Converter station, control method and control device thereof and storage medium

Abstract

The invention relates to a converter station, a control method thereof, a control device and a storage medium, the converter station comprises a rectification side and an inversion side, the rectification side is connected with a first alternating current end and a direct current end through an LCC, the inversion side is connected with the direct current end and a second alternating current end through a CLCC pulse bridge, the CLCC pulse bridge carries out commutation result prediction through a commutation prediction verification unit, and the commutation prediction verification unit carries out commutation result prediction. If the commutation prediction verification result is successful, the CLCC pulse bridge is controlled to be in an LCC mode, and commutation action is carried out; and if the commutation prediction verification result is failure, controlling the CLCC pulse bridge to be in a CLCC mode, and carrying out commutation action. Compared with the prior art, the method has the advantages of small reactive power vacancy, fast AC voltage recovery and the like.

Description

Technical Field

[0001] The present invention relates to the field of power grid control, and in particular to a converter station and a control method, a control device and a storage medium thereof. Background Art

[0002] With the increase in the number of UHV DC points, the regional power grid will form a more intensive multi-feed DC, the coupling between stations will be closer, and multi-station chain commutation failure failures will often occur. In order to solve the commutation failure problem, while considering the feasibility and economy of the project, in the prior art, a controllable grid commutation converter topology with controllable shutdown capability is adopted. This topology is based on a hybrid structure of fully controlled IGBTs and semi-controlled thyristors. The main thyristor current is transferred to the auxiliary branch containing IGBT by using the shutdown capability of IGBT, and the thyristor is reliably restored by increasing the thyristor shutdown time. Finally, the shutdown capability of the auxiliary branch IGBT is used to cut off the bridge arm current to complete the commutation between the bridge arms.

[0003] In traditional LCC control, the commutation failure prediction link can increase the turn-off angle according to the voltage drop at the receiving end to reduce the risk of commutation failure. However, while increasing the turn-off angle, the commutation failure prediction link also reduces the power factor cosφI, increases the reactive power consumed by the converter valve, and slows down the recovery of the system AC voltage. After the CLCC converter is adopted on the transformer side, commutation failure will not occur on the inverter side. At this time, the purpose of DC transmission should be to maintain the DC transmission power as much as possible and provide reactive support for the AC system as much as possible. CLCC is no longer in the problem of commutation failure. When the AC voltage at the receiving end drops, there is no need to increase the turn-off angle to avoid commutation failure. However, shielding the commutation failure prediction link can only ensure that the turn-off angle of CLCC does not increase during the fault period, and cannot give full play to the advantages of CLCC controllable commutation, improve the dynamic characteristics of the AC power grid, and reduce the reactive power shortage of the AC system. Summary of the invention

[0004] The purpose of the present invention is to provide a converter station and its control method, control device and storage medium in order to overcome the defect of reactive power shortage in the AC system in the above-mentioned prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A converter station includes a rectifier side and an inverter side, wherein the rectifier side is connected to a first AC terminal and a DC terminal via an LCC, and the inverter side is connected to a DC terminal and a second AC terminal via a CLCC pulsating bridge. The CLCC pulsating bridge predicts a commutation result via a commutation prediction verification unit. If the commutation prediction verification result is successful, the CLCC pulsating bridge is controlled to be in an LCC mode to perform a commutation action; if the commutation prediction verification result is a failure, the CLCC pulsating bridge is controlled to be in a CLCC mode to perform a commutation action.

[0007] Furthermore, the topological structure of the CLCC pulsating bridge includes multiple bridge arms, each bridge arm is composed of a main branch and an auxiliary branch in parallel, the main branch includes a LCC thyristor V11 and a main full-control valve V12 connected in series, and the auxiliary branch includes an auxiliary full-control valve V13 and a small current thyristor valve V14 connected in series.

[0008] Furthermore, the main full-control valve V12 is an IGBT element, and the auxiliary full-control valve V13 is composed of an IGBT element and a lightning arrester connected in parallel.

[0009] Furthermore, the topological structure of the inverter side converter station, the CLCC pulsating bridge includes the LCC mode and the CLCC mode. The working process of the LCC mode is to simultaneously turn on the LCC thyristor V11, the main full-control valve V12 and the auxiliary full-control valve V13 to turn on the main branch; after the main branch is turned on for 120°, the bridge arm starts to change phases. During the phase change of the bridge arm, the main full-control valve V12 is turned off, and the current starts to transfer to the auxiliary branch until the main branch current passes through zero, and the LCC thyristor V11 valve is subjected to reverse pressure, and after the bridge arm completes natural phase change; the auxiliary full-control valve V13 is turned off at zero current, the bridge arm restores the blocking capacity, and the phase change between the bridge arms is completed;

[0010] The working process of the CLCC mode is that the main full-control valve V12 is turned off, and the current is transferred to the auxiliary branch; until the main thyristor valve is turned off at zero crossing, after the main full-control valve V12 is restored, the auxiliary full-control valve V13 is turned off and the current is transferred to the lightning arrester connected in parallel. The lightning arrester establishes the action voltage and enhances the commutation voltage to complete the commutation between the bridge arms.

[0011] A second aspect of the present invention provides a control method for a converter station, comprising:

[0012] Rectifier side control: obtaining a first current command value according to a DC voltage measurement value on the rectifier side, obtaining a first trigger angle based on the first current command value and a first input current, and generating a first trigger pulse to implement rectifier side control when the first trigger angle meets a first threshold;

[0013] Inverter side control: According to the measured value of the AC voltage on the inverter side, a second current command value is obtained, and based on the second current command value and the second input current, a second trigger angle is obtained, and a commutation prediction is performed on the second trigger angle. If the result of the commutation prediction is successful, the CLCC pulsating bridge is controlled to be in LCC mode and the second trigger angle is increased; if the result of the commutation prediction is a failure, the CLCC pulsating bridge is controlled to be in CLCC mode and the second trigger angle is reduced.

[0014] Furthermore, the commutation prediction verification includes the following steps:

[0015] Single-phase fault verification: verify the sum of the three-phase voltages through zero-sequence detection to determine whether there is a single-phase fault;

[0016] Three-phase fault verification: Determine whether there is a three-phase fault by calculating the difference between the output vector of the AC voltage and the steady-state value.

[0017] Further, the increase value of the second trigger angle is increased from 6 degrees to 20 degrees.

[0018] Furthermore, the calculation expression of the second trigger angle is:

[0019]

[0020] α max =π-β

[0021] In the formula, β is the arcing angle, γ is the arcing angle, I ord is the DC current command value, I dN is the DC current rating, U di0N is the rated value of the no-load DC voltage on the inverter side, U di0 is the no-load DC voltage on the inverter side, α max is the second trigger angle.

[0022] A third aspect of the present invention is a control device for a converter station, comprising a memory, a processor, and a program stored in the memory, wherein the processor implements any of the above control methods for the converter station when executing the program.

[0023] A fourth aspect of the present invention is a storage medium having a program stored thereon, wherein when the program is executed, any of the above control methods for a converter station is implemented.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) The present invention uses a CLCC pulsating bridge to improve the inverter of the converter station. Through two different working states, the LCC mode and the CLCC mode, the commutation process of the CLCC pulsating bridge is realized, so that when there is a fault at the AC end, the commutation can be carried out smoothly, thereby ensuring the stable operation of the converter station.

[0026] 2) The present invention sets a commutation failure prediction control link on the inverter side, adjusts the working mode of the CLCC pulsating bridge, ensures smooth commutation through the CLCC pulsating bridge, and at the same time provides more reactive power support in the CLCC mode for the converter station system by increasing the trigger angle, thereby promoting the recovery of the system AC voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the structural diagram of the primary connection converter station of the LCC-CLCC DC system.

[0028] Figure 2 This is the topology diagram of the CLCC pulsating bridge.

[0029] Figure 3 This is the CLCC pulsating bridge trigger timing diagram.

[0030] Figure 4 This is the voltage and current waveform diagram of the CLCC natural commutation process.

[0031] Figure 5 This is the voltage and current waveform of the CLCC forced commutation process.

[0032] Figure 6 This is a schematic diagram of the control process on the rectifier side.

[0033] Figure 7 This is a schematic diagram of the inverter side control process.

[0034] Figure 8 Schematic diagram of the commutation failure prediction process.

[0035] Fig. 9 This is the control block diagram of the CLCC inverter station.

[0036] Fig.10 This is the control flow chart of CLCC inverter station.

[0037] Fig.11 The following is a comparison chart of the characteristics of CLCC before and after optimized control under three-phase grounding fault.

[0038] Fig.12 The following is a comparison chart of the characteristics of CLCC before and after optimized control under three-phase grounding fault.

[0039] Explanation of the markings in the figure: V11, LCC thyristor, V12, main full-control valve, V13, auxiliary full-control valve, V14, small current thyristor valve. DETAILED DESCRIPTION

[0040] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0041] Example 1

[0042] The present invention relates to a converter station and a control method, a control device and a storage medium thereof.

[0043] 1. LCC-CLCC DC primary connection converter station

[0044] The LCC-CLCC DC primary connection converter station proposed in the present invention is as follows: Figure 1As shown in the figure, the topology of the inverter-side converter station is composed of a mixed connection of fully controlled IGBTs and half-controlled thyristors. The IGBT's turn-off capability is used to transfer the main thyristor current to the auxiliary branch containing the IGBT, and the thyristor turn-off time is increased to enable reliable recovery. Finally, the turn-off capability of the auxiliary branch IGBT is used to cut off the bridge arm current to complete the phase change between the bridge arms.

[0045] like Figure 2 As shown in the figure, the basic topology of the CLCC pulsating bridge, in which each bridge arm (V1-V6) is composed of a main branch and an auxiliary branch in parallel. The main branch is based on the traditional LCC thyristor V11, with a main full-control valve V12 in series, while the auxiliary branch is composed of an auxiliary full-control valve V13 and a small current thyristor valve V14 in series. RC damping and RCD damping circuits are connected in parallel to the thyristor element and the IGBT element respectively, the purpose of which is to ensure that each element maintains a balanced pressure state during the dynamic process. The main full-control valve V12 is an IGBT element, and the auxiliary full-control valve V13 is composed of an IGBT element and a lightning arrester in parallel.

[0046] 2. CLCC commutation principle

[0047] The controllable commutation modes of the South Bridge CLCC converter include normal operation and AC fault forced commutation operation. Figure 3 As shown, taking the CLCC converter bridge arm VT1 to bridge arm VT3 commutation and the control timing of each valve when VT1 is turned on as an example, the high-voltage thyristor valve V11 control signal Sg11, the main full-controlled valve V12 control signal Sg12, the high-voltage full-controlled valve V13 control signal Sg13, the low-current thyristor valve V14 signal Sg14 and the voltage and current stress of the bridge arm are given respectively.

[0048] like Figure 4 As shown in the figure, the working principle of the CLCC pulsating bridge in normal operation mode is analyzed. It is divided into the flow stage [t0, t1], the natural commutation stage [t1, t5] and the valve arm shut-off stage [t5, 2π+t0]. The first stage is the bridge arm flow stage [t0, t1], at which time the V11, V12 and V13 valves are triggered to conduct at the same time, and the main branch is flowing; the second stage is the bridge arm commutation stage, as shown in Figure 4 [t1, t5]. After the main branch is turned on for 120°, the bridge arm begins to commutate. During the commutation of the bridge arm, at t2, the V12 valve is turned off and the current begins to transfer to the auxiliary branch; at t3, the commutation is completed, the main branch current passes through zero, the V11 valve is subjected to reverse pressure, and enters the blocking recovery period; at t4, the bridge arm completes natural commutation; at t5, the V13 valve is turned off with zero current, and the entire bridge arm restores its blocking capacity; the third stage is the bridge arm shutdown stage, starting from t5 to the next trigger.

[0049] When an AC side fault occurs, the CLCC pulsating bridge operates in forced commutation mode. Figure 5 As shown in the figure, since the bridge arm current cannot be naturally commutated during the fault period, during the commutation period, at t2, the main branch IGBT valve is turned off and the current is transferred to the auxiliary branch; at t3, the main thyristor valve is turned off at zero crossing, and after the main thyristor valve is restored, the auxiliary branch IGBT valve is turned off and the current is transferred to the lightning arrester connected in parallel. The lightning arrester establishes the action voltage and enhances the commutation voltage, successfully completing the commutation between the bridge arms and avoiding commutation failure. The peak current of the auxiliary branch generally does not exceed 2 times the rated current. Considering the commutation time of the main and auxiliary branches and the recovery time of the main branch thyristor, the current conduction time generally does not exceed 1ms.

[0050] From the working principle, it can be known that the normal operating mode is the LCC mode. The working process is to turn on the LCC thyristor V11, the main full-control valve V12 and the auxiliary full-control valve V13 at the same time to make the main branch conductive; after the main branch is turned on for 120°, the bridge arm starts to change phases. During the phase change of the bridge arm, the main full-control valve V12 is turned off, and the current begins to transfer to the auxiliary branch until the main branch current passes zero, and the LCC thyristor V11 valve is subjected to reverse pressure. After the bridge arm completes the natural phase change; the auxiliary full-control valve V13 is turned off at zero current, the bridge arm restores the blocking capacity, and the phase change between the bridge arms is completed;

[0051] The forced commutation mode is the CLCC mode. The working process is that the main full-control valve V12 is turned off, and the current is transferred to the auxiliary branch; until the main thyristor valve is turned off at zero crossing, after the main full-control valve V12 is restored, the auxiliary full-control valve V13 is turned off and the current is transferred to the lightning arrester connected in parallel. The lightning arrester establishes the operating voltage and enhances the commutation voltage to complete the commutation between the bridge arms.

[0052] 3. LCC-CLCC control method

[0053] The control method of the present invention comprises:

[0054] Rectifier side control: obtaining a first current command value according to a DC voltage measurement value on the rectifier side, obtaining a first trigger angle based on the first current command value and a first input current, and generating a first trigger pulse to implement rectifier side control when the first trigger angle meets a first threshold;

[0055] Inverter side control: According to the AC voltage measurement value on the inverter side, a second current command value is obtained, and based on the second current command value and the second input current, a second trigger angle is obtained, and a commutation prediction verification is performed on the second trigger angle. If the result of the commutation prediction is successful, the inverter station is controlled to be in LCC mode and the second trigger angle is increased; if the result of the commutation prediction is a failure, the inverter station is controlled to be in CLCC mode and the second trigger angle is reduced.

[0056] The control strategy of the rectifier side of the LCC-CLCC converter station is as follows: Figure 6As shown. Among them, VDCOL (Voltage Dependent Current Order Limitation) is a low-voltage current limiting link, the input UdcR is the DC voltage measurement value on the rectifier side, and IVDCOL is the DC current command value output through the VDCOL link. CCA (Current Control Amplifier) ​​is a constant current control, which controls the deviation between the input DC current Idc and the command value IVDCOL, and outputs the first firing angle α0. AMIN (Minimum Firing Angle Control) link is the minimum firing angle control, and outputs α order =max{α0,α min}, αmin is generally taken as 5°. CFC (Converter Firing Control) is the trigger control link, which is used to generate trigger pulses.

[0057] The inverter side control strategy of the LCC-CLCC converter station is as follows: Figure 7 As shown, the control system includes constant voltage control, fixed arc extinction angle control, constant current control, etc. In addition, the inverter side control system also adopts a commutation failure prediction control link (CFPREV for short). When an AC fault is detected, the maximum α limit value of AMAX (fixed arc extinction angle control) will be reduced to prevent commutation failure due to AC fault. In addition to shielding the commutation failure prediction control link in CLCC, the other links remain unchanged. Among them, UdcI is the DC voltage on the inverter side, and ΔI0 is the current margin instruction to keep the inverter side current less than the rectifier side, which is generally 0.1pu.

[0058] 4. Analysis of the impact of CFPREV link on the commutation process

[0059] like Figure 8 As shown in the figure, the fault detection link in the commutation failure prediction control link (CFPREV) includes two parallel parts. One is the zero sequence detection to detect whether a single-phase AC fault occurs, and the other is to use the α / β decomposition method of the AC voltage to detect a three-phase fault. In the case of an AC fault, the input of CFPRED is the AC voltage, and the output angle is input to AMAX. The principle of detection is: in the case of a single-phase fault, the sum of the three-phase voltages is not zero; in the case of a three-phase fault, the output vector of the AC voltage α / β conversion is less than the value in the steady state.

[0060] Fault detection of the AC power grid. Once the system detects that the inverter is at risk of commutation failure, CFPREV will respond quickly by reducing the trigger angle to provide the inverter with a larger commutation margin, thereby preventing commutation failure. CFPREV (Commutation Failure Prevention) is a commutation failure prediction link. The output αCFPREV is the α value triggered in advance, which is subtracted from the CCA output α0 to obtain α1. In the AMAX link, the arc extinction angle is indirectly adjusted by changing the inverter's lead angle. The calculation expression is:

[0061]

[0062] α max =π-β

[0063] In the formula, β is the arcing angle, γ is the arcing angle, I ord is the DC current command value, I dN is the DC current rating, U di0N is the rated value of the no-load DC voltage on the inverter side, U di0 is the no-load DC voltage on the inverter side, α max However, this adjustment not only acts on the DC transmission system, but also may affect the AC power grid at the receiving end, especially in terms of voltage and reactive power characteristics.

[0064] When the commutation failure prediction link is started, if the valve side voltage remains unchanged, the reduction of the trigger angle will lead to a decrease in the DC voltage on the inverter side. If the DC current remains unchanged, the DC transmission power will decrease. At the same time, the power factor of the inverter decreases, and the proportion of reactive power required by the inverter increases, resulting in a decrease in the voltage amplitude of the AC system commutation bus. The reactive power provided by the AC filter cannot meet the demand, and part of the reactive power is provided by the receiving AC system, which exacerbates the reactive power shortage of the AC system after the fault.

[0065] CLCC no longer has the problem of commutation failure, and there is no need to increase the turn-off angle to avoid commutation failure when the AC voltage at the receiving end drops. However, shielding the commutation failure prediction link can only ensure that the turn-off angle of CLCC does not increase during the fault, and cannot give full play to the advantages of CLCC's controllable commutation and improve the dynamic characteristics of the AC power grid. From the working mechanism of CLCC, it can be seen that with the help of the auxiliary branch, the inverter can also successfully commutate when the arc extinction angle = 0. Within the allowable range, it is possible to consider setting the trigger angle setting value to a larger value to provide more reactive power support for the system. Therefore, the CFPREV module is switched and controlled as follows. When the commutation failure prediction link predicts a commutation failure, when the inverter station is in CLCC mode, Ctrl = 1, and the second trigger angle is increased; when the inverter station is in LCC mode, Ctrl = 0, and the second trigger angle is reduced. The CLCC control block diagram is as follows. Fig. 9As shown, the control logic of the CLCC inverter station is as follows Fig.10 shown.

[0066] 5. Simulation verification

[0067] A CLCC-HVDC model was built using the PSCAD simulation software. For single-phase grounding and three-phase grounding fault conditions, a CLCC control method based on an improved commutation prediction link was adopted. Simulation experimental analysis was carried out on the PSCAD simulation platform to compare the differences in CLCC fault characteristics before and after the optimization control method was adopted.

[0068] like Fig.11 The following is a comparison of the characteristics of CLCC before and after the optimization control under three-phase grounding fault. Fig.12 The figure shows the characteristics comparison of CLCC before and after the optimization control under single-phase ground fault. The red curve is the response waveform of CLCC after optimization, and the blue curve is the response waveform of CLCC before optimization. After adopting the CLCC control method with improved commutation prediction link, the trigger angle command of CLCC inverter side is increased by 6°~20°. After the fault line is cut off, the DC power of the receiving-end converter valve is increased faster under the control of the improved commutation prediction link, and the energy loss of the receiving-end AC system is smaller. At the same time, the reactive power consumed by the receiving-end converter valve under the control of the improved commutation prediction link is smaller, and the AC filter of the converter station injects more reactive power into the AC system, which is conducive to improving the AC voltage recovery speed of the power grid.

[0069] The program code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

[0070] In the context of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0071] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A converter station, characterized in that: It includes a rectifier side and an inverter side, the rectifier side is connected to a first AC end and a DC end through an LCC, the inverter side is connected to a DC end and a second AC end through a CLCC pulsating bridge, the CLCC pulsating bridge predicts a commutation result through a commutation prediction verification unit, if the commutation prediction verification result is successful, the CLCC pulsating bridge is controlled to be in LCC mode, and commutation action is performed; if the commutation prediction verification result is a failure, the CLCC pulsating bridge is controlled to be in CLCC mode, and commutation action is performed.

2. A converter station according to claim 1, characterized in that: The topological structure of the CLCC pulsating bridge includes multiple bridge arms, each of which is composed of a main branch and an auxiliary branch in parallel. The main branch includes a LCC thyristor V11 and a main full-controlled valve V12 connected in series, and the auxiliary branch includes an auxiliary full-controlled valve V13 and a small current thyristor valve V14 connected in series.

3. A converter station according to claim 2, characterized in that: The main full-control valve V12 is an IGBT element, and the auxiliary full-control valve V13 is composed of an IGBT element and a lightning arrester connected in parallel.

4. A converter station according to claim 2, characterized in that: The topological structure of the inverter-side converter station, the CLCC pulsating bridge includes the LCC mode and the CLCC mode, the working process of the LCC mode is to simultaneously turn on the LCC thyristor V11, the main full-control valve V12 and the auxiliary full-control valve V13 to turn on the main branch; after the main branch is turned on for 120°, the bridge arm starts to change phases, during the bridge arm phase change, the main full-control valve V12 is turned off, and the current starts to transfer to the auxiliary branch until the main branch current passes zero, the LCC thyristor V11 valve is subjected to reverse pressure, and after the bridge arm completes natural phase change; the auxiliary full-control valve V13 is turned off at zero current, the bridge arm restores the blocking capacity, and the phase change between the bridge arms is completed; The working process of the CLCC mode is as follows: the main full-control valve V12 is turned off, and the current is transferred to the auxiliary branch; the main thyristor valve is turned off at zero crossing, and after the main full-control valve V12 is restored, the auxiliary full-control valve V13 is turned off and the current is transferred to the lightning arrester connected in parallel with it. The lightning arrester establishes an operating voltage and enhances the commutation voltage to complete the commutation between the bridge arms.

5. A control method for a converter station, characterized in that: include: Rectifier side control: obtaining a first current command value according to a DC voltage measurement value on the rectifier side, obtaining a first trigger angle based on the first current command value and a first input current, and generating a first trigger pulse to implement rectifier side control when the first trigger angle meets a first threshold; Inverter side control: According to the measured value of the AC voltage on the inverter side, a second current command value is obtained, and based on the second current command value and the second input current, a second trigger angle is obtained, and a commutation prediction is performed on the second trigger angle. If the result of the commutation prediction is successful, the CLCC pulsating bridge is controlled to be in LCC mode and the second trigger angle is increased; if the result of the commutation prediction is a failure, the CLCC pulsating bridge is controlled to be in CLCC mode and the second trigger angle is reduced.

6. A control method for a converter station according to claim 1, characterized in that: The commutation prediction verification comprises the following steps: Single-phase fault verification: verify the sum of the three-phase voltages through zero-sequence detection to determine whether there is a single-phase fault; Three-phase fault verification: Determine whether there is a three-phase fault by calculating the difference between the output vector of the AC voltage and the steady-state value.

7. A control method for a converter station according to claim 1, characterized in that: The increase in the second trigger angle is from 6 degrees to 20 degrees.

8. A control method for a converter station according to claim 1, characterized in that: The calculation expression of the second trigger angle is: α max ＝π-β In the formula, β is the arcing angle, γ is the arcing angle, I ord is the DC current command value, I dN is the DC current rating, U di0N is the rated value of the no-load DC voltage on the inverter side, U di0 is the no-load DC voltage on the inverter side, α max is the second trigger angle.

9. A control device for a control method of a converter station, comprising a memory, a processor, and a program stored in the memory, characterized in that: When the processor executes the program, a control method for a converter station as described in any one of claims 5 to 8 is implemented.

10. A storage medium having a program stored thereon, characterized in that: When the program is executed, a control method for a converter station as described in any one of claims 5 to 8 is implemented.

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