Direct current converter valve, control method and system

Abstract

The application provides a direct current converter valve, a control method and a system. The direct current converter valve comprises: a plurality of bridge arms, a plurality of power components are connected in series in each bridge arm, the power component comprises at least one power device; a plurality of voltage sharing modules are connected in parallel at the input end and the output end of the power component, the voltage sharing module comprises a dynamic voltage sharing unit and a static voltage sharing unit connected in parallel, the dynamic voltage sharing unit is connected in parallel with the power component, the dynamic voltage sharing unit comprises a branch formed by a switching component and a preset capacitor, the dynamic voltage sharing unit is used for voltage sharing of the power device in a fault recovery conduction state and a fault state, and the static voltage sharing unit is used for voltage sharing of the power device in a blocking state, so that the problem of insufficient voltage sharing effect of a plurality of semiconductor devices connected in series in the bridge arm of the converter valve is solved.

Description

Technical Field

[0001] This application relates to the field of high voltage direct current transmission technology, and more specifically, to a DC converter valve, a control method for the DC converter valve, and a DC converter valve system. Background Technology

[0002] High-voltage direct current (HVDC) transmission technology is a crucial means of achieving long-distance, high-capacity power transmission in my country's power system. The reliability and economy of its core component, the DC converter valve, directly affect the safe and stable operation of the entire power system. Traditional converter valves are constructed using high-voltage, high-power devices connected in series, including IGBTs and IGCTs. However, inherent parameter dispersion exists between these devices, particularly inconsistencies in their turn-off characteristics. This leads to uneven voltage stress on the series-connected devices during turn-off, posing risks of overvoltage and voltage stress overshoot, thus threatening the operational reliability of the devices. Summary of the Invention

[0003] The main objective of this application is to provide a DC converter valve, control method, and system to at least solve the problem of insufficient voltage equalization effect for multiple semiconductor devices connected in series in the converter valve bridge arm in the related art.

[0004] To achieve the above objectives, according to one aspect of this application, a DC converter valve is provided, comprising: multiple bridge arms, each bridge arm having multiple power components connected in series, each power component including at least one power device; multiple voltage equalization modules connected in parallel to the input and output terminals of the power components, each voltage equalization module including a dynamic voltage equalization unit and a static voltage equalization unit connected in parallel, the dynamic voltage equalization unit being connected in parallel with the power components, the dynamic voltage equalization unit including a branch formed by a switching component and a preset capacitor electrically connected, the dynamic voltage equalization unit being used to equalize the voltage of the power devices in fault recovery conduction and fault shutdown states, and the static voltage equalization unit being used to equalize the voltage of the power devices in a blocking state.

[0005] Optionally, the power component includes a power device, and the dynamic voltage equalization unit includes: a first voltage equalization unit and a second voltage equalization unit connected in parallel, wherein the first voltage equalization unit is connected in parallel across the power device, and the second voltage equalization unit is connected in parallel across the first voltage equalization unit.

[0006] Optionally, the power component includes a power device, and the dynamic voltage equalization unit includes a first voltage equalization unit and a second voltage equalization unit, wherein the first voltage equalization unit is connected in parallel across the two ends of the power device, and the second voltage equalization unit is connected in parallel across the two ends of the damping capacitor in the first voltage equalization unit.

[0007] Optionally, the second voltage equalization unit includes: a first switching assembly, a first capacitor, and a first resistor, wherein a first terminal of the first switching assembly is electrically connected to the first voltage equalization unit, a second terminal of the first switching assembly is electrically connected to the first terminal of the first capacitor and the first terminal of the first resistor, and the second terminals of the first capacitor and the first resistor are both electrically connected to the output terminal of the first voltage equalization unit.

[0008] Optionally, the second voltage equalization unit includes: a second switching assembly and a second capacitor, wherein a first terminal of the second switching assembly is electrically connected to a first terminal of the damping capacitor, a second terminal of the second switching assembly is electrically connected to a first terminal of the second capacitor, and a second terminal of the second capacitor is electrically connected to a second terminal of the damping capacitor.

[0009] Optionally, the power assembly includes two power devices, namely a first power device and a second power device. The dynamic voltage equalization unit includes a third voltage equalization unit and a fourth voltage equalization unit. The first end of the third voltage equalization unit is electrically connected to the anode of the first power device, the second end of the third voltage equalization unit is electrically connected to the cathode of the first power device and the anode of the second power device, and the third end of the third voltage equalization unit is electrically connected to the cathode of the first power device and the anode of the second power device, with the second end close to the first power device and the third end close to the second power device. The first end of the fourth voltage equalization unit is the second end of the third voltage equalization unit, the second end of the fourth voltage equalization unit is the third end of the third voltage equalization unit, and the third end of the fourth voltage equalization unit is electrically connected to the cathode of the second power device.

[0010] Optionally, the third voltage equalization unit and the fourth voltage equalization unit share a damping resistor, a first diode, and a second diode. The third voltage equalization unit includes: a third switching assembly, a damping capacitor, a third capacitor, a damping resistor, a first diode, and a second diode. The first terminal of the third switching assembly is electrically connected to the anode of the first power device and the first terminal of the damping capacitor, respectively. The second terminal of the third switching assembly is electrically connected to the first terminal of the third capacitor. The second terminal of the damping capacitor is electrically connected to the anode of the first diode, the second terminal of the third capacitor, and the first terminal of the damping resistor, respectively. The cathode of the first diode is electrically connected to the cathode of the first power device and the anode of the second power device, respectively. The second terminal of the damping resistor is electrically connected to the cathode of the second diode. The anode of the second diode is also electrically connected to the anode of the second power device.

[0011] Optionally, the third voltage equalization unit and the fourth voltage equalization unit share a damping resistor, a first diode, and a second diode. The fourth voltage equalization unit includes: a fourth switching assembly, a damping capacitor, a fourth capacitor, a damping resistor, a first diode, and a second diode. The cathode of the first diode is electrically connected to the cathode of the first power device, the anode of the second power device, and the anode of the second diode, respectively. The anode of the first diode is electrically connected to the first end of the damping resistor. The second end of the damping resistor is electrically connected to the cathode of the second diode, the first end of the fourth switching assembly, and the first end of the damping capacitor, respectively. The anode of the second diode is also electrically connected to the anode of the second power device. The second end of the fourth switching assembly is electrically connected to the first end of the fourth capacitor. The second end of the fourth capacitor is electrically connected to the second end of the damping capacitor and the cathode of the second power device, respectively.

[0012] Optionally, the power component includes a power device, and the dynamic voltage equalization unit includes a fifth voltage equalization unit and a sixth voltage equalization unit, wherein the fifth voltage equalization unit is connected in parallel across the two ends of the power device, and the sixth voltage equalization unit is connected in series with the damping capacitor and damping resistor in the fifth voltage equalization unit.

[0013] Optionally, the fifth voltage equalization unit includes a damping resistor, a third diode, a damping capacitor, and a fifth capacitor. The first end of the damping resistor is electrically connected to the anode of the power device and the anode of the third diode, respectively. The first end of the damping capacitor is electrically connected to the second end of the damping resistor and the cathode of the third diode, respectively. The second end of the damping capacitor is electrically connected to the first end of the fifth capacitor, and the second end of the fifth capacitor is electrically connected to the cathode of the power device. The sixth voltage equalization unit includes a fifth switching assembly, which is connected in parallel across the two ends of the damping capacitor.

[0014] Optionally, the power assembly includes two power devices, namely a third power device and a fourth power device, and the dynamic voltage equalization unit includes a seventh voltage equalization unit and an eighth voltage equalization unit. The first end of the seventh voltage equalization unit is electrically connected to the anode of the third power device, the second end of the seventh voltage equalization unit is electrically connected to the cathode of the third power device and the anode of the fourth power device, and the third end of the seventh voltage equalization unit is electrically connected to the cathode of the third power device and the anode of the fourth power device, with the second end close to the third power device and the third end close to the fourth power device. The first end of the eighth voltage equalization unit is the second end of the seventh voltage equalization unit, the second end of the eighth voltage equalization unit is the third end of the seventh voltage equalization unit, and the third end of the eighth voltage equalization unit is electrically connected to the cathode of the fourth power device.

[0015] Optionally, the seventh voltage equalization unit and the eighth voltage equalization unit share a damping resistor, a fourth diode, and a fifth diode. The seventh voltage equalization unit includes: a sixth switching assembly, a damping capacitor, a sixth capacitor, a damping resistor, a fourth diode, and a fifth diode. The first terminal of the damping capacitor is electrically connected to the anode of the third power device and the first terminal of the sixth switching assembly, respectively. The second terminal of the damping capacitor is electrically connected to the second terminal of the sixth switching assembly and the first terminal of the sixth capacitor, respectively. The second terminal of the sixth capacitor is electrically connected to the anode of the fourth diode and the first terminal of the damping resistor, respectively. The cathode of the fourth diode is electrically connected to the anode of the fifth diode, the cathode of the third power device, and the anode of the fourth power device, respectively. The anode of the fifth diode is also electrically connected to the anode of the fourth power device, and the cathode of the fifth diode is electrically connected to the second terminal of the damping resistor.

[0016] Optionally, the seventh voltage equalization unit and the eighth voltage equalization unit share a damping resistor, a fourth diode, and a fifth diode. The eighth voltage equalization unit includes: a seventh switching assembly, a damping capacitor, a seventh capacitor, a damping resistor, a fourth diode, and a fifth diode. The cathode of the fourth diode is electrically connected to the cathode of the third power device, the anode of the fifth diode, and the anode of the fourth power device, respectively. The anode of the fourth diode is electrically connected to the first end of the damping resistor. The first end of the damping capacitor is electrically connected to the cathode of the fifth diode, the second end of the damping resistor, and the first end of the seventh switching assembly, respectively. The first end of the seventh capacitor is electrically connected to the second end of the damping capacitor and the second end of the seventh switching assembly, respectively. The second end of the seventh capacitor is electrically connected to the cathode of the fourth power device.

[0017] According to another aspect of this application, a control method for a DC converter valve is provided, the control method comprising: acquiring operating information of the AC side of the DC converter valve, the operating information indicating whether an AC fault has occurred on the AC side; when no AC fault has occurred on the AC side, controlling a plurality of dynamic voltage equalization units in the DC converter valve to shut down; when an AC fault has occurred on the AC side, controlling the power devices in the faulty bridge arm corresponding to the AC fault in the DC converter valve to actively shut down, and turning on a dynamic voltage equalization unit connected in parallel across at least one of the power devices, the dynamic voltage equalization unit performing voltage equalization on the power devices in the actively shut-down state; after the AC fault is recovered, controlling the power devices in the original faulty bridge arm to turn on, and turning off the dynamic voltage equalization unit to release the electrical energy stored in the dynamic voltage equalization unit, and resetting the dynamic voltage equalization unit.

[0018] Optionally, controlling the power device in the faulty bridge arm of the DC converter valve corresponding to the occurrence of the AC fault to actively shut down, and the dynamic voltage equalization unit connected in parallel across at least one of the power devices to turn on, includes: controlling the power device in the faulty bridge arm to actively shut down and sending a positive pressure signal to the switching component of the dynamic voltage equalization unit, so that the switching component turns on in response to the received positive pressure signal, thereby turning on the dynamic voltage equalization unit.

[0019] Optionally, controlling the power device of the original faulty bridge arm to turn on and the dynamic voltage equalization unit to turn off includes: after the AC fault is restored, controlling the power device of the original faulty bridge arm to turn on and sending a negative voltage signal to the switching component of the dynamic voltage equalization unit, so that the switching component turns off in response to the received negative voltage signal, thereby turning off the dynamic voltage equalization unit.

[0020] According to another aspect of this application, a DC converter valve system is provided, including a controller and the DC converter valve, wherein the controller is used to execute a control method for the DC converter valve.

[0021] By applying the technical solution of this application, a voltage equalization module is connected in parallel at the power components of the DC converter valve bridge arm. The parallel connection of the dynamic voltage equalization unit and the static voltage equalization unit in the voltage equalization module realizes voltage equalization control of the power devices under different states, improving the flexibility and efficiency of voltage equalization. Specifically, the switching component in the dynamic voltage equalization unit conducts when the device is in a fault recovery conduction state or a fault shutdown state. The preset capacitor charges when the switching component is on and discharges when the switching component is off, thereby regulating the voltage change rate across the device, reducing dynamic voltage differences, and achieving voltage equalization. The static voltage equalization unit balances leakage current and reduces static voltage differences when the device is in a blocking state during normal commutation of the DC converter valve. The static and dynamic voltage equalization work together to solve the problem of insufficient voltage equalization effect for multiple semiconductor devices connected in series in the converter valve bridge arm in related technologies. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0023] Figure 1 A schematic diagram of the structure of a first DC converter valve provided in an embodiment of this application is shown;

[0024] Figure 2 A schematic diagram of the structure of a second DC converter valve provided in an embodiment of this application is shown;

[0025] Figure 3 A schematic diagram of the structure of a third DC converter valve provided in an embodiment of this application is shown;

[0026] Figure 4 A schematic diagram of the structure of a fourth DC converter valve provided in an embodiment of this application is shown;

[0027] Figure 5 A schematic diagram of the structure of a fifth DC converter valve provided in an embodiment of this application is shown;

[0028] Figure 6 A schematic diagram of the structure of a sixth DC converter valve provided in an embodiment of this application is shown;

[0029] Figure 7 A schematic diagram of the structure of a seventh DC converter valve provided in an embodiment of this application is shown;

[0030] Figure 8 A schematic diagram of the structure of an eighth DC converter valve provided in an embodiment of this application is shown;

[0031] Figure 9 A schematic diagram of the structure of a ninth DC converter valve provided in an embodiment of this application is shown;

[0032] Figure 10 A schematic flowchart of a control method for a DC converter valve provided in an embodiment of this application is shown.

[0033] The above figures include the following reference numerals:

[0034] 10. Power component; 11. Power device; 12. First power device; 13. Second power device; 14. Third power device; 15. Fourth power device; 20. Voltage equalization module; 21. Dynamic voltage equalization unit; 22. Static voltage equalization unit; 23. First voltage equalization unit; 24. Second voltage equalization unit; 25. Third voltage equalization unit; 26. Fourth voltage equalization unit; 231. Damping capacitor; 232. Damping resistor; 233. Diode. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0037] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0038] As described in the background section, in related technologies, converter valves are constructed by connecting high-voltage, high-power devices in series. These devices experience uneven voltage stress during the turn-off process, posing risks of overvoltage and voltage stress overshoot, which threatens the operational reliability of the devices. To address the problem of insufficient voltage equalization effect for multiple semiconductor devices connected in series in the converter valve bridge arm, embodiments of this application provide a DC converter valve, control method, and system.

[0039] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0040] According to one aspect of the embodiments of this application, a DC converter valve is provided, such as... Figure 1 As shown, it includes: multiple bridge arms, each bridge arm having multiple power components 10 connected in series, each power component 10 including at least one power device; multiple voltage equalization modules 20 connected in parallel to the input and output terminals of the power components 10, each voltage equalization module 20 including a dynamic voltage equalization unit 21 and a static voltage equalization unit 22 connected in parallel, the dynamic voltage equalization unit 21 being connected in parallel with the power components 10, the dynamic voltage equalization unit 21 including a branch formed by a switching component and a preset capacitor electrically connected, the dynamic voltage equalization unit 21 being used to equalize the voltage of the power devices in the fault recovery conduction and fault shutdown states, and the static voltage equalization unit 22 being used to equalize the voltage of the power devices in the blocking state.

[0041] By connecting a voltage equalization module with dynamic and static voltage equalization units in parallel at the power components of the DC converter valve bridge arm, voltage equalization control of the power devices under different states (active shutdown, conduction, and blocking) can be achieved, improving the flexibility and efficiency of voltage equalization. Specifically, when an AC fault occurs and the power device is actively shut down, the switching assembly receives the positive voltage signal generated by the active shutdown and then conducts, connecting a preset capacitor to the circuit to limit the voltage rise across the power device, thereby suppressing voltage stress overshoot. When the device resumes conduction after shutdown, the switching assembly receives the negative voltage signal generated by the device resuming conduction and then disconnects, allowing the preset capacitor to discharge to the power device through the switching assembly, buffering the voltage drop rate during turn-on. This flexible capacitor switching mechanism significantly reduces the rate of change of voltage stress and improves the voltage equalization effect. During normal commutation of the DC converter valve, when the device is in a blocking state, the static voltage equalization unit can balance leakage current and reduce static voltage differences. The aforementioned DC converter valve solves the problem of insufficient voltage equalization effect for multiple semiconductor devices connected in series in the converter valve bridge arm in related technologies.

[0042] The static voltage equalization unit mentioned above can be a resistor with a high resistance value. After the static voltage equalization unit is connected in parallel with the power device, the resistance value of the static voltage equalization unit is smaller than the equivalent impedance value of the power device in the blocking state. This helps to balance the leakage current in the blocking state, reduce the static voltage difference between devices, and ensure that the voltage distribution between devices is consistent under steady-state operating conditions, thus achieving voltage equalization.

[0043] The aforementioned power components can be connected in series with one power device or two power devices. The power devices can be fully controlled devices, such as insulated gate bipolar transistors (IGBTs) and integrated gate commutated thyristors (IGCTs). The aforementioned switching components can be fully controlled devices or semi-controlled devices. The preset capacitor has a relatively large capacitance value in order to absorb or provide more current when the power devices are actively turned off and on, thereby improving the reliability of the voltage equalization module.

[0044] To further enhance the pressure equalization effect, in some optional implementations, such as Figure 2 As shown, the power assembly includes a power device 11, and the dynamic voltage equalization unit includes a first voltage equalization unit 23 and a second voltage equalization unit 24 connected in parallel. The first voltage equalization unit 23 is connected in parallel across the power device 11, and the second voltage equalization unit 24 is connected in parallel across the first voltage equalization unit 23. The first voltage equalization unit 23 is directly connected in parallel with the power device 11 to absorb voltage fluctuations during switching transients. The second voltage equalization unit 24 can control the connection and disconnection of a large capacitor (preset capacitor) according to the state of the power device 11, thereby effectively suppressing voltage overshoot.

[0045] To further enhance the flexibility of the voltage equalization circuit, the first and second voltage equalization units can also have different connection methods. In some optional implementations, such as... Figure 3 As shown, the power component includes a power device 11, and the dynamic voltage equalization unit includes a first voltage equalization unit 23 and a second voltage equalization unit 24. The first voltage equalization unit 23 is connected in parallel across the two ends of the power device 11, and the second voltage equalization unit 24 is connected in parallel across the two ends of the damping capacitor in the first voltage equalization unit 23.

[0046] like Figure 4 and Figure 5 As shown, the first voltage equalization unit includes a damping capacitor 231, a damping resistor 232, and a diode 233. The first voltage equalization unit operates continuously in the circuit during the daily operation of the converter valve to absorb redundant current generated by the power device 11 during switching, thereby achieving daily voltage equalization. Alternatively, the first voltage equalization unit can also be formed by simply connecting the damping capacitor 231 and the damping resistor 232 in series.

[0047] In some alternative implementations, such as Figure 4 and Figure 5 As shown, the second voltage equalization unit includes: a first switching component T1, a first capacitor C1, and a first resistor R1. The first terminal of the first switching component T1 is electrically connected to the first voltage equalization unit 23. The second terminal of the first switching component T1 is electrically connected to both the first terminal of the first capacitor C1 and the first terminal of the first resistor R1. The second terminals of both the first capacitor C1 and the first resistor R1 are electrically connected to the output terminal of the first voltage equalization unit 23. The first switching component T1 can be a fully controllable device (IGCT, IGBT, etc.) or a thyristor. Figure 4 As shown, the first terminal of the first switching assembly T1 is electrically connected to the input terminal of the first voltage equalization unit 23, as follows: Figure 5As shown, the first terminal of the first switching component T1 of the second voltage equalization unit 24 is electrically connected to the first terminal of the damping capacitor 231. The second terminals of the first capacitor C1 and the first resistor R1 are both electrically connected to the second terminal of the damping capacitor 231. When the power device 11 in the figure experiences voltage imbalance with other power devices 11 due to reverse recovery charge during reverse recovery, the power device 11 in the figure bears a negative voltage. Reverse recovery voltage equalization is mainly achieved through the damping capacitor 231 and the damping resistor 232. When the power device 11 in the figure is actively turned off, the first switching component T1 is turned on under positive voltage. The first capacitor C1 is connected as an active voltage equalization capacitor, and the damping capacitor 231 is also connected through the diode 233. Together with the first capacitor C1, they suppress the voltage inconsistency during the active turn-off process. When the power device 11 in the figure is turned on again, the first switching component T1 is turned off under reverse voltage. The first switching component T1 is only turned on when the power device 11 in the figure is actively turned off and when it is turned on after being actively turned off. During the normal reverse recovery from turn-off and off-state process, the first switching component T1 is in the off-state, which can reduce losses during the daily use of the converter valve.

[0048] To further reduce costs, in some alternative implementations, such as Figure 6 As shown, the second voltage equalization unit includes a second switching component T2 and a second capacitor C2. The first end of the second switching component T2 is electrically connected to the first end of the damping capacitor 231, the second end of the second switching component T2 is electrically connected to the first end of the second capacitor C2, and the second end of the second capacitor C2 is electrically connected to the second end of the damping capacitor 231. The second switching component T2 can be a fully controlled device (IGCT, IGBT) anti-parallel thyristor, or a bidirectional switching transistor, or two fully controlled devices anti-parallel. When the power device 11 is actively turned off, the second switching component T2 is turned on, and a large capacitor (second capacitor C2) is used for voltage equalization. When the power device 11 is turned off and in the on state, the second capacitor C2 and the damping capacitor 231 of the first voltage equalization unit 23 share the damping resistor 232 for discharge. This can save resistors and reduce costs.

[0049] To further reduce costs and improve the interoperability between multiple power devices, in some optional embodiments, the power assembly includes two power devices, designated as a first power device and a second power device. The dynamic voltage equalization unit includes a third voltage equalization unit and a fourth voltage equalization unit. The first terminal of the third voltage equalization unit is electrically connected to the anode of the first power device, the second terminal is electrically connected to both the cathode of the first power device and the anode of the second power device, and the third terminal is electrically connected to both the cathode of the first power device and the anode of the second power device, with the second terminal close to the first power device and the third terminal close to the second power device. The first terminal of the fourth voltage equalization unit is the second terminal of the third voltage equalization unit, the second terminal is the third terminal of the third voltage equalization unit, and the third terminal is electrically connected to the cathode of the second power device. The third voltage equalization unit is used to equalize the voltage of the first power device, while the fourth voltage equalization unit is used to equalize the voltage of the second power device. For a power assembly consisting of two power devices, by sharing a port between the third and fourth voltage equalization units, the number of components is reduced, saving costs and reducing circuit area. Furthermore, the linkage control of the two power devices enables more precise voltage stress control.

[0050] In some alternative implementations, such as Figure 7As shown, the third voltage equalization unit 25 and the fourth voltage equalization unit 26 share a damping resistor 232, a first diode (diode 233 of the first power device 12), and a second diode (diode 233 of the second power device 13). The third voltage equalization unit 25 includes: a third switching assembly T3, a damping capacitor 231, a third capacitor C3, a damping resistor 232, a first diode (diode 233 of the first power device 12), and a second diode (diode 233 of the second power device 13). The first terminal of the third switching assembly T3 is electrically connected to the anode of the first power device 12 and the first terminal of the damping capacitor 231, respectively. The first terminal of the third capacitor C3 is electrically connected to the second terminal of the damping capacitor 231. The second terminal of the damping capacitor 231 is electrically connected to the anode of the first diode (diode 233 of the first power device 12), the second terminal of the third capacitor C3, and the first terminal of the damping resistor 232. The cathode of the first diode (diode 233 of the first power device 12) is electrically connected to the cathode of the first power device 12 and the anode of the second power device 13. The second terminal of the damping resistor 232 is electrically connected to the cathode of the second diode (diode 233 of the second power device 13). The anode of the second diode (diode 233 of the second power device 13) is also electrically connected to the anode of the second power device 13. The above circuit structure can extend the parallel structure of large and small capacitors (the large capacitor is the third capacitor C3, and the small capacitor is the damping capacitor 231) to two devices. In this case, the damping resistor 232 can be shared, reducing the number of components. Furthermore, a current-limiting inductor L can be added to the above structure to limit the turn-on di / dt (rate of change of current). The third switching component T3 can be a fully controlled device (IGCT, IGBT) anti-parallel thyristor, a bidirectional switching transistor, or two fully controlled devices anti-parallel.

[0051] In some alternative implementations, such as Figure 7As shown, the third voltage equalization unit 25 and the fourth voltage equalization unit 26 share a damping resistor 232, a first diode (diode 233 of the first power device 12), and a second diode (diode 233 of the second power device 13). The fourth voltage equalization unit 26 includes: a fourth switching assembly T4, a damping capacitor 231, a fourth capacitor C4, a damping resistor 232, a first diode (diode 233 of the first power device 12), and a second diode (diode 233 of the second power device 13). The cathode of the first diode is connected to the cathode of the first power device 12 and the second diode, respectively. The anodes of the two power devices 13 and the second diode are electrically connected. The anode of the first diode is electrically connected to the first terminal of the damping resistor 232. The second terminal of the damping resistor 232 is electrically connected to the cathode of the second diode, the first terminal of the fourth switching assembly T4, and the first terminal of the damping capacitor 231. The anode of the second diode is also electrically connected to the anode of the second power device 13. The second terminal of the fourth switching assembly T4 is electrically connected to the first terminal of the fourth capacitor C4. The second terminal of the fourth capacitor C4 is electrically connected to the second terminal of the damping capacitor 231 and the cathode of the second power device 13. This circuit structure can extend the parallel connection of large and small capacitors (the large capacitor is the fourth capacitor C4, and the small capacitor is the damping capacitor 231) to two devices. In this case, the damping resistor 232 can be shared, reducing the number of components. Furthermore, a current-limiting inductor L can be added to the above structure to limit the turn-on di / dt (rate of change of current), and the damping resistor 232 can suppress overcurrent spikes. The fourth switching component T4 can be a fully controlled device (IGCT, IGBT) anti-parallel thyristor, a bidirectional switching transistor, or two fully controlled devices anti-parallel.

[0052] When the bridge arm containing the first power device 12 and the second power device 13 is actively turned off, the third switch assembly T3 and the fourth switch assembly T4 are turned on, so that the current flows into the second power device 13 through the damping capacitor 231, the third capacitor C3 and the first diode of the first power device 12. Since the second power device 13 is actively turned off, the current flows into the next power device through the second diode, the damping capacitor 231 and the fourth capacitor C4 of the second power device 13.

[0053] When the bridge arm containing the first power device 12 and the second power device 13 is in the conduction phase after active shutdown, the fourth switch assembly T4 and the fifth switch assembly T5 are in the open state, discharging the electrical energy stored in the damping capacitor 231, the second capacitor C2, and the fourth capacitor C4 during active shutdown. This prepares for the next active shutdown, enabling the current method to have continuous active shutdown capability. The discharge circuit at the first power device 12 is as follows: the first terminal of the damping capacitor 231 -- the first power device 12 -- the current-limiting inductor L -- the second diode -- the damping resistor 232 -- the second terminal of the damping capacitor 231; the first terminal of the third capacitor C3 -- the fourth switch assembly T4 -- the first power device 12 -- the current-limiting inductor L -- the second diode -- the damping resistor 232 -- the second terminal of the third capacitor C3. The discharge circuit at the second power device 13 is as follows: the first end of the damping capacitor 231 -- the damping resistor 232 -- the first diode -- the current limiting inductor L -- the second power device 13 -- the second end of the damping capacitor 231; the first end of the fourth capacitor C4 -- the fourth switching assembly T4 -- the damping resistor 232 -- the first diode -- the current limiting inductor L -- the second power device 13 -- the second end of the fourth capacitor C4.

[0054] By repeatedly using damping resistors and current-limiting inductors between two power devices, the two power devices have a complete RC (composed of a damping capacitor and a damping resistor connected in series) buffer circuit. The buffer circuit is used to slow down the rate of change of voltage across the power devices during the turn-on transient, thereby reducing the dynamic voltage difference between the power devices.

[0055] The above describes the case where the capacitors of the two voltage equalization units in the voltage equalization module are connected in parallel. The capacitors of the two voltage equalization units can also be connected in series. In some optional embodiments, the power component includes a power device, and the dynamic voltage equalization unit includes a fifth voltage equalization unit and a sixth voltage equalization unit. The fifth voltage equalization unit is connected in parallel across the power device, and the sixth voltage equalization unit is connected in series with the damping resistor and damping capacitor in the fifth voltage equalization unit. The capacitor in the sixth voltage equalization unit, after being connected in series with the damping capacitor, is equivalent to a capacitor with a small capacitance value. With reasonable parameter adjustments, the problem of reverse recovery of uneven voltage by the power device can be effectively suppressed.

[0056] In some alternative implementations, such as Figure 8As shown, the fifth voltage equalization unit includes a damping resistor 232, a third diode (diode 233 of the power device 11 mentioned above), a damping capacitor 231, and a fifth capacitor C5. The first terminal of the damping resistor 232 is electrically connected to the anode of the power device 11 and the anode of the third diode. The first terminal of the damping capacitor 231 is electrically connected to the second terminal of the damping resistor 232 and the cathode of the third diode. The second terminal of the damping capacitor 231 is electrically connected to the first terminal of the fifth capacitor C5, and the second terminal of the fifth capacitor C5 is electrically connected to the cathode of the power device 11. The sixth voltage equalization unit includes a fifth switching assembly T5, which is connected in parallel across the damping capacitor 231. The sixth voltage equalization unit selectively conducts the fifth switching assembly T5, short-circuiting the damping capacitor 231 when needed, allowing only the fifth capacitor C5 with its large capacitance to operate. This suppresses voltage imbalance caused by inconsistent device turn-off, enhancing dynamic voltage equalization capability, especially during active device turn-off, where it more effectively controls the voltage rise rate.

[0057] The aforementioned fifth switching component T5 can be a fully controllable device (IGCT, IGBT, etc.) or a thyristor. When the power device 11 reverses and recovers, the third diode is turned off due to the negative voltage. The reverse recovery voltage equalization is achieved by the fifth capacitor C5, the damping capacitor 231, and the damping resistor 232 connected in series. The damping capacitor 231 and the fifth capacitor C5 are equivalent to a capacitor with a small capacitance value. With reasonable parameter settings, the problem of uneven reverse recovery voltage can be effectively suppressed. When the power device 11 actively turns off, the third diode conducts under a positive voltage. At this time, the fifth switching component T5 is subjected to the positive voltage of the damping capacitor 231. After applying the conduction signal, the damping capacitor 231 is bypassed. At this time, the fifth capacitor C5 (with a large capacitance value) mainly suppresses the uneven voltage phenomenon caused by inconsistent device turn-off. In practical applications, existing series voltage equalization methods include, but are not limited to, RC and RCD circuits ( Figure 8 The circuit in the middle is an RCD circuit, which is formed by connecting the third diode (diode 233), damping capacitor 231 and damping resistor 232.

[0058] In some optional implementations, the power assembly includes two power devices, designated as a third and a fourth power device. The dynamic voltage equalization unit includes a seventh and an eighth voltage equalization unit. The first terminal of the seventh voltage equalization unit is electrically connected to the anode of the third power device, the second terminal is electrically connected to both the cathode of the third power device and the anode of the fourth power device, and the third terminal is also electrically connected to both the cathode of the third power device and the anode of the fourth power device, with the second terminal close to the third power device and the third terminal close to the fourth power device. The first terminal of the eighth voltage equalization unit is the second terminal of the seventh voltage equalization unit, the second terminal of the eighth voltage equalization unit is the third terminal of the seventh voltage equalization unit, and the third terminal of the eighth voltage equalization unit is electrically connected to the cathode of the fourth power device. The seventh and eighth voltage equalization units provide more comprehensive voltage equalization support for the power assembly composed of the two devices. By sharing components, the circuit structure is simplified and costs are reduced without affecting the overall voltage equalization effect.

[0059] In some alternative implementations, such as Figure 9 As shown, the seventh voltage equalization unit and the eighth voltage equalization unit share a damping resistor 232, a fourth diode (diode 233 of the third power device 14), and a fifth diode (diode 233 of the fourth power device 15). The seventh voltage equalization unit includes: a sixth switching assembly T6, a damping capacitor 231, a sixth capacitor C6, a damping resistor 232, a fourth diode, and a fifth diode. The first end of the damping capacitor 231 is electrically connected to the anode of the third power device 14 and the first end of the sixth switching assembly T6, respectively. The second end of the damping capacitor 231 is electrically connected to the second end of the sixth switching assembly T6 and the first end of the sixth capacitor C6, respectively. The second end of the sixth capacitor C6 is electrically connected to the anode of the fourth diode and the first end of the damping resistor 232, respectively. The cathode of the fourth diode is electrically connected to the anode of the fifth diode, the cathode of the third power device 14, and the anode of the fourth power device 15, respectively. The anode of the fifth diode is also electrically connected to the anode of the fourth power device 15, and the cathode of the fifth diode is electrically connected to the second end of the damping resistor 232. By sharing components, the seventh and eighth voltage equalization units simplify the circuit structure and reduce costs without affecting the overall voltage equalization effect. The sixth switch component T6 is used to control the connection of the damping capacitor 231 to meet different switching state requirements and ensure the consistency and reliability of voltage equalization.

[0060] In some alternative implementations, such as Figure 9As shown, the seventh and eighth voltage equalization units share a damping resistor 232, a fourth diode (diode 233 of the third power device 14), and a fifth diode (diode 233 of the fourth power device 15). The eighth voltage equalization unit includes a seventh switching assembly T7, a damping capacitor 231, a seventh capacitor C7, a damping resistor 232, a fourth diode, and a fifth diode. The cathode of the fourth diode is electrically connected to the cathode of the third power device 14, the anode of the fifth diode, and the anode of the fourth power device 15, respectively. The anode of the fourth diode is electrically connected to the first end of the damping resistor 232. The first end of the damping capacitor 231 is electrically connected to the cathode of the fifth diode, the second end of the damping resistor 232, and the first end of the seventh switching assembly T7, respectively. The first end of the seventh capacitor C7 is electrically connected to the second end of the damping capacitor 231 and the second end of the seventh switching assembly T7, respectively. The second end of the seventh capacitor C7 is electrically connected to the cathode of the fourth power device 15.

[0061] When the bridge arm containing the third power device 14 and the fourth power device 15 is actively turned off, the sixth switch assembly T6 and the seventh switch assembly T7 are turned on, so that the current flows through the sixth switch assembly T6, the sixth capacitor C6, and the diode 233 (fourth diode) of the third power device 14 into the fourth power device 15. Since the fourth power device 15 is actively turned off, the current flows through the diode 233 (fifth diode) and the seventh capacitor C7 of the fourth power device 15 into the next power device.

[0062] When the bridge arm containing the third power device 14 and the fourth power device 15 is in the conduction phase after active turn-off, the sixth switch assembly T6 and the seventh switch assembly T7 are in the open state, discharging the electrical energy stored in the sixth capacitor C6 and the seventh capacitor C7 during active turn-off. This prepares for the next active turn-off, enabling the current method to have continuous active turn-off capability. The discharge circuit at the third power device 14 is: the first terminal of the sixth capacitor C6 -- damping capacitor 231 -- third power device 14 -- current-limiting inductor L -- fifth diode -- damping resistor 232 -- the second terminal of the sixth capacitor C6. The discharge circuit at the fourth power device 15 is: the first terminal of the seventh capacitor C7 -- damping capacitor 231 -- damping resistor 232 -- fourth diode -- current-limiting inductor L -- fourth power device 15 -- the second terminal of the seventh capacitor C7.

[0063] By repeatedly using damping resistors, diodes, and current-limiting inductors between two power devices, the two power devices have a complete RC (composed of a damping capacitor and a damping resistor connected in series) buffer circuit. The buffer circuit is used to slow down the rate of change of voltage across the power devices during the turn-on transient, thereby reducing the dynamic voltage difference between the power devices.

[0064] The circuit structure of the converter valve described in this application replaces the original voltage clamping circuit in related technologies by introducing fully controlled devices in parallel or series with large capacitors. This enables the dynamic voltage equalization circuit to not only have the function of reverse recovery of voltage equalization, but also to suppress the uneven voltage phenomenon caused by device delay during active shutdown. Furthermore, the circuit structure of this application does not use a surge arrester, which also reduces the circuit size.

[0065] In some implementations, the aforementioned damping resistor can be an electromagnetically adjustable resistor. The resistance value of this resistor can be adjusted by changing the position of the magnetic core and the current in the coil. Furthermore, the voltage across the power device is monitored. When the voltage rises too quickly, the resistance value of the damping resistor is increased to slow the voltage rise; conversely, when the voltage drops too quickly, the resistance value is decreased to buffer the voltage drop rate. This improves the adaptability of the voltage equalization circuit to different operating conditions, thereby further optimizing the voltage equalization effect.

[0066] The control steps are as follows:

[0067] Before starting the DC converter valve system, the electromagnetic adjustable resistor is initialized. The resistance value of the electromagnetic adjustable resistor after initialization can be an intermediate value. According to the expected operating conditions of the DC converter valve, such as rated voltage, maximum current, ambient temperature and other parameters, the initial resistance value can be set to a medium resistance value to adapt to voltage fluctuations under normal operating conditions.

[0068] When the DC converter valve system starts operating, the control voltage stress monitoring module is activated to continuously monitor voltage changes across each power device. The voltage stress monitoring module employs a high-speed ADC (analog-to-digital converter) and real-time data processing algorithms to ensure accurate capture of voltage changes.

[0069] If the voltage rise rate across the power device exceeds a first preset threshold, the magnetic core of the electromagnetic adjustable resistor is moved to a position where the resistance value is increased, and the current through the coil is increased, thereby raising the resistance value of the electromagnetic adjustable resistor until the voltage rise rate decreases to a safe range. The resistance adjustment can be completed within milliseconds, effectively slowing down the voltage rise rate and protecting the power device from damage caused by overvoltage stress.

[0070] If the voltage drop rate across the power device exceeds a second preset threshold, the magnetic core of the electromagnetic adjustable resistor is moved to a position where the resistance is reduced, and the current through the coil is decreased. This lowers the resistance of the electromagnetic adjustable resistor until the voltage drop rate decreases to a safe range. Reducing the resistance helps lower the impedance of the voltage drop path, buffers the voltage drop rate, prevents the device from experiencing excessive reverse voltage stress, and ensures reliable device operation.

[0071] When an abnormality is detected in the damping resistor, such as a sudden change in resistance, core jamming, or control signal distortion, the dynamic voltage equalization unit of the backup voltage equalization module is turned on to ensure the continuous operation of the voltage equalization circuit and prevent the device from being subjected to improper voltage stress due to a voltage equalization circuit failure.

[0072] In some implementations, multiple dynamic voltage equalization units are connected in parallel across the power device. This provides finer voltage control and can also serve as a backup voltage equalization module, especially in scenarios where the power device is subjected to higher voltage levels, enabling more reliable suppression of voltage overshoot.

[0073] The control method is as follows:

[0074] Before starting the DC converter valve system, all parallel dynamic and static voltage equalization units are initialized. Initialization includes checking the integrity of each unit and the preset operating parameters. The preset operating parameters include at least the trigger threshold, capacitance value, and resistance value, to ensure that each dynamic and static voltage equalization unit is in standby mode and can intervene in the voltage equalization process at any time.

[0075] When the voltage rise rate across the power device exceeds a preset first-level threshold, the dynamic voltage equalization unit with first priority is turned on. If the dynamic voltage equalization unit with first priority fails to reduce the voltage rise rate to a predetermined safe range, the dynamic voltage equalization unit with second priority is turned on, and so on, until the voltage rise rate is within a predetermined full-reverse range.

[0076] When a fault occurs during the operation of the DC converter system valve, the dynamic voltage equalization unit with the first priority is turned on. If a fault is detected in the dynamic voltage equalization unit with the first priority, such as failure of the entire control device or capacitor leakage, the dynamic voltage equalization unit with the second priority is turned on to replace the dynamic voltage equalization unit with the first priority for voltage control, so as to ensure that the power devices are always balanced by the dynamic voltage equalization unit when the DC converter system valve fails.

[0077] In some implementations, a backup switching assembly is connected in parallel with the switching assembly in the dynamic voltage equalization unit. During normal operation, the backup switching assembly is in standby mode and does not participate in the voltage equalization process, thereby reducing energy consumption and improving economy. If the switching assembly in the main circuit fails, the control system immediately switches to the backup switching assembly to ensure the continuous operation of the voltage equalization circuit.

[0078] In some implementations, the first, fifth, sixth, and seventh switching components can be fully controllable devices (IGCT, IGBT, etc.) or thyristors, and can also be discharge gaps, specifically discharge ball gaps. When the power device is actively turned off, after the voltage at the discharge gap reaches a certain level, the discharge gap is turned on to put the preset capacitor into the circuit for operation. After the power device is actively turned off, the preset capacitor is turned on, and when the voltage at the discharge gap drops to a certain level, the discharge gap is turned off.

[0079] According to another aspect of the embodiments of this application, such as Figure 10 As shown, a control method for a DC converter valve is provided for controlling the aforementioned DC converter valve. The control method includes:

[0080] Step S1: Obtain the operating information of the AC side of the DC converter valve. The operating information indicates whether an AC fault has occurred on the AC side.

[0081] Specifically, acquiring the operating information of the AC side of the DC converter valve can include parameters such as current, voltage, and frequency. By monitoring the electrical characteristics of the AC side in real time, it is possible to determine whether a fault has occurred on the AC side, such as a short circuit, open circuit, or voltage drop. This allows for timely detection and response to AC faults, preventing the fault from escalating and improving system safety.

[0082] Step S2: If no AC fault occurs on the AC side, control the multiple dynamic pressure equalization units in the DC converter valve to shut down.

[0083] Specifically, when the AC side is operating normally and no faults are detected, the dynamic voltage equalization unit is turned off and does not participate in voltage equalization. At this time, during the normal commutation process of the DC converter valve, the static voltage equalization unit can balance the leakage current and reduce the static voltage difference by connecting in parallel with the power devices through its internal resistor, thus achieving voltage equalization for the power devices in the blocking state.

[0084] Step S3: In the event of an AC fault on the AC side, the power devices in the fault arm of the DC converter valve corresponding to the AC fault are actively turned off, and the dynamic voltage equalization unit connected in parallel across at least one power device is turned on. The dynamic voltage equalization unit equalizes the voltage of the power devices in the actively turned-off state.

[0085] Specifically, when a fault is detected on the AC side, such as a voltage drop or power loss, the power devices in the faulty bridge arm are actively turned off, and simultaneously the dynamic voltage equalization unit connected in parallel across the power devices is turned on. The dynamic voltage equalization unit is connected to the circuit to limit the voltage rise across the power devices, thereby achieving voltage stress equalization.

[0086] Step S4: After the AC fault is restored, the power devices of the original faulty bridge arm are turned on and the dynamic voltage equalization unit is turned off to release the electrical energy stored in the dynamic voltage equalization unit and reset the dynamic voltage equalization unit.

[0087] Specifically, after the AC fault is cleared and the AC side returns to normal operating conditions, the power devices in the original faulty bridge arm are controlled to resume conduction, while the dynamic voltage equalization unit is turned off to release the electrical energy stored in the dynamic voltage equalization unit, thus completing the reset of the voltage equalization unit and ensuring the readiness for the next voltage equalization process.

[0088] The presence of an AC fault is determined by detecting the voltage on the AC side. If an AC fault is detected, an active shutdown signal is sent to the faulty bridge arm. Simultaneously, a dynamic voltage equalization unit is connected to the circuit. This unit reduces the voltage change rate, limits the voltage rise across the power devices, suppresses voltage overshoot, and reduces dynamic voltage differences between the power devices, thus achieving voltage equalization. When the devices are turned on again after being turned off, the power devices are controlled to turn on, and the dynamic voltage equalization unit is disconnected from the circuit. The dynamic voltage equalization unit discharges its stored energy to buffer the voltage drop rate during turn-on. In the absence of an AC fault, the dynamic voltage equalization unit is not connected to the circuit, further reducing losses. This control method for the DC converter valve solves the problem of insufficient voltage equalization for multiple semiconductor devices connected in series in the converter valve bridge arm in related technologies.

[0089] In some optional implementations, controlling the power devices in the faulty bridge arm corresponding to the AC fault in the DC converter valve to actively shut down, and turning on the dynamic voltage equalization unit connected in parallel across at least one power device, includes: controlling the power devices in the faulty bridge arm to actively shut down and sending a positive voltage signal to the switching component of the dynamic voltage equalization unit, causing the switching component to turn on in response to the received positive voltage signal, thereby turning on the dynamic voltage equalization unit. When a fault is detected on the AC side, controlling the power devices in the faulty bridge arm to actively shut down prevents fault current from causing excessive voltage stress through the devices. Simultaneously, when the power devices are shut down, the voltage rises to a preset threshold, generating a positive voltage signal. This positive voltage signal causes the switching component in the dynamic voltage equalization unit to turn on. The turn-on of the dynamic voltage equalization unit connects the internal preset capacitor to the bridge arm, begins to absorb overvoltage, limits the voltage rise rate, and achieves a voltage equalization effect.

[0090] In some optional implementations, controlling the power devices of the original faulty bridge arm to turn on and the dynamic voltage equalization unit to turn off includes: after the AC fault is restored, controlling the power devices of the original faulty bridge arm to turn on and send a negative voltage signal to the switching component of the dynamic voltage equalization unit, causing the switching component to turn off in response to the received negative voltage signal, thereby turning off the dynamic voltage equalization unit. When the AC fault is cleared and the AC side voltage returns to normal operating conditions, controlling the power devices in the faulty bridge arm to turn on and restore normal operation, at which time the voltage across the power devices drops below a preset discharge threshold, generating a negative voltage signal. The negative voltage signal causes the switching component to turn off, the dynamic voltage equalization unit to turn off, and the preset capacitor inside the dynamic voltage equalization unit begins to discharge to the power devices, releasing the stored energy and completing the reset of the dynamic voltage equalization unit. In this way, the dynamic voltage equalization unit can be immediately put into the circuit for dynamic voltage equalization when the next AC fault occurs.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0093] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0094] 1) The DC converter valve of this application, by connecting a voltage equalization module with dynamic and static voltage equalization units in parallel at the power components of the bridge arm, can achieve voltage equalization control of power devices in different states (active shutdown, resumption of conduction, and shutdown), improving the flexibility and efficiency of voltage equalization. Specifically, when the power device is in a shutdown transient state, the switching component receives a control signal and turns on, causing a preset capacitor to connect to the circuit, limiting the voltage rise across the power device and thus suppressing voltage stress overshoot. When the device resumes conduction after shutdown, the switching component disconnects, and the preset capacitor discharges to the power device through the switching component to buffer the voltage drop rate during turn-on. This flexible capacitor switching mechanism significantly reduces the rate of change of voltage stress and improves the voltage equalization effect. The static voltage equalization unit balances leakage current when the device is shut down, reducing static voltage differences. The aforementioned DC converter valve solves the problem of insufficient voltage equalization effect for multiple semiconductor devices connected in series in the converter valve bridge arm in related technologies.

[0095] 2) The DC converter valve of this application is designed for power modules consisting of two power devices. By sharing multiple components through two voltage equalization units and a fourth voltage equalization unit, the number of components is reduced, saving costs and reducing circuit area. Furthermore, the linkage control of the two power devices enables more precise voltage stress control.

[0096] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A DC converter valve, characterized in that, include: Multiple bridge arms, each bridge arm having multiple power components connected in series, the power components including at least one power device; Multiple voltage equalization modules are connected in parallel to the input and output terminals of the power component. Each voltage equalization module includes a dynamic voltage equalization unit and a static voltage equalization unit connected in parallel. The dynamic voltage equalization unit is connected in parallel with the power component and includes a branch formed by the electrical connection of a switching component and a preset capacitor. The dynamic voltage equalization unit is used to equalize the voltage of the power device when it is in a fault recovery conduction state and a fault shutdown state. The static voltage equalization unit is used to equalize the voltage of the power device when it is in a blocking state. The power assembly includes two power devices, namely a first power device and a second power device. The dynamic voltage equalization unit includes a third voltage equalization unit and a fourth voltage equalization unit. The third voltage equalization unit and the fourth voltage equalization unit share a damping resistor, a first diode, and a second diode. The third voltage equalization unit includes a third switching assembly, a damping capacitor, a third capacitor, the damping resistor, the first diode, and the second diode. The first terminal of the third switching assembly is electrically connected to the anode of the first power device and the first terminal of the damping capacitor. The second terminal of the third switching assembly is electrically connected to the first terminal of the third capacitor. The second terminal of the damping capacitor is electrically connected to the anode of the first diode, the second terminal of the third capacitor, and the first terminal of the damping resistor. The cathode of the first diode is electrically connected to the cathode of the first power device and the anode of the second power device. The second terminal of the damping resistor is electrically connected to the cathode of the second diode. The anode of the second diode is also electrically connected to the anode of the second power device.

2. The DC converter valve according to claim 1, characterized in that, The power component includes one power device, and the dynamic voltage equalization unit includes: a first voltage equalization unit and a second voltage equalization unit connected in parallel, wherein the first voltage equalization unit is connected in parallel across the two ends of the power device, and the second voltage equalization unit is connected in parallel across the two ends of the first voltage equalization unit.

3. The DC converter valve according to claim 1, characterized in that, The power component includes a power device, and the dynamic voltage equalization unit includes a first voltage equalization unit and a second voltage equalization unit, wherein the first voltage equalization unit is connected in parallel across the two ends of the power device, and the second voltage equalization unit is connected in parallel across the two ends of the damping capacitor in the first voltage equalization unit.

4. The DC converter valve according to claim 2 or 3, characterized in that, The second voltage equalization unit includes: a first switching assembly, a first capacitor, and a first resistor, wherein, The first end of the first switching assembly is electrically connected to the first voltage equalization unit, the second end of the first switching assembly is electrically connected to the first end of the first capacitor and the first end of the first resistor, and the second end of the first capacitor and the second end of the first resistor are both electrically connected to the output end of the first voltage equalization unit.

5. The DC converter valve according to claim 3, characterized in that, The second voltage equalization unit includes: a second switching assembly and a second capacitor. The first end of the second switching assembly is electrically connected to the first end of the damping capacitor, the second end of the second switching assembly is electrically connected to the first end of the second capacitor, and the second end of the second capacitor is electrically connected to the second end of the damping capacitor.

6. The DC converter valve according to claim 1, characterized in that, The first end of the third voltage equalization unit is electrically connected to the anode of the first power device, the second end of the third voltage equalization unit is electrically connected to the cathode of the first power device and the anode of the second power device, and the third end of the third voltage equalization unit is electrically connected to the cathode of the first power device and the anode of the second power device. The second end is close to the first power device, and the third end is close to the second power device. The first end of the fourth voltage equalization unit is the second end of the third voltage equalization unit, the second end of the fourth voltage equalization unit is the third end of the third voltage equalization unit, and the third end of the fourth voltage equalization unit is electrically connected to the cathode of the second power device.

7. The DC converter valve according to claim 6, characterized in that, The third voltage equalization unit and the fourth voltage equalization unit share a damping resistor, a first diode, and a second diode. The fourth voltage equalization unit includes a fourth switching assembly, a damping capacitor, a fourth capacitor, the damping resistor, the first diode, and the second diode. The cathode of the first diode is electrically connected to the cathode of the first power device, the anode of the second power device, and the anode of the second diode. The anode of the first diode is electrically connected to the first end of the damping resistor. The second end of the damping resistor is electrically connected to the cathode of the second diode, the first end of the fourth switching assembly, and the first end of the damping capacitor. The anode of the second diode is also electrically connected to the anode of the second power device. The second end of the fourth switching assembly is electrically connected to the first end of the fourth capacitor. The second end of the fourth capacitor is electrically connected to the second end of the damping capacitor and the cathode of the second power device.

8. The DC converter valve according to claim 1, characterized in that, The power component includes one power device, and the dynamic voltage equalization unit includes a fifth voltage equalization unit and a sixth voltage equalization unit, wherein the fifth voltage equalization unit is connected in parallel across the two ends of the power device, and the sixth voltage equalization unit is connected in series with the damping capacitor and damping resistor in the fifth voltage equalization unit.

9. The DC converter valve according to claim 8, characterized in that, The fifth voltage equalization unit includes a damping resistor, a third diode, the damping capacitor, and a fifth capacitor. The first end of the damping resistor is electrically connected to the anode of the power device and the anode of the third diode, respectively. The first end of the damping capacitor is electrically connected to the second end of the damping resistor and the cathode of the third diode, respectively. The second end of the damping capacitor is electrically connected to the first end of the fifth capacitor, and the second end of the fifth capacitor is electrically connected to the cathode of the power device. The sixth voltage equalization unit includes a fifth switching assembly, which is connected in parallel across the two ends of the damping capacitor.

10. The DC converter valve according to claim 1, characterized in that, The power assembly includes two power devices, namely a third power device and a fourth power device, and the dynamic voltage equalization unit includes a seventh voltage equalization unit and an eighth voltage equalization unit, wherein... The first end of the seventh voltage equalization unit is electrically connected to the anode of the third power device, the second end of the seventh voltage equalization unit is electrically connected to the cathode of the third power device and the anode of the fourth power device, the third end of the seventh voltage equalization unit is electrically connected to the cathode of the third power device and the anode of the fourth power device, the second end is close to the third power device, and the third end is close to the fourth power device. The first end of the eighth voltage equalization unit is the second end of the seventh voltage equalization unit, the second end of the eighth voltage equalization unit is the third end of the seventh voltage equalization unit, and the third end of the eighth voltage equalization unit is electrically connected to the cathode of the fourth power device.

11. The DC converter valve according to claim 10, characterized in that, The seventh voltage equalization unit and the eighth voltage equalization unit share a damping resistor, a fourth diode, and a fifth diode. The seventh voltage equalization unit includes: a sixth switching assembly, a damping capacitor, a sixth capacitor, the damping resistor, the fourth diode, and the fifth diode. The first terminal of the damping capacitor is electrically connected to the anode of the third power device and the first terminal of the sixth switching assembly. The second terminal of the damping capacitor is electrically connected to the second terminal of the sixth switching assembly and the first terminal of the sixth capacitor. The second terminal of the sixth capacitor is electrically connected to the anode of the fourth diode and the first terminal of the damping resistor. The cathode of the fourth diode is electrically connected to the anode of the fifth diode, the cathode of the third power device, and the anode of the fourth power device. The anode of the fifth diode is also electrically connected to the anode of the fourth power device. The cathode of the fifth diode is electrically connected to the second terminal of the damping resistor.

12. The DC converter valve according to claim 10, characterized in that, The seventh voltage equalization unit and the eighth voltage equalization unit share a damping resistor, a fourth diode, and a fifth diode. The eighth voltage equalization unit includes a seventh switching assembly, a damping capacitor, a seventh capacitor, the damping resistor, the fourth diode, and the fifth diode. The cathode of the fourth diode is electrically connected to the cathode of the third power device, the anode of the fifth diode, and the anode of the fourth power device, respectively. The anode of the fourth diode is electrically connected to the first end of the damping resistor. The first end of the damping capacitor is electrically connected to the cathode of the fifth diode, the second end of the damping resistor, and the first end of the seventh switching assembly, respectively. The first end of the seventh capacitor is electrically connected to the second end of the damping capacitor and the second end of the seventh switching assembly, respectively. The second end of the seventh capacitor is electrically connected to the cathode of the fourth power device.

13. A control method for a DC converter valve, characterized in that, The control method for controlling the DC converter valve according to any one of claims 1 to 12 includes: Obtain the operating information of the AC side of the DC converter valve, wherein the operating information indicates whether an AC fault has occurred on the AC side; In the absence of the AC fault on the AC side, multiple dynamic pressure equalization units in the DC converter valve are shut down. In the event of an AC fault on the AC side, the power device in the fault bridge arm corresponding to the AC fault in the DC converter valve is actively shut down, and a dynamic voltage equalization unit connected in parallel across at least one of the power devices is turned on. The dynamic voltage equalization unit equalizes the voltage of the power device in the actively shut-down state. After the AC fault is restored, the power device of the original faulty bridge arm is turned on, and the dynamic voltage equalization unit is turned off to release the electrical energy stored in the dynamic voltage equalization unit and reset the dynamic voltage equalization unit.

14. The control method according to claim 13, characterized in that, The control of actively shutting down the power devices in the fault arm of the DC converter valve corresponding to the AC fault, and turning on the dynamic voltage equalization unit connected in parallel across at least one of the power devices, includes: The power device of the faulty bridge arm is actively turned off and sends a positive voltage signal to the switching component of the dynamic voltage equalization unit, so that the switching component turns on in response to the received positive voltage signal, thereby turning on the dynamic voltage equalization unit.

15. The control method according to claim 13, characterized in that, The control of turning on the power device of the original faulty bridge arm and turning off the dynamic voltage equalization unit includes: After the AC fault is restored, the power device of the original faulty bridge arm is turned on and sends a negative voltage signal to the switching component of the dynamic voltage equalization unit, so that the switching component turns off in response to the received negative voltage signal, thereby turning off the dynamic voltage equalization unit.

16. A DC converter valve system, characterized in that, The device includes a controller and a DC converter valve according to any one of claims 1 to 12, wherein the controller is used to perform the control method of the DC converter valve according to any one of claims 13 to 15.

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