A protection control method, device, medium and product for a flexible DC converter valve

Abstract

The present invention discloses a protection control method, device, medium and product for a flexible DC converter valve, which obtains the bridge arm current of each bridge arm of the flexible DC converter valve; determines whether the preset safe operation conditions are met according to the bridge arm current; when the safe operation conditions are not met, reduces the DC transmission power of the flexible DC converter valve until the safe operation conditions are met. The present invention can effectively improve the response speed and protection effect of the flexible DC power transmission system under station faults, thereby effectively ensuring the safe and stable operation of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible direct current power transmission, and in particular to a protection control method, device, medium and product of a flexible direct current converter valve. Background Art

[0002] With the development of power electronic devices and the application of renewable energy generation technologies such as wind and solar power, flexible DC transmission technology has been rapidly developed and applied at home and abroad. Compared with traditional high-voltage DC transmission technology, flexible DC transmission is a new type of DC transmission method with more flexible control and less harmonics, and has been widely used in various fields.

[0003] At present, flexible direct current transmission has become the main technical solution for large-scale long-distance transmission and consumption of new energy. 3kA-level IGBT devices have become the preferred devices for ultra-high voltage flexible direct current converter valves. IGBT devices of this level have a maximum shutdown current limitation. When a valve short circuit or other fault occurs, the sub-module capacitor discharges rapidly. If the corresponding protection measures are not implemented in time, the bridge arm current will exceed the maximum shutdown current in a very short time, causing a major impact on the reliable operation of the flexible direct current transmission system. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a protection control method, device, medium and product for a flexible DC converter valve, which can effectively improve the response speed and protection effect of the flexible DC transmission system under station faults, thereby effectively ensuring the safe and stable operation of the system.

[0005] To achieve the above object, an embodiment of the present invention provides a protection control method for a flexible DC converter valve, comprising:

[0006] Obtaining the bridge arm current of each bridge arm of the flexible DC converter valve;

[0007] According to the bridge arm current, determining whether a preset safe operation condition is met;

[0008] When the safe operation condition is not met, the DC transmission power of the flexible DC converter valve is reduced until the safe operation condition is met.

[0009] As an improvement of the above solution, judging whether a preset safe operation condition is met according to the bridge arm current includes:

[0010] Calculating the steady-state current utilization rate of the bridge arm current;

[0011] When the steady-state current utilization rate of the bridge arm current is less than or equal to a preset first current threshold, it is determined that the safe operation condition is met.

[0012] As an improvement of the above solution, judging whether a preset safe operation condition is met according to the bridge arm current includes:

[0013] Calculate the DC component, fundamental frequency AC component and harmonic component of the bridge arm current;

[0014] When the DC component is less than or equal to a preset second current threshold, the fundamental frequency AC component is less than or equal to a preset third current threshold, and the harmonic component is less than or equal to a preset fourth current threshold, it is determined that the safe operation condition is met.

[0015] As an improvement of the above solution, after obtaining the bridge arm current of each bridge arm of the flexible DC converter valve, the method further includes:

[0016] Calculating the rising rate of the bridge arm current;

[0017] Determining whether a corresponding locking condition is triggered according to the bridge arm current and the rising rate;

[0018] When the locking condition is triggered, the flexible DC converter valve is controlled to perform a corresponding locking operation.

[0019] As an improvement of the above solution, the locking condition includes a single bridge arm temporary locking condition and a full valve locking condition;

[0020] Then, judging whether a corresponding locking condition is triggered according to the bridge arm current and the rising rate includes:

[0021] When the rising rate is less than the preset rate threshold, and the bridge arm current is greater than the preset fifth current threshold, and the duration is greater than or equal to the preset first time threshold, it is determined that the single bridge arm temporary locking condition is triggered;

[0022] When the rising rate is greater than or equal to the rate threshold, and the bridge arm current is greater than a preset sixth current threshold, and the duration is greater than or equal to a preset second time threshold, it is determined that the full valve locking condition is triggered;

[0023] When the locking condition is triggered, the flexible DC converter valve is controlled to perform a corresponding locking operation, including:

[0024] When the temporary blocking condition of the single bridge arm is triggered, the corresponding bridge arm is controlled to be temporarily blocked;

[0025] When the full-valve locking condition is triggered, the flexible DC converter valve is controlled to be fully valve locked.

[0026] As an improvement of the above solution, the method further includes:

[0027] After the bridge arm is controlled to be temporarily locked, when the bridge arm current of the bridge arm is less than a preset seventh current threshold and the duration is greater than or equal to a preset third time threshold, the bridge arm is controlled to be unlocked.

[0028] The embodiment of the present invention further provides a protection control device for a flexible DC converter valve, comprising:

[0029] A bridge arm current acquisition module, used to acquire the bridge arm current of each bridge arm of the flexible DC converter valve;

[0030] An operating condition judgment module, used to judge whether a preset safe operating condition is met according to the bridge arm current;

[0031] The protection control module is used to reduce the DC transmission power of the flexible DC converter valve when the safe operation condition is not met until the safe operation condition is met.

[0032] An embodiment of the present invention also provides a protection and control device for a flexible DC converter valve, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, the protection and control method for the flexible DC converter valve as described in any one of the above items is implemented.

[0033] An embodiment of the present invention also provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the protection control method of the flexible DC converter valve as described in any one of the above.

[0034] An embodiment of the present invention further provides a computer program product, which includes a computer program or computer instructions. When the computer program or the computer instructions are executed by a processor, the protection control method of the flexible DC converter valve as described in any one of the above items is implemented.

[0035] Compared with the prior art, the protection and control method, device, medium and product of the flexible DC converter valve disclosed in the present invention pre-sets corresponding safe operating conditions based on the bridge arm current of the flexible DC converter valve, and reduces the bridge arm current by real-time detection and evaluation of the bridge arm current. When it is determined that the safe operating conditions are not met, the DC transmission power is reduced to reduce the bridge arm current, thereby ensuring that the flexible DC transmission system maintains safe operation without affecting the transmission efficiency, effectively improving the response speed and protection effect of the flexible DC transmission system under station faults, thereby effectively ensuring the safe and stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1It is a flow chart of a protection control method of a flexible DC converter valve provided by an embodiment of the present invention;

[0037] Figure 2 It is a flow chart of a preferred protection and control method of a flexible DC converter valve in an embodiment of the present invention;

[0038] Figure 3 It is a structural schematic diagram of a protection control device for a flexible DC converter valve provided by an embodiment of the present invention;

[0039] Figure 4 It is a structural schematic diagram of another protection control device for a flexible DC converter valve provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 creative work are within the scope of protection of the present invention.

[0041] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0042] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0043] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] See also Figure 1 , is a flow chart of a protection control method for a flexible DC converter valve provided by an embodiment of the present invention. The embodiment of the present invention provides a protection control method for a flexible DC converter valve, and the method includes steps S11 to S13:

[0045] S11, obtaining the bridge arm current of each bridge arm of the flexible DC converter valve;

[0046] S12, judging whether the preset safe operation conditions are met according to the bridge arm current;

[0047] S13. When the safe operation condition is not met, reducing the DC transmission power of the flexible DC converter valve until the safe operation condition is met.

[0048] It should be noted that the embodiment of the present invention ensures that the flexible DC transmission system can respond quickly and accurately to various possible station faults through an efficient bridge arm current protection strategy, thereby ensuring the safe and stable operation of the system. As an example, the system configuration example of the flexible DC transmission system is as follows:

[0049] System architecture: The embodiment of the present invention is applicable to the ±800kV / 5GW ultra-high voltage flexible direct current transmission system, which adopts a true bipolar wiring scheme, with each pole cascaded by two valve groups, and the DC voltage of each valve group is 400kV.

[0050] Main circuit parameters: submodule rated working voltage 2.0kV; submodule capacitance 15mF; bridge arm reactor 35mH; current limiting reactor 300mH; DC transmission line length 1500km, using 6 split conductors, line resistance is about 10Ω.

[0051] Valve group configuration: The valve group adopts a full half-bridge hybrid module, and the full-bridge ratio is 60%.

[0052] Control strategy: The AC side of the sending-end converter station is in networking mode, adopting a fixed active power and fixed reactive power control strategy; the receiving-end converter station adopts a fixed DC voltage and fixed reactive power control strategy.

[0053] It can be understood that the above system configuration is only used as an example. In actual application, the corresponding flexible direct current transmission system can be configured according to actual conditions, which does not affect the beneficial effects achieved by the present invention.

[0054] In an embodiment of the present invention, when a converter valve fails, the submodule capacitor of the converter valve may be discharged quickly, and the bridge arm current will rise rapidly. The embodiment of the present invention pre-sets corresponding safe operation conditions based on the bridge arm current parameter of the flexible DC converter valve to reflect whether the system has abnormal discharge. Furthermore, during the operation of the system, the bridge arm current of each bridge arm of the flexible DC converter valve is obtained in real time through a high-precision current sensor, and the monitored current data is pre-processed, including filtering, denoising, etc., to improve data accuracy. It is determined whether the safe operation condition is met based on the bridge arm current. When the safe operation condition is met, the flexible DC power transmission system operates normally. When the safe operation condition is not met, it indicates that the system fails, and the control system automatically adjusts the output of the DC transmission power to reduce the DC transmission power of the flexible DC converter valve, thereby reducing the bridge arm current until the safe operation condition is met to protect the stable operation of the system.

[0055] By adopting the technical means of the embodiments of the present invention, corresponding safe operating conditions are pre-set based on the bridge arm current of the flexible DC converter valve. Through real-time detection and evaluation of the bridge arm current, the DC transmission power is reduced to reduce the bridge arm current when it is determined that the safe operating conditions are not met. This can ensure that the flexible DC transmission system maintains safe operation without affecting the transmission efficiency, effectively improve the response speed and protection effect of the flexible DC transmission system under station faults, thereby effectively ensuring the safe and stable operation of the system.

[0056] As a preferred implementation mode, the embodiment of the present invention is further implemented on the basis of the above-mentioned embodiment, and the means for setting the safe operating conditions is optimized and limited.

[0057] In the first implementation manner, step S12, i.e., judging whether a preset safe operation condition is met according to the bridge arm current, includes:

[0058] Calculating the steady-state current utilization rate of the bridge arm current;

[0059] When the steady-state current utilization rate of the bridge arm current is less than or equal to a preset first current threshold, it is determined that the safe operation condition is met.

[0060] It should be noted that the steady-state current utilization rate of the bridge arm current refers to the ratio between the actual current flowing through the bridge arm under steady-state conditions and the theoretical maximum current or rated current. This ratio reflects the effective utilization of the bridge arm current under steady-state conditions, as well as the efficiency of the rectifier or inverter in steady-state operation. In a rectifier or inverter, the bridge arm is usually composed of multiple semiconductor devices (such as rectifier tubes or switching tubes), which need to withstand a certain current in steady-state operation. A high steady-state current utilization rate means that under the same input conditions, the bridge arm can more efficiently convert the current into the required output form, thereby improving the overall efficiency of the equipment.

[0061] The steady-state current utilization rate is usually expressed as a current value. In the embodiment of the present invention, a first current threshold is preset as a limiting condition of the steady-state current utilization rate.

[0062] Preferably, the first current threshold is 2.15A.

[0063] During the application process, by obtaining or calculating the steady-state current utilization rate of the bridge arm current, when the steady-state current utilization rate is less than or equal to 2.15A, it is determined that the safe operating conditions are met; when the steady-state current utilization rate is greater than 2.15A, it is determined that the safe operating conditions are not met.

[0064] By adopting the technical means of the embodiments of the present invention, the steady-state current utilization rate of the bridge arm current is limited, so as to ensure that the bridge arm current operates within a safe range, thereby preventing equipment damage or system instability caused by excessive current.

[0065] In the second implementation, step S12, i.e., judging whether a preset safe operation condition is met according to the bridge arm current, includes:

[0066] Calculate the DC component, fundamental frequency AC component and harmonic component of the bridge arm current;

[0067] When the DC component is less than or equal to a preset second current threshold, the fundamental frequency AC component is less than or equal to a preset third current threshold, and the harmonic component is less than or equal to a preset fourth current threshold, it is determined that the safe operation condition is met.

[0068] It should be noted that the DC component of harmonic current is the average value of the signal. In the power system, the DC component usually refers to the DC component in the current, and the fundamental frequency AC component refers to the AC component in the current corresponding to the fundamental frequency (usually the power system's power frequency, such as 50Hz or 60Hz). Harmonic components are components whose frequencies are integer multiples of the fundamental frequency, and are used to describe the frequency components and energy distribution of the signal.

[0069] There is a certain mutual influence between the DC component, the fundamental frequency AC component and the harmonic component. For example, when the DC component increases, it may affect the distribution of the fundamental frequency AC component and the harmonic component; similarly, when the fundamental frequency AC component or the harmonic component increases, it may also affect the DC component. Therefore, when designing and optimizing the flexible DC transmission system, it is necessary to comprehensively consider the influence of these three components.

[0070] In an embodiment of the present invention, a second current threshold, a third current threshold and a fourth current threshold are pre-set as limiting conditions for the DC component, the fundamental frequency AC component and the harmonic component, respectively. The DC component is less than or equal to the second current threshold, which is used to limit the DC component in the bridge arm current. The fundamental frequency AC component is used to limit the AC component in the bridge arm current. The harmonic component is less than or equal to the fourth current threshold, which is used to limit the high frequency component in the bridge arm current.

[0071] Preferably, the second current threshold is 1.04 kA, the third current threshold is 1.83 kA, and the fourth current threshold is 0.37 kA.

[0072] In the application process, by obtaining or calculating the DC component, fundamental frequency AC component and harmonic component of the bridge arm current, when the DC component is less than or equal to 1.04kA, the fundamental frequency AC component is less than or equal to 1.83kA, and the harmonic component is less than or equal to 0.37kA, it is determined that the safe operation condition is met; otherwise, it is determined that the safe operation condition is not met.

[0073] By adopting the technical means of the embodiments of the present invention, by limiting the values ​​of the DC component, fundamental frequency AC component and harmonic component of the bridge arm current, it is possible to ensure that each component in the bridge arm current is within a safe range, ensure that the bridge arm current operates within a safe range, and prevent equipment damage or system instability caused by excessive current.

[0074] As a preferred embodiment, see Figure 2 , is a flow chart of a preferred protection control method of a flexible DC converter valve in an embodiment of the present invention. The embodiment of the present invention is further implemented on the basis of any of the above embodiments. In step S11, that is, after obtaining the bridge arm current of each bridge arm of the flexible DC converter valve, the method further includes steps S14 to S16:

[0075] S14, calculating the rising rate of the bridge arm current;

[0076] S15, judging whether a corresponding locking condition is triggered according to the bridge arm current and the rising rate;

[0077] S16: When the locking condition is triggered, control the flexible DC converter valve to perform a corresponding locking operation.

[0078] It should be noted that if a converter valve fails, the submodule capacitor of the converter valve may be discharged quickly, and the bridge arm current will rise rapidly. In the embodiment of the present invention, the rising rate of the bridge arm current is used to reflect whether there is an abnormal discharge.

[0079] In the embodiment of the present invention, different locking conditions and locking operations corresponding to the bridge arm currents and their rising rates are preset. During the application process, it is determined whether the corresponding locking condition is triggered according to the bridge arm current and the rising rate of the bridge arm current. If the corresponding locking condition is triggered, the flexible DC converter valve is controlled to perform the corresponding locking operation.

[0080] As a preferred embodiment, the locking condition includes a single bridge arm temporary locking condition and a full valve locking condition. Thus, when the bridge arm current increases abnormally, by quickly locking a single bridge arm or the entire valve group of the converter valve, the fault current can be quickly cut off to prevent the fault from expanding.

[0081] Then step S15, i.e. judging whether the corresponding locking condition is triggered according to the bridge arm current and the rising rate, comprises steps S151 to S152:

[0082] S151, when the rising rate is less than the preset rate threshold, and the bridge arm current is greater than the preset fifth current threshold, and the duration is greater than or equal to the preset first time threshold, it is determined that a single bridge arm temporary locking condition is triggered;

[0083] S152: When the rising rate is greater than or equal to the rate threshold, and the bridge arm current is greater than the preset sixth current threshold, and the duration is greater than or equal to the preset second time threshold, it is determined that the full valve locking condition is triggered.

[0084] Then step S16, that is, when the locking condition is triggered, controlling the flexible DC converter valve to perform a corresponding locking operation, includes steps S161 to S162:

[0085] S161, when the temporary locking condition of the single bridge arm is triggered, controlling the corresponding bridge arm to be temporarily locked;

[0086] S162: When the full-valve locking condition is triggered, control the full-valve locking of the flexible DC converter valve.

[0087] In an embodiment of the present invention, a rate threshold is pre-set as a judgment condition for the rising rate of the bridge arm current, and the fifth current threshold and the sixth current threshold are set as limiting conditions for the bridge arm current, and the first time threshold and the second time threshold are set as limiting conditions for the duration of the fault.

[0088] When the rising rate of the bridge arm current is relatively low, it means that the bridge arm current does not rise much in a short period of time. If a single bridge arm fails at this time, that is, the bridge arm current is greater than the fifth current threshold and the duration exceeds the first time threshold, then only the single bridge arm needs to be temporarily locked. When the rising rate of the bridge arm current is higher, it means that the bridge arm current rises more in a short period of time. At this time, it is necessary to be alert to whether a fault occurs. If the bridge arm current of any bridge arm is greater than the sixth current threshold and the duration exceeds the second time threshold, then all valves need to be directly locked.

[0089] Preferably, the preset rate threshold is 8A / μs, the fifth current threshold is 4.7kA, the sixth current threshold is 4kA, and the first time threshold and the second time threshold are both 100μs.

[0090] During the application process, when the rising rate of the bridge arm current is less than 8A / μs, the bridge arm current is greater than 4.7kA and lasts for 100μs, it is determined that the single bridge arm temporary locking condition is triggered, and the corresponding single bridge arm in the flexible DC converter valve is controlled to be temporarily locked. When the rising rate of the bridge arm current is greater than or equal to 8A / μs, the bridge arm current is greater than 4kA and lasts for 100μs, it is determined that the full valve locking condition is triggered, and the flexible DC converter valve is controlled to be fully locked.

[0091] As a preferred implementation, after step S161, the method further includes:

[0092] After the bridge arm is controlled to be temporarily locked, when the bridge arm current of the bridge arm is less than a preset seventh current threshold and the duration is greater than or equal to a preset third time threshold, the bridge arm is controlled to be unlocked.

[0093] In an embodiment of the present invention, a bridge arm unlocking condition is preset, and during application, the bridge arm current of a single bridge arm that has been temporarily locked is continuously monitored, and when the bridge arm unlocking condition is met, the bridge arm is unlocked.

[0094] Preferably, the seventh current threshold is 3.5 kA, and the third time threshold is 5 ms.

[0095] During the application process, during the temporary blocking state of the bridge arm, when the bridge arm current is lower than 3.5kA and the delay is at least 5ms, it is considered that the current fault of the single bridge arm has been resolved, and the single bridge arm is unlocked.

[0096] It should be noted that, in the embodiment of the present invention, the converter valve can also be unlocked when all valves are locked, but the unlocking conditions are different from the specific threshold settings of the unlocking conditions in the above-mentioned temporary locked state, and need to be set according to actual conditions.

[0097] By adopting the technical means of the embodiment of the present invention, based on the real-time detection and evaluation of the bridge arm current, different fault conditions are distinguished by setting different current thresholds and delay conditions. When an abnormal current is detected, first try to reduce the impact of the fault by temporarily locking a single bridge arm. This local protection measure can reduce the impact on the entire system and give the system a certain recovery time. If the fault situation persists or worsens, the protection measures are gradually upgraded to full valve locking, thereby effectively ensuring the safe and stable operation of the system. At the same time, in order to avoid unnecessary locking operations, corresponding unlocking conditions are set to quickly restore the normal operation of the system after the fault is eliminated.

[0098] The embodiments of the present invention can timely discover and handle faults through real-time monitoring, rapid response and hierarchical protection strategies to prevent fault expansion and system damage; the unlocking and recovery mechanism and the fault recording and alarm function can ensure that the system quickly resumes normal operation after a fault, thereby improving the reliability and stability of the system; and by accurately controlling the locking and unlocking conditions of the bridge arm current, the operating performance of the system can be optimized, and the transmission efficiency and energy utilization rate can be improved.

[0099] See also Figure 3 , is a schematic diagram of a structure of a protection control device for a flexible DC converter valve provided in an embodiment of the present invention. The embodiment of the present invention further provides a protection control device 10 for a flexible DC converter valve, including:

[0100] A bridge arm current acquisition module 11 is used to acquire the bridge arm current of each bridge arm of the flexible DC converter valve;

[0101] An operating condition judgment module 12 is used to judge whether a preset safe operating condition is met according to the bridge arm current;

[0102] The protection control module 13 is used to reduce the DC transmission power of the flexible DC converter valve when the safe operation condition is not met until the safe operation condition is met.

[0103] As a preferred implementation, the operating condition judgment module 12 is specifically used for:

[0104] Calculating the steady-state current utilization rate of the bridge arm current;

[0105] When the steady-state current utilization rate of the bridge arm current is less than or equal to a preset first current threshold, it is determined that the safe operation condition is met.

[0106] As another preferred implementation, the operating condition judgment module 12 is specifically used for:

[0107] Calculate the DC component, fundamental frequency AC component and harmonic component of the bridge arm current;

[0108] When the DC component is less than or equal to a preset second current threshold, the fundamental frequency AC component is less than or equal to a preset third current threshold, and the harmonic component is less than or equal to a preset fourth current threshold, it is determined that the safe operation condition is met.

[0109] By adopting the technical means of the embodiments of the present invention, corresponding safe operating conditions are pre-set based on the bridge arm current of the flexible DC converter valve. Through real-time detection and evaluation of the bridge arm current, the DC transmission power is reduced to reduce the bridge arm current when it is determined that the safe operating conditions are not met. This can ensure that the flexible DC transmission system maintains safe operation without affecting the transmission efficiency, effectively improve the response speed and protection effect of the flexible DC transmission system under station faults, thereby effectively ensuring the safe and stable operation of the system.

[0110] As a preferred embodiment, the device 10 further includes:

[0111] A rising rate calculation module, used to calculate the rising rate of the bridge arm current;

[0112] A locking condition judgment module, used for judging whether a corresponding locking condition is triggered according to the bridge arm current and the rising rate;

[0113] The locking operation control module is used to control the flexible DC converter valve to perform a corresponding locking operation when the locking condition is triggered.

[0114] As a preferred embodiment, the locking condition includes a single bridge arm temporary locking condition and a full valve locking condition;

[0115] The locking condition judgment module is specifically used to:

[0116] When the rising rate is less than the preset rate threshold, and the bridge arm current is greater than the preset fifth current threshold, and the duration is greater than or equal to the preset first time threshold, it is determined that the single bridge arm temporary locking condition is triggered;

[0117] When the rising rate is greater than or equal to the rate threshold, and the bridge arm current is greater than a preset sixth current threshold, and the duration is greater than or equal to a preset second time threshold, it is determined that the full valve locking condition is triggered;

[0118] The locking operation control module is specifically used for:

[0119] When the temporary blocking condition of the single bridge arm is triggered, the corresponding bridge arm is controlled to be temporarily blocked;

[0120] When the full-valve locking condition is triggered, the flexible DC converter valve is controlled to be fully valve locked.

[0121] Preferably, the device further comprises:

[0122] The unlocking operation control module is used to control the bridge arm to unlock after the bridge arm is temporarily locked when the bridge arm current of the bridge arm is less than a preset seventh current threshold and the duration is greater than or equal to a preset third time threshold.

[0123] By adopting the technical means of the embodiment of the present invention, different fault conditions are distinguished by setting different current thresholds and delay conditions based on the real-time detection and evaluation of the bridge arm current. When an abnormal current is detected, first try to reduce the impact of the fault by temporarily locking a single bridge arm. This local protection measure can reduce the impact on the entire system and give the system a certain recovery time. If the fault situation persists or worsens, the protection measures are gradually upgraded to full valve locking, thereby effectively ensuring the safe and stable operation of the system. At the same time, in order to avoid unnecessary locking operations, corresponding unlocking conditions are set to quickly restore the normal operation of the system after the fault is eliminated. By implementing the protection strategy of the present invention, the response speed and protection effect of the flexible direct current transmission system under various station faults can be significantly improved, thereby effectively ensuring the safe and stable operation of the system.

[0124] It should be noted that the protection control device for a flexible DC converter valve provided in an embodiment of the present invention is used to execute all process steps of a protection control method for a flexible DC converter valve in the above embodiment. The working principles and beneficial effects of the two correspond one to one, and thus will not be described in detail.

[0125] See also Figure 4 , is a structural schematic diagram of another protection and control device for a flexible DC converter valve provided in an embodiment of the present invention. The embodiment of the present invention also provides a protection and control device 20 for a flexible DC converter valve, comprising a processor 21, a memory 22, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the protection and control method for the flexible DC converter valve as described in any one of the above embodiments is implemented.

[0126] An embodiment of the present invention also provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the protection control method of the flexible DC converter valve as described in any one of the above embodiments.

[0127] An embodiment of the present invention further provides a computer program product, which includes a computer program or computer instructions. When the computer program or the computer instructions are executed by a processor, the protection control method for the flexible DC converter valve as described in any one of the above embodiments is implemented.

[0128] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0129] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A protection and control method for a flexible DC converter valve, characterized in that: include: Obtaining the bridge arm current of each bridge arm of the flexible DC converter valve; According to the bridge arm current, determining whether a preset safe operation condition is met; When the safe operation condition is not met, the DC transmission power of the flexible DC converter valve is reduced until the safe operation condition is met.

2. The protection control method of the flexible DC converter valve according to claim 1, characterized in that: The determining, based on the bridge arm current, whether a preset safe operation condition is met includes: Calculating the steady-state current utilization rate of the bridge arm current; When the steady-state current utilization rate of the bridge arm current is less than or equal to a preset first current threshold, it is determined that the safe operation condition is met.

3. The protection and control method for a flexible DC converter valve according to claim 1, characterized in that: The determining, based on the bridge arm current, whether a preset safe operation condition is met includes: Calculate the DC component, fundamental frequency AC component and harmonic component of the bridge arm current; When the DC component is less than or equal to a preset second current threshold, the fundamental frequency AC component is less than or equal to a preset third current threshold, and the harmonic component is less than or equal to a preset fourth current threshold, it is determined that the safe operation condition is met.

4. The protection and control method for a flexible DC converter valve according to any one of claims 1 to 3, characterized in that: After obtaining the bridge arm current of each bridge arm of the flexible DC converter valve, the method further includes: Calculating the rising rate of the bridge arm current; Determining whether a corresponding locking condition is triggered according to the bridge arm current and the rising rate; When the locking condition is triggered, the flexible DC converter valve is controlled to perform a corresponding locking operation.

5. The protection and control method of the flexible DC converter valve according to claim 4, characterized in that: The locking conditions include temporary locking conditions of a single bridge arm and full valve locking conditions; Then, judging whether a corresponding locking condition is triggered according to the bridge arm current and the rising rate includes: When the rising rate is less than the preset rate threshold, and the bridge arm current is greater than the preset fifth current threshold, and the duration is greater than or equal to the preset first time threshold, it is determined that the single bridge arm temporary locking condition is triggered; When the rising rate is greater than or equal to the rate threshold, and the bridge arm current is greater than a preset sixth current threshold, and the duration is greater than or equal to a preset second time threshold, it is determined that the full valve locking condition is triggered; When the locking condition is triggered, the flexible DC converter valve is controlled to perform a corresponding locking operation, including: When the temporary blocking condition of the single bridge arm is triggered, the corresponding bridge arm is controlled to be temporarily blocked; When the full-valve locking condition is triggered, the flexible DC converter valve is controlled to be fully valve locked.

6. The protection and control method of the flexible DC converter valve according to claim 4, characterized in that: The method further comprises: After the bridge arm is controlled to be temporarily locked, when the bridge arm current of the bridge arm is less than a preset seventh current threshold and the duration is greater than or equal to a preset third time threshold, the bridge arm is controlled to be unlocked.

7. A protection control device for a flexible DC converter valve, characterized in that: include: A bridge arm current acquisition module, used to acquire the bridge arm current of each bridge arm of the flexible DC converter valve; An operating condition judgment module, used to judge whether a preset safe operating condition is met according to the bridge arm current; The protection control module is used to reduce the DC transmission power of the flexible DC converter valve when the safe operation condition is not met until the safe operation condition is met.

8. A protection control device for a flexible DC converter valve, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, the protection control method for the flexible DC converter valve according to any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the protection control method for the flexible DC converter valve according to any one of claims 1 to 6.

10. A computer program product, characterized in that The computer program product includes a computer program or a computer instruction, and when the computer program or the computer instruction is executed by a processor, the protection and control method of the flexible DC converter valve according to any one of claims 1 to 6 is implemented.

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