Short-circuit current suppression method, device and equipment and readable storage medium

Abstract

The invention discloses a short-circuit current suppression method, apparatus and device, and a readable storage medium. The method comprises the steps of obtaining an AC voltage of each converter station in a modular multi-level flexible DC power transmission system; judging whether a short-circuit fault occurs in the alternating current system connected with the converter station corresponding to any alternating current voltage characterization or not; if yes, circuit parameters of the target converter station are collected, and a valve control instruction used for regulating and controlling output alternating current of the target converter station and suppressing short-circuit current in an alternating current system connected with the target converter station is generated based on the circuit parameters. Therefore, the AC voltage can be analyzed to realize rapid sensing of the short-circuit current fault, and the short-circuit current suppression process is accelerated; when it is determined that a short-circuit current suppression scheme needs to be triggered, MMC converter station current regulation replaces a traditional hard removal mode, equipment such as a series reactor does not need to be additionally arranged, and the hardware cost and the occupied area of the system are reduced while the problem that short-circuit current exceeds the standard is solved.

Description

Technical Field

[0001] This application relates to the field of flexible DC technology, and more specifically, to a short-circuit current suppression method, apparatus, device, and readable storage medium. Background Technology

[0002] The AC system is the core carrier for the generation, transmission and consumption of electricity, and undertakes the key functions of grid connection of the vast majority of power sources and power supply to loads.

[0003] With the rapid growth in electricity demand and the continuous expansion of AC systems, the problem of excessive short-circuit current in the system has become increasingly prominent. In some areas, the short-circuit current level has far exceeded the rated breaking capacity of AC circuit breakers of the corresponding voltage level, resulting in the circuit breaker being unable to reliably interrupt the fault when it occurs, making it difficult to quickly clear the fault, which seriously threatens the safe and stable operation of AC-DC interconnection systems.

[0004] Existing technologies often use the addition of series reactors to suppress short-circuit current, but series reactors occupy a large area, have high equipment costs, and are prone to resource waste. Summary of the Invention

[0005] In view of this, this application provides a short-circuit current suppression method, apparatus, device and readable storage medium to solve the shortcomings of existing short-circuit current suppression technologies, such as large footprint, high equipment cost and easy waste of resources.

[0006] To achieve the above objectives, the following solution is proposed:

[0007] A short-circuit current suppression method includes:

[0008] Obtain the AC voltage of each converter station in a modular multilevel flexible DC transmission system;

[0009] Determine whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station;

[0010] If so, the converter station connected to the AC system with the short-circuit fault is taken as the target converter station; the circuit parameters of the target converter station are collected, and a valve control command is generated based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

[0011] Optionally, determining whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station includes:

[0012] Obtain the voltage reference value of each converter station under normal operating conditions;

[0013] Calculate the first ratio of each AC voltage to the corresponding voltage reference value;

[0014] When any first ratio is not greater than a first threshold, it is determined that a short-circuit fault has occurred in the AC system corresponding to that first ratio.

[0015] When all the first ratios are greater than the first threshold, it is determined that no short-circuit fault has occurred in the connected AC systems.

[0016] Optionally, after generating the valve control command based on the circuit parameters, the method further includes:

[0017] Re-acquire the latest AC voltage of the target converter station;

[0018] Determine whether the latest AC voltage indicates that the corresponding AC system has eliminated the short-circuit fault;

[0019] If not, return to the step of collecting the circuit parameters of the target converter station until the corresponding AC system has eliminated the short circuit fault.

[0020] Optionally, determining whether the latest AC voltage indicates that the corresponding AC system has eliminated the short-circuit fault includes:

[0021] Obtain the voltage reference coefficient of the target converter station;

[0022] Calculate the second ratio of the latest AC voltage to the voltage reference coefficient;

[0023] When the second ratio is not less than the second threshold, it is determined that the AC system corresponding to the second ratio has eliminated the short-circuit fault;

[0024] When the second ratio is less than the second threshold, it is determined that the AC system corresponding to the second ratio still has a short-circuit fault.

[0025] Optionally, generating valve control commands based on the circuit parameters includes:

[0026] Based on the short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current of the target converter station, calculate the reference value of the d-axis current of the target AC station.

[0027] Set the q-axis current reference value of the target AC station to 0;

[0028] Based on the d-axis current reference value and the q-axis current reference value, valve control commands are generated.

[0029] Optionally, calculating the d-axis current reference value of the target AC substation based on the short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current includes:

[0030] Calculate the converter station difference between the short-circuit capacity and the rated power;

[0031] Based on the converter station difference, the rated voltage, the rated current, the fault AC voltage, and the fault AC current, calculate the d-axis current reference value of the target AC station.

[0032] Optionally, calculating the d-axis current reference value of the target AC station based on the converter station differential, the rated voltage, the rated current, the fault AC voltage, and the fault AC current includes:

[0033] Combining the preset current reference value calculation function, the d-axis current reference value of the target AC station is calculated based on the converter station difference, the rated voltage, the rated current, the fault AC voltage, and the fault AC current.

[0034] The function for calculating the current reference value is as follows:

[0035]

[0036] In the formula, This is the reference value for the d-axis current. The faulty AC voltage; This is the fault AC current; Rated voltage; Rated current; This represents the difference between the converter stations.

[0037] A short-circuit current suppression device, comprising:

[0038] The acquisition module is used to acquire the AC voltage of each converter station in the modular multilevel flexible DC transmission system;

[0039] The judgment module is used to determine whether any AC voltage indicates a short circuit fault in the AC system connected to the corresponding converter station; if so, the generation module is executed.

[0040] The generation module is used to select a converter station connected to a short-circuit faulted AC system as a target converter station; collect the circuit parameters of the target converter station, and generate a valve control command based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

[0041] A short-circuit current suppression device includes a memory and a processor;

[0042] The memory is used to store programs;

[0043] The processor is used to execute the program to implement the various steps of the above-described short-circuit current suppression method.

[0044] A readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described short-circuit current suppression method.

[0045] As can be seen from the above technical solutions, the short-circuit current suppression method provided in this application can obtain the AC voltage of each converter station in a modular multilevel flexible DC transmission system (MMC); determine whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station; based on this, this application can monitor the AC voltage of each converter station in the MMC, capture abnormal operating conditions such as voltage drops and phase changes caused by faults, complete the identification of AC system short-circuit faults, and determine whether to initiate subsequent suppression measures based on the identification results, avoiding ineffective regulation when there is no fault, and ensuring the steady-state operating efficiency of the system. When a short-circuit fault is determined, this application can use the converter station connected to the AC system with the short-circuit fault as the target converter station; collect the circuit parameters of the target converter station, and generate a valve control command based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station to suppress the short-circuit current in the AC system connected to the target converter station; based on this, this application can achieve short-circuit current suppression through the output AC current of the target converter station connected to the AC system with the short-circuit fault in the modular multilevel flexible DC transmission system. Therefore, short-circuit current suppression in AC systems can be achieved without adding series reactors, solving the resource waste problem caused by adding series reactors. It is evident that this application can assess whether a short-circuit current suppression scheme needs to be triggered by acquiring AC voltage. The assessment method is relatively simple, enabling rapid detection of short-circuit current faults and accelerating the short-circuit current suppression process. When it is determined that a short-circuit current suppression scheme needs to be triggered, current regulation of the MMC converter station replaces the traditional hard-cut-off method, eliminating the need for additional series reactors and other equipment. This solves the problem of excessive short-circuit current while reducing the system's hardware cost and footprint. Furthermore, using the above scheme, the target converter station can maintain its connection with the AC system while suppressing short-circuit current. After the fault is cleared, power transmission can be quickly restored without reconnection to the grid, improving the stability and reliability of the MMC-HVDC system's interconnection with the AC grid. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0047] Figure 1 A schematic diagram of current flow under a short-circuit fault in an AC system is provided as an embodiment of this application;

[0048] Figure 2 This is a flowchart of a short-circuit current suppression method disclosed in an embodiment of this application;

[0049] Figure 3 This is a structural block diagram of a short-circuit current suppression device disclosed in an embodiment of this application;

[0050] Figure 4 This is a hardware structure block diagram of a short-circuit current suppression device disclosed in an embodiment of this application. Detailed Implementation

[0051] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0052] Modular multilevel flexible direct current (DC) transmission systems are a core technology for large-scale, ultra-long-distance transmission of renewable energy, and they are deeply coupled with AC systems. At the sending end of the modular multilevel flexible DC transmission system, the AC power output from the renewable energy power plant needs to be rectified into DC for efficient transmission. At the receiving end, the AC power needs to be inverted and injected into the AC system to ultimately achieve energy consumption.

[0053] See Figure 1 It can be observed that after a ground fault occurs at any point in the AC system, all AC equivalent power sources and the flexible DC converter stations in the modular multilevel flexible DC transmission system connected to the AC system will simultaneously feed short-circuit current into the short-circuit point, resulting in the fault current near the fault point exceeding the standard.

[0054] Based on this, this application finds that as the flexible DC AC current decreases, the flexible DC changes from injecting short-circuit current to absorbing short-circuit current, thereby achieving the diversion of short-circuit current, reducing the short-circuit current near the fault point, and achieving the purpose of suppressing short-circuit current.

[0055] Therefore, this application gradually adjusts the flexible DC current by adjusting the phase angle or AC voltage to reduce the short-circuit current fed into the flexible DC, thereby allowing the flexible DC to absorb a portion of the short-circuit current and thus suppressing the short-circuit current in the AC system.

[0056] Based on the above-mentioned control principle, this application provides a short-circuit current suppression method.

[0057] This short-circuit current suppression method can be applied to various modular multilevel flexible DC transmission systems, as well as to various computer terminals or smart terminals. The executing entity can be the processor or server of the computer terminal or smart terminal.

[0058] Next, combine Figure 2 The method described in this application is detailed, including the following steps:

[0059] Step S1: Obtain the AC voltage of each converter station in the modular multilevel flexible DC transmission system.

[0060] Specifically, the effective value of the AC voltage at each AC port in a modular multilevel flexible DC transmission system can be collected as the AC voltage of the corresponding converter station.

[0061] Step S2: Determine if any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station. If yes, proceed to step S3.

[0062] Specifically, pre-processing operations such as cleaning can be performed on the AC voltage of each converter station;

[0063] Each AC voltage after preprocessing is compared and analyzed to detect whether any AC voltage indicates a short circuit fault in the AC system connected to the corresponding converter station.

[0064] If so, proceed to step S3.

[0065] If not, no action is required, and the modular multilevel flexible DC transmission system remains in operation.

[0066] Step S3: Select the converter station connected to the AC system with a short-circuit fault as the target converter station; collect the circuit parameters of the target converter station, and generate a valve control command based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

[0067] Specifically, the converter station corresponding to the AC voltage characterizing a short-circuit fault can be used as the target converter station.

[0068] The short-circuit capacity, rated power, rated voltage, and rated current of the target converter station can be obtained.

[0069] Collect the fault AC voltage and fault AC current of the target converter station;

[0070] Valve control commands can be generated based on the short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current of the target converter station.

[0071] Valve control commands can be used to adjust the output AC voltage or phase angle of the target converter station in order to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

[0072] As can be seen from the above technical solutions, the short-circuit current suppression method provided in this application can obtain the AC voltage of each converter station in a modular multilevel flexible DC transmission system (MMC); determine whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station; based on this, this application can monitor the AC voltage of each converter station in the MMC, capture abnormal operating conditions such as voltage drops and phase changes caused by faults, complete the identification of AC system short-circuit faults, and determine whether to initiate subsequent suppression measures based on the identification results, avoiding ineffective regulation when there is no fault, and ensuring the steady-state operating efficiency of the system. When a short-circuit fault is determined, this application can use the converter station connected to the AC system with the short-circuit fault as the target converter station; collect the circuit parameters of the target converter station, and generate a valve control command based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station to suppress the short-circuit current in the AC system connected to the target converter station; based on this, this application can achieve short-circuit current suppression through the output AC current of the target converter station connected to the AC system with the short-circuit fault in the modular multilevel flexible DC transmission system. Therefore, short-circuit current suppression in AC systems can be achieved without adding series reactors, solving the resource waste problem caused by adding series reactors. It is evident that this application can assess whether a short-circuit current suppression scheme needs to be triggered by acquiring AC voltage. The assessment method is relatively simple, enabling rapid detection of short-circuit current faults and accelerating the short-circuit current suppression process. When it is determined that a short-circuit current suppression scheme needs to be triggered, current regulation of the MMC converter station replaces the traditional hard-cut-off method, eliminating the need for additional series reactors and other equipment. This solves the problem of excessive short-circuit current while reducing the system's hardware cost and footprint. Furthermore, using the above scheme, the target converter station can maintain its connection with the AC system while suppressing short-circuit current. After the fault is cleared, power transmission can be quickly restored without reconnection to the grid, improving the stability and reliability of the MMC-HVDC system's interconnection with the AC grid.

[0073] In some embodiments of this application, the process of determining whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station in step S2 is described in detail, and the steps are as follows:

[0074] S20. Obtain the voltage reference value of each converter station under normal operating conditions.

[0075] Specifically, for each converter station, a voltage reference value can be determined to characterize the converter station as being in normal operating condition, based on the grid architecture and fault type of the AC system to which the converter station is connected.

[0076] The voltage reference value for each converter station can be 0.7 times the rated voltage of that converter station.

[0077] S21. Calculate the first ratio of each AC voltage to the corresponding voltage reference value.

[0078] Specifically, the AC voltage of each converter station can characterize the voltage drop of the MMC-HVDC system caused by a short-circuit fault in the AC system.

[0079] When the AC voltage of the converter station drops very little after a fault, it indicates that the MMC-HVDC system has poor ability to suppress short-circuit current at the short-circuit point, and even if the short-circuit suppression function is activated, the effect will not be very obvious.

[0080] The ratio between the AC voltage and the voltage reference value can be calculated as the first ratio.

[0081] S22. When any first ratio is not greater than a first threshold, determine that a short circuit fault has occurred in the AC system corresponding to the first ratio.

[0082] Specifically, each first ratio can be compared with a preset first threshold.

[0083] When any first ratio is less than or equal to a first threshold, it can be determined that a short-circuit fault has occurred in the AC system connected to the converter station corresponding to the first ratio, and step S3 can be executed.

[0084] S23. When all the first ratios are greater than the first threshold, it is determined that no short-circuit fault has occurred in the connected AC systems.

[0085] Specifically, when all first ratios are greater than the first threshold, it can be determined that no short-circuit faults have occurred in any of the AC systems connected to the modular multilevel flexible DC transmission system.

[0086] As can be seen from the above technical solution, this embodiment provides an optional method for determining whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station. This method further improves the accuracy and efficiency of short-circuit fault detection, ensuring that subsequent suppression measures can be initiated promptly when a short-circuit fault occurs in the AC system. Simultaneously, this method avoids unnecessary adjustments in fault-free conditions, ensuring the steady-state operating efficiency of the modular multilevel flexible DC transmission system. Furthermore, this judgment method, based on the calculation of a voltage reference value and a first ratio, has high flexibility and scalability, and can be adjusted and optimized according to different grid architectures and fault types.

[0087] In some embodiments of this application, considering that short-circuit faults in the AC system can be eliminated by maintenance personnel, it is not necessary to suppress the short-circuit current of the AC system. Therefore, after generating the valve control command based on the circuit parameters in step S3, a short-circuit fault elimination detection process can be added. The short-circuit fault elimination detection process will be described in detail below, with the following steps:

[0088] S4. Reacquire the latest AC voltage of the target converter station.

[0089] Specifically, the effective value of the AC voltage of the target converter station can be used as the latest AC voltage.

[0090] S5. Determine whether the latest AC voltage indicates that the corresponding AC system has eliminated the short-circuit fault. If not, return to step S3 to collect the circuit parameters of the target converter station until the corresponding AC system has eliminated the short-circuit fault.

[0091] Specifically, the latest AC voltage and voltage reference coefficient can be compared to assess whether the AC system connected to the target converter station has eliminated short-circuit faults.

[0092] If so, then the short-circuit current suppression circuit is turned off.

[0093] If not, return to step S3 to collect the circuit parameters of the target converter station until the corresponding AC system has eliminated the short circuit fault.

[0094] As can be seen from the above technical solution, this embodiment adds a new short-circuit fault elimination and detection process. Through this process, after the AC system short-circuit fault is eliminated by maintenance personnel, the short-circuit current suppression circuit can be shut down promptly, avoiding unnecessary energy loss and equipment wear, saving energy, and extending equipment lifespan. This significantly improves the intelligence and adaptability of the short-circuit current suppression method, enabling it to automatically adjust the suppression strategy according to the actual operating state of the AC system, thereby ensuring the safe and stable operation of the system while achieving efficient energy utilization and long-term reliable equipment operation.

[0095] In some embodiments of this application, the process of determining whether the latest AC voltage indicates that the corresponding AC system has eliminated the short-circuit fault is described in detail in step S5, and the steps are as follows:

[0096] S50. Obtain the voltage reference coefficient of the target converter station.

[0097] Specifically, the voltage reference factor can be the same as the voltage reference value.

[0098] S51. Calculate the second ratio of the latest AC voltage to the voltage reference coefficient.

[0099] Specifically, the ratio of the latest AC voltage to the voltage reference coefficient can be calculated as the second ratio.

[0100] S52. When the second ratio is not less than the second threshold, it is determined that the AC system corresponding to the second ratio has eliminated the short circuit fault.

[0101] Specifically, the second ratio can be compared with the second threshold. When the second ratio is greater than or equal to the second threshold, it can be determined that the AC system corresponding to the second ratio has eliminated the short-circuit fault.

[0102] The first and second thresholds are equivalent to hysteresis, preventing frequent switching on and off of the short-circuit current suppression function.

[0103] The first threshold can be determined based on the voltage range of the converter station under short-circuit fault, and the first threshold can be 0.95.

[0104] The second threshold can be determined based on the voltage range of the converter station under normal operating conditions, and the second threshold can be 1.05.

[0105] S53. When the second ratio is less than the second threshold, it is determined that the AC system corresponding to the second ratio still has a short circuit fault.

[0106] Specifically, when the second ratio is less than the second threshold, it can be determined that the AC system still has a short-circuit fault and short-circuit current suppression is still required.

[0107] As can be seen from the above technical solution, this embodiment provides an optional method for determining whether the latest AC voltage indicates that the corresponding AC system has eliminated the short-circuit fault. This method further improves the accuracy and reliability of short-circuit fault elimination judgment, ensuring that the short-circuit current suppression circuit is promptly shut down after the AC system short-circuit fault is truly eliminated, avoiding unnecessary operations and resource waste. Simultaneously, the setting of the first and second thresholds effectively prevents frequent switching on and off of the short-circuit current suppression function, improving the stability and reliability of the system.

[0108] In some embodiments of this application, the process of generating valve control commands based on the circuit parameters in step S3 is described in detail, and the steps are as follows:

[0109] S30. Based on the short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current of the target converter station, calculate the d-axis current reference value of the target AC station.

[0110] Specifically, the short-circuit capacity varies depending on the AC system wiring.

[0111] The short-circuit capacity of the converter station can be obtained in real time by using methods such as pulse method or stable signal injection method.

[0112] Alternatively, the typical short-circuit capacity under different seasons can be used to determine the typical short-circuit capacity matching the current season as the short-circuit capacity.

[0113] The fault AC voltage can be the average voltage of the target converter station between time t1 and time t2 after a short-circuit fault.

[0114] The fault AC current can be the average current of the target converter station between time t1 and time t2 after the short-circuit fault.

[0115] Time t1 can be 5ms after the fault, and time t2 can be 15ms after the fault.

[0116] A preset formula can be used to calculate the reference value of the d-axis current of the target AC station by combining the above parameters.

[0117] S31. Set the q-axis current reference value of the target AC station to 0.

[0118] Specifically, the reference value of the q-axis current of the target AC station can be directly set to 0.

[0119] S32. Generate valve control commands based on the d-axis current reference value and the q-axis current reference value.

[0120] Specifically, the measured current and measured current phase angle of the target converter station can be transformed by DQ transformation to obtain the measured values ​​of the d-axis current and the q-axis current.

[0121] The measured voltage and phase angle of the target converter station can be transformed by DQ transformation to obtain the measured values ​​of the d-axis voltage and the q-axis voltage.

[0122] Based on the error between the d-axis current reference value and the measured d-axis current value, an initial voltage command is generated via PI regulation. To achieve dynamic decoupling between the d-axis and q-axis currents, the error between this initial voltage command and the measured d-axis voltage value, plus w times the measured q-axis current value, is further PI-regulated to generate a d-axis voltage modulation signal. Here, w is the grid synchronization angular frequency.

[0123] An initial voltage signal is generated based on the error between the q-axis current reference value and the measured q-axis current value via PI regulation. To achieve dynamic decoupling between the d-axis and q-axis currents, the error between this initial voltage signal and the measured q-axis voltage and d-axis current values ​​is further adjusted via PI regulation to generate a q-axis voltage modulation signal.

[0124] The d-axis voltage modulation signal and q-axis voltage modulation signal, after being limited by the voltage limiter, are combined with the phase angle and subjected to inverse Park transformation to convert them back to the modulation wave signal in the three-phase stationary coordinate system.

[0125] The modulated wave signal is input to the valve control module to generate valve control commands to control the output AC voltage and output AC current of the converter station's AC port, thereby achieving short-circuit current suppression.

[0126] As can be seen from the above technical solution, this embodiment provides an optional method for generating valve control commands based on the circuit parameters. Through this method, various circuit parameters of the target converter station can be comprehensively considered, including short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current, enabling the generated valve control commands to better adapt to different fault conditions and system operating states. Simultaneously, by separately processing and dynamically decoupling the d-axis and q-axis currents, the control accuracy and stability of the system are improved, ensuring the effectiveness and reliability of the short-circuit current suppression effect.

[0127] In some embodiments of this application, the process of calculating the d-axis current reference value of the target AC station based on the short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current of the target converter station is described in detail, and the steps are as follows:

[0128] S300. Calculate the converter station difference between the short-circuit capacity and the rated power.

[0129] Specifically, the converter station difference can be determined using the following function:

[0130]

[0131] S is the converter station differential; S is the short-circuit capacity; P is the rated power.

[0132] S301. Based on the converter station difference, the rated voltage, the rated current, the fault AC voltage, and the fault AC current, calculate the d-axis current reference value of the target AC station.

[0133] Specifically, the above parameters can be combined and a preset algorithm model or preset formula can be used to calculate the reference value of the d-axis current of the target AC station.

[0134] Algorithm models or preset formulas can be generated based on the operating characteristics of the communication system.

[0135] As can be seen from the above technical solution, this embodiment provides an optional method for calculating the d-axis current reference value of the target AC station based on its short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current. This method allows for a deeper consideration of the intrinsic relationships and interactions between various key circuit parameters of the target converter station, enabling comprehensive analysis and calculation from a system-wide perspective. This allows the generated valve control commands to more accurately control the output AC current of the converter station's AC ports, ultimately achieving more effective short-circuit current suppression and ensuring the safe and stable operation of the power system.

[0136] In some embodiments of this application, the process of calculating the d-axis current reference value of the target AC station based on the converter station difference, the rated voltage, the rated current, the fault AC voltage, and the fault AC current is described in detail below:

[0137] S3010. Combining the preset current reference value calculation function, calculate the d-axis current reference value of the target AC station based on the converter station difference, the rated voltage, the rated current, the fault AC voltage, and the fault AC current.

[0138] Specifically, the current reference value calculation function is as follows:

[0139]

[0140] In the formula, This is the reference value for the d-axis current. The faulty AC voltage; This is the fault AC current; Rated voltage; Rated current; This represents the difference between the converter stations.

[0141] As can be seen from the above technical solution, this embodiment provides an optional method for calculating the d-axis current reference value of the target AC station based on the converter station differential, the rated voltage, the rated current, the fault AC voltage, and the fault AC current. Through this method, a preset current reference value calculation function can be fully utilized to organically integrate key parameters such as the converter station differential, rated voltage, rated current, fault AC voltage, and fault AC current to generate an accurate d-axis current reference value. This d-axis current reference value serves as an important basis for generating valve control commands, ensuring precise control of the output AC current at the converter station's AC port, thereby achieving more effective short-circuit current suppression.

[0142] Next, we will combine Figure 3The short-circuit current suppression device provided in this application is described in detail. The short-circuit current suppression device described below can be compared with the short-circuit current suppression method described above.

[0143] See Figure 3 It can be observed that the short-circuit current suppression device may include:

[0144] The acquisition module 10 is used to acquire the AC voltage of each converter station in the modular multilevel flexible DC transmission system;

[0145] The judgment module 20 is used to determine whether any AC voltage indicates a short circuit fault in the AC system connected to the corresponding converter station; if so, the generation module is executed.

[0146] The generation module 30 is used to select a converter station connected to a short-circuit faulted AC system as a target converter station; collect the circuit parameters of the target converter station, and generate a valve control command based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

[0147] Furthermore, the judgment module 20 may include:

[0148] The first judgment unit is used to obtain the voltage reference value of each converter station under normal operating conditions;

[0149] The second judgment unit is used to calculate the first ratio of each AC voltage to the corresponding voltage reference value;

[0150] The third judgment unit is used to determine that a short circuit fault has occurred in the AC system corresponding to any first ratio when the first ratio is not greater than the first threshold.

[0151] The fourth judgment unit is used to determine that no short-circuit fault has occurred in the connected AC systems when all the first ratios are greater than the first threshold.

[0152] Furthermore, the short-circuit current suppression device may also include:

[0153] The acquisition module is used to reacquire the latest AC voltage of the target converter station;

[0154] The detection module is used to determine whether the latest AC voltage indicates that the corresponding AC system has eliminated the short circuit fault; if not, the generation module 30 is called until the corresponding AC system has eliminated the short circuit fault.

[0155] Furthermore, the detection module may include:

[0156] The first detection unit is used to obtain the voltage reference coefficient of the target converter station;

[0157] The second detection unit is used to calculate a second ratio between the latest AC voltage and the voltage reference coefficient;

[0158] The third detection unit is used to determine that the AC system corresponding to the second ratio has eliminated the short circuit fault when the second ratio is not less than the second threshold.

[0159] The fourth detection unit is used to determine that when the second ratio is less than the second threshold, the AC system corresponding to the second ratio still has a short circuit fault.

[0160] Furthermore, the generation module 30 may include:

[0161] The d-axis current reference value calculation unit is used to calculate the d-axis current reference value of the target AC station based on the short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage and fault AC current of the target converter station.

[0162] The q-axis current reference value determination unit is used to set the q-axis current reference value of the target AC station to 0;

[0163] The valve control command generation unit is used to generate valve control commands based on the d-axis current reference value and the q-axis current reference value.

[0164] Furthermore, the d-axis current reference value calculation unit may include:

[0165] The converter station difference calculation subunit is used to calculate the converter station difference between the short-circuit capacity and the rated power;

[0166] The converter station differential utilization subunit is used to calculate the d-axis current reference value of the target AC station based on the converter station differential, the rated voltage, the rated current, the fault AC voltage, and the fault AC current.

[0167] Furthermore, the converter station differential utilization sub-unit may include:

[0168] The current reference value calculation function is combined with a component to calculate the d-axis current reference value of the target AC station based on the converter station difference, the rated voltage, the rated current, the fault AC voltage, and the fault AC current, in conjunction with a preset current reference value calculation function.

[0169] The function for calculating the current reference value is as follows:

[0170]

[0171] In the formula, This is the reference value for the d-axis current. The faulty AC voltage; This is the fault AC current; Rated voltage; Rated current; This represents the difference between the converter stations.

[0172] The short-circuit current suppression device provided in this application embodiment can be applied to short-circuit current suppression equipment, such as PC terminals, cloud platforms, servers, and server clusters. Optionally, Figure 4 The hardware structure block diagram of the short-circuit current suppression device is shown, with reference to... Figure 4 The hardware structure of a short-circuit current suppression device may include: at least one processor 1, at least one communication interface 2, at least one memory 3, and at least one communication bus 4;

[0173] In this embodiment of the application, the number of processor 1, communication interface 2, memory 3, and communication bus 4 is at least one, and processor 1, communication interface 2, and memory 3 communicate with each other through communication bus 4;

[0174] Processor 1 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0175] Memory 3 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device;

[0176] The memory stores a program, which the processor can call. The program is used for:

[0177] Obtain the AC voltage of each converter station in a modular multilevel flexible DC transmission system;

[0178] Determine whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station;

[0179] If so, the converter station connected to the AC system with the short-circuit fault is taken as the target converter station; the circuit parameters of the target converter station are collected, and a valve control command is generated based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

[0180] Optionally, the refined and extended functions of the program can be referred to the above description.

[0181] This application embodiment also provides a readable storage medium that can store a program suitable for execution by a processor, the program being used for:

[0182] Obtain the AC voltage of each converter station in a modular multilevel flexible DC transmission system;

[0183] Determine whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station;

[0184] If so, the converter station connected to the AC system with the short-circuit fault is taken as the target converter station; the circuit parameters of the target converter station are collected, and a valve control command is generated based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

[0185] Optionally, the refined and extended functions of the program can be referred to the above description.

[0186] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0187] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0188] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. The various embodiments of this application can be combined with each other. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A short-circuit current suppression method, characterized in that, include: Obtain the AC voltage of each converter station in a modular multilevel flexible DC transmission system; Determine whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station; If so, the converter station connected to the AC system with the short-circuit fault will be designated as the target converter station. The circuit parameters of the target converter station are collected, and a valve control command is generated based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

2. The short-circuit current suppression method according to claim 1, characterized in that, The determination of whether any AC voltage indicates a short-circuit fault in the AC system connected to the corresponding converter station includes: Obtain the voltage reference value of each converter station under normal operating conditions; Calculate the first ratio of each AC voltage to the corresponding voltage reference value; When any first ratio is not greater than a first threshold, it is determined that a short-circuit fault has occurred in the AC system corresponding to that first ratio. When all the first ratios are greater than the first threshold, it is determined that no short-circuit fault has occurred in the connected AC systems.

3. The short-circuit current suppression method according to claim 1, characterized in that, After generating the valve control command based on the circuit parameters, the method further includes: Re-acquire the latest AC voltage of the target converter station; Determine whether the latest AC voltage indicates that the corresponding AC system has eliminated the short-circuit fault; If not, return to the step of collecting the circuit parameters of the target converter station until the corresponding AC system has eliminated the short circuit fault.

4. The short-circuit current suppression method according to claim 3, characterized in that, The determination of whether the latest AC voltage indicates that the corresponding AC system has eliminated the short-circuit fault includes: Obtain the voltage reference coefficient of the target converter station; Calculate the second ratio of the latest AC voltage to the voltage reference coefficient; When the second ratio is not less than the second threshold, it is determined that the AC system corresponding to the second ratio has eliminated the short-circuit fault; When the second ratio is less than the second threshold, it is determined that the AC system corresponding to the second ratio still has a short-circuit fault.

5. The short-circuit current suppression method according to claim 1, characterized in that, The generation of valve control commands based on the circuit parameters includes: Based on the short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current of the target converter station, calculate the reference value of the d-axis current of the target AC station. Set the q-axis current reference value of the target AC station to 0; Based on the d-axis current reference value and the q-axis current reference value, valve control commands are generated.

6. The short-circuit current suppression method according to claim 5, characterized in that, The calculation of the d-axis current reference value of the target AC station based on its short-circuit capacity, rated power, rated voltage, rated current, fault AC voltage, and fault AC current includes: Calculate the converter station difference between the short-circuit capacity and the rated power; Based on the converter station difference, the rated voltage, the rated current, the fault AC voltage, and the fault AC current, calculate the d-axis current reference value of the target AC station.

7. The short-circuit current suppression method according to claim 6, characterized in that, The calculation of the d-axis current reference value of the target AC station based on the converter station differential, the rated voltage, the rated current, the fault AC voltage, and the fault AC current includes: Combining the preset current reference value calculation function, the d-axis current reference value of the target AC station is calculated based on the converter station difference, the rated voltage, the rated current, the fault AC voltage, and the fault AC current. The function for calculating the current reference value is as follows: In the formula, This is the reference value for the d-axis current. The faulty AC voltage; This is the fault AC current; Rated voltage; Rated current; This represents the difference between the converter stations.

8. A short-circuit current suppression device, characterized in that, include: The acquisition module is used to acquire the AC voltage of each converter station in the modular multilevel flexible DC transmission system; The judgment module is used to determine whether any AC voltage indicates a short circuit fault in the AC system connected to the corresponding converter station. If so, then execute the generation module; The generation module is used to select a converter station connected to a short-circuit faulted AC system as a target converter station; collect the circuit parameters of the target converter station, and generate a valve control command based on the circuit parameters. The valve control command is used to regulate the output AC current of the target converter station and suppress the short-circuit current in the AC system connected to the target converter station.

9. A short-circuit current suppression device, characterized in that, Including memory and processor; The memory is used to store programs; The processor is configured to execute the program to implement the various steps of the short-circuit current suppression method as described in any one of claims 1-7.

10. A readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements each step of the short-circuit current suppression method as described in any one of claims 1-7.

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