Unit protection identification method, system, device and medium for cascade voltage source converter startup phase

Abstract

The present invention discloses a unit protection identification method, system, device and medium in the startup phase of a cascaded voltage source converter. The present invention realizes accurate detection of converter unit faults through a unit fault detection strategy during the charging startup process of a cascaded voltage source converter with redundant communication. The present invention can be applied to all cascaded voltage source converter units composed of fully controlled switching devices, capacitors and auxiliary devices, and can accurately identify faulty units in the startup phase, improve equipment availability, and avoid primary equipment damage.

Description

Technical Field

[0001] The present invention relates to a voltage source converter, and in particular to a unit protection identification method, system, equipment and medium in a startup phase of a cascaded voltage source converter. Background Art

[0002] Voltage source converters generally use fully controlled power electronic devices, including IGBT, IGCT and GTO. It is fundamentally different from the traditional thyristor-based current source converter. Voltage source converters are particularly suitable for asynchronous grid connection, passive / isolated load power supply, urban distribution network expansion and reconstruction, and connection to wind power, solar power and other new energy power generation power sources due to their flexible controllability, robustness to grid conditions, compactness of their own systems, convenience of design and construction, and environmental protection.

[0003] To date, voltage source converters can be divided into two basic types: switch converters and controllable voltage source converters. Early voltage source converters mainly used switch converters, which were only used as controllable switches and had only two working states: on and off. At present, mainstream voltage source converters all use controllable voltage source converters. This type of converter uses standardized units in a certain topology cascade structure, and effectively approximates sinusoidal voltage by outputting high-level step voltage waves. The smallest unit used by the controllable voltage source converter valve generally includes fully controlled devices, energy storage capacitors and other necessary accessories.

[0004] During the charging process of the cascade converter, the unit will go through a process from a voltage of 0 to a voltage that can drive the unit control board to work normally. When the unit voltage reaches the working threshold of the unit control board, the unit will establish communication with the control system; if the control system receives the fault information sent by the unit or cannot receive the status information sent by the unit, it is considered that the unit has failed during the charging process. The types of faults sent by the unit generally include full-control device failure, power supply failure, overvoltage, undervoltage, downstream communication failure, and bypass switch refusal to operate; the reasons why the control system cannot receive unit information generally include upstream optical fiber failure, power supply failure, unit control board failure, and control system pulse board receiving optical port failure, which is a comprehensive manifestation of the failure of the control system to establish communication with the unit. In order to minimize the probability of communication failure between the control system and the unit, a unit message can be sent and received not only by the unit itself, but also through its adjacent units to achieve redundant communication.

[0005] At present, the startup of cascade converters includes AC charging and DC charging. Generally, the capacitor of the unit is charged to make the self-powered power supply work, and then unlocked and operated after the unlocking conditions are met. During the charging stage, if there is a unit failure, it is necessary to provide necessary protection for these faulty units to prevent the voltage of the faulty unit from being charged to overvoltage in an uncontrollable manner, causing the device to explode and even endanger the safety of the entire converter. Therefore, it is very important to accurately identify the faulty unit during the startup process to prevent it from endangering the safety of the converter.

[0006] At present, in the project, all units that cannot establish uplink communication during the charging phase are treated as faulty modules. The disadvantage of the prior art is that there are many reasons for uplink communication failure. If it is an uplink optical port failure or a fiber transmission failure, the module can be bypassed correctly. Indiscriminate shutdown causes a decrease in availability. In addition, it does not take into account that there is another fault situation in the actual situation, that is, the uplink communication is normal, the control system can receive the normal status information sent by the unit, but the unit voltage is significantly lower than other normally charged units. This unit must be identified, otherwise, it will also cause damage to the unit and other equipment. Summary of the invention

[0007] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a unit protection identification method, system, device and medium in the startup phase of a cascaded voltage source converter, which can accurately identify faulty units in the startup phase, improve equipment availability and avoid primary equipment damage.

[0008] In order to achieve the above object, a method for determining unit protection during the startup phase of a cascaded voltage source converter is provided, comprising the following steps:

[0009] Step 1: When charging for the first time, set all units to normal status;

[0010] Step 2: After charging starts, when the voltage of all cells exceeds the preset voltage value U 1 When the fault is cleared, a command is issued, and the status information sent by the storage unit is S1;

[0011] Step 3: Fault detection and discrimination strategy in the startup phase: if there is no faulty unit, charging is completed; if there is a faulty unit, the status of redundant communication transmission is detected, and if charging is not completed, the power switch is turned off;

[0012] Step 4: After switching to manual bypass or replacing the faulty unit, re-execute step 2 until the unlocking conditions are met.

[0013] In step 3, the specific method of the stage fault detection and discrimination strategy is as follows:

[0014] Read the unit main communication system status S2. If no faulty unit is found, it is determined that the unlocking condition is met;

[0015] If the status information of the unit main communication system status S2 read twice is inconsistent, the status S3 sent by the redundant communication is retrieved. If the status S3 sent by the redundant system is consistent with the status information S1 sent by the unit, it is determined that the unlocking condition is met;

[0016] If the status information S3 sent by the redundant system is inconsistent with the status information S1 sent by the unit, and the voltage value sent by the unit with inconsistent status information is less than the working threshold, charging is stopped and the power switch is tripped.

[0017] In step 3, the status of redundant communication transmission is detected once every 1 ms.

[0018] If the voltage value sent by the unit with inconsistent status information is lower than the working threshold within the time of △t≥1s, charging will be stopped and the power switch will be turned off.

[0019] A unit protection identification system for a cascade voltage source converter during a startup phase, comprising:

[0020] A preset module is used to set all units to normal status during initial charging;

[0021] The control module is used to start charging when the upper voltage of all units exceeds the preset voltage value U 1 When the fault is cleared, a command is issued, and the status information sent by the storage unit is S1;

[0022] The stage fault detection and discrimination strategy module is used to determine the faulty unit. If there is no faulty unit, the charging is completed; if there is a faulty unit, the redundant communication status is detected. If the charging is not completed, the power switch is disconnected;

[0023] Processing module, used to switch manual bypass or replace faulty unit.

[0024] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of a unit protection determination method in the startup phase of a parallel voltage source converter are implemented.

[0025] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, a unit protection discrimination method in a startup phase of a parallel voltage source converter is implemented.

[0026] Compared with the prior art, the present invention analyzes the unit charging process of the cascade voltage source converter with redundant communication, studies the detection principle of unit faults during the charging process, and after the start of charging, when the voltage sent by all units exceeds the preset voltage value, sends a command to clear the fault, and stores the status information sent by the unit; the fault detection and discrimination strategy in the startup phase, if there is no faulty unit, the charging is completed; if there is a faulty unit, the status of the redundant communication is detected, and if the charging is not completed, the power switch is disconnected; after switching to manual bypass or replacing the faulty unit, the above steps are repeated until the unlocking conditions are met. The present invention realizes accurate detection of converter unit faults through the unit fault detection strategy during the charging startup process of the cascade voltage source converter with redundant communication. The present invention can be applied to all cascade voltage source converter units composed of fully controlled switching devices, capacitors and auxiliary devices, and can accurately identify faulty units in the startup phase, improve equipment availability, and avoid damage to primary equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of the present invention;

[0028] Figure 2 It is a system diagram of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] The unit structures of cascaded voltage source converters vary, but they are all composed of fully controlled switching devices, capacitors and auxiliary devices.

[0031] See also Figure 1 , a unit protection determination method for a cascaded voltage source converter during the startup phase, comprising the following steps:

[0032] Step 1: When charging for the first time, set all units to normal status;

[0033] Step 2: After charging starts, when the voltage of all cells exceeds the preset voltage value U 1 When the fault is cleared, a command is issued, and the status information sent by the storage unit is S1;

[0034] Step 3: Fault detection and discrimination strategy in the startup phase: if there is no faulty unit, charging is completed; if there is a faulty unit, the status of redundant communication transmission is detected, and if charging is not completed, the power switch is turned off;

[0035] Step 4: After switching to manual bypass or replacing the faulty unit, re-execute step 2 until the unlocking conditions are met.

[0036] The specific method of the stage fault detection and discrimination strategy is as follows:

[0037] Read the unit main communication system status S2. If no faulty unit is found, it is determined that the unlocking condition is met;

[0038] If the status information of the unit main communication system status S2 read twice is inconsistent, the status S3 sent by the redundant communication is retrieved. If the status S3 sent by the redundant system is consistent with the status information S1 sent by the unit, it is determined that the unlocking condition is met;

[0039] If the status information S3 sent by the redundant system is inconsistent with the status information S1 sent by the unit, and the voltage value sent by the unit with inconsistent status information is less than the working threshold, charging is stopped and the power switch is tripped.

[0040] The status of redundant communication is checked once every 1ms. If the voltage value sent by the unit with inconsistent status information is less than the working threshold within the time of △t≥1s, charging is stopped and the power switch is tripped.

[0041] See also Figure 2 , a unit protection discrimination system for a cascade voltage source converter during a startup phase, comprising:

[0042] A preset module is used to set all units to normal status during initial charging;

[0043] The control module is used to start charging when the upper voltage of all units exceeds the preset voltage value U 1 When the fault is cleared, a command is issued, and the status information sent by the storage unit is S1;

[0044] The stage fault detection and discrimination strategy module is used to determine the faulty unit. If there is no faulty unit, the charging is completed; if there is a faulty unit, the redundant communication status is detected. If the charging is not completed, the power switch is disconnected;

[0045] Processing module, used to switch manual bypass or replace faulty unit.

[0046] In another embodiment of the present invention, a computer device is provided, the computer device comprising a processor and a memory, the memory being used to store a computer program, the computer program comprising program instructions, and the processor being used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of a unit protection discrimination method in the startup phase of a parallel voltage source converter.

[0047] In another embodiment of the present invention, the present invention further provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the unit protection judgment method in the startup phase of a coupled voltage source converter in the above embodiment.

[0048] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0049] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0050] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0051] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

Claims

1. A method for determining unit protection during the startup phase of a cascaded voltage source converter, characterized in that: The following steps are involved: Step 1: When charging for the first time, set all units to normal status; Step 2: After charging starts, when the voltage sent by all units exceeds the preset voltage value U1, a command to clear the fault is issued, and the status information sent by the storage unit is S1; Step 3: Start the fault detection and discrimination strategy in the startup phase. If there is no faulty unit, charging is completed; if there is a faulty unit, the status of redundant communication transmission is detected. If charging is not completed, the power switch is disconnected. The specific method of the stage fault detection and discrimination strategy is as follows: Read the unit main communication system status S2. If no faulty unit is found, it is determined that the unlocking condition is met; If the status information of the unit main communication system status S2 read twice is inconsistent, the status S3 sent by the redundant communication is retrieved. If the status S3 sent by the redundant system is consistent with the status information S1 sent by the unit, it is determined that the unlocking condition is met; If the status information S3 sent by the redundant system is inconsistent with the status information S1 sent by the unit, and the voltage value sent by the unit with inconsistent status information is less than the working threshold, charging is stopped and the power switch is tripped; Step 4: After switching to manual bypass or replacing the faulty unit, re-execute step 2 until the unlocking conditions are met.

2. A method for determining unit protection during the startup phase of a cascaded voltage source converter according to claim 1, characterized in that: In step 3, the status of redundant communication transmission is detected once every 1 ms.

3. The method for determining unit protection during the startup phase of a cascaded voltage source converter according to claim 2, characterized in that: If the voltage value sent by the unit with inconsistent status information is lower than the working threshold within the time of △t≥1s, charging will be stopped and the power switch will be turned off.

4. A unit protection identification system for a cascaded voltage source converter during the startup phase, characterized in that: include: A preset module is used to set all units to normal status during initial charging; The control module is used to send a command to clear the fault when the voltage sent by all units exceeds the preset voltage value U1 after charging starts, and store the status information sent by the unit as S1; The stage fault detection and discrimination strategy module is used to determine the faulty unit. If there is no faulty unit, the charging is completed; if there is a faulty unit, the redundant communication status is detected. If the charging is not completed, the power switch is disconnected. The specific method of the stage fault detection and discrimination strategy is as follows: Read the unit main communication system status S2. If no faulty unit is found, it is determined that the unlocking condition is met; If the status information of the unit main communication system status S2 read twice is inconsistent, the status S3 sent by the redundant communication is retrieved. If the status S3 sent by the redundant system is consistent with the status information S1 sent by the unit, it is determined that the unlocking condition is met; If the status information S3 sent by the redundant system is inconsistent with the status information S1 sent by the unit, and the voltage value sent by the unit with inconsistent status information is less than the working threshold, charging is stopped and the power switch is tripped; Processing module, used to switch manual bypass or replace faulty unit.

5. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the unit protection identification method in the startup phase of a parallel voltage source converter as described in any one of claims 1 to 3 are implemented.

6. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it implements a unit protection identification method in the startup phase of a parallel voltage source converter as described in any one of claims 1 to 3.

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