Flexible direct current converter valve and power module communication fault protection method thereof, and computer equipment

Abstract

The invention belongs to the technical field of converter valves, and particularly relates to a flexible direct current converter valve, a power module communication fault protection method thereof and computer equipment. Comprising the following steps that when a converter valve controller cannot receive power module state information sent by a central control board of a certain power module, it is judged that the power module has an uplink communication fault, and the following uplink communication fault protection process is executed on the power module; and if yes, the converter valve controller sends a control instruction to the central control board of the power module to cut off the power module. Overvoltage damage caused by overcharge of the power module when uplink communication fails and the current direction is the charging direction can be avoided, and safe and stable operation of the converter valve is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of converter valves, and particularly relates to a flexible DC converter valve, a communication fault protection method for its power module, and a computer device. Background Art

[0002] In the prior art, most flexible DC converter valves adopt a modular multilevel topology and the nearest level approximation modulation method to sort the capacitor voltages of power modules in a bridge arm, and achieve voltage balance by controlling switching. Specific balance strategies include a charging voltage equalization strategy that preferentially inputs power modules with lower capacitor voltages during charging and a discharging voltage equalization strategy that preferentially inputs power modules with higher capacitor voltages during discharging. When a communication fault occurs between a certain power module and the converter valve controller, and the converter valve controller cannot receive the capacitor voltage of the power module, it is impossible to control the power module based on the capacitor voltage of the power module. To solve this problem, a communication fault protection strategy for power modules has been proposed in the prior art. When a communication fault occurs in the converter valve power module, first, the upper and lower two switching tubes are blocked, and then the corresponding protection strategy is selected according to the direction of the current. When the current direction is the charging direction, the upper switching tube is turned on to charge the capacitor of the power module. When the current direction is the discharging direction, the lower switching tube is turned on to cut off the power module. When the valve control cannot receive the capacitor voltage sent by the power module, if the capacitor voltage is high but the current direction continuously charges the capacitor of the charging module in the charging direction, it may cause the power module to be damaged due to overcharging and overvoltage, thus affecting the safe and stable operation of the entire converter valve. Summary of the Invention

[0003] The purpose of the present invention is to provide a flexible DC converter valve, a communication fault protection method for its power module, and a computer device to solve the technical problem that when the valve control in the prior art cannot receive the capacitor voltage of the power module and the current direction of the converter valve is the charging direction of the power module, the power module is damaged due to overvoltage, affecting the safe and stable operation of the converter valve.

[0004] To solve the above technical problem, the present invention provides a communication fault protection method for a flexible DC converter valve power module, including the following steps: When the converter valve controller cannot receive the power module status information sent by the control panel of a certain power module, it is determined that an uplink communication fault has occurred in the power module, and the following uplink communication fault protection process is executed for the power module: If the charging direction of the converter valve is the charging direction of the power module capacitor, the converter valve controller sends a control instruction to the control panel of the power module to cut off the power module.

[0005] Further, the process of the converter valve controller sending a control instruction to the central control board of the power module to cut off the power module includes: setting the capacitor voltage of the power module after the upstream communication failure according to the capacitor voltage reported last time before the upstream communication failure of the power module; the set capacitor voltage is greater than the capacitor voltage reported last time and is the larger value within the range of the capacitor voltages of all power modules in the converter valve, and implementing a charging voltage equalization strategy according to the capacitor voltage of the power module after the upstream communication failure.

[0006] Further, if the current direction of the converter valve is the direction of capacitor discharge of the power module, then set the capacitor voltage of the power module after the upstream communication failure according to the capacitor voltage reported last time before the upstream communication failure of the power module; the set capacitor voltage is less than the capacitor voltage reported last time and is the smaller value within the range of the capacitor voltages of all power modules in the converter valve, and implement a discharging voltage equalization strategy according to the capacitor voltage of the power module after the upstream communication failure.

[0007] Further, the following steps are also included: When the central control board of the power module cannot receive the control instruction sent by the converter valve controller, it is determined that the power module has a downstream communication failure, and the protection process for the downstream communication failure is executed: the central control board sends an instruction to the switching device of the power module to cut off the power module from the converter valve.

[0008] Further, the following steps are also included: After executing the corresponding communication failure protection strategy, judge whether the communication between the converter valve controller and the central control board of the power module is restored: if the communication is restored, end the corresponding communication failure protection process, and control the power module according to the control strategy of the converter valve controller; if the communication failure still exists, continue to execute the corresponding communication failure protection process, and execute the power module capacitor under-voltage protection strategy.

[0009] The present invention is an improved invention creation, and its beneficial effects are as follows: When the converter valve controller cannot receive the power module status information sent by the central control board of the power module, the present invention determines that the power module has an upstream communication failure. At this time, since the converter valve controller cannot receive the capacitor voltage sent by the power module and cannot execute the corresponding voltage equalization control strategy. At this time, if the current direction is the charging direction of the power module, it may cause overcharging of the capacitor and damage to the power module. To prevent this problem, after the power module has an upstream communication failure, the present invention first judges the current direction of the converter valve. If it is the charging direction of the power module, the converter valve controller sends a control instruction to the power module to control the power module to be cut off, thereby avoiding overcharging of the power module and ensuring the safe and stable operation of the converter valve and the power module.

[0010] To solve the above technical problems, the present invention also provides a computer device, including a processor, and the processor implements the method steps described in the flexible DC converter valve power module communication fault protection method of the present invention when executing a computer program.

[0011] The present invention is an improved invention, and its beneficial effects are the same as those of the flexible DC converter valve power module communication fault protection method of the present invention.

[0012] To solve the above technical problems, the present invention also provides a flexible DC converter valve, including a converter valve controller and a plurality of power modules. Each power module includes a central control board, and the converter valve controller includes a valve control processor. The valve control processor is used to implement the following flexible DC converter valve power module communication fault protection method when executing a computer program: When the converter valve controller cannot receive the power module status information sent by the central control board of a certain power module, it is determined that the power module has an upstream communication fault, and the following upstream communication fault protection process is executed for the power module: If the charging direction of the converter valve is the charging direction of the power module capacitor, the converter valve controller sends a control instruction to the central control board of the power module to cut off the power module.

[0013] Further, the process of the converter valve controller sending a control instruction to the central control board of the power module to cut off the power module includes: setting the capacitor voltage of the power module after the upstream communication fault according to the capacitor voltage reported last before the upstream communication fault of the power module; the set capacitor voltage is greater than the capacitor voltage reported last and is the larger value in the capacitor voltage range of all power modules in the converter valve, and the charging voltage equalization strategy is executed according to the capacitor voltage of the power module after the upstream communication fault.

[0014] Further, if the current direction of the converter valve is the discharging direction of the power module capacitor, the capacitor voltage of the power module after the upstream communication fault is set according to the capacitor voltage reported last before the upstream communication fault of the power module; the set capacitor voltage is less than the capacitor voltage reported last and is the smaller value in the capacitor voltage range of all power modules in the converter valve, and the discharging voltage equalization strategy is executed according to the capacitor voltage of the power module after the upstream communication fault.

[0015] Further, the central control board includes a central control board processor, and the central control board processor is used to implement the following flexible DC converter valve power module communication fault protection method when executing a computer program: When the central control board of the power module cannot receive the control instruction sent by the converter valve controller, it is determined that the power module has a downstream communication fault, and the protection process of the downstream communication fault is executed: the central control board sends an instruction to the switching device of the power module to cut off the power module from the converter valve.

[0016] This invention is an improved invention, and its beneficial effects are the same as those of the communication fault protection method for the power module of the flexible DC converter valve of this invention. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the power module structure of the flexible DC converter valve embodiment of this invention and the communication between the converter valve controller. Figure 2a and Figure 2b They are respectively schematic diagrams of the communication fault protection strategies when the current directions of the converter valves in the prior art mentioned in the flexible DC converter valve embodiment of this invention are different. Figure 3a and Figure 3b They are respectively schematic diagrams of the communication fault protection strategies when the current directions of the converter valves in the flexible DC converter valve embodiment of this invention are different. Figure 4 It is a flowchart of the communication fault protection method for the converter valve power module of the flexible DC converter valve embodiment of this invention. Detailed Embodiment

[0018] For a flexible DC converter valve of this invention, its power module communication fault protection method, and computer device, when the converter valve controller fails to receive the power module status information sent by the central control board of the power module, the power module is determined to have an upstream communication fault. At this time, since the converter valve controller cannot receive the capacitor voltage sent by the power module and cannot execute the corresponding voltage equalization control strategy. At this time, if the current direction is the charging direction of the power module, it may cause the capacitor to be overcharged and damage the power module. To prevent this problem, after the power module has an upstream communication fault, this invention first judges the current direction of the converter valve. If it is the charging direction of the power module, a control instruction is sent to the power module through the converter valve controller to control the power module to be cut off, thus avoiding overcharging of the power module and ensuring the safe and stable operation of the converter valve and the power module.

[0019] To make the purpose, technical solution, and advantages of this invention clearer, the following further details this invention in combination with the drawings and embodiments.

[0020] Embodiment of the flexible DC converter valve: Each arm of the flexible DC converter consists of hundreds of power modules connected in series, and all power modules are controlled by the converter valve controller (hereinafter referred to as valve control). The structure of a power module (half-bridge topology) and its communication relationship with the valve control are as Figure 1As shown in the figure, the power module includes two IGBTs (upper and lower), capacitors, bypass switches, and a central control board. The IGBT is the core power device of the converter valve; the function of the capacitor is to support the DC voltage of the system; the central control board is the core control unit of the power module, which uploads the current status information of the power module to the valve control, and after receiving and parsing the instructions from the valve control, controls the power module; the equalizing resistor plays a role in equalizing the voltages of each power module in the bridge arm and discharging the capacitor voltage after the power module fails and is bypassed; the function of the bypass switch is to receive the instruction from the control board and quickly bypass the power module when the power module fails. The converter valve controller includes a valve control processor. Among them, the valve control processor can be a processing device such as a microprocessor MCU or a programmable logic device FPGA. In this embodiment, a half-bridge topology is taken as an example for illustration. As other implementation manners, the present invention can also be applied to converter valves with other topology manners, and the principle of the communication fault protection strategy for the power module remains unchanged.

[0021] A pair of optical fibers are used to connect the communication interface between the valve control and the central control board of the power module, including an upstream optical fiber and a downstream optical fiber. The direction from the central control board of the power module to the valve control is called upstream. The direction from the valve control to the central control board of the power module is called downstream. The upstream communication content includes: power module status, power module capacitor voltage, power module fault, etc. The downstream communication content includes: drive, bypass switch instruction.

[0022] When there is no communication fault between the power module and the valve control, the equalizing strategy of the valve control module is: sort the capacitor voltages of all power modules, and control the on-off status of the IGBTs of the corresponding power modules according to the sorting situation of the capacitor voltages of each power module and the current direction of the power module; when the current is in the charging direction, the power module with a lower capacitor voltage is put into operation, and when the current is in the discharging direction, the power module with a higher capacitor voltage is put into operation. The communication fault protection strategies in the prior art are as Figure 2a and Figure 2b shown; Figure 2a is the protection strategy when the current direction is the charging direction of the power module. At this time, the upper switch tube of the power module is turned on, and the power module is put into charging, Figure 2b is the protection strategy when the current direction is the discharging direction of the power module. At this time, the lower switch tube of the power module is turned on, and the power module is cut off.

[0023] When there is a communication fault between the power module and the valve control, the communication fault protection method for the converter valve power module of the present invention has a specific process as Figure 4 shown, including the following steps: Step 1: Determine whether the communication fault is an upstream communication fault or a downstream communication fault.

[0024] If it is an upstream communication fault, the valve control sets the capacitors of the power modules according to the direction of the current, then sorts the capacitor voltages of all the power modules, and controls the states of the switching tubes of the faulty modules according to the sorting of the capacitor voltages of the power modules with communication faults and the direction of the current. The valve control processor is used to execute a computer program to implement the upstream communication fault protection process. The specific steps are as follows: 1.1. Judge the current direction of the converter valve.

[0025] Judge the current direction of the converter valve through the current mutual induction module of the converter valve. If the current direction is the charging direction of the power module, the valve control sets the capacitor voltage of the current power module to a larger value. If the current direction is the discharging direction, the valve control sets the capacitor voltage of the power module to a smaller value.

[0026] In this embodiment, the method of setting the capacitor voltage of the power module with communication fault to a larger value / smaller value is to multiply the capacitor voltage reported by the power module for the last time before the fault by a corresponding coefficient to obtain a larger value / smaller value. Specifically: Take the product of the capacitor voltage reported by the power module for the last time before the upstream communication fault and the first setting coefficient as the capacitor voltage of the power module after the upstream communication fault, and execute the charging equalization strategy according to the capacitor voltage of the power module after the upstream communication fault. The first setting coefficient is used to set the capacitor voltage of the power module after the upstream communication fault to a larger value among the capacitor voltages of all the power modules in the converter valve. The first setting coefficient is greater than one. The set capacitor voltage is greater than the capacitor voltage reported for the last time and is a larger value within the range of the capacitor voltages of all the power modules in the converter valve.

[0027] If the judgment result of the current direction of the converter valve is the capacitor discharging direction of the power module, take the product of the capacitor voltage reported by the power module for the last time before the upstream communication fault and the second setting coefficient as the capacitor voltage of the power module after the upstream communication fault, and execute the discharging equalization strategy according to the capacitor voltage of the power module after the upstream communication fault. The second setting coefficient is used to set the capacitor voltage of the power module after the upstream communication fault to a smaller value among the capacitor voltages of all the power modules in the converter valve. The second setting coefficient is less than one. The set capacitor voltage is less than the capacitor voltage reported for the last time and is a smaller value within the range of the capacitor voltages of all the power modules in the converter valve.

[0028] 1.2. Sort the voltages of all the power modules in the converter valve.

[0029] After setting the capacitor voltage of the power module with a completed fault, the capacitor voltages of all power modules in the converter valve can be sorted. Then, according to the sorting result and the direction of the current, the corresponding voltage equalization strategy (charging voltage equalization strategy or discharging voltage equalization strategy) is executed. The valve control sends a control instruction to the central control board of the power module with a communication fault according to the voltage equalization strategy to control the state of the switching tube of the power module, thereby realizing the switching on and off of the power module.

[0030] 1.3. The central control board controls the switching tube according to the received control, thereby realizing the switching on and off of the power module.

[0031] When the current direction is the charging direction, the valve control sets the capacitor voltage of the current power module to a larger value. At this time, the voltage equalization strategy is to give priority to putting the power module with a lower capacitor voltage into operation. Therefore, in most cases, the current power module needs to be cut off. In this embodiment, this situation is taken as an example for illustration. At this time, the instruction sent by the valve control to the central control board of the power module is a cut-off instruction. After receiving the cut-off instruction, the central control board controls the lower tube to conduct and cuts off the current power module. After the power module is cut off, the capacitor voltage of the power module is continuously discharged through the voltage equalizing resistor R. As Figure 3a shown.

[0032] When the current direction is the discharging direction, the valve control sets the capacitor voltage of the current power module to a smaller value. At this time, the voltage equalization strategy is to give priority to putting the power module with a higher capacitor voltage into operation. Therefore, in this case, most of the time, the current power module with a communication fault needs to be cut off to prevent it from discharging and maintain the stability of its capacitor voltage. In this embodiment, this situation is taken as an example for illustration. At this time, the instruction sent by the valve control to the central control board of the power module is a cut-off instruction. After receiving the cut-off instruction, the central control board controls the lower tube to conduct and cuts off the current power module. After the power module is cut off, the capacitor voltage of the power module is continuously discharged through the voltage equalizing resistor R. As Figure 3b shown.

[0033] In addition to the upstream communication fault, the communication fault of the power module also includes the downstream communication fault. When the communication fault of the power module is the downstream communication fault, at this time, the central control board of the power module cannot receive the control instruction from the valve control. The communication fault protection method at this time includes the following steps: 2.1. When an upstream communication fault occurs between the power module and the valve control, the central control board of the power module directly sends an instruction to the switching tube of the power module to control the lower switching tube of the fault module to conduct, realizing the cut-off of the power module. This can prevent the power module from remaining in a charging / discharging working mode for a long time because it cannot receive the control instruction from the valve control all the time, thereby causing abnormal capacitor voltage and affecting the normal use of the power module.

[0034] When a communication fault occurs in the power module for the upstream communication, the communication fault protection of the power module is carried out through steps 1.1 to 1.3. When a downstream communication fault occurs, the communication fault protection is carried out through step 2.1.

[0035] Step 2: Determine whether the communication between the valve control and the central control board has been restored.

[0036] The central control board processor is used to implement the protection process for the downstream communication fault of the power module when executing the computer program. The specific process is as follows: If the communication between the two is restored, the protection logic is exited and the control is restored to the valve control. Otherwise, the central control board determines whether to perform undervoltage protection according to the capacitor voltage. When the capacitor voltage is lower than the set undervoltage threshold, the undervoltage protection is triggered; otherwise, it is not triggered.

[0037] After the power module is removed, the valve control or the central control board of the power module will continuously detect the status of the communication signal. When it is detected that the communication signal of this path is restored and a delay judgment is passed, it is determined that the valve control resumes the control of this power module, and the communication fault protection process provided by the present invention is exited. If the communication of this path cannot be restored, the faulty power module will be in a continuous cut-off state and will naturally discharge through the equalizing resistor R inside the power module. Finally, the bypass protection logic for the capacitor undervoltage threshold of the power module is triggered, the central control board issues a bypass switch trigger command, and the bypass trigger board triggers the bypass switch to close, realizing the removal of the faulty power module from the main circuit. The valve control logic of the above protection method is as Figure 4 shown.

[0038] Example of the communication fault protection method for the power module of the flexible DC converter valve: The communication fault protection method for the power module of the flexible DC converter valve of the present invention is as described in the embodiment of the flexible DC converter valve. The specific process, principle, beneficial effects, etc. of this method have been described in detail in the method embodiment, and will not be repeated in this embodiment.

[0039] Example of the computer device: A computer device of the present invention includes a processor. When the processor executes the computer program, it implements the method steps for the upstream communication fault protection of the power module described in the embodiment of the flexible DC converter valve. The specific process, principle, beneficial effects, etc. of this method have been described in detail in the method embodiment, and will not be repeated in this embodiment.

[0040] In summary, for a flexible DC converter valve of the present invention, its power module communication fault protection method, and computer device, when an upstream communication fault occurs between the power module and the converter valve controller, the current direction of the converter valve is judged. If it is the charging direction of the power module, the converter valve controller sends a control instruction to the power module, thereby controlling the power module to be cut off, ensuring that the power module capacitor will not be damaged due to overcharging and overvoltage, and thus ensuring the reliable and safe operation of the entire converter valve. Further, the present invention sets the voltage of the power module with an upstream communication fault to a relatively large value, and then sorts the capacitor voltages of all power modules in the converter valve, so as to cut off the power module by means of the charging voltage equalization strategy in the converter valve controller, without the need for major modification of the original control logic of the converter valve controller, and the solution is simple and easy to implement. Further, when the upstream communication of the power module fails and the current direction is the discharging direction, the present invention cuts off the power module by setting the capacitor voltage of the power module to a relatively small value, and also realizes it by means of the original logic of the controller, and the solution is simple and easy to implement. In addition to the upstream communication fault protection strategy, the present invention also proposes a downstream communication fault protection strategy. In the case of a downstream communication fault, the power module cannot receive instructions from the converter valve controller. Therefore, in this case, the central control board of the power module directly controls the lower switch tube to conduct, cutting off the power module to prevent overcharging damage of the power module and further ensuring the safe use of the converter valve.

Claims

1. A method for protecting a power module of a flexible direct current converter valve from a communication fault, characterized in that: The following steps are involved: When the converter valve controller cannot receive the power module status information sent by the central control board of a power module, it is determined that an uplink communication failure occurs in the power module, and the following uplink communication failure protection process is performed on the power module: If the charging direction of the converter valve is the charging direction of the power module capacitor, the converter valve controller sends a control instruction to the central control board of the power module to cut off the power module.

2. The method for protecting a power module of a flexible direct current converter valve from a communication fault according to claim 1, characterized in that: The process of the converter valve controller sending a control instruction to the central control board of the power module to cut off the power module includes: setting the capacitor voltage of the power module after the uplink communication failure according to the last reported capacitor voltage before the uplink communication failure of the power module; the set capacitor voltage is greater than the last reported capacitor voltage and is a larger value in the range of the capacitor voltages of all power modules in the converter valve, and executing a charging voltage equalization strategy according to the capacitor voltage after the uplink communication failure of the power module.

3. The method for protecting a power module of a flexible direct current converter valve from a communication fault according to claim 1, characterized in that: If the current direction of the converter valve is the discharge direction of the power module capacitor, the capacitor voltage after the uplink communication failure of the power module is set according to the capacitor voltage reported last time before the uplink communication failure of the power module occurs; the set capacitor voltage is smaller than the capacitor voltage reported last time and is a smaller value in the range of the capacitor voltages of all power modules in the converter valve, and the discharge voltage equalization strategy is executed according to the capacitor voltage after the uplink communication failure of the power module.

4. The method for protecting a power module of a flexible direct current converter valve from a communication fault according to claim 1, characterized in that: The following steps are also included: When the central control board of the power module cannot receive the control command sent by the converter valve controller, it is determined that a downlink communication failure occurs in the power module, and the protection process of the downlink communication failure is executed: the central control board sends a command to the switch device of the power module to realize the removal of the power module from the converter valve.

5. The method for protecting a power module of a flexible direct current converter valve from a communication fault according to any one of claims 1 to 4, characterized in that: The following steps are also included: After executing the corresponding communication fault protection strategy, determine whether the communication between the converter valve controller and the power module central control board is restored: if the communication is restored, end the corresponding communication fault protection process, and control the power module according to the control strategy of the converter valve controller; if the communication fault still exists, continue to execute the corresponding communication fault protection process, and execute the power module capacitor undervoltage protection strategy.

6. A computer device comprising a processor, characterized in that: The processor implements the steps of the flexible direct current converter valve power module communication fault protection method as described in any one of claims 1 to 3 when executing the computer program.

7. A flexible direct current converter valve, comprising a converter valve controller and a plurality of power modules, each power module comprising a central control board, and the converter valve controller comprising a valve control processor, characterized in that: The valve control processor is used to implement the following flexible direct current converter valve power module communication fault protection method when executing the computer program: When the converter valve controller cannot receive the power module status information sent by the central control board of a power module, it is determined that an uplink communication failure occurs in the power module, and the following uplink communication failure protection process is performed on the power module: If the charging direction of the converter valve is the charging direction of the power module capacitor, the converter valve controller sends a control instruction to the central control board of the power module to cut off the power module.

8. The flexible direct current valve according to claim 7, characterized in that: The process of the converter valve controller sending a control instruction to the central control board of the power module to cut off the power module includes: setting the capacitor voltage of the power module after the uplink communication failure according to the last reported capacitor voltage before the uplink communication failure of the power module; the set capacitor voltage is greater than the last reported capacitor voltage and is a larger value in the range of the capacitor voltages of all power modules in the converter valve, and executing a charging voltage equalization strategy according to the capacitor voltage after the uplink communication failure of the power module.

9. The flexible direct current valve according to claim 7, characterized in that: If the current direction of the converter valve is the discharge direction of the power module capacitor, the capacitor voltage after the uplink communication failure of the power module is set according to the capacitor voltage reported last time before the uplink communication failure of the power module occurs; the set capacitor voltage is smaller than the capacitor voltage reported last time and is a smaller value in the range of the capacitor voltages of all power modules in the converter valve, and the discharge voltage equalization strategy is executed according to the capacitor voltage after the uplink communication failure of the power module.

10. The flexible direct current converter valve according to claim 7, characterized in that: The central control board includes a central control board processor, and the central control board processor is used to implement the following flexible direct current converter valve power module communication fault protection method when executing a computer program: When the central control board of the power module cannot receive the control command sent by the converter valve controller, it is determined that a downlink communication failure occurs in the power module, and the protection process of the downlink communication failure is executed: the central control board sends a command to the switch device of the power module to realize the removal of the power module from the converter valve.

Images