WO2020065095A1 - Control system, control method, control device and sub-module of an mmc - Google Patents

Control system, control method, control device and sub-module of an mmc Download PDF

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Publication number
WO2020065095A1
WO2020065095A1 PCT/EP2019/076435 EP2019076435W WO2020065095A1 WO 2020065095 A1 WO2020065095 A1 WO 2020065095A1 EP 2019076435 W EP2019076435 W EP 2019076435W WO 2020065095 A1 WO2020065095 A1 WO 2020065095A1
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WIPO (PCT)
Prior art keywords
sub
module
modules
mmc
control
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PCT/EP2019/076435
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French (fr)
Inventor
Yan Feng Zhao
Ji Long Yao
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Siemens Aktiengesellschaft
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Publication of WO2020065095A1 publication Critical patent/WO2020065095A1/en

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage

Definitions

  • the present application relates to the field of MMCs, and in particular relates to a control system, control method, control device and sub-module of an MMC .
  • An MMC a new voltage conversion circuit, can output a high voltage by cascading a plurality of sub-modules, and in addition, an MCC outputs a small amount of harmonic waves and is highly modularized. Therefore, MMCs have wide application prospects in power systems.
  • common sub-module topologies include half-bridge sub-modules, full-bridge sub-modules and clamp double sub-modules. Among them, half-bridge sub-modules are the most popular in current projects. However, half-bridge sub-modules have no DC fault ride-through capability and need to rely on a DC breaker to cut off a fault current. Full-bridge sub-modules and clamp double sub-modules have the DC fault ride-through capability, but they have no large-scale project applications because of huge investments and running losses.
  • the embodiments of the present invention are intended to provide a control system, control method, control device and sub-module of an MMC .
  • a control system of an MMC is provided, wherein said MMC comprises N sub-modules and said control system comprises:
  • control module used to send a control instruction
  • concentrator connected with said N sub-modules respectively to receive said control instruction and send said control instruction to said N sub-modules
  • each sub-module of said N sub-modules is used to determine the sub-module set adapting to execute said control instruction, and execute said control instruction when said sub-module set it belongs to is determined, wherein N is a positive integer greater than or equal to 2.
  • said sub-module set comprises:
  • main control sub-module is used to send a synchronous clock signal to said one or more non-main control sub-modules via said concentrator after said sub-module set is determined but before said control instruction is executed, and said one or more non-main control sub-modules are used to keep synchronous with the clock of said main control sub-module based on said synchronous clock signal .
  • the embodiments of the present invention realize the clock synchronization in the sub-module set based on the information transmission function of the concentrator.
  • each sub-module of said N sub-modules contains its respective processing module
  • processing module is used to determine the sub-module set adapting to execute said control instruction and determine the main control sub-module and non-main control sub-modules in said sub-module set .
  • the sub-modules in the embodiments of the present invention contain processing modules which are capable of determining the sub-module set and determining the main control sub-module and non-main control sub-modules in the sub-module set, and intelligent sub-modules are realized.
  • each sub-module of said N sub-modules is further used to measure the voltage of its own capacitor and send the voltage to said concentrator,
  • said concentrator is further used to send respective voltages of said N sub-modules to each sub-module of said N sub-modules, and each sub-module of said N sub-modules is further used to control the working state of its own capacitor based on respective voltages of said N sub-modules.
  • sub-modules can mutually transmit their respective voltages based on the information transmission function of the concentrator .
  • a sub-module of an MMC comprises: a communication module, connected with the concentrator to receive a control instruction,
  • a processing module used to determine the sub-module set adapting to execute said control instruction and send said control instruction to an execution module when said sub-module is determined to belong to said sub-module set, and
  • said execution module used to execute said control instruction.
  • the sub-modules in the embodiments of the present invention are capable of determining a sub-module set and can execute a control instruction without any uniform central control unit, and intelligent sub-modules are realized.
  • the sub-module of an MMC further comprises: a storage module, used to store a first logic, said first logic adapting to determine the sub-module set,
  • processing module is used to invoke said first logic from said storage module and determine the sub-module set adapting to execute said control instruction based on said first logic.
  • the sub-modules in the embodiments of the present invention can conveniently determine the sub-module set based on the built-in first logic.
  • said storage module is further used to store a second logic and said second logic adapts to determine a main control sub-module and one or more non-main control sub-modules
  • said processing module is further used to invoke said second logic from said storage module and determine a main control sub-module and one or more non-main sub-modules in said sub-module set based on said second logic.
  • the sub-module in the embodiments of the present invention can conveniently determine the main control sub-module and non-main control sub-modules based on the built-in second logic.
  • the sub-module of an MMC further comprises: a protection module, used to detect the working state of said sub-module, and used to isolate said sub-module and send a fault alarm message to said concentrator via said communication module when said working state is abnormal.
  • the sub-module in the embodiments of the present invention further has the protection function, the sub-module can be isolated and a fault alarm will be sent out when the working state of the sub-module is abnormal.
  • the sub-module of an MMC further comprises: a capacitance alarm module, used to calculate the capacitance of said sub-module, and used to send a capacitance alarm message to said concentrator via said communication module when said capacitance is lower than a preset threshold.
  • the sub-module in the embodiments of the present invention has the capacitance alarm function and a fault alarm will be sent out when the capacitance is low.
  • the sub-module of an MMC further comprises: a check module, used to detect said protection module when said sub-module is in a standby state or maintenance state, and used to send a protection module alarm message to said concentrator via said communication module when the protection module is detected to be abnormal .
  • the sub-module in the embodiments of the present invention further has the check function for the protection module and a fault alarm will be sent out when the protection module is abnormal .
  • said sub-module comprises at least one of the following: half-bridge sub-module, full-bridge sub-module and clamp double sub-module .
  • An MMC comprises any of above-mentioned sub-modules.
  • a control method of an MMC comprises N sub-modules, wherein N is a positive integer greater than or equal to 2, and the method comprises:
  • each sub-module of said N sub-modules determines the sub-module set adapting to execute said control instruction and execute said control instruction when said sub-module set it belongs to is determined.
  • the method further comprises storing a first logic in each sub-module of said N sub-modules in advance, said first logic adapting to determine a sub-module set,
  • the sub-modules in the embodiments of the present invention can conveniently determine the sub-module set based on the built-in first logic.
  • the method further comprises storing a second logic in each sub-module of said N sub-modules in advance, said second logic adapting to determine a main control sub-module and one or more non-main control sub-modules, and
  • said method further comprises:
  • each sub-module in said sub-module set to invoke said second logic to determine a main control sub-module and one or more non-main control sub-modules in said sub-module set based on said second logic
  • the main control sub-module and non-main control sub-modules can conveniently be determined based on the built-in second logic in sub-modules, and in addition, clock synchronization is realized in the sub-module set based on the information transmission function of the concentrator.
  • the method further comprises:
  • sub-modules can mutually transmit their respective voltages based on the information transmission function of the concentrator .
  • a control device of an MMC comprises a processor and a memory, wherein applications, which can be executed by said processor to enable said processor to perform the above-mentioned control method of an MMC, are stored in said memory.
  • a computer readable storage medium is provided, computer readable instructions are stored in said computer readable storage medium and said computer readable instructions are used to execute the above-mentioned control method of an MMC.
  • Fig. 1 shows the structure of the control system of an MMC in the prior art .
  • Fig. 2 shows the structure of the control system of an MMC according to the embodiments of the present invention.
  • Fig. 3 shows clock synchronization in the sub-module set according to the embodiments of the present invention.
  • Fig. 4 shows the structure of the sub-module of an MMC according to the embodiments of the present invention.
  • Fig. 5 is a flowchart of the control method of an MMC according to the embodiments of the present invention.
  • Fig. 6 shows the structure of the control device of an MMC according to the embodiments of the present invention.
  • the term “comprise” refers to “including but not limited to” and the term “according to" refers to “at least according to..., but not limited to only according to" .
  • the number of a component hereinafter can be one or more or can be understood as at least one, unless otherwise specified.
  • Fig. 1 shows the structure of the control system of an MMC in the prior art .
  • the MMC 60 comprises a plurality of sub-modules, which are sub-module 11, sub-module 12,..., and sub-module IN, respectively, wherein N is a positive integer greater than or equal to 2. All sub-modules 11, 12, ..., IN of the MMC 60 are controlled by a uniform central control unit 20 in a centralized way.
  • the control module 40 sends a control instruction for controlling the MMC60.
  • the central control unit 20 is connected with the control module 40. After receiving the control instruction from the control module 40, the central control unit determines a specific sub-module used to execute the control instruction according to the allocation algorithm 21 built in the central control unit 20, and then orders the specific sub-module to execute the control instruction.
  • Fig. 2 shows the structure of the control system of an MMC according to the embodiments of the present invention.
  • the MMC 70 comprises a plurality of sub-modules, which are sub-module 31, sub-module 32, ..., and sub-module 3N, respectively, wherein N is a positive integer greater than or equal to 2.
  • the control system 100 comprises:
  • control module 80 which is used to send a control instruction
  • a concentrator 50 which is connected with the plurality of sub-modules 31, 32,..., 3N respectively to receive the control instruction and send the control instruction to each sub-module of the plurality of sub-modules,
  • control module 80 can be implemented as a remote control module and can send a control instruction for controlling the MMC 70 to the concentrator 50 via Bluetooth, infrared, cellular data network and wireless fidelity (WiFi) .
  • control module 80 can have a wired connection (preferably, optical fiber connection) with the concentrator 50 and can send a control instruction for controlling the MMC 70 to the concentrator 50 based on the wired connection.
  • wired connection preferably, optical fiber connection
  • the concentrator 50 has a wired connection (preferably, optical fiber connection) with a plurality of sub-modules 31, 32, ..., 3N respectively and can send the control instruction for controlling the MMC 70 to each sub-module of the plurality of sub-modules 31,
  • Each sub-module of the plurality of sub-modules 31, 32, ..., 3N contains its respective processing module 311, 321, ..., 3N1.
  • the sub-module 31 contains a processing module 311
  • the sub-module 32 contains a processing module 321, ...
  • the sub-module 3N contains a processing module 3N1.
  • the processing modules 311, 321, ..., 3N1 can respectively determine the sub-module set adapting to execute a control instruction.
  • the processing modules 311, 321, ..., 3N1 respectively contain the same sub-module allocation algorithm and the sub-module allocation algorithm is used to determine the sub-module set adapting to execute the control instruction. Therefore, the sub-module sets determined by the processing modules 311, 321, ..., 3N1 are all the same.
  • Each sub-module of the plurality of sub-modules 31, 21, ..., 3N executes the control instruction when determining that it belongs to the sub-module set . Wherein each sub-module in the sub-module set determines the workload it bears based on a uniform task allocation algorithm when executing the control instruction.
  • control module 80 sends out a control instruction A and the control instruction A is used to instruct the MMC 70 to generate a sine wave with a frequency of 50 Hz and a voltage of 10 KV.
  • the concentrator 50 sends by broadcast the control instruction A to all sub-modules 31, 32, ..., 3N. Then, each sub-module of the sub-modules 31, 32, ... 3N determines the sub-module set adapting to execute the control instruction A based on the same sub-module allocation algorithm.
  • the sub-module sets determined by the sub-modules 31, 32, ..., 3N are all the same.
  • Supposing the sub-module set contains sub-module 31, sub-module 32 and sub-module 35.
  • sub-modules except sub-module 31, sub-module 32 and sub-module 35 find that they do not belong to the sub-module set and will not participate in the execution of the control instruction A.
  • sub-module 31, sub-module 32 and sub-module 35 After determining their respective sub-module sets, sub-module 31, sub-module 32 and sub-module 35 find that they belong to the sub-module set and will jointly execute the control instruction A to generate a sine wave with a frequency of 50 Hz and a voltage of 10 KV. Wherein sub-module 31, sub-module 32 and sub-module 35 respectively determine the workloads they respectively bear based on a uniform task allocation algorithm (for example, the task allocation algorithm is also contained their respective processing modules) , and respectively work based on their respective workloads to jointly produce a sine wave with a frequency of 50 Hz and a voltage of 10 KV.
  • a uniform task allocation algorithm for example, the task allocation algorithm is also contained their respective processing modules
  • each sub-module can determine a sub-module set adapting to execute a control instruction, and will execute the control instruction when determining that it belongs to the sub-module set.
  • a technical solution for controlling sub-modules in a distributed way is realized .
  • the MMC can be controlled by providing the control function in each sub-module.
  • the security problem caused by the faulty central control unit can be overcome. For example, when a sub-module is faulty, other sub-modules can still normally determine the sub-module set and normally execute the control instruction.
  • each sub-module of N sub-modules 31, ..., 3N is further used to measure the voltage of its own capacitor and send the voltage to the concentrator 50, and the concentrator 50 is further used to send respective voltages of N sub-modules 31, ..., 3N to each sub-module of N sub-modules 31, ..., 3N (for example, as scheduled or periodically) .
  • Each sub-module of N sub-modules 31, ..., 3N is further used to control the working state of its own capacitor based on respective voltages of N sub-modules 31, ..., 3N.
  • a sub-module M calculates the average voltage of all sub-modules, and lets the capacitor of the sub-module M enter the charging state when the voltage of the sub-module M is determined to be less than the average voltage.
  • a sub-module K calculates the average voltage of all sub-modules, and lets the capacitor of the sub-module K enter the discharging state when the voltage of the sub-module K is determined to be greater than the average voltage. Examples of controlling the working state of capacitors are described above. Those skilled in the art can know that the description is only used for the exemplary purpose, but not used to limit the scope of protection of the embodiments of the present invention .
  • the embodiments of the present invention further realize a technical solution for keeping synchronized the clocks of the sub-modules in the sub-module set.
  • the sub-modules can jointly execute the control instruction in order.
  • the sub-module set comprises:
  • main control sub-module is used to send a synchronous clock signal to one or more non-main control sub-modules via the concentrator 50 after the sub-module set is determined but before the control instruction is executed, and one or more non-main control sub-modules are used to keep synchronous with the clock of the main control sub-module based on the synchronous clock signal.
  • Fig. 3 shows clock synchronization in the sub-module set according to the embodiments of the present invention.
  • the MMC 70 comprises a plurality of sub-modules, which are sub-module 31, sub-module 32, sub-module 33, ..., and sub-module 3N, respectively, wherein N is a positive integer greater than or equal to 4.
  • the sub-module 31 contains a processing module 311, the sub-module 32 contains a processing module 321, the sub-module 33 contains a processing module 331, ..., and the sub-module 3N contains a processing module 3N1.
  • the processing modules 311, 321, ..., 3N1 respectively contain the same sub-module allocation algorithm. Therefore, after the processing modules 311 , 321, ..., 3N1 respectively receive the control instruction from the concentrator 50, the sub-module sets determined are the same.
  • processing modules 311, 321, ..., 3N1 respectively contain the same main control sub-module determination algorithm.
  • the main control sub-module algorithm can be implemented as follows: the sub-module with the smallest sub-module number is determined to be the main control sub-module, or the sub-module whose current load is minimum is determined to be the main control sub-module, etc.
  • the sub-module set 55 determined by the processing modules 311, 321, ..., 3N1 based on the main control sub-module determination algorithm contains sub-module 31, sub-module 32 and sub-module 33, and the main control sub-module determined by the processing modules 311, 321, ..., 3N1 based on the main control sub-module determination algorithm is sub-module 32, then, in the sub-module set 55, the main control sub-module is sub-module 32, and the non-main control sub-modules are sub-module 31 and sub-module 33.
  • sub-module 31 as the main control sub-module sends a synchronous clock signal to sub-module 31 and sub-module 33 via the concentrator 50, as indicated by the dotted arrow.
  • Sub-module 31 and sub-module 33 keep synchronous with the clock of sub-module 31 based on the synchronous clock signal sent from sub-module 31.
  • the sub-modules can execute the control instruction.
  • the embodiments of the present invention further provide a sub-module of an MMC .
  • the sub-module in the embodiments of the present invention has the function of determining the sub-module set, and thus the uniform central control unit can be saved.
  • Fig. 4 shows the structure of the sub-module of an MMC according to the embodiments of the present invention.
  • the sub-module comprises:
  • a communication module 301 connected with the concentrator to receive a control instruction
  • a processing module 302 used to determine the sub-module set adapting to execute the control instruction and send the control instruction to an execution module 303 when the sub-module is determined to belong to the sub-module set, and
  • the execution module 303 used to execute the control instruction.
  • the sub-module of an MMC further comprises: a storage module 305, used to store a first logic, said first logic adapting to determine the sub-module set,
  • processing module 302 is used to invoke the first logic from the storage module 305 and determine the sub-module set adapting to execute the control instruction based on the first logic .
  • the storage module 305 can be implemented as a read-only memory (ROM) or random access memory (RAM) .
  • the first logic can specifically be implemented as a computer readable instruction generated based on the sub-module allocation algorithm.
  • the storage module 305 is further used to store a second logic and said second logic adapts to determine a main control sub-module and one or more non-main control sub-modules, wherein the processing module 302 is further used to invoke the second logic from the storage module 305 and determine a main control sub-module and one or more non-main sub-modules in the sub-module set based on the second logic.
  • the second logic can specifically be implemented as a computer readable instruction generated based on the main control sub-module determination algorithm.
  • the sub-module of an MMC further comprises: a protection module 306, used to detect the working state of the sub-module 300, and used to isolate the sub-module 300 and send a fault alarm message to the concentrator via the communication module 301 when the working state is abnormal.
  • a protection module 306 used to detect the working state of the sub-module 300, and used to isolate the sub-module 300 and send a fault alarm message to the concentrator via the communication module 301 when the working state is abnormal.
  • the protection module 306 can be implemented as a switch.
  • the switch is closed to disconnect the other part of the sub-module 300.
  • the communication module 301 sends a fault alarm message to the concentrator, the concentrator sends the fault alarm message to a man-machine interface, and the man-machine interface displays the fault alarm message, thus reminding the user that the sub-module 300 is faulty.
  • the sub-module in the embodiments of the present invention further has the protection function, the sub-module can be isolated and a fault alarm will be sent out when the working state of the sub-module is abnormal.
  • the sub-module of an MMC further comprises: a capacitance alarm module 304, used to calculate the capacitance of the sub-module 300, and used to send a capacitance alarm message to the concentrator via the communication module 301 when the capacitance is lower than a preset threshold.
  • the concentrator sends the capacitance alarm message to the man-machine interface and the man-machine interface displays the capacitance alarm message, thus reminding the user that the capacitance of the sub-module 300 is insufficient .
  • the sub-module of an MMC further comprises: a check module 307, used to detect said protection module 306 when the sub-module 300 is in a standby state or maintenance state, and used to send a protection module alarm message to the concentrator when the protection module 306 is detected to be abnormal.
  • the concentrator sends the protection module alarm message to the man-machine interface and the man-machine interface displays the protection module alarm message, thus reminding the user that the protection module 306 is abnormal.
  • the sub-module comprises at least one of the following: half-bridge sub-module, full-bridge sub-module and clamp double sub-module .
  • the sub-module in the embodiments of the present invention can control its running time and sequence during running. Once a fault occurs, it will also be protected quickly.
  • the sub-module in the embodiments of the present more powerful and can bring about a plurality of advantages.
  • the control system is simpler and the number of communication channels can be reduced, thus saving a large number of optical fibers .
  • the cost is reduced.
  • the fault rate of the system is lowered.
  • the periodical check function can prevent adverse effects caused by faults of key components .
  • the early warning of the service life of capacitors makes the system more reliable and safer.
  • Fig. 5 is a flowchart of the control method of an MMC according to the embodiments of the present invention.
  • the MMC comprises N sub-modules, wherein N is a positive integer greater than or equal to 2.
  • the method comprises:
  • Step 501 Enabling each sub-module of N sub-modules to receive a control instruction from the concentrator.
  • Step 502 Enabling each sub-module of N sub-modules to determine the sub-module set adapting to execute the control instruction and execute the control instruction when the sub-module set it belongs to is determined.
  • the method further comprises: storing a first logic in each sub-module of N sub-modules in advance, the first logic adapting to determine a sub-module set, wherein enabling each sub-module of N sub-modules to determine the sub-module set adapting to execute the control instruction in step 502 comprises: enabling each sub-module of N sub-modules to analyze the control instruction to determine the overall workload, and enabling each sub-module of N sub-modules to invoke the first logic to determine the sub-module set whose work capacity satisfies the overall workload based on the first logic.
  • the method further comprises storing a second logic in each sub-module of N sub-modules in advance, said second logic adapting to determine a main control sub-module and one or more non-main control sub-modules, and the method further comprises: enabling each sub-module in the sub-module set to invoke the second logic to determine a main control sub-module and one or more non-main control sub-modules in said sub-module set based on the second logic, enabling the main control sub-module to send a synchronous clock signal to the non-main control sub-modules before executing said control instruction, and enabling the non-main control sub-modules to keep synchronous with the clock of the main control sub-module based on the synchronous clock signal.
  • the method further comprises: enabling each sub-module of N sub-modules to measure the voltage of its own capacitor and send the voltage to the concentrator, enabling the concentrator to send respective voltages of N sub-modules to each sub-module of N sub-modules, and enabling each sub-module of N sub-modules to control the working state of its own capacitor based on respective voltages of N sub-modules.
  • the embodiments of the present invention further provide a control device of an MMC .
  • Fig. 6 shows the structure of the control device of an MMC according to the embodiments of the present invention.
  • the control device comprises a processor 601 and a memory 602, wherein applications, which can be executed by the processor 601 to enable the processor 601 to perform the above-mentioned control method of an MMC, are stored in the memory 602.
  • the embodiments of the present invention further provide a computer readable storage medium, wherein computer readable instructions are stored in the computer readable storage medium and the computer readable instructions are used to execute the above-mentioned control method of an MMC.
  • the partition of the modules is a functional partition for the convenience of description.
  • the function of a module can be realized by a plurality of modules, and the functions of a plurality of modules can be realized by one module and these modules can be located in the same equipment or can be located in different equipment.
  • a hardware module can comprise specially designed permanent circuits or logic devices (for example, application-specific processors such as FPGA or ASIC) to complete specific operations .
  • a hardware module can also comprise programmable logic devices or circuits (for example, general processors or other programmable processors) temporarily configured by software to perform specific operations. Whether a hardware module is realized mechanically, or by use of a dedicated permanent circuit or a temporarily configured circuit (for example, configured by software) can depend on the considerations of the cost and the time.
  • the present invention further provides a machine readable storage medium, in which instructions allowing a machine to execute the method described in this document are stored.
  • a system or device equipped with a storage medium can be provided.
  • Software program codes which can realize the function in any of above-mentioned embodiments are stored in the storage medium and the computer (or CPU or MPU) of the system or device can read and execute the program codes stored in the storage medium.
  • the operating system on the computer can complete a part of or all of practical operations.
  • the program code read out of a storage medium can be written into the memory in the expansion board in a computer or can be written into a memory in an expansion unit connected to the computer, and then the instructions based on the program code let the CPU installed on the expansion board or expansion unit execute a part or all of practical operations to realize the function in any of the above-mentioned embodiments.
  • Storage media used to provide program codes include floppy disk, hard disk, magneto-optical disk, compact disk (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW) , magnetic tape, non-volatile memory card, and read-only memory (ROM) .
  • the program codes can be downloaded from the server computer over a communication network.

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Abstract

The embodiments of the present invention disclose a control system, control method, control device and sub-module of a modular multilevel converter (MMC). The MMC comprises N sub-modules, and the control system comprises a control module,which is used to send a control instruction, and a concentrator, which is connected to N sub-modules respectively to receive said control instruction and send said control instruction to said N sub-modules, wherein each sub-module of N sub-modules is used to determine the sub-module set adapting to execute said control instruction and execute said control instruction when the sub-module set it belongs to is determined, wherein N is a positive integer greater than or equal to 2. The embodiments of the present invention realize a technical solution for controlling an MMC in a distributed way and the technical solution can overcome the security problem of centralized control.

Description

Description
Control System, Control Method, Control Device and Sub-module of an MMC
Technical Field
The present application relates to the field of MMCs, and in particular relates to a control system, control method, control device and sub-module of an MMC .
Background Art
An MMC, a new voltage conversion circuit, can output a high voltage by cascading a plurality of sub-modules, and in addition, an MCC outputs a small amount of harmonic waves and is highly modularized. Therefore, MMCs have wide application prospects in power systems. Currently common sub-module topologies include half-bridge sub-modules, full-bridge sub-modules and clamp double sub-modules. Among them, half-bridge sub-modules are the most popular in current projects. However, half-bridge sub-modules have no DC fault ride-through capability and need to rely on a DC breaker to cut off a fault current. Full-bridge sub-modules and clamp double sub-modules have the DC fault ride-through capability, but they have no large-scale project applications because of huge investments and running losses.
In the prior art, all sub-modules are controlled by a central control unit in a centralized way.
However, centralized control involve security problems. For example, when the central control unit is faulty, all sub-modules are unable to work. In addition, the control of the uniform central control unit over all sub-modules may also reduce the real-time performance of the MMC. Summary of the Invention
In view of this, the embodiments of the present invention are intended to provide a control system, control method, control device and sub-module of an MMC .
The technical solution of the embodiments of the present invention is realized in this way: a control system of an MMC is provided, wherein said MMC comprises N sub-modules and said control system comprises:
a control module, used to send a control instruction, and a concentrator, connected with said N sub-modules respectively to receive said control instruction and send said control instruction to said N sub-modules,
wherein each sub-module of said N sub-modules is used to determine the sub-module set adapting to execute said control instruction, and execute said control instruction when said sub-module set it belongs to is determined, wherein N is a positive integer greater than or equal to 2.
It can be seen that no uniform central control unit is provided, but the control function is provided in each sub-module in the embodiments of the present invention. A technical solution for controlling the MMC in a distributed way is realized and the technical solution can overcome the security problems of centralized control.
In one embodiment, said sub-module set comprises:
a main control sub-module, and
one or more non-main control sub-modules,
wherein said main control sub-module is used to send a synchronous clock signal to said one or more non-main control sub-modules via said concentrator after said sub-module set is determined but before said control instruction is executed, and said one or more non-main control sub-modules are used to keep synchronous with the clock of said main control sub-module based on said synchronous clock signal .
Therefore, the embodiments of the present invention realize the clock synchronization in the sub-module set based on the information transmission function of the concentrator.
In one embodiment, each sub-module of said N sub-modules contains its respective processing module,
wherein said processing module is used to determine the sub-module set adapting to execute said control instruction and determine the main control sub-module and non-main control sub-modules in said sub-module set .
It can be seen that the sub-modules in the embodiments of the present invention contain processing modules which are capable of determining the sub-module set and determining the main control sub-module and non-main control sub-modules in the sub-module set, and intelligent sub-modules are realized.
In one embodiment, each sub-module of said N sub-modules is further used to measure the voltage of its own capacitor and send the voltage to said concentrator,
said concentrator is further used to send respective voltages of said N sub-modules to each sub-module of said N sub-modules, and each sub-module of said N sub-modules is further used to control the working state of its own capacitor based on respective voltages of said N sub-modules.
Therefore, sub-modules can mutually transmit their respective voltages based on the information transmission function of the concentrator .
A sub-module of an MMC comprises: a communication module, connected with the concentrator to receive a control instruction,
a processing module, used to determine the sub-module set adapting to execute said control instruction and send said control instruction to an execution module when said sub-module is determined to belong to said sub-module set, and
said execution module, used to execute said control instruction.
Therefore, the sub-modules in the embodiments of the present invention are capable of determining a sub-module set and can execute a control instruction without any uniform central control unit, and intelligent sub-modules are realized.
In one embodiment, the sub-module of an MMC further comprises: a storage module, used to store a first logic, said first logic adapting to determine the sub-module set,
wherein said processing module is used to invoke said first logic from said storage module and determine the sub-module set adapting to execute said control instruction based on said first logic.
It can be seen that the sub-modules in the embodiments of the present invention can conveniently determine the sub-module set based on the built-in first logic.
In one embodiment, said storage module is further used to store a second logic and said second logic adapts to determine a main control sub-module and one or more non-main control sub-modules, wherein said processing module is further used to invoke said second logic from said storage module and determine a main control sub-module and one or more non-main sub-modules in said sub-module set based on said second logic.
It can be seen that the sub-module in the embodiments of the present invention can conveniently determine the main control sub-module and non-main control sub-modules based on the built-in second logic. In one embodiment, the sub-module of an MMC further comprises: a protection module, used to detect the working state of said sub-module, and used to isolate said sub-module and send a fault alarm message to said concentrator via said communication module when said working state is abnormal.
It can be seen that the sub-module in the embodiments of the present invention further has the protection function, the sub-module can be isolated and a fault alarm will be sent out when the working state of the sub-module is abnormal.
In one embodiment, the sub-module of an MMC further comprises: a capacitance alarm module, used to calculate the capacitance of said sub-module, and used to send a capacitance alarm message to said concentrator via said communication module when said capacitance is lower than a preset threshold.
It can be seen that the sub-module in the embodiments of the present invention has the capacitance alarm function and a fault alarm will be sent out when the capacitance is low.
In one embodiment, the sub-module of an MMC further comprises: a check module, used to detect said protection module when said sub-module is in a standby state or maintenance state, and used to send a protection module alarm message to said concentrator via said communication module when the protection module is detected to be abnormal .
It can be seen that the sub-module in the embodiments of the present invention further has the check function for the protection module and a fault alarm will be sent out when the protection module is abnormal . In one embodiment, said sub-module comprises at least one of the following: half-bridge sub-module, full-bridge sub-module and clamp double sub-module .
An MMC comprises any of above-mentioned sub-modules.
A control method of an MMC is provided, said MMC comprises N sub-modules, wherein N is a positive integer greater than or equal to 2, and the method comprises:
enabling each sub-module of said N sub-modules to receive a control instruction from the concentrator, and
enabling each sub-module of said N sub-modules to determine the sub-module set adapting to execute said control instruction and execute said control instruction when said sub-module set it belongs to is determined.
Therefore, no uniform central control unit is provided in the embodiments of the present invention, but the control function is provided in each sub-module. A technical solution for controlling the MMC in a distributed way is realized and the technical solution can overcome the security problem of centralized control.
In one embodiment, the method further comprises storing a first logic in each sub-module of said N sub-modules in advance, said first logic adapting to determine a sub-module set,
wherein said enabling each sub-module of said N sub-modules to determine the sub-module set adapting to execute said control instruction comprises:
enabling each sub-module of said N sub-modules to analyze said control instruction to determine the overall workload, and enabling each sub-module of said N sub-modules to invoke said first logic to determine the sub-module set whose work capacity satisfies said overall workload based on said first logic. Therefore, the sub-modules in the embodiments of the present invention can conveniently determine the sub-module set based on the built-in first logic.
In one embodiment, the method further comprises storing a second logic in each sub-module of said N sub-modules in advance, said second logic adapting to determine a main control sub-module and one or more non-main control sub-modules, and
said method further comprises:
enabling each sub-module in said sub-module set to invoke said second logic to determine a main control sub-module and one or more non-main control sub-modules in said sub-module set based on said second logic,
enabling said main control sub-module to send a synchronous clock signal to said non-main control sub-modules before executing said control instruction, and
enabling said non-main control sub-modules to keep synchronous with the clock of said main control sub-module based on said synchronous clock signal.
It can be seen that in the embodiments of the present invention, the main control sub-module and non-main control sub-modules can conveniently be determined based on the built-in second logic in sub-modules, and in addition, clock synchronization is realized in the sub-module set based on the information transmission function of the concentrator.
In one embodiment, the method further comprises:
enabling each sub-module of said N sub-modules to measure the voltage of its own capacitor and send the voltage to said concentrator,
enabling said concentrator to send respective voltages of said N sub-modules to each sub-module of said N sub-modules, and enabling each sub-module of said N sub-modules to control the working state of its own capacitor based on respective voltages of said N sub-modules.
Therefore, sub-modules can mutually transmit their respective voltages based on the information transmission function of the concentrator .
A control device of an MMC comprises a processor and a memory, wherein applications, which can be executed by said processor to enable said processor to perform the above-mentioned control method of an MMC, are stored in said memory.
A computer readable storage medium is provided, computer readable instructions are stored in said computer readable storage medium and said computer readable instructions are used to execute the above-mentioned control method of an MMC.
Brief Description of the Drawings
Fig. 1 shows the structure of the control system of an MMC in the prior art .
Fig. 2 shows the structure of the control system of an MMC according to the embodiments of the present invention.
Fig. 3 shows clock synchronization in the sub-module set according to the embodiments of the present invention.
Fig. 4 shows the structure of the sub-module of an MMC according to the embodiments of the present invention.
Fig. 5 is a flowchart of the control method of an MMC according to the embodiments of the present invention. Fig. 6 shows the structure of the control device of an MMC according to the embodiments of the present invention.
Description of reference numerals in the drawings:
Figure imgf000010_0001
Detailed Description of the Invention
To make the technical solutions and advantages of the present invention clearer, the following further describes in detail the present invention in combination with the drawings and embodiments. It should be understood that the specific embodiments described here are used only to illustrate the present invention, but not restrict the scope of protection of the present invention.
For the purposes of simplicity and intuitiveness of the description, the following gives some representative embodiments to illustrate the present invention. A large amount of details in the embodiments are only used to help to understand the solutions of the present invention. Obviously, the technical solutions of the present invention are not limited to these details, however. To avoid unnecessarily making the solutions of the present invention confusing, some embodiments are not described in detail, and only their frameworks are given.
Below, the term "comprise" refers to "including but not limited to" and the term "according to..." refers to "at least according to..., but not limited to only according to..." . In view of the linguistic habits of Chinese, the number of a component hereinafter can be one or more or can be understood as at least one, unless otherwise specified.
Fig. 1 shows the structure of the control system of an MMC in the prior art .
In Fig. 1, the MMC 60 comprises a plurality of sub-modules, which are sub-module 11, sub-module 12,..., and sub-module IN, respectively, wherein N is a positive integer greater than or equal to 2. All sub-modules 11, 12, ..., IN of the MMC 60 are controlled by a uniform central control unit 20 in a centralized way.
The control module 40 sends a control instruction for controlling the MMC60. The central control unit 20 is connected with the control module 40. After receiving the control instruction from the control module 40, the central control unit determines a specific sub-module used to execute the control instruction according to the allocation algorithm 21 built in the central control unit 20, and then orders the specific sub-module to execute the control instruction.
The applicant finds that when the central control unit 20 is faulty, all sub-modules 11, 12, ..., IN in Fig. 1 will be unable to work. In addition, the control of the uniform central control unit 20 over all sub-modules may also reduce the real-time performance of the MMC 60.
In view of the disadvantages of centralized control over sub-modules in the prior art, a technical solution for controlling sub-modules in a distributed way is provided in the embodiments of the present invention. In particular, no uniform central control unit is provided, but the control function is provided in each sub-module in the embodiments of the present invention.
Fig. 2 shows the structure of the control system of an MMC according to the embodiments of the present invention.
In Fig. 2, the MMC 70 comprises a plurality of sub-modules, which are sub-module 31, sub-module 32, ..., and sub-module 3N, respectively, wherein N is a positive integer greater than or equal to 2.
The control system 100 comprises:
a control module 80, which is used to send a control instruction, and
a concentrator 50, which is connected with the plurality of sub-modules 31, 32,..., 3N respectively to receive the control instruction and send the control instruction to each sub-module of the plurality of sub-modules,
wherein each sub-module of the plurality of sub-modules 31, 32,..., 3N is used to determine the sub-module set adapting to execute the control instruction and execute the control instruction when the sub-module set it belongs to is determined. In one embodiment, the control module 80 can be implemented as a remote control module and can send a control instruction for controlling the MMC 70 to the concentrator 50 via Bluetooth, infrared, cellular data network and wireless fidelity (WiFi) .
In another embodiment, the control module 80 can have a wired connection (preferably, optical fiber connection) with the concentrator 50 and can send a control instruction for controlling the MMC 70 to the concentrator 50 based on the wired connection.
Preferably, the concentrator 50 has a wired connection (preferably, optical fiber connection) with a plurality of sub-modules 31, 32, ..., 3N respectively and can send the control instruction for controlling the MMC 70 to each sub-module of the plurality of sub-modules 31,
32, ..., 3N.
Each sub-module of the plurality of sub-modules 31, 32, ..., 3N contains its respective processing module 311, 321, ..., 3N1.
As shown in Fig. 2, the sub-module 31 contains a processing module 311, the sub-module 32 contains a processing module 321, ..., and the sub-module 3N contains a processing module 3N1. The processing modules 311, 321, ..., 3N1 can respectively determine the sub-module set adapting to execute a control instruction.
Specifically, the processing modules 311, 321, ..., 3N1 respectively contain the same sub-module allocation algorithm and the sub-module allocation algorithm is used to determine the sub-module set adapting to execute the control instruction. Therefore, the sub-module sets determined by the processing modules 311, 321, ..., 3N1 are all the same. Each sub-module of the plurality of sub-modules 31, 21, ..., 3N executes the control instruction when determining that it belongs to the sub-module set . Wherein each sub-module in the sub-module set determines the workload it bears based on a uniform task allocation algorithm when executing the control instruction.
For example, the control module 80 sends out a control instruction A and the control instruction A is used to instruct the MMC 70 to generate a sine wave with a frequency of 50 Hz and a voltage of 10 KV. After receiving the control instruction A, the concentrator 50 sends by broadcast the control instruction A to all sub-modules 31, 32, ..., 3N. Then, each sub-module of the sub-modules 31, 32, ... 3N determines the sub-module set adapting to execute the control instruction A based on the same sub-module allocation algorithm. The sub-module sets determined by the sub-modules 31, 32, ..., 3N are all the same.
Supposing the sub-module set contains sub-module 31, sub-module 32 and sub-module 35.
After determining their respective sub-module sets, the sub-modules except sub-module 31, sub-module 32 and sub-module 35 find that they do not belong to the sub-module set and will not participate in the execution of the control instruction A.
After determining their respective sub-module sets, sub-module 31, sub-module 32 and sub-module 35 find that they belong to the sub-module set and will jointly execute the control instruction A to generate a sine wave with a frequency of 50 Hz and a voltage of 10 KV. Wherein sub-module 31, sub-module 32 and sub-module 35 respectively determine the workloads they respectively bear based on a uniform task allocation algorithm (for example, the task allocation algorithm is also contained their respective processing modules) , and respectively work based on their respective workloads to jointly produce a sine wave with a frequency of 50 Hz and a voltage of 10 KV. It can be seen that in the embodiments of the present invention, each sub-module can determine a sub-module set adapting to execute a control instruction, and will execute the control instruction when determining that it belongs to the sub-module set. Thus, a technical solution for controlling sub-modules in a distributed way is realized .
With the embodiments of the present invention adopted, no uniform central control unit is required and the MMC can be controlled by providing the control function in each sub-module. Thus, the security problem caused by the faulty central control unit can be overcome. For example, when a sub-module is faulty, other sub-modules can still normally determine the sub-module set and normally execute the control instruction.
In one embodiment, each sub-module of N sub-modules 31, ..., 3N is further used to measure the voltage of its own capacitor and send the voltage to the concentrator 50, and the concentrator 50 is further used to send respective voltages of N sub-modules 31, ..., 3N to each sub-module of N sub-modules 31, ..., 3N (for example, as scheduled or periodically) . Each sub-module of N sub-modules 31, ..., 3N is further used to control the working state of its own capacitor based on respective voltages of N sub-modules 31, ..., 3N.
For example, after receiving respective voltages of all sub-modules from the concentrator 50, a sub-module M calculates the average voltage of all sub-modules, and lets the capacitor of the sub-module M enter the charging state when the voltage of the sub-module M is determined to be less than the average voltage.
Again, for example, after receiving respective voltages of all sub-modules from the concentrator 50, a sub-module K calculates the average voltage of all sub-modules, and lets the capacitor of the sub-module K enter the discharging state when the voltage of the sub-module K is determined to be greater than the average voltage. Examples of controlling the working state of capacitors are described above. Those skilled in the art can know that the description is only used for the exemplary purpose, but not used to limit the scope of protection of the embodiments of the present invention .
Preferably, the embodiments of the present invention further realize a technical solution for keeping synchronized the clocks of the sub-modules in the sub-module set. After the clocks of the sub-modules in the sub-module set are synchronized, the sub-modules can jointly execute the control instruction in order.
In one embodiment, the sub-module set comprises:
a main control sub-module, and
one or more non-main control sub-modules,
wherein the main control sub-module is used to send a synchronous clock signal to one or more non-main control sub-modules via the concentrator 50 after the sub-module set is determined but before the control instruction is executed, and one or more non-main control sub-modules are used to keep synchronous with the clock of the main control sub-module based on the synchronous clock signal.
Fig. 3 shows clock synchronization in the sub-module set according to the embodiments of the present invention.
As shown in Fig. 3, the MMC 70 comprises a plurality of sub-modules, which are sub-module 31, sub-module 32, sub-module 33, ..., and sub-module 3N, respectively, wherein N is a positive integer greater than or equal to 4.
The sub-module 31 contains a processing module 311, the sub-module 32 contains a processing module 321, the sub-module 33 contains a processing module 331, ..., and the sub-module 3N contains a processing module 3N1. The processing modules 311, 321, ..., 3N1 respectively contain the same sub-module allocation algorithm. Therefore, after the processing modules 311 , 321, ..., 3N1 respectively receive the control instruction from the concentrator 50, the sub-module sets determined are the same.
In addition, the processing modules 311, 321, ..., 3N1 respectively contain the same main control sub-module determination algorithm. For example, the main control sub-module algorithm can be implemented as follows: the sub-module with the smallest sub-module number is determined to be the main control sub-module, or the sub-module whose current load is minimum is determined to be the main control sub-module, etc.
Supposing that the sub-module set 55 determined by the processing modules 311, 321, ..., 3N1 based on the main control sub-module determination algorithm contains sub-module 31, sub-module 32 and sub-module 33, and the main control sub-module determined by the processing modules 311, 321, ..., 3N1 based on the main control sub-module determination algorithm is sub-module 32, then, in the sub-module set 55, the main control sub-module is sub-module 32, and the non-main control sub-modules are sub-module 31 and sub-module 33.
After the sub-module set is determined but before the control instruction is executed, sub-module 31 as the main control sub-module sends a synchronous clock signal to sub-module 31 and sub-module 33 via the concentrator 50, as indicated by the dotted arrow. Sub-module 31 and sub-module 33 keep synchronous with the clock of sub-module 31 based on the synchronous clock signal sent from sub-module 31. After the clocks of all the sub-modules in the sub-module set are synchronized, the sub-modules can execute the control instruction. Based on the description above, the embodiments of the present invention further provide a sub-module of an MMC . The sub-module in the embodiments of the present invention has the function of determining the sub-module set, and thus the uniform central control unit can be saved.
Fig. 4 shows the structure of the sub-module of an MMC according to the embodiments of the present invention.
As shown in Fig. 4, the sub-module comprises:
a communication module 301, connected with the concentrator to receive a control instruction,
a processing module 302, used to determine the sub-module set adapting to execute the control instruction and send the control instruction to an execution module 303 when the sub-module is determined to belong to the sub-module set, and
the execution module 303, used to execute the control instruction.
In one embodiment, the sub-module of an MMC further comprises: a storage module 305, used to store a first logic, said first logic adapting to determine the sub-module set,
wherein the processing module 302 is used to invoke the first logic from the storage module 305 and determine the sub-module set adapting to execute the control instruction based on the first logic .
Wherein the storage module 305 can be implemented as a read-only memory (ROM) or random access memory (RAM) . The first logic can specifically be implemented as a computer readable instruction generated based on the sub-module allocation algorithm.
In one embodiment, the storage module 305 is further used to store a second logic and said second logic adapts to determine a main control sub-module and one or more non-main control sub-modules, wherein the processing module 302 is further used to invoke the second logic from the storage module 305 and determine a main control sub-module and one or more non-main sub-modules in the sub-module set based on the second logic.
Wherein the second logic can specifically be implemented as a computer readable instruction generated based on the main control sub-module determination algorithm.
In one embodiment, the sub-module of an MMC further comprises: a protection module 306, used to detect the working state of the sub-module 300, and used to isolate the sub-module 300 and send a fault alarm message to the concentrator via the communication module 301 when the working state is abnormal.
For example, the protection module 306 can be implemented as a switch. When the working state of the sub-module 300 is abnormal, the switch is closed to disconnect the other part of the sub-module 300. In addition, the communication module 301 sends a fault alarm message to the concentrator, the concentrator sends the fault alarm message to a man-machine interface, and the man-machine interface displays the fault alarm message, thus reminding the user that the sub-module 300 is faulty.
It can be seen that the sub-module in the embodiments of the present invention further has the protection function, the sub-module can be isolated and a fault alarm will be sent out when the working state of the sub-module is abnormal.
In one embodiment, the sub-module of an MMC further comprises: a capacitance alarm module 304, used to calculate the capacitance of the sub-module 300, and used to send a capacitance alarm message to the concentrator via the communication module 301 when the capacitance is lower than a preset threshold. The concentrator sends the capacitance alarm message to the man-machine interface and the man-machine interface displays the capacitance alarm message, thus reminding the user that the capacitance of the sub-module 300 is insufficient .
In one embodiment, the sub-module of an MMC further comprises: a check module 307, used to detect said protection module 306 when the sub-module 300 is in a standby state or maintenance state, and used to send a protection module alarm message to the concentrator when the protection module 306 is detected to be abnormal. The concentrator sends the protection module alarm message to the man-machine interface and the man-machine interface displays the protection module alarm message, thus reminding the user that the protection module 306 is abnormal.
Preferably, the sub-module comprises at least one of the following: half-bridge sub-module, full-bridge sub-module and clamp double sub-module .
Therefore, the sub-module in the embodiments of the present invention can control its running time and sequence during running. Once a fault occurs, it will also be protected quickly.
It can be seen that the sub-module in the embodiments of the present more powerful and can bring about a plurality of advantages. First of all, the control system is simpler and the number of communication channels can be reduced, thus saving a large number of optical fibers . The cost is reduced. In addition, the fault rate of the system is lowered. The periodical check function can prevent adverse effects caused by faults of key components . In particular, the early warning of the service life of capacitors makes the system more reliable and safer.
Based on the description above, the present invention further provides a control method of an MMC. Fig. 5 is a flowchart of the control method of an MMC according to the embodiments of the present invention. The MMC comprises N sub-modules, wherein N is a positive integer greater than or equal to 2.
As shown in Fig. 5, the method comprises:
Step 501: Enabling each sub-module of N sub-modules to receive a control instruction from the concentrator.
Step 502: Enabling each sub-module of N sub-modules to determine the sub-module set adapting to execute the control instruction and execute the control instruction when the sub-module set it belongs to is determined.
In one embodiment, the method further comprises: storing a first logic in each sub-module of N sub-modules in advance, the first logic adapting to determine a sub-module set, wherein enabling each sub-module of N sub-modules to determine the sub-module set adapting to execute the control instruction in step 502 comprises: enabling each sub-module of N sub-modules to analyze the control instruction to determine the overall workload, and enabling each sub-module of N sub-modules to invoke the first logic to determine the sub-module set whose work capacity satisfies the overall workload based on the first logic.
In one embodiment, the method further comprises storing a second logic in each sub-module of N sub-modules in advance, said second logic adapting to determine a main control sub-module and one or more non-main control sub-modules, and the method further comprises: enabling each sub-module in the sub-module set to invoke the second logic to determine a main control sub-module and one or more non-main control sub-modules in said sub-module set based on the second logic, enabling the main control sub-module to send a synchronous clock signal to the non-main control sub-modules before executing said control instruction, and enabling the non-main control sub-modules to keep synchronous with the clock of the main control sub-module based on the synchronous clock signal.
In one embodiment, the method further comprises: enabling each sub-module of N sub-modules to measure the voltage of its own capacitor and send the voltage to the concentrator, enabling the concentrator to send respective voltages of N sub-modules to each sub-module of N sub-modules, and enabling each sub-module of N sub-modules to control the working state of its own capacitor based on respective voltages of N sub-modules.
The embodiments of the present invention further provide a control device of an MMC .
Fig. 6 shows the structure of the control device of an MMC according to the embodiments of the present invention.
As shown in Fig. 6, the control device comprises a processor 601 and a memory 602, wherein applications, which can be executed by the processor 601 to enable the processor 601 to perform the above-mentioned control method of an MMC, are stored in the memory 602.
The embodiments of the present invention further provide a computer readable storage medium, wherein computer readable instructions are stored in the computer readable storage medium and the computer readable instructions are used to execute the above-mentioned control method of an MMC.
It should be noted that not all steps or modules in the above-mentioned processes and structural diagrams are required, and some steps or modules can be ignored, depending on the actual requirements. The execution sequence of the steps is not fixed and can be adjusted as required. The partition of the modules is a functional partition for the convenience of description. In the practical implementation, the function of a module can be realized by a plurality of modules, and the functions of a plurality of modules can be realized by one module and these modules can be located in the same equipment or can be located in different equipment.
The hardware modules in different embodiments can mechanically or electronically be realized. For example, a hardware module can comprise specially designed permanent circuits or logic devices (for example, application-specific processors such as FPGA or ASIC) to complete specific operations . A hardware module can also comprise programmable logic devices or circuits (for example, general processors or other programmable processors) temporarily configured by software to perform specific operations. Whether a hardware module is realized mechanically, or by use of a dedicated permanent circuit or a temporarily configured circuit (for example, configured by software) can depend on the considerations of the cost and the time.
The present invention further provides a machine readable storage medium, in which instructions allowing a machine to execute the method described in this document are stored. In particular, a system or device equipped with a storage medium can be provided. Software program codes which can realize the function in any of above-mentioned embodiments are stored in the storage medium and the computer (or CPU or MPU) of the system or device can read and execute the program codes stored in the storage medium. In addition, through the instructions based on the program code, the operating system on the computer can complete a part of or all of practical operations. In addition, the program code read out of a storage medium can be written into the memory in the expansion board in a computer or can be written into a memory in an expansion unit connected to the computer, and then the instructions based on the program code let the CPU installed on the expansion board or expansion unit execute a part or all of practical operations to realize the function in any of the above-mentioned embodiments.
Storage media used to provide program codes include floppy disk, hard disk, magneto-optical disk, compact disk (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW) , magnetic tape, non-volatile memory card, and read-only memory (ROM) . Alternatively, the program codes can be downloaded from the server computer over a communication network.
The embodiments described above are preferred embodiments of the present invention, but are not used to limit the scope of protection of the present invention. Any modification, equivalent replacement, and improvement within the spirit and principle of the present invention should fall within the scope of protection of the present invention .

Claims

Claims
1. A control system (100) of an MMC (70) , characterized in that said MMC (70) comprises N sub-modules (31, ..., 3N) and said control system 100 comprises:
a control module (80) , which is used to send a control instruction, and
a concentrator (50) , which is connected with said N sub-modules (31, ..., 3N) respectively to receive said control instruction and send said control instruction to said N sub-modules (31, ..., 3N) , wherein each sub-module of said N sub-modules (31, ..., 3N) is used to determine the sub-module set adapting to execute said control instruction, and execute said control instruction when said sub-module set it belongs to is determined, wherein N is a positive integer greater than or equal to 2.
2. The control system (100) of an MMC as claimed in claim 1, characterized in that said sub-module set comprises:
a main control sub-module, and
one or more non-main control sub-modules,
wherein said main control sub-module is used to send a synchronous clock signal to said one or more non-main control sub-modules via said concentrator 50 after said sub-module set is determined but before said control instruction is executed, and said one or more non-main control sub-modules are used to keep synchronous with the clock of said main control sub-module based on said synchronous clock signal.
3. The control system (100) of an MMC (70) as claimed in claim 2, characterized in that
each sub-module of said N sub-modules (31, ..., 3N) contains its respective processing module (311, ..., 3N1) ,
wherein said processing module (311, ..., 3N1) is used to determine the sub-module set adapting to execute said control instruction and determine the main control sub-module and non-main control sub-modules in said sub-module set.
4. The control system (100) of an MMC as claimed in claim 1, characterized in that
each sub-module of said N sub-modules (31, ..., 3N) is further used to measure the voltage of its own capacitor and send the voltage to said concentrator (50) ,
said concentrator (50) is further used to send respective voltages of said N sub-modules (31, ..., 3N) to said each sub-module of said N sub-modules (31, ..., 3N) , and
each sub-module of said N sub-modules (31, ..., 3N) is further used to control the working state of its own capacitor based on respective voltages of said N sub-modules (31, ..., 3N) .
5. A sub-module (300) of an MMC, comprising:
a communication module (301) , connected with a concentrator to receive a control instruction,
a processing module (302), used to determine the sub-module set adapting to execute said control instruction and send said control instruction to an execution module (303) when said sub-module is determined to belong to said sub-module set, and
said execution module (303) , used to execute said control instruction .
6. The sub-module (300) of an MMC as claimed in claim 5, further comprising :
a storage module (305) , used to store a first logic, said first logic adapting to determine the sub-module set,
wherein said processing module (302) is used to invoke said first logic from said storage module (305) and determine the sub-module set adapting to execute said control instruction based on said first logic .
7. The sub-module (300) of an MMC as claimed in claim 6, characterized in that
said storage module (305) is further used to store a second logic and said second logic adapts to determine a main control sub-module and one or more non-main control sub-modules,
wherein said processing module (302) is further used to invoke said second logic from said storage module (305) and determine a main control sub-module and one or more non-main sub-modules in said sub-module set based on said second logic.
8. The sub-module (300) of an MMC as claimed in claim 5, further comprising :
a protection module (306) , used to detect the working state of said sub-module (300), and used to isolate said sub-module (300) and send a fault alarm message to said concentrator via said communication module (301) when said working state is abnormal.
9. The sub-module (300) of an MMC as claimed in claim 5, further comprising :
a capacitance alarm module (304) , used to calculate the capacitance of said sub-module (300) , and used to send a capacitance alarm message to said concentrator via said communication module (301) when said capacitance is lower than a preset threshold.
10. The sub-module (300) of an MMC as claimed in claim 8, further comprising :
a check module (307), used to detect said protection module (306) when said sub-module (300) is in a standby state or maintenance state, and used to send a protection module alarm message to said concentrator via said communication module (301) when the protection module (306) is detected to be abnormal.
11. The sub-module (300) of an MMC as claimed in any of claims 5 to 10, characterized in that said sub-module (300) comprises at least one of the following: half-bridge sub-module, full-bridge sub-module and clamp double sub-module .
12. An MMC , comprising a sub-module as claimed in any of claims 5 to 11.
13. A control method of an MMC, characterized in that said MMC comprises N sub-modules, wherein N is a positive integer greater than or equal to 2, and the method comprises:
enabling each sub-module of said N sub-modules to receive a control instruction from the concentrator (501) , and
enabling each sub-module of said N sub-modules to determine the sub-module set adapting to execute said control instruction and execute said control instruction when said sub-module set it belongs to is determined (502) .
14. The control method of an MMC as claimed in claim 13 , characterized in that the method further comprises storing a first logic in each sub-module of said N sub-modules in advance, said first logic adapting to determine a sub-module set,
wherein said enabling each sub-module of said N sub-modules to determine the sub-module set adapting to execute said control instruction comprises:
enabling each sub-module of said N sub-modules to analyze said control instruction to determine the overall workload, and enabling each sub-module of said N sub-modules to invoke said first logic to determine the sub-module set whose work capacity satisfies said overall workload based on said first logic.
15. The control method of an MMC as claimed in claim 14 , characterized in that the method further comprises storing a second logic in each sub-module of said N sub-modules in advance, said second logic adapting to determine a main control sub-module and one or more non-main control sub-modules, and said method further comprises:
enabling each sub-module in said sub-module set to invoke said second logic to determine a main control sub-module and one or more non-main control sub-modules in said sub-module set based on said second logic,
enabling said main control sub-module to send a synchronous clock signal to said non-main control sub-modules before executing said control instruction, and
enabling said non-main control sub-modules to keep synchronous with the clock of said main control sub-module based on said synchronous clock signal.
16. The control method of an MMC as claimed in claim 13 , characterized in that the method further comprises:
enabling each sub-module of said N sub-modules to measure the voltage of its own capacitor and send the voltage to said concentrator,
enabling said concentrator to send respective voltages of said N sub-modules to each sub-module of said N sub-modules, and enabling each sub-module of said N sub-modules to control the working state of its own capacitor based on respective voltages of said N sub-modules.
17. A control device of an MMC, comprising a processor (601) and a memory ( 602 ) ,
wherein applications, which can be executed by said processor 601 to enable said processor (601) to perform the control method of an MMC as claimed in any of claims 13 to 16, are stored in said memory (602) .
18. A computer readable storage medium, characterized in that computer readable instructions are stored in said computer readable storage medium and said computer readable instructions are used to execute the control method of an MMC as claimed in any of claims 13 to 16.
PCT/EP2019/076435 2018-09-30 2019-09-30 Control system, control method, control device and sub-module of an mmc WO2020065095A1 (en)

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