Optimized reactive power control and fault ride-through method and system for hybrid commutated converter

Abstract

The present invention discloses a method and system for optimizing reactive power control and fault ride-through for a hybrid commutation converter. By introducing reactive power control and constant voltage control with negative turn-off angle limitations, under steady-state conditions, the fully controlled components in the converter are actively shut down to achieve extremely low turn-off angle control, thereby meeting high power factor requirements and reducing investment in passive filter equipment. Under AC fault conditions, the fully controlled components are actively shut down to achieve forced commutation and negative turn-off angle operation, effectively supporting the receiving-end grid voltage while avoiding commutation failures in the half-controlled thyristors in the hybrid commutation converter, thereby improving the level of active power transmission during faults. The present invention fully utilizes the fully controlled characteristics of the reverse-resistance integrated gate-commutated thyristors in the hybrid commutation converter, and achieves reactive power control under steady-state conditions and stable power transmission under AC faults by optimizing active turn-off control. The method has wide applicability and good application prospects.

Description

Technical Field

[0001] The present invention relates to the field of high-voltage direct current transmission, and in particular to a method and system for optimizing reactive power control and fault ride-through of a hybrid commutation converter. Background Art

[0002] Grid-commutated converter-based high-voltage direct current (HVDC) transmission has been widely adopted worldwide due to its advantages, including large-capacity transmission, long-distance transmission, and low operating losses. However, LCC-HVDC systems have inherent operational issues that limit their development, the most serious of which is commutation failure. Because the commutation devices in LCC-HVDC systems are half-controlled thyristors, they rely on the AC grid voltage to assist in commutation. Therefore, AC grid faults can cause commutation failures in HVDC systems. This can lead to DC voltage drops, DC current surges, and DC power oscillations. Commutation failures on a single DC transmission line can trigger multiple subsequent commutation failures, resulting in converter lockup, DC power transmission interruptions, and grid frequency drops, posing a serious threat to the safety and stability of the power grid.

[0003] In recent years, fully controlled integrated gate thyristors (IGCTs) have made significant progress in manufacturing processes and operating losses, particularly in the reverse-blocking IGCT (RB-IGCT). Because IGCTs are derived from thyristors and share much of their manufacturing processes, their conduction principles, capabilities, and reliability are similar to those of thyristors, and their conduction losses are much lower than those of other similarly fully controlled devices.

[0004] Existing literature explores the concept of integrating IGCTs into LCC-HVDC to improve system resilience to commutation failures. By introducing fully controlled devices into LCC converters, commutation failures can be eliminated at the mechanistic level. Researchers at home and abroad have gradually begun studying hybrid commutation converters based on IGCTs. Current topological results primarily focus on different approaches to suppressing overvoltage at the RB-IGCT shutdown state. These include common topologies that rely on overvoltage operation and energy dissipation of valve arresters and those that reuse valve-side filter capacitors for overvoltage suppression. Because arresters are prone to failure due to prolonged operation, which can reduce system reliability, reuse of valve-side filter capacitors for RB-IGCT overvoltage suppression can ensure higher reliability. However, current control methods for this type of topology mostly inherit the control architecture of conventional DC transmission LCCs, employing fixed shutdown angle control. This still requires certain reactive power compensation equipment. Utilizing the controllable shutdown characteristics of RB-IGCTs, enabling reactive power regulation at extreme or negative shutdown angles, and maintaining high power levels during faults, remain key challenges. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for optimizing reactive power control and fault ride-through of a hybrid commutation converter in view of the shortcomings of the existing technology, so as to ensure the high power factor of the hybrid commutation converter under normal working conditions and stable power transmission under fault conditions.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a method for optimizing reactive power control and fault ride-through of a hybrid commutation converter, wherein the hybrid commutation converter includes three parallel commutation valve arms, each commutation valve arm includes two upper and lower sub-commutation valve arms; each of the sub-commutation valve arm groups includes m thyristor modules connected in series and n reverse-resistance integrated gate-level commutation thyristor modules connected in series; a filter capacitor is connected in parallel between the phases of each commutation valve arm; a filter inductor is connected in series on each phase outlet side of each commutation valve arm; each thyristor and reverse-resistance integrated gate-level commutation thyristor module is connected to a buffer branch, and the buffer branch includes a buffer capacitor and a damping resistor connected in series; the hybrid commutation converter is connected to the DC side of the DC transmission system in series, and the hybrid commutation converter is connected to the receiving end power grid via a YY or DY converter transformer; the method comprises the following steps:

[0007] S1, detect the three-phase AC voltage u of the receiving end power grid a 、u b 、u c and the DC voltage U on the inverter side of the DC transmission system meas , inverter side DC current I di_meas , receiving end active power P imeas and reactive power Q imeas ; Three-phase AC voltage u of the receiving end grid a 、u b 、u c Perform AC fault detection and obtain the receiving end AC fault flag F _Uac , the system DC voltage U meas Through the filter, the DC voltage U DM , the system DC current I di_meas Through the filter, the inverter side DC current I DM ;

[0008] S2, the DC voltage instruction U Dref With DC voltage U DM The DC voltage deviation ΔU is obtained by making a difference, and the DC voltage deviation ΔU is sent to the first PI controller to obtain the fixed DC voltage control leading trigger angle instruction β CU ;

[0009] S3, DC voltage U DM Input the low voltage current limiting control module, and compare the obtained low voltage current limiting DC current instruction with the initial current instruction I set Compare and take the smaller value as the rectifier side current command Idr , rectifier side current command I dr Subtract the current margin I m Get the inverter side current command I di , the inverter side DC current I DM and the rectifier side current command I dr The deviation ΔI is obtained by subtraction d , and then ΔI d With the current margin I m The DC current deviation Δe is obtained by subtracting I , DC current deviation Δe I Send it to the second PI controller to get the constant DC current control leading trigger angle instruction β CC ;

[0010] S4. Subtract the measured inverter side reactive power Q from the reactive power command 0 under unity power factor operation. imeas , difference superposition ΔI d The output Δβ after inputting the current deviation control module is obtained as Q error , Q error Send it to the third PI controller to get β CQ0 , the output β of the third PI controller CQ0 With fault flag F _Uac Multiply them to get the leading trigger angle command β of the constant reactive power control CQ ;

[0011] S5, determine the DC current leading trigger angle instruction β CC and fixed reactive power control leading trigger angle command β CQ The larger value is compared with the fixed DC voltage leading trigger angle instruction β CU , and the smaller value is used as the leading trigger angle instruction β of the receiving inverter inv , subtract β from π inv Get the receiving inverter trigger angle command α inv ;

[0012] S6, using the receiving inverter trigger angle instruction α inv Generate trigger signals for each valve arm to control the opening and closing of the thyristors and reverse-blocking integrated gate-level commutation thyristors in the hybrid commutation converter.

[0013] By introducing reactive power control and constant voltage control with negative turn-off angle limitations, the present invention utilizes active shutdown of fully controlled devices in the converter to achieve extremely low turn-off angle control under steady-state conditions, thereby meeting high power factor requirements and reducing investment in passive filter equipment. Under AC fault conditions, the present invention utilizes active shutdown of fully controlled devices to achieve forced commutation and negative turn-off angle operation, effectively supporting the receiving-end grid voltage while avoiding commutation failures in the half-controlled thyristors in the hybrid-commutated converter and improving the level of active power transmission during faults. This invention fully utilizes the fully controlled characteristics of the reverse-resistance integrated gate-commutated thyristors in the hybrid-commutated converter, achieving reactive power control under steady-state conditions and stable power transmission under AC faults by optimizing active shutdown control. The present invention has broad applicability and promising application prospects.

[0014] The low-voltage current limiting control module expression is:

[0015]

[0016] The current deviation control module expression is: k is the conversion coefficient between the turn-off angle command compensation value and the current deviation value, ΔI H is the current deviation upper limit setting value, Δβ max Indicates the maximum value of the Δβ compensation command.

[0017] The lower limit value constraint of the first PI controller is: CU_min >0.1222-arcsin(η),β CU_min is the lower limit of the first PI controller, η is the ratio of the reverse-resistance integrated gate-level commutation thyristors in the sub-converter valve arm of the hybrid commutation converter to the total power devices in the sub-converter valve arm, η=n / (n+m), where n represents the number of reverse-resistance integrated gate-level commutation thyristors in the sub-converter valve arm, and m represents the number of conventional thyristors in the sub-converter valve arm.

[0018] The lower limit value of the third PI controller is 0.0468°, which ensures that the reverse resistance integrated gate-level commutation thyristor can successfully commutate naturally under steady-state conditions.

[0019] The constant reactive power control controls the leading trigger angle instruction β CQ The expression is: CQ =β CQ0 ·F _Uac , β CQ0 is the output of the third PI controller in the constant reactive power control, F _Uac F is the receiving end AC fault flag _Uac , when AC fault occurs at the receiving end, F _Uac =0, when there is no fault F _Uac =1.

[0020] As an inventive concept, the present invention also provides an optimized reactive power control and fault ride-through control system for a hybrid commutated converter, comprising a memory, a processor, and a computer program stored on the memory; the processor executes the computer program to implement the steps of the above method.

[0021] As an inventive concept, the present invention also provides a computer-readable storage medium having a computer program / instruction stored thereon; the computer program / instruction implements the steps of the above method when executed by a processor.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention makes full use of the wide range trigger angle adjustment characteristics of the hybrid commutation converter, proposes an optimized reactive power control under unity power factor operation and a constant voltage control fault ride-through control considering the negative turn-off angle limit, realizes the high power factor requirement under steady-state conditions, avoids the commutation failure of the half-controlled thyristor under AC fault conditions, and improves the active power transmission level during the fault under AC fault conditions, and reduces the investment in DC filters. The proposed method is also applicable to other low-frequency phase-controlled converters with flexible trigger angle adjustment capabilities, and has a wider applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is an inverter topology diagram of a DC power transmission system based on a hybrid commutated converter according to an embodiment of the present invention;

[0024] Figure 2 This is an implementation process of a method for optimizing reactive power control and fault ride-through of a hybrid commutated converter according to an embodiment of the present invention;

[0025] Figure 3 This is a block diagram of a DC power transmission control system according to an embodiment of the present invention;

[0026] Figure 4 This is the simulation experiment result of the AC system three-phase fault (ground inductance 0.15H) according to the embodiment of the present invention;

[0027] Figure 5 This is the simulation experiment result of a single-phase metallic grounding fault in an AC system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0029] Example 1

[0030] Figure 1 FIG is an inverter topology diagram of a DC power transmission system based on a hybrid commutation converter according to an embodiment of the present invention. Figure 1 As shown in the figure, the hybrid commutation converter transforms the commutation valve group in the original grid commutation converter based on thyristor elements, introduces fully controlled devices and utilizes the fully controlled characteristics of the fully controlled devices to achieve controllable shutdown of the commutation current without the risk of commutation failure. During the fault of the receiving end grid, the inverter trigger angle can be adjusted over a wide range, providing a basis for forced commutation and high-level power transmission of the DC transmission system. The hybrid commutation converter includes three parallel-connected converter valve arms, each of which includes two upper and lower sub-converter valve arms; each sub-converter valve arm group includes m thyristor modules and n reverse-resistance integrated gate-level commutation thyristor modules; a filter capacitor is connected in parallel between the phases of each converter valve arm; a filter inductor is connected in series on the outlet side of each phase of each converter valve; each thyristor and reverse-resistance integrated gate-level commutation thyristor (RB-IGCT) module is connected to a buffer branch, and the buffer branch includes a buffer capacitor and a damping resistor connected in series; the hybrid commutation converter is connected to the DC side of the DC transmission system via a series connection, and the hybrid commutation converter is connected to the receiving power grid via a YY or DY converter transformer.

[0031] Figure 2 This is an implementation process of a hybrid commutation converter optimized reactive power control and fault ride-through method according to an embodiment of the present invention. Figure 2 Describe the method. Figure 2 As shown, the method includes the following steps:

[0032] Step 1: Detect the three-phase AC voltage u of the receiving end grid a 、u b 、u c and the DC voltage U on the inverter side of the DC transmission system meas , inverter side DC current I di_meas , receiving end active power P imeas and reactive power Q imeas ; The receiving end three-phase AC voltage u a 、u b 、u c Through the single-phase three-phase fault detection module, the receiving end AC fault flag F is obtained _Uac , the system DC voltage U meas The DC voltage U is extracted by the filter DM , the system DC current I di_meas The DC current I is extracted by the filter DM .

[0033] Step 2: Set the DC voltage command U Dref and the filtered DC voltage U DMThe DC voltage deviation ΔU is obtained by making a difference, and the DC voltage deviation ΔU is sent to the first PI controller to obtain the fixed DC voltage control leading trigger angle instruction β CU In order to ensure the reliable commutation of the thyristors in the converter valve arms, the lower limit value of the first PI controller in the constant DC voltage control is constrained as follows: β CU_min >0.1222-arcsin(η),β CU_min is the lower limit of the first PI controller, η is the ratio of the reverse-resistance integrated gate-level commutation thyristors in the sub-converter valve arm of the hybrid commutation converter to the total power devices in the sub-converter valve arm, and η = n / (n+m), where n represents the number of reverse-resistance integrated gate-level commutation thyristors in the sub-converter valve arm, and m represents the number of conventional thyristors in the sub-converter valve arm.

[0034] Step 3: Convert the filtered DC voltage U DM Input the low voltage current limiting control module, and compare the obtained low voltage current limiting DC current instruction with the initial current instruction I set Compare and take the smaller value as the rectifier side current command I dr , rectifier side current command I dr Subtract the current margin I m Get the inverter side current command I di , the DC current on the inverter side after filtering I DM and the rectifier side current command I dr The deviation ΔI is obtained by subtraction d , and then ΔI d With the current margin I m The DC current deviation Δe is obtained by subtracting I , DC current deviation Δe I Send it to the second PI controller to get the constant DC current control leading trigger angle instruction β CC ;

[0035] Among them, the expression of the low-voltage current limiting control module is:

[0036] 0.4pu≤U DM <0.9pu,U d Extract the DC voltage U for the filter DM , I VL is the output value of the low-voltage current limiting control module;

[0037] The current deviation control curve expression is:

[0038] k is the conversion coefficient between the turn-off angle command compensation value and the current deviation value, ΔI H is the current deviation upper limit setting value, Δβ max Indicates the maximum value of the Δβ compensation command.

[0039] Step 4: Subtract the measured inverter side reactive power Q from the reactive power command 0 under unity power factor operation imeas And superimpose the above ΔI d The output Δβ after inputting the current deviation control module is obtained as Q error , Q error Send it to the third PI controller to get β CQ0 , the output of the third PI controller β CQ0 With fault flag F _Uac Multiply to get the constant reactive power control control leading trigger angle instruction β CQ .

[0040] Among them, in order to ensure that the reverse resistance integrated gate-level commutation thyristor can successfully commutate naturally under steady-state conditions, given that the RB-IGCT turn-off recovery time is about 26us, the corresponding electrical angle is about 0.0468°, so the lower limit value of the third PI controller in the constant reactive power control is set to 0.0468°.

[0041] Among them, the AC fault freezes the reactive power control controller, that is, during the fault period, its output is set to 0, so the leading trigger angle command β CQ The expression is: CQ =β CQ0 ·F _Uac , β CQ0 is the output of the third PI controller in the constant reactive power control, F _Uac F is the receiving end AC fault flag _Uac , when AC fault occurs at the receiving end, F _Uac =0, when there is no fault F _Uac = 1. Therefore, when AC failure occurs, the receiving end AC failure flag F _Uac The low reactive power controller output can be set to 0.

[0042] Step 5: Determine the DC current leading trigger angle instruction β CC and fixed reactive power control leading trigger angle command β CQ The larger value of the fixed DC voltage leading trigger angle command β CU Compare and take the smaller value as the leading trigger angle instruction β of the receiving inverter inv , subtract β from π inv Get the receiving inverter trigger angle command α inv ;

[0043] Step 6: Use the final output instruction α inv Generate trigger signals for each valve arm to control the opening and closing of the thyristors and reverse-blocking integrated gate-level commutation thyristors in the hybrid commutation converter.

[0044] Figure 4 、 Figure 5 This is the real-time simulation experiment result of the embodiment of the present invention.

[0045] Figure 4 、 Figure 5 It demonstrates that the DC transmission system of the hybrid commutation converter according to the embodiment of the present invention can still effectively avoid commutation failure under extreme fault conditions and ensure the stable transmission of a certain amount of active power; the proposed method has wide applicability, and the simulation results under three-phase severe grounding faults and single-phase metallic grounding faults show that the proposed control strategy effectively suppresses thyristor commutation failure and improves the stability of transient power transmission under system faults.

[0046] Figure 4 、 Figure 5 The feasibility and practical value of this method have been verified, which can effectively improve the transient steady-state performance of the hybrid commutated converter and is conducive to the further development of new hybrid converters in actual engineering.

[0047] Example 2

[0048] Embodiment 2 of the present invention provides a terminal device corresponding to the above-mentioned embodiment 1. The terminal device can be a processing device for a client, such as a mobile phone, a laptop computer, a tablet computer, a desktop computer, etc., to execute the method of the above-mentioned embodiment.

[0049] The terminal device of this embodiment includes a memory, a processor, and a computer program stored in the memory; the processor executes the computer program in the memory to implement the steps of the method in the above-mentioned embodiment 1.

[0050] In some implementations, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk storage.

[0051] In other implementations, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors, which are not limited herein.

[0052] Example 3

[0053] Embodiment 3 of the present invention provides a computer-readable storage medium corresponding to the above-mentioned embodiment 1, on which a computer program / instruction is stored. When the computer program / instruction is executed by a processor, the steps of the method of the above-mentioned embodiment 1 are implemented.

[0054] Computer readable storage media can be tangible devices that hold and store instructions used by instruction execution devices. Computer readable storage media can be, for example, but not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any combination thereof.

[0055] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiment of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal translation scripting language JavaScript, etc.

[0056] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0057] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0058] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0059] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for optimizing reactive power control and fault ride-through of a hybrid commutation converter, wherein the hybrid commutation converter comprises three parallel commutation valve arms, each commutation valve arm comprises an upper and a lower sub-commutation valve arm; each of the sub-commutation valve arm groups comprises m series-connected thyristor modules and n series-connected reverse-resistance integrated gate-level commutation thyristor modules; a filter capacitor is connected in parallel between phases of each commutation valve arm; a filter inductor is connected in series on each phase outlet side of each commutation valve arm; each thyristor and reverse-resistance integrated gate-level commutation thyristor module is connected to a buffer branch, and the buffer branch comprises a buffer capacitor and a damping resistor connected in series; the hybrid commutation converter is connected in series to the DC side of a DC transmission system, and the hybrid commutation converter is connected to a receiving-end power grid via a YY or DY converter transformer; and is characterized in that: The following steps are involved: S1, detect the three-phase AC voltage u of the receiving end power grid a 、u b 、u c and the DC voltage U on the inverter side of the DC transmission system meas , inverter side DC current I di_meas , receiving end active power P imeas and reactive power Q imeas ; Three-phase AC voltage u of the receiving end grid a 、u b 、u c Perform AC fault detection and obtain the receiving end AC fault flag F _Uac , the system DC voltage U meas Through the filter, the DC voltage U DM , the system DC current I di_meas Through the filter, the inverter side DC current I DM ; S2, the DC voltage instruction U Dref With DC voltage U DM The DC voltage deviation ΔU is obtained by making a difference, and the DC voltage deviation ΔU is sent to the first PI controller to obtain the fixed DC voltage control leading trigger angle instruction β CU ; S3, DC voltage U DM Input the low voltage current limiting control module, and compare the obtained low voltage current limiting DC current instruction with the initial current instruction I set Compare and take the smaller value as the rectifier side current command I dr , rectifier side current command I dr Subtract the current margin I m Get the inverter side current command I di , the inverter side DC current I DM and the rectifier side current command I dr The deviation ΔI is obtained by subtraction d , and then ΔI d With the current margin I m The DC current deviation Δe is obtained by subtracting I , DC current deviation Δe I Send it to the second PI controller to get the constant DC current control leading trigger angle instruction β CC ; S4. Subtract the measured inverter side reactive power Q from the reactive power command 0 under unity power factor operation. imeas , difference superposition ΔI d The output Δβ after inputting the current deviation control module is obtained as Q error , Q error Send it to the third PI controller to get β CQ0 , the output β of the third PI controller CQ0 With fault flag F _Uac Multiply them to get the leading trigger angle command β of the constant reactive power control CQ ; S5, determine the DC current leading trigger angle instruction β CC and fixed reactive power control leading trigger angle command β CQ The larger value is compared with the fixed DC voltage leading trigger angle instruction β CU , and the smaller value is used as the leading trigger angle instruction β of the receiving inverter inv , subtract β from π inv Get the receiving inverter trigger angle command α inv ; S6, using the receiving inverter trigger angle instruction α inv Generate trigger signals for each valve arm to control the opening and closing of the thyristors and reverse-blocking integrated gate-level commutation thyristors in the hybrid commutation converter.

2. The method for optimizing reactive power control and fault ride-through of a hybrid commutated converter according to claim 1, characterized in that: The low-voltage current limiting control module expression is:

3. The method for optimizing reactive power control and fault ride-through of a hybrid commutated converter according to claim 1, wherein: The current deviation control module expression is: k is the conversion coefficient between the turn-off angle command compensation value and the current deviation value, ΔI H is the current deviation upper limit setting value, Δβ max Indicates the maximum value of the Δβ compensation command.

4. The method for optimizing reactive power control and fault ride-through of a hybrid commutated converter according to claim 1, wherein: The lower limit value constraint of the first PI controller is: CU_min >0.1222-arcsin(η),β CU_min is the lower limit of the first PI controller, η is the ratio of the reverse-resistance integrated gate-level commutation thyristors in the sub-converter valve arm of the hybrid commutation converter to the total power devices in the sub-converter valve arm, η=n / (n+m), where n represents the number of reverse-resistance integrated gate-level commutation thyristors in the sub-converter valve arm, and m represents the number of conventional thyristors in the sub-converter valve arm.

5. The method for optimizing reactive power control and fault ride-through of a hybrid commutated converter according to claim 1, wherein: The lower limit value of the third PI controller is 0.0468°.

6. The method for optimizing reactive power control and fault ride-through of a hybrid commutated converter according to claim 1, characterized in that: The constant reactive power control controls the leading trigger angle instruction β CQ The expression is: CQ =β CQ0 ·F _Uac , β CQ0 is the output of the third PI controller in the constant reactive power control, F _Uac F is the receiving end AC fault flag _Uac , when AC fault occurs at the receiving end, F _Uac =0, when there is no fault F _Uac =1.

7. An optimized reactive power control and fault ride-through control system for a hybrid commutated converter, comprising a memory, a processor, and a computer program stored in the memory; characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program / instruction stored thereon; characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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