structure according to the number of the switch circuits and the full-bridge structures to be conducted;

scheme 5: modular multilevel DC-DC converter experiment

Selecting a control and debugging program of the modular multilevel DC-DC converter, selecting only one pair of upper and lower bridge arm modules for the modular multilevel DC-DC converter with single-ended output by a main circuit, wherein an output resonance circuit consists of an inductance module and another bridge arm module, and an output port of a bridge arm where the main circuit is located is connected with an output port of the other bridge arm module through the inductance module; the upper bridge arm module and the lower bridge arm module of the main circuit control the full-bridge sub-modules to be in a full-bridge structure state or a half-bridge structure state according to the number of required full-bridge structures or half-bridge structures, the bridge arm modules of the output resonant circuit are used as adjustable capacitors, the size of the whole capacitance value of the bridge arm modules is adjusted by controlling the switching number of the full-bridge sub-modules, and charging is not needed during operation;

and step 3: and starting the power module, executing corresponding control and debugging programs through the main controller, and acquiring and storing experimental data.

Based on the technical scheme, compared with the prior art, the invention has the following advantages:

(1) the multifunctional MMC topology universal experimental platform provided by the invention adopts the series-connected full-bridge sub-modules to form 6 bridge arms, is converted into a shaping circuit formed by a full-bridge structure or a half-bridge structure through control or into a conducting switch circuit, is matched with a modularly designed inductance module, can select a corresponding connection mode and a control and modulation algorithm according to different topology types, can meet relevant experiments of MMC topologies such as MMC, HMMC, AAMC, HCMC and a modular multilevel DC-DC converter, achieves the aim of modular universal design of multiple functions of one universal experimental platform, has the advantages of convenience and quickness in switching of different MMC topologies, high safety and reliability, strong flexibility and expansibility and the like, and is favorable for accelerating the conversion of scientific research results.

(2) The universal experiment platform provided by the invention is respectively reserved with ports on the AC side and the DC side, can be connected with AC and DC sources, can also be interconnected with various experiment platforms, and is convenient for developing multi-terminal cooperative control related experiments.

(3) This general experiment platform has adopted multistage protection, including direct current side protection, interchange side protection and full-bridge submodule piece protection, and each level protection contains hardware and software protection, has guaranteed the safe and reliable of experimentation.

(4) The sampling module adopted by the invention comprises converter-level sampling and full-bridge submodule sampling, so that the obtained experimental data is more comprehensive, and the required data can be selected according to the experimental requirements.

Drawings

FIG. 1 is a schematic diagram of a modular multi-functional MMC topology-like universal experimental platform according to the present invention;

FIG. 2 is a block diagram of a modular multi-functional MMC topology-like universal experimental platform according to the present invention;

FIG. 3 is a diagram of a full bridge configuration;

FIG. 4 is a diagram of a full bridge submodule;

FIG. 5 is a diagram of a converter level sampling architecture;

FIG. 6 is a diagram of the main controller structure;

fig. 7 is a structural view of an inductance module;

FIG. 8 is a schematic block diagram of an MMC principle;

FIG. 9 is a schematic block diagram of HMMC;

FIG. 10 is a schematic structural view of AAMC;

FIG. 11 is a schematic structural view of HCMC;

FIG. 12 is a schematic block diagram of a modular multilevel DC-DC converter;

FIG. 13 is a schematic diagram showing the connection of modules of the universal experimental platform during MMC, HMMC and AAMC experiments;

FIG. 14 is a schematic diagram showing the connection of modules in an HCMC experiment performed by the universal experiment platform;

fig. 15 is a schematic diagram of connection of modules when the general experiment platform performs a modularized multi-level DC-DC experiment.

Detailed Description

In order to more specifically describe the present invention, the following detailed description is provided for the technical solution of the present invention with reference to the accompanying drawings and the specific embodiments.

As shown in fig. 1-2, a modular multi-functional MMC topology universal experimental platform is composed of a cabinet and modular hardware installed in the cabinet. The voltage of the direct current side is adjustable at 800V, the effective value of the phase voltage of the alternating current side is adjustable at 220V, and the total power reaches 10 KVA.

The modularized hardware comprises a bridge arm module, a sampling module, a power supply module, a control module, an inductance module, an isolation transformer and a protection module, and can be expanded according to requirements.

The bridge arm modules are three groups which respectively represent A, B, C three phases, and each group of bridge arm modules comprises an upper bridge arm module and a lower bridge arm module which are 6 bridge arm modules in total. The input end of each phase upper bridge arm module is connected with the positive pole of a direct current side power port of a power module after being sampled by a converter level current of a sampling module and protected by a direct current side of a protection module, the input end of a lower bridge arm module is connected with the negative pole of the direct current side power port of the power module, the output ends of the upper bridge arm module and the lower bridge arm module are connected with the input end of an inductance module after being sampled by the converter level current of the sampling module, the two output ends of each phase of the inductance module are connected with each other, the output ends of the isolation transformer are connected with the input end of an isolation transformer after being sampled by the converter level current of the sampling module and protected by an alternating current side of the protection module, and the output end of the isolation transformer.

The sampling module is provided with a plurality of voltage and current detection ports, the voltage detection ports are connected in parallel with the upper bridge arm module, the lower bridge arm module, the input end and the output end of the isolation transformer and a direct current side power supply port of the power supply module.

A plurality of display screens are arranged in the cabinet. One part of the bridge arm module is connected with the main controller through a network cable and can display the states of the bridge arm module, including a normal state, an operation state, an overvoltage state, an overcurrent state, an overtemperature state and a communication error; the other part is connected with the power module and the sampling module and can display the voltage and the current of each node of the current converter. The display screen can help experimenters to quickly and accurately know various data and state information, conveniently and accurately locate fault points when faults occur, and quickly determine fault reasons.

In a specific implementation of the present invention, as shown in fig. 2, each bridge arm is provided with 6 full-bridge submodules, the total number of which is 36, which can be expanded; the full-control power device used by the full-bridge submodule is an IGBT. The full-bridge submodule structure is shown in fig. 4, and is formed by full-bridge submodule sampling of a sampling module, full-bridge submodule protection of a slave controller, a power board and a protection module, and the IGBT module is cooled by a cooling fan. The front side of the intelligent power supply is provided with a status indicator lamp which can display fault types and running status information, and the back side of the intelligent power supply comprises a power interface and an optical fiber interface. In one specific implementation of the invention, the full-bridge sub-modules are installed in a drawer-type case structure, and one drawer-type case comprises 3 sub-modules, namely A, B, C three phases, so that the expansion is convenient.

The full-bridge submodule can be converted into a shaping circuit formed by the full-bridge submodule or the half-bridge submodule through control, and can also be converted into a conducting switch circuit through control. As shown in fig. 3, when T1 and T4, and T2 and T3 are complementarily turned on alternately, the sub-modules are converted into a shaping circuit composed of full-bridge sub-modules; when T3 is opened, T4 is closed, and T1 and T2 are conducted complementarily, the sub-modules are converted into a shaping circuit formed by half-bridge sub-modules; when T2 and T4 are turned off, and T1 and T3 are turned on and off simultaneously, or T1 and T3 are turned off, and T2 and T4 are turned on and off simultaneously, the sub-modules transition to turn on switch circuits.

The sampling module is divided into converter-level sampling and full-bridge sub-module sampling, and the structure of the converter-level sampling is shown in figure 5 and comprises converter-level voltage and current sampling. The converter-level sampling is an independent unit with complete functions, and is composed of a sampling plate and a slave controller, and can provide 14 paths of voltage signals and 7 paths of current signals for sampling, and the reverse side of the converter-level sampling comprises a power interface and an optical fiber interface. In one specific implementation of the invention, the sampling modules are installed by adopting drawer-type chassis, and one drawer-type chassis comprises 2 sampling modules, so that the expansion is convenient.

The power supply module comprises an auxiliary power module, an alternating current side power supply port and a direct current side power supply port. The alternating current side power supply port and the direct current side power supply port can be connected with independent alternating current and direct current sources, and can also be connected with a plurality of universal experiment platforms or other types of converters, so that multi-end cooperative control experiments can be conveniently carried out.

The control module comprises a master controller and a slave controller. The structure of the master controller is shown in fig. 6, and is PE-Expert4 of Myway corporation, integrates DSP, FPGA and a plurality of optical fiber communication interfaces, and communicates with each slave controller through optical fibers, so that the expansion is facilitated. From integrated high performance DSP and the optical fiber communication interface of controller, it is small-size and convenient.

Modularized software is integrated in the control module, the control module comprises basic control and debugging algorithms suitable for MMC, HMMC, AAMC, HCMH and a modularized multi-level DC-DC converter, and new control and modulation algorithms can be inserted into corresponding positions of corresponding algorithms of the modularized software according to scientific research needs. In the process of one-time power-on experiment, the universal experiment platform can be directly switched among a plurality of experiment modes through a software command.

The structure of the inductance module is shown in fig. 7, and the inductance module is composed of 6 groups of inductance sub-modules, which are AP, AN, BP, BN, CP and CN, each group is composed of 4 inductances with the same inductance value, 4 different inductance values are realized by different series connection modes, which are 3.2mH, 6.4mH, 9.6mH and 12.8mH, and when more inductance values or larger inductance values are needed, AN inductance coil can be replaced or the inductance module can be directly connected in series. In one specific implementation of the invention, the inductance module is designed in a drawer type, so that the expansion is convenient.

The protection module comprises direct current side protection, alternating current side protection and full-bridge submodule protection, and all the protection modules comprise hardware protection and software protection. The hardware parts of the direct current side protection and the alternating current side protection respectively comprise an air switch and a controllable circuit breaker which are connected in series, wherein one controllable circuit breaker is connected with one buffer resistor as shown in figure 1 and is mainly used when the full-bridge sub-module capacitor is charged, and the other controllable circuit breaker is connected with the buffer resistor and the controllable circuit breaker in parallel and is responsible for cutting off the buffer resistor when the charging is completed. The protection module realizes multi-stage protection in the experimental process.

Further, the modular multifunctional MMC topology universal experimental platform provided by the invention comprises the following experimental steps:

step 1: and determining the number of topology types, shaping circuits and conducting switch circuits according to experimental requirements. The shaping circuit and the conducting switch circuit are realized as follows:

for the shaping circuit, it can be operated in a full bridge configuration as shown in fig. 3 and a half bridge configuration. When the shaping circuit operates in a full-bridge structure, T1 and T4 are controlled to be conducted, T2 and T3 are controlled to be turned off, and then a positive level is output and is expressed as an input state; controlling T1 and T4 to be turned off, and controlling T2 and T3 to be turned on, so that a negative level is output and the state is expressed as an input state; and controlling the T1 and the T3 to be conducted, the T2 and the T4 to be turned off, or the T1 and the T3 to be turned off, and the T2 and the T4 to be conducted, a zero level is output, and the cutting-off state is represented. When the shaping circuit operates in a half-bridge structure, the T3 is controlled to be normally off, the T4 is normally closed, and the T1 and the T2 are alternately conducted to realize capacitor switching.

For the conducting switch circuit, the T1 and the T3 are controlled to be conducted, the T2 and the T4 are controlled to be turned off, or the T1 and the T3 are controlled to be turned off, and the T2 and the T4 are controlled to be conducted, so that the switching function of the full-bridge submodule can be realized.

And adjusting the number of the full-bridge sub-modules loaded for operation according to the number requirements of the shaping circuit and the conducting switch circuit. If the number of the full-bridge sub-modules required by the operation is less than that provided by the general experiment platform, controlling redundant full-bridge sub-modules to be in an excision state through modular software; if the number of the full-bridge sub-modules required by the operation is equal to that provided by the universal experiment platform, the modularized software does not need to be adjusted; if the number of the full-bridge submodules required by the operation is larger than that provided by the general experiment platform, a plurality of additional full-bridge submodules are added in series.

Step 2: and selecting a corresponding connection mode and a control and modulation algorithm according to the topology type. The method specifically comprises the following scheme:

scheme 1: MMC experiment

The schematic structure diagram of the MMC is shown in fig. 8, the MMC control and debugging algorithm is written in the corresponding position of the modular software according to the experimental requirements, and since the bridge arm modules of the MMC topology are formed by serially connecting shaping circuits formed by full-bridge sub-modules, a non-conducting switch circuit is implemented corresponding to the proposed general experimental platform, as shown in fig. 13. Taking one phase as an example, the 6 full-bridge submodules of the upper bridge arm and the lower bridge arm are mutually connected in series, the direct current side of the full-bridge submodules is connected to a direct current bus, and one ends of the upper bridge arm and the lower bridge arm, which are close to the alternating current side, are converged into an alternating current bus through a bus after passing through a current converter stage sampling module and an inductance module and enter an isolation transformer. At the moment, the full-bridge sub-modules are all controlled to be shaping circuits, and can all operate in a full-bridge or half-bridge structure state, so that experiments can be carried out.

Scheme 2: HMMC experiments

The schematic structure diagram of the HMMC is shown in fig. 9, and according to the experimental requirements, the HMMC control and debugging algorithm is written in the corresponding position of the modular software, since the bridge arm modules of the HMMC topology are formed by serially connecting shaping circuits, and a full-bridge structure and a half-bridge structure exist simultaneously, and there is no conducting switch circuit, the HMMC control and debugging algorithm is shown in fig. 13 corresponding to the proposed general experimental platform. Taking one of the phases as an example, on the connection of hardware, the HMMC is the same as the MMC; the difference lies in that, need be according to the quantity of required full-bridge and half-bridge structure, control full-bridge submodule is in full-bridge or half-bridge configuration state, can carry out the experiment.

Scheme 3: AAMC experiments

The schematic structure diagram of the AAMC is shown in fig. 10, and the AAMC control and debugging algorithm is written in the corresponding position of the modular software according to the experimental needs, because the bridge arm module of the AAMC topology is formed by connecting the shaping circuit and the conducting switch circuit in series, and the shaping circuit can be a full-bridge or half-bridge structure, which is shown in fig. 13 corresponding to the proposed general experimental platform. Taking one of the phases as an example, AAMC is the same as MMC and HMMC on the connection of hardware; the difference lies in, need be according to the quantity that the required switch circuit, full-bridge and half-bridge structure switched on, control full-bridge submodule piece and be in switch circuit, full-bridge or half-bridge configuration state, can experiment.

Scheme 4: HCMC assay

The schematic structure diagram of the HCMC is shown in fig. 11, and according to the experimental requirements, the HCMC control and debugging algorithm is written in the corresponding position of the modular software, and since the bridge arm module of the HCMC topology is composed of the shaping circuit and the conducting switch circuit, the shaping circuit is located on the ac output side and connected in series with each other, and the conducting switch circuit is located on the upper bridge arm and the lower bridge arm and connected in series with each other, the general experimental platform provided in correspondence is shown in fig. 14. Taking one of the phases as an example, on the connection of hardware, the connection mode of the full-bridge sub-module needs to be finely adjusted, that is: the full-bridge submodules used as the conducting switch circuits are kept in series, the full-bridge submodules used as the shaping circuits are also kept in series, the conducting switch circuits of the upper bridge arm and the lower bridge arm need to be connected and converged and are connected with the input port of the shaping circuit, the other end of the shaping circuit is used as the output end and is connected with the input end of the inductance module, and other connection modes are not changed. At this moment, the full-bridge submodule is controlled to be in a state of conducting the switch circuit or the full-bridge structure according to the number of the switch circuit and the full-bridge structure which are needed to be conducted, and then the experiment can be carried out.

Scheme 5: modular multilevel DC-DC converter experiment

The schematic structure diagram of the modular multilevel DC-DC converter is shown in fig. 12, and according to experimental requirements, a control and debugging algorithm of the modular multilevel DC-DC converter is written in a corresponding position of modular software, for the modular multilevel DC-DC converter with single-ended output, a main circuit only needs one upper bridge arm module and one lower bridge arm module, and an output resonance circuit can be composed of an inductance module and another bridge arm module. The general experimental platform proposed in correspondence is embodied as shown in fig. 15. And (3) connecting the output port of the bridge arm where the main circuit is located with the output port of the other bridge arm module through the inductance module in the hardware connection. In control, the upper bridge arm module and the lower bridge arm module of the main circuit control the full-bridge sub-modules to be in a full-bridge or half-bridge structure state according to the number of required full-bridge or half-bridge structures, the bridge arm modules of the output resonant circuit are used as adjustable capacitors, the size of the whole capacitance value of the bridge arm modules is adjusted by controlling the switching number of the full-bridge sub-modules, and charging is not needed during operation. The full-bridge sub-module IGBTs of the rest bridge arm modules are not applied with any signal and are in a disconnected state, and then the experiment can be carried out.

And step 3: and starting the power module, writing the corresponding modular software into the main controller, running the main controller, and detecting corresponding data.

In summary, the modular multifunctional MMC topology universal experiment platform provided by the invention utilizes modular hardware and matches with corresponding modular software, not only can satisfy various MMC topology experiments, but also can interconnect various experiment platforms through a reserved port on an AC/DC side, thereby achieving the purpose of multi-end cooperative control. The universal experimental platform has the advantages of small occupied area, convenience and quickness in switching among topologies, high safety and reliability, strong flexibility and expansibility and the like, and is favorable for accelerating the conversion of scientific research achievements.

The embodiments described above are presented to enable a person having ordinary skill in the art to make and use the invention. It will be readily apparent to those skilled in the art that various modifications to the above-described embodiments may be made, and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications to the present invention based on the disclosure of the present invention within the protection scope of the present invention.

Claims (10)

1. A modular multifunctional MMC topology universal experimental platform is characterized by comprising a cabinet and modular hardware installed in the cabinet, wherein the modular hardware comprises a bridge arm module, a sampling module, a power supply module, a control module, an inductance module, an isolation transformer and a protection module;

the bridge arm modules comprise an upper bridge arm module and a lower bridge arm module, and the input end of each phase of the upper bridge arm module is connected with the positive pole of the direct current side power port of the power module after being sampled by the current converter level current of the sampling module and protected by the direct current side of the protection module; the input end of the lower bridge arm module is connected with the negative electrode of the direct-current side power port of the power module; the output ends of the upper bridge arm module and the lower bridge arm module are sampled by a current converter stage of the sampling module and then are connected with the input end of the inductance module; the two output ends of each phase in the inductance module are connected, and are connected with the input end of the isolation transformer after being subjected to current converter level sampling of the sampling module and alternating current side protection of the protection module; the output end of the isolation transformer is connected with an alternating current side power supply port of the power supply module;

the sampling module is provided with a plurality of voltage detection ports and current detection ports, the voltage detection ports are arranged on an upper bridge arm module, a lower bridge arm module, an input end and an output end of an isolation transformer and a direct current side power supply port of a power supply module in parallel, and the current detection ports are arranged on a bridge arm side, an alternating current side and a direct current side of the converter; the working states of the bridge arm module, the sampling module, the power supply module, the inductance module, the isolation transformer and the protection module are all controlled by the control module.

2. The modular multifunctional MMC topology universal experimental platform of claim 1, wherein the control module comprises a master controller and slave controllers, the master controller is provided with a plurality of optical fiber communication interfaces for communicating with each slave controller through optical fibers; the slave controller is integrated with a high performance DSP.

3. The modular multifunctional MMC topology universal experimental platform of claim 2, wherein a bridge arm module status display screen and a voltage current display screen are arranged in the cabinet, the bridge arm module status display screen is connected with the main controller through a network cable, and the bridge arm module status that can be displayed comprises a normal status, an operating status, an overvoltage status, an overcurrent status, an overtemperature status and a communication error; and the voltage and current display screen is connected with the power supply module and the sampling module.

4. The modular multi-functional MMC class topology universal experimental platform of claim 1, wherein, the sampling module is divided into converter-level sampling and full-bridge sub-module sampling, and the converter-level sampling and the full-bridge sub-module sampling are composed of a sampling plate and a slave controller, and both comprise voltage sampling and current sampling.

5. The modular multi-functional MMC-like topology universal experimental platform of claim 1, wherein the protection module comprises dc-side protection, ac-side protection, and full-bridge sub-module protection, the dc-side protection and ac-side protection comprising series-connected air switches and controllable circuit breakers.

6. The modular multifunctional MMC topology universal experimental platform of claim 4 or 5, wherein the bridge arm module is composed of a plurality of full-bridge sub-modules connected in series, each full-bridge sub-module is an independent unit composed of a full-bridge sub-module sampling of the sampling module, a slave controller, a power board and a full-bridge sub-module protection of the protection module.

7. The modular multifunctional MMC topology universal experimental platform of claim 6, wherein a full-bridge sub-module in the bridge arm module is controlled by the control module and then can be converted into a conducting switch circuit and a shaping circuit formed by a full-bridge structure or a half-bridge structure.

8. The modular multi-functional MMC-like topology universal experimental platform of claim 1, wherein the power module comprises an auxiliary power module, an ac side power port, and a dc side power port.

9. The modular multi-functional MMC-like topology universal experimental platform of claim 1, wherein the inductance module is composed of 6 sets of inductance modules with adjustable inductance values.

10. An experimental method of the modular multi-functional MMC-like topological generic experimental platform of claim 7, characterized in that it comprises the following steps:

step 1: determining the topology type and the number of full-bridge submodules required by a shaping circuit and a conducting switch circuit according to the experiment requirement, and controlling redundant full-bridge submodules to be in a cutting state if the required number is less than the number provided by a general experiment platform; if the quantity is equal to the quantity provided by the general experiment platform, the adjustment is not needed; if the number of the sub-modules is larger than that provided by the universal experiment platform, a plurality of additional full-bridge sub-modules are added in series;

step 2: the method is characterized in that a modular program is integrated in a control module of the test platform, the modular program comprises an MMC, an HMMC, an AAMC, an HCMH and a control and debugging program of a modular multilevel DC-DC converter, and a corresponding connection mode and a control and modulation program are selected according to a topology type:

scheme 1: MMC experiment

Selecting an MMC control and debugging program, controlling all the full-bridge sub-modules into shaping circuits, and operating in a full-bridge structure or a half-bridge structure state;

scheme 2: HMMC experiments

Selecting an HMMC control and debugging program, controlling all the full-bridge sub-modules into shaping circuits, and controlling the full-bridge sub-modules to be in a full-bridge structure state or a half-bridge structure state according to the number of the required full-bridge structures and half-bridge structures;

scheme 3: AAMC experiments

Selecting an AAMC control and debugging program, and controlling the full-bridge submodule to be in a state of conducting a switch circuit, a full-bridge structure or a half-bridge structure according to the AAMC topology;

scheme 4: HCMC assay

Selecting an HCMC control and debugging program, connecting the conduction switch circuits in series, connecting the shaping circuits in series, connecting the conduction switch circuits of the upper bridge arm module and the lower bridge arm module with the input port of the shaping circuit in common, and connecting the output port of the shaping circuit with the input port of the inductance module; then controlling the full-bridge submodule to be in a state of conducting the switch circuit or the full-bridge structure according to the number of the switch circuits and the full-bridge structures to be conducted;

scheme 5: modular multilevel DC-DC converter experiment

Selecting a control and debugging program of the modular multilevel DC-DC converter, selecting only one pair of upper and lower bridge arm modules for the modular multilevel DC-DC converter with single-ended output by a main circuit, wherein an output resonance circuit consists of an inductance module and another bridge arm module, and an output port of a bridge arm where the main circuit is located is connected with an output port of the other bridge arm module through the inductance module; the upper bridge arm module and the lower bridge arm module of the main circuit control the full-bridge sub-modules to be in a full-bridge structure state or a half-bridge structure state according to the number of required full-bridge structures or half-bridge structures, the bridge arm modules of the output resonant circuit are used as adjustable capacitors, the size of the whole capacitance value of the bridge arm modules is adjusted by controlling the switching number of the full-bridge sub-modules, and charging is not needed during operation;

and step 3: and starting the power module, executing corresponding control and debugging programs through the main controller, and acquiring and storing experimental data.

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