Direct-current power transmission system commutation failure suppression method, system and device and medium

Abstract

The invention relates to the technical field of power transmission systems, and discloses a direct-current power transmission system commutation failure suppression method, system and device and a medium. The method is applied to a direct current transmission system equipped with VDCOL control, and comprises the following steps: measuring a rectification side direct current value, and obtaining a rectification side direct current change rate based on the rectification side direct current value; determining a receiving end AC system operation state based on the rectification side DC current change rate; when the operation state of the receiving end alternating current system is an unsteady state, an inverse compensation voltage is obtained based on the direct current change rate of the rectification side, and the inverse compensation voltage is configured to be a regulating variable of dynamic compensation VDCOL control input; and performing dynamic correction on the rectification side current instruction based on the back compensation voltage to obtain a current limiting instruction, and suppressing inversion side commutation failure according to the current limiting instruction. According to the invention, a complete control link from current change rate detection to commutation failure suppression is constructed, and the operation stability and reliability of the DC power transmission system under complex working conditions are improved.

Description

Technical Field

[0001] This invention relates to the field of power transmission system technology, and in particular to a method, system, device and medium for suppressing commutation failure in a DC power transmission system. Background Technology

[0002] In complex power grid environments with multiple DC-DC interactions, commutation failure severely impacts the safe and stable operation of the system. Essentially, commutation failure occurs when valves in the converter, under reverse voltage conditions, fail to promptly restore their blocking capability or complete the commutation process due to AC system faults, abnormal trigger pulses, or other factors. This causes the valve being commutated to switch phases with the valve originally intended to be de-conducted. This phenomenon not only causes a sharp drop in DC transmission power and triggers drastic voltage and current fluctuations, but it can also trigger a chain reaction, leading to simultaneous commutation failures at multiple inverter stations, and in extreme cases, even grid collapse.

[0003] VDCOL (Voltage Dependent Current Order Limiter) is a crucial control component in DC transmission systems. It adjusts current commands based on DC voltage and other signals, playing a role in commutation failure suppression. However, traditional VDCOL control often relies on static voltage-current characteristic curves for current limiting, resulting in a lag in response to dynamic operating conditions of the receiving-end AC system. This makes it difficult to accurately adapt to the rapid switching requirements of the system state, thus limiting the effectiveness of commutation failure suppression.

[0004] Therefore, it is necessary to design an efficient and reliable commutation failure suppression strategy for DC transmission systems to improve the operational safety and reliability of AC / DC systems. Summary of the Invention

[0005] The purpose of this invention is to reduce the number of commutation failures in DC transmission systems and significantly improve the operational safety and reliability of converter stations. To achieve the above objective, this invention provides a method, system, device, and medium for suppressing commutation failures in DC transmission systems.

[0006] In a first aspect, embodiments of the present invention provide a method for suppressing commutation failure in a DC transmission system, applicable to a DC transmission system equipped with VDCOL control, the method comprising: Measure the DC current value on the rectifier side, and obtain the rate of change of the DC current on the rectifier side based on the DC current value on the rectifier side; The operating state of the receiving-end AC system is determined based on the rate of change of the rectifier-side DC current, and the operating state of the receiving-end AC system includes steady state and unsteady state; When the AC system at the receiving end is in an unsteady state, an anti-compensation voltage is obtained based on the rate of change of the DC current on the rectifier side, wherein the anti-compensation voltage is configured to dynamically compensate the adjustment amount of the VDCOL control input. The current limiting command is obtained by dynamically correcting the rectifier-side current command based on the anti-compensation voltage, and the inverter-side commutation failure is suppressed according to the current limiting command.

[0007] Preferably, the step of measuring the rectifier-side DC current value and obtaining the rectifier-side DC current change rate based on the rectifier-side DC current value includes: The DC current value of the rectifier side after VDCOL control and adjustment is measured, and the first-order inertial differential operation is performed on the DC current value of the rectifier side to obtain the rate of change of the DC current of the rectifier side.

[0008] Preferably, determining the operating state of the receiving-end AC system based on the rate of change of the rectifier-side DC current includes: if the rate of change of the rectifier-side DC current is a positive value less than a preset threshold, then the operating state of the receiving-end AC system is determined to be steady state; if the rate of change of the rectifier-side DC current is a non-zero value, then the operating state of the receiving-end AC system is determined to be faulty. If the rate of change of the DC current on the rectifier side decreases and converges to zero, then the operating state of the AC system at the receiving end is determined to be fault recovery.

[0009] Preferably, when the receiving-end AC system is in an unsteady state, obtaining the inverse compensation voltage based on the rate of change of the rectifier-side DC current includes: When the AC system at the receiving end is in a fault state, the DC current change rate on the rectifier side is processed by a first calculation to obtain a first inverse compensation voltage. The first calculation includes modulus taking, power correction of the first voltage acceleration compensation coefficient, and weighting of the voltage compensation coefficient.

[0010] Preferably, the step of obtaining the inverse compensation voltage based on the rate of change of the rectifier-side DC current when the receiving-end AC system is in an unsteady state further includes: When the AC system at the receiving end is in a fault recovery state, the DC current change rate on the rectifier side is processed by a second operation to obtain a second inverse compensation voltage. The second operation includes modulus taking, power correction of the second voltage acceleration compensation coefficient, and weighting of the voltage compensation coefficient.

[0011] Preferably, the step of dynamically correcting the rectifier-side current command based on the anti-compensation voltage to obtain a current-limiting command, and suppressing inverter-side commutation failure according to the current-limiting command, includes: The combined control voltage is obtained by superimposing the inverse compensation voltage and the inverter-side DC voltage. Based on the comprehensive control voltage, the rectifier-side current command is dynamically corrected through VDCOL control to obtain a current limiting command; based on the current limiting command, the inverter-side commutation failure is suppressed by regulating the DC line current.

[0012] Secondly, embodiments of the present invention provide a commutation failure suppression system for a DC transmission system, applied to the commutation failure suppression method for a DC transmission system as described above, wherein the commutation failure suppression system for a DC transmission system includes: The rate of change determination module is used to measure the DC current value on the rectifier side and obtain the rate of change of the DC current on the rectifier side based on the DC current value on the rectifier side. The state determination module is used to determine the operating state of the receiving-end AC system based on the rate of change of the DC current on the rectifier side. The operating state of the receiving-end AC system includes steady state and unsteady state. The inverse compensation voltage determination module is used to obtain the inverse compensation voltage based on the rate of change of the DC current on the rectifier side when the AC system at the receiving end is in an unsteady state. The inverse compensation voltage is configured as the adjustment amount of the VDCOL control input to dynamically compensate. The commutation failure suppression module is used to dynamically correct the rectifier-side current command based on the anti-compensation voltage to obtain a current limiting command, and suppress the inverter-side commutation failure according to the current limiting command.

[0013] Preferably, the rate of change determination module includes: The differential operation unit is used to measure the DC current value of the rectifier side after VDCOL control and adjustment, and to perform first-order inertial differential operation on the DC current value of the rectifier side to obtain the rate of change of the DC current of the rectifier side.

[0014] Thirdly, embodiments of the present invention provide a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the DC transmission system commutation failure suppression method as described above.

[0015] Fourthly, embodiments of the present invention provide a computer-readable storage medium comprising a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to perform the DC transmission system commutation failure suppression method as described above.

[0016] Compared with existing technologies, the present invention discloses a method, system, device, and medium for suppressing commutation failure in a DC transmission system. Its advantages lie in the following: By measuring the rectifier-side DC current in real time and calculating its rate of change, the steady-state and unsteady-state states of the receiving-end AC system are accurately identified. This ensures that the generation of the anti-compensation voltage closely matches the actual operating conditions, improving the response sensitivity and control accuracy of the low-voltage current limiting link to dynamic disturbances. Based on the dynamic generation of the anti-compensation voltage according to the DC current rate of change, and using this to correct the rectifier-side current command, the resulting current limiting command can specifically suppress commutation failure on the inverter side, effectively enhancing the DC transmission system's ability to withstand commutation failure risks. This invention constructs a complete control link from current rate of change detection to commutation failure suppression, realizing full-process coordination from state identification and voltage compensation to current regulation. This ensures rapid current limiting protection during faults and lays the foundation for a smooth transition during fault recovery, improving the operational stability and reliability of the DC transmission system under complex operating conditions. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a method for suppressing commutation failure in a DC transmission system according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the full-process optimized control of the timing sequence of voltage antisymmetric faults in an AC system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a DC transmission system commutation failure suppression system according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a terminal device according to an embodiment of the present invention; Figure label: 1. Rate of change determination module; 2. State determination module; 3. Inverse compensation voltage determination module; 4. Commutation failure suppression module; 5000, Terminal equipment; 5001, Processor; 5002, Bus; 5003, Memory; 5004, Transceiver. Detailed Implementation

[0018] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0019] In the description of this invention, it should be understood that the terms "first" and "second," etc., are used to distinguish different objects, rather than to describe a specific order.

[0020] In the description of this invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] It should be noted that the commutation failure suppression method for DC transmission systems in this embodiment of the invention is applied to DC transmission systems equipped with VDCOL control. As a core component of the DC transmission system, VDCOL's core function is to dynamically adjust the DC current output level by monitoring the voltage drop after an AC system fault in real time. The key role of this control mechanism lies in optimizing commutation conditions. When a fault on the AC side causes a sudden voltage drop, VDCOL can precisely regulate the DC current to avoid commutation failure caused by insufficient voltage during the commutation process, thereby improving the stability of the DC transmission system under fault conditions.

[0022] The control process of VDCOL is explained in detail below: When the input DC voltage passes through a time constant of T i After the first-order inertial element, the DC current command value is output through the measurement element and the piecewise function. This value is compared with the DC current setpoint, and the smaller value is taken as the actual current command value and transmitted to the rectifier side, i.e., the constant current control command value of the rectifier side. The actual current command value is reduced by a current margin (usually 0.1 pu) and transmitted to the inverter side, i.e., the constant current control command value of the inverter side.

[0023] Piecewise functions are a typical configuration for VDCOL. As the DC voltage decreases, the DC current also decreases accordingly, exhibiting a piecewise function. Specifically: when the DC voltage is below the upper limit, it enters the DC current linear limiting stage, and the DC current command value is selected according to the corresponding curve; when the DC voltage reaches the lower limit, the DC current command value is set to a certain value that is greater than the minimum DC current command value (generally 0.1 pu).

[0024] However, as the scale of AC / DC hybrid power grids continues to expand and operating scenarios become increasingly complex, the inherent defects of traditional VDCOL systems are becoming increasingly apparent. Their fixed starting voltage setting is difficult to adapt to diverse power grid conditions; the linear input-output slope limits the precision of current regulation; and the single control input command mode cannot meet the multi-dimensional regulation needs under complex fault conditions. These limitations result in slow response of DC transmission systems to rapid voltage changes and a lack of flexible adjustment capabilities during post-fault recovery, making it difficult to fully leverage the dynamic performance advantages of DC transmission systems. Therefore, this invention provides a method for suppressing commutation failure in DC transmission systems to overcome these defects.

[0025] like Figure 1 The diagram shown is a flowchart illustrating a method for suppressing commutation failure in a DC transmission system according to an embodiment of the present invention. (Refer to...) Figure 1 An embodiment of the present invention provides a method for suppressing commutation failure in a DC transmission system, comprising the following steps: S1. Measure the DC current value on the rectifier side and obtain the rate of change of the DC current on the rectifier side based on the DC current value on the rectifier side; Specifically, the DC current value of the rectifier side after being regulated by VDCOL is measured, and the rate of change of the DC current on the rectifier side is obtained by performing a first-order inertial differential operation on the DC current value on the rectifier side.

[0026] In DC transmission systems, the first-order inertial differential operation is performed through RC differentiating circuits or digital differentiating algorithms to obtain the rate of change of DC current on the rectifier side.

[0027] S2. Determine the operating status of the receiving-end AC system based on the rate of change of DC current on the rectifier side; Specifically, the operating states of the receiving-end AC system include steady state and unsteady state.

[0028] The rate of change of DC current on the rectifier side is a core parameter reflecting the dynamic process of the system, and its magnitude is directly related to the operating state. Further, step S2 includes: 1) If the rate of change of the DC current on the rectifier side is a positive value less than a preset threshold, then the AC system at the receiving end is determined to be in a steady state; the preset threshold is a positive value close to 0. In other words, when the rate of change of the DC current on the rectifier side is basically 0, the AC system at the receiving end is determined to be in a steady state.

[0029] 2) If the rate of change of the DC current on the rectifier side is non-zero, then the operating status of the AC system at the receiving end is determined to be faulty; When the rate of change of the rectifier-side DC current is non-zero, that is, when the rectifier-side DC current changes rapidly, the operating status of the AC system at the receiving end is determined to be faulty.

[0030] 3) If the rate of change of DC current on the rectifier side decreases and converges to zero, then the operating status of the AC system at the receiving end is determined to be fault recovery.

[0031] When the rate of change of the DC current on the rectifier side decreases and converges to zero, the operating state of the AC system at the receiving end is determined to be fault recovery. It is understandable that fault and fault recovery together constitute a non-steady state.

[0032] S3. When the AC system at the receiving end is in an unsteady state, the inverse compensation voltage is obtained based on the rate of change of the DC current on the rectifier side. Specifically, the anti-compensation voltage is configured to dynamically compensate the adjustment amount of the VDCOL control input. Further, step S3 includes: 1) when the AC system at the receiving end is in a fault state, performing a first calculation on the rate of change of the rectifier-side DC current to obtain the first anti-compensation voltage; The first processing step includes modulo operation, power-law correction of the first voltage acceleration compensation coefficient, and weighting of the voltage compensation coefficient.

[0033] In one embodiment, the first arithmetic process is characterized by the following formula to calculate the first inverse compensation voltage: Among them, U dc_1 K1 represents the first anti-compensation voltage, and I represents the voltage compensation coefficient (K1≥0). d K represents the DC current value on the rectifier side. 21 This represents the first voltage acceleration compensation coefficient.

[0034] During the fault, the rate of change of DC current dI d / dt is a changing value, and K1 can adjust the voltage compensation ratio. 21 The compensation speed (K) of the first reverse compensation voltage can be adjusted. 21 ≥1), associated AC voltage sag. Simultaneously, to accelerate the DC current limiting on the rectifier side and fully ensure the flexible response of the DC transmission system, a voltage sag coefficient h is set for the receiving-end AC system. The following formula applies: When the AC voltage drops significantly, K 21 The value is 1; when the AC voltage drops significantly, a faster current limiting command is needed, in which case K is increased. 21 To achieve faster current limiting.

[0035] In another embodiment, a first computational process based on an artificial intelligence model is implemented to calculate the first anti-compensation voltage: by collecting the mapping relationship between the rectifier-side DC current change rate, VDCOL input voltage, and the first anti-compensation voltage from historical operating data, a neural network model is constructed with the rectifier-side DC current change rate as the input feature and the first anti-compensation voltage as the output target; during the model training phase, the physical operation results of "modulo operation, power-law correction of the first voltage acceleration compensation coefficient, and weighting of the voltage compensation coefficient" in the actual system are used as labels, and the network parameters are optimized through the gradient descent algorithm to enable the model to learn the nonlinear compensation law; during online operation, the real-time detected rectifier-side DC current change rate is input into the trained model, and the model output value is the first anti-compensation voltage equivalent to the first computational process, realizing intelligent fitting and dynamic adaptation of traditional physical operations.

[0036] 2) When the AC system at the receiving end is in the fault recovery state, the second calculation is performed on the DC current change rate on the rectifier side to obtain the second anti-compensation voltage.

[0037] The second processing includes modulo operation, power-law correction of the second voltage acceleration compensation coefficient, and weighting of the voltage compensation coefficient.

[0038] In one embodiment, the second arithmetic process is characterized by the following formula to calculate the second anti-compensation voltage: Among them, U dc_2 K represents the second anti-compensation voltage. 22 Indicates the second voltage acceleration compensation coefficient (K) 22 ≥1).

[0039] During fault recovery, as the rectifier-side DC current gradually approaches its rated value, the rate of change of DC current dI d As / dt approaches 0, the compensation effect gradually diminishes. Here, the second voltage acceleration compensation coefficient K... 22 Based on the degree of AC voltage recovery, the following formula applies: Among them, U c This indicates the current restored voltage of the AC system at the receiving end, expressed in per-unit (pu).

[0040] In another embodiment, a second computational process is implemented based on an artificial intelligence model to calculate the second anti-compensation voltage: by collecting the mapping relationship between the rectifier-side DC current change rate, VDCOL input voltage, and the second anti-compensation voltage from historical operating data, a neural network model is constructed with the rectifier-side DC current change rate as the input feature and the second anti-compensation voltage as the output target; during the model training phase, the physical operation results of "modulo operation, power-law correction of the second voltage acceleration compensation coefficient, and weighting of the voltage compensation coefficient" in the actual system are used as labels, and the network parameters are optimized through the gradient descent algorithm to enable the model to learn the nonlinear compensation law; during online operation, the real-time detected rectifier-side DC current change rate is input into the trained model, and the model output value is the second anti-compensation voltage equivalent to the second computational process, which not only retains the control intent of the original operation logic, but also improves the accuracy of the compensation amount under unsteady conditions through the self-learning ability of the artificial intelligence model.

[0041] It should be noted that step S3 embodies the full-process optimized control strategy for AC system voltage anti-symmetric fault timing. For example... Figure 2 As shown, this is a schematic diagram of the full-process optimized control of the timing sequence of an AC system voltage antisymmetric fault according to an embodiment of the present invention. (Refer to...) Figure 2The horizontal axis represents the corresponding DC voltage operating value under VDCOL control, and the vertical axis represents the corresponding DC current command value under VDCOL control. Wherein, U dL U represents the minimum operating value of the DC voltage under VDCOL control. dH I represents the highest operating value of the DC voltage under VDCOL control. dH I represents the maximum command value of DC current under VDCOL control. dL This indicates the minimum command value of DC current under VDCOL control.

[0042] Observing the curves during the fault period, the arrows along the curves point in the direction of decreasing current, illustrating the process by which the DC current rapidly changes from its initial value to the minimum allowable current due to the decrease in AC system voltage, according to the control strategy. This reflects the dynamic adjustment trend of "reducing DC current with a larger slope." Because the AC system voltage decreases, the instantaneous AC voltage decrease is relatively large, requiring a larger slope to reduce the DC current; therefore, the slope decreases rapidly in the initial stage. Similarly, observing the fault recovery curves, the arrows along the curves point in the direction of increasing current, representing the process by which the DC current recovers from the minimum DC current command value to the maximum allowable current when the AC system voltage recovers. This reflects the control logic of "rapid slope and rapid increase in current command value during the initial recovery period, followed by a slow recovery," visually presenting the trend of current change with the fault sequence.

[0043] S4. Based on the reverse compensation voltage, the rectifier side current command is dynamically corrected to obtain the current limiting command, and the inverter side commutation failure is suppressed according to the current limiting command.

[0044] Specifically, step S4 includes: 1) The inverse compensation voltage and the inverter-side DC voltage are superimposed to obtain the comprehensive control voltage; The anti-compensation voltage is an adjustment quantity used in VDCOL control to dynamically correct the rectifier side current command. The inverter side DC voltage is the original input signal. The combined control voltage formed by the superposition of the two is directly applied to the control logic.

[0045] In practice, the DC voltage on the inverter side is filtered by inertia and then superimposed with the anti-compensation voltage to obtain the comprehensive control voltage.

[0046] 2) Based on the comprehensive control voltage, the rectifier-side current command is dynamically corrected through VDCOL control to obtain the current limiting command; The integrated control voltage is directly applied to the control logic of VDCOL to dynamically correct the rectifier-side current command and obtain the current limiting command.

[0047] 3) Based on the current limiting command, the inverter side commutation failure is suppressed by regulating the DC line current.

[0048] The current limiting command directly affects the current in the DC line. By limiting the DC line current, it reduces the current stress during commutation on the inverter side, thereby suppressing commutation failure.

[0049] To verify the effectiveness of the commutation failure suppression method for a DC transmission system according to an embodiment of the present invention, in one embodiment, a DC transmission model is built using PSCAD simulation software to verify the transient steady-state operating characteristics of the DC transmission system.

[0050] The following describes the verification process for the transient steady-state operating characteristics of the DC transmission system: 1) Comparison of steady-state characteristics when the voltage compensation coefficient K1 takes different parameters; In steady state, when K1 = 0 and K1 = 0.25, the trend of DC current change is stable and consistent, indicating that the present invention does not affect the steady-state DC transmission system parameters.

[0051] 2) Comparison of transient characteristics when the voltage compensation coefficient K1 takes different parameters; During the transient state, the DC current changes differently when K1 = 0 and K1 = 0.25 during the fault recovery period. When K1 = 0.25, the DC current can recover faster and the recovery time is shorter.

[0052] 3) Second voltage acceleration compensation coefficient K 22 Comparison of transient characteristics with different parameters.

[0053] In the transient state, when K1 = 1, K 22 =1 and K 22 When K = 2, the DC current differs during fault recovery, and K 22 When the value is 2, the direct current can recover more quickly and the recovery time is shorter.

[0054] This invention discloses a method for suppressing commutation failure in a DC transmission system. By measuring the DC current on the rectifier side in real time and calculating its rate of change, it accurately identifies the steady-state and unsteady-state states of the receiving-end AC system. This ensures that the generation of the anti-compensation voltage closely matches the actual operating conditions, improving the response sensitivity and control accuracy of the low-voltage current limiting link to dynamic disturbances. Based on the DC current rate of change, the anti-compensation voltage is dynamically generated and used to correct the rectifier side current command. The resulting current limiting command can specifically suppress commutation failure on the inverter side, effectively enhancing the DC transmission system's ability to withstand commutation failure risks. This invention constructs a complete control link from current rate of change detection to commutation failure suppression, achieving full-process coordination from state identification and voltage compensation to current regulation. This ensures rapid current limiting protection during faults and lays the foundation for a smooth transition during fault recovery, improving the operational stability and reliability of the DC transmission system under complex operating conditions.

[0055] like Figure 3The diagram shown is a structural schematic of a commutation failure suppression system for a DC transmission system according to an embodiment of the present invention. (Refer to...) Figure 3 This invention provides a commutation failure suppression system for a DC transmission system, applied to the commutation failure suppression method for a DC transmission system as described above. The commutation failure suppression system for a DC transmission system includes: The rate of change determination module 1 is used to measure the DC current value on the rectifier side and obtain the rate of change of the DC current on the rectifier side based on the DC current value on the rectifier side. Specifically, the rate of change determination module includes: The differential operation unit is used to measure the DC current value of the rectifier side after VDCOL control and regulation, and to perform first-order inertial differential operation on the DC current value of the rectifier side to obtain the rate of change of the DC current of the rectifier side.

[0056] State determination module 2 is used to determine the operating state of the receiving-end AC system based on the rate of change of the rectifier-side DC current. The operating state of the receiving-end AC system includes steady state and unsteady state. The reverse compensation voltage determination module 3 is used to obtain the reverse compensation voltage based on the rate of change of the DC current on the rectifier side when the AC system at the receiving end is in an unsteady state. The reverse compensation voltage is configured as the adjustment amount of the VDCOL control input to dynamically compensate. The commutation failure suppression module 4 is used to dynamically correct the rectifier side current command based on the reverse compensation voltage to obtain the current limiting command, and suppress the commutation failure on the inverter side according to the current limiting command.

[0057] It should be noted that each module in the aforementioned DC transmission system commutation failure suppression system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module. For specific limitations regarding the DC transmission system commutation failure suppression system, please refer to the limitations of the DC transmission system commutation failure suppression method described above; both have the same function and role, and will not be repeated here.

[0058] This invention also provides a terminal device, which includes: Processor, memory, and bus; The bus is used to connect the processor and the memory; The memory is used to store operation instructions; The processor is configured to execute operations corresponding to the above-described method for suppressing commutation failure in a DC transmission system by invoking the operation instructions.

[0059] In one alternative embodiment, a terminal device is provided, such as Figure 4As shown, Figure 4 The terminal device 5000 shown includes a processor 5001 and a memory 5003. The processor 5001 and the memory 5003 are connected, for example, via a bus 5002. Optionally, the terminal device 5000 may also include a transceiver 5004. It should be noted that in practical applications, the transceiver 5004 is not limited to one type, and the structure of this terminal device 5000 does not constitute a limitation on the embodiments of the present invention.

[0060] Processor 5001 may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in connection with this disclosure. Processor 5001 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0061] Bus 5002 may include a path for transmitting information between the aforementioned components. Bus 5002 may be a PCI bus or an EISA bus, etc. Bus 5002 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 4 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0062] The memory 5003 may be a ROM or other type of static storage device capable of storing static information and instructions, RAM or other type of dynamic storage device capable of storing information and instructions, or it may be an EEPROM, CD-ROM or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage medium or other magnetic storage device, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto.

[0063] The memory 5003 is used to store application code that executes the present invention, and its execution is controlled by the processor 5001. The processor 5001 is used to execute the application code stored in the memory 5003 to implement the content shown in any of the foregoing method embodiments.

[0064] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for suppressing commutation failure in a DC transmission system.

[0065] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take 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.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0066] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0067] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0068] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0069] In summary, this invention provides a method, system, device, and medium for suppressing commutation failure in a DC transmission system. By measuring the rectifier-side DC current in real time and calculating its rate of change, it accurately identifies the steady-state and unsteady-state states of the receiving-end AC system. This ensures that the generation of the anti-compensation voltage closely matches the actual operating conditions, improving the response sensitivity and control accuracy of the low-voltage current limiting link to dynamic disturbances. Based on the dynamic generation of the anti-compensation voltage according to the DC current rate of change, and using this to correct the rectifier-side current command, the resulting current limiting command can specifically suppress commutation failure on the inverter side, effectively enhancing the DC transmission system's ability to withstand commutation failure risks. This invention constructs a complete control link from current rate of change detection to commutation failure suppression, realizing full-process coordination from state identification, voltage compensation to current regulation. This ensures rapid current limiting protection during faults and lays the foundation for a smooth transition during fault recovery, improving the operational stability and reliability of the DC transmission system under complex operating conditions.

[0070] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for suppressing commutation failure in a DC transmission system, characterized in that, A method for suppressing commutation failure in a DC transmission system equipped with VDCOL control includes: Measure the DC current value on the rectifier side, and obtain the rate of change of the DC current on the rectifier side based on the DC current value on the rectifier side; The operating state of the receiving-end AC system is determined based on the rate of change of the rectifier-side DC current, and the operating state of the receiving-end AC system includes steady state and unsteady state; When the AC system at the receiving end is in an unsteady state, an anti-compensation voltage is obtained based on the rate of change of the DC current on the rectifier side, wherein the anti-compensation voltage is configured to dynamically compensate the adjustment amount of the VDCOL control input. The current limiting command is obtained by dynamically correcting the rectifier-side current command based on the anti-compensation voltage, and the inverter-side commutation failure is suppressed according to the current limiting command.

2. The method for suppressing commutation failure in a DC transmission system according to claim 1, characterized in that, The measurement of the rectifier-side DC current value and the determination of the rectifier-side DC current change rate based on the rectifier-side DC current value include: The DC current value of the rectifier side after VDCOL control and adjustment is measured, and the first-order inertial differential operation is performed on the DC current value of the rectifier side to obtain the rate of change of the DC current of the rectifier side.

3. The method for suppressing commutation failure in a DC transmission system according to claim 1, characterized in that, The determination of the receiving-end AC system operating status based on the rate of change of the rectifier-side DC current includes: If the rate of change of the rectifier-side DC current is a positive value less than a preset threshold, the operating state of the receiving-end AC system is determined to be steady state; if the rate of change of the rectifier-side DC current is a non-zero value, the operating state of the receiving-end AC system is determined to be faulty. If the rate of change of the DC current on the rectifier side decreases and converges to zero, then the operating state of the AC system at the receiving end is determined to be fault recovery.

4. The method for suppressing commutation failure in a DC transmission system according to claim 3, characterized in that, The step of obtaining the inverse compensation voltage based on the DC current change rate of the rectifier side when the AC system at the receiving end is in an unsteady state includes: when the AC system at the receiving end is in a fault state, performing a first calculation on the DC current change rate of the rectifier side to obtain a first inverse compensation voltage, wherein the first calculation includes modulus taking, power correction of the first voltage acceleration compensation coefficient, and weighting of the voltage compensation coefficient.

5. The method for suppressing commutation failure in a DC transmission system according to claim 3, characterized in that, The step of obtaining the inverse compensation voltage based on the DC current change rate of the rectifier side when the AC system at the receiving end is in an unsteady state further includes: when the AC system at the receiving end is in a fault recovery state, performing a second calculation on the DC current change rate of the rectifier side to obtain a second inverse compensation voltage, wherein the second calculation includes modulus taking, power correction of the second voltage acceleration compensation coefficient, and weighting of the voltage compensation coefficient.

6. The method for suppressing commutation failure in a DC transmission system according to claim 1, characterized in that, The process of dynamically correcting the rectifier-side current command based on the inverse compensation voltage to obtain a current-limiting command, and suppressing inverter-side commutation failure according to the current-limiting command, includes: The combined control voltage is obtained by superimposing the inverse compensation voltage and the inverter-side DC voltage. Based on the comprehensive control voltage, the rectifier-side current command is dynamically corrected through VDCOL control to obtain a current limiting command; based on the current limiting command, the inverter-side commutation failure is suppressed by regulating the DC line current.

7. A commutation failure suppression system for a DC transmission system, characterized in that, The method for suppressing commutation failure in a DC transmission system as described in any one of claims 1 to 6, wherein the DC transmission system commutation failure suppression system comprises: The rate of change determination module is used to measure the DC current value on the rectifier side and obtain the rate of change of the DC current on the rectifier side based on the DC current value on the rectifier side. The state determination module is used to determine the operating state of the receiving-end AC system based on the rate of change of the DC current on the rectifier side. The operating state of the receiving-end AC system includes steady state and unsteady state. The inverse compensation voltage determination module is used to obtain the inverse compensation voltage based on the rate of change of the DC current on the rectifier side when the AC system at the receiving end is in an unsteady state. The inverse compensation voltage is configured as the adjustment amount of the VDCOL control input to dynamically compensate. The commutation failure suppression module is used to dynamically correct the rectifier-side current command based on the anti-compensation voltage to obtain a current limiting command, and suppress the inverter-side commutation failure according to the current limiting command.

8. The DC transmission system commutation failure suppression system according to claim 7, characterized in that, The rate of change determination module includes: The differential operation unit is used to measure the DC current value of the rectifier side after VDCOL control and adjustment, and to perform first-order inertial differential operation on the DC current value of the rectifier side to obtain the rate of change of the DC current of the rectifier side.

9. A terminal device, characterized in that, The method includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the DC transmission system commutation failure suppression method as described in any one of claims 1 to 6.

10. 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, it controls the device containing the computer-readable storage medium to perform the DC transmission system commutation failure suppression method as described in any one of claims 1 to 6.

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