Voltage recovery control method and device based on multi-fault scenario division

Abstract

The application discloses a voltage recovery control method and device based on multi-fault scene division, relates to the technical field of power operation and maintenance, and mainly aims to solve the problem of insufficient AC voltage support capability after the receiving end fault. Mainly includes determining the real-time fault scene category according to the real-time obtained fault characteristic data; in the multiple control stages successively experienced, the target reactive current reference value is determined according to the real-time fault scene category and the corresponding reactive power output strategy of the current control stage, and the reactive power output of the receiving end converter station is controlled according to the target reactive current reference value; under the condition of meeting the active power absorption coordination condition, the active power absorption amount of different generator units is determined according to the active power absorption strategy, and the corresponding generator unit absorbs the surplus active power of the receiving end power grid with the active power absorption amount, so as to preferentially guarantee the reactive power output under the current limit constraint. Mainly used for voltage recovery after fault.

Description

Technical Field

[0001] This invention relates to the field of power operation and maintenance technology, and in particular to a voltage recovery control method and device based on multiple fault scenario division. Background Technology

[0002] With the continuous growth of installed capacity of new energy sources, high-voltage direct current (HVDC) transmission technology using modular multilevel converters has become a core technology solution for long-distance, large-capacity grid connection of new energy sources due to its advantages such as high transmission efficiency, flexible control, and no risk of commutation failure. However, the receiving-end AC grid is prone to various AC faults due to its wide distribution of lines, complex equipment types, and diverse external disturbances. These faults pose a severe challenge to the grid connection system.

[0003] Currently, most reactive power output strategies are used to provide reactive power support for grid faults. However, this results in over-compensation for minor faults and insufficient support for severe faults, making it impossible to achieve rapid voltage recovery. Consequently, there are significant deficiencies in the accuracy of reactive power support, as well as in the efficiency and stability of AC voltage recovery. Summary of the Invention

[0004] In view of this, the present invention provides a voltage recovery control method and device based on multiple fault scenario division, the main purpose of which is to solve the problem of insufficient AC voltage support capability after receiving-end fault.

[0005] According to one aspect of the present invention, a voltage recovery control method based on multi-fault scenario partitioning is provided, comprising: The real-time fault scenario category is determined based on the fault characteristic data acquired in real time; In the multiple control stages that are experienced in sequence, the target reactive current reference value is determined based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage, and the reactive power output of the receiving-end converter station is controlled based on the target reactive current reference value. Under the condition of active power absorption coordination, the active power absorption amount of different generator sets is determined according to the active power absorption strategy, and the corresponding generator sets are controlled to absorb the surplus active power of the receiving end grid with the active power absorption amount, so as to give priority to ensuring reactive power output under the current limit constraint.

[0006] Furthermore, the fault characteristic data includes fault type, fault duration, and voltage drop depth; Based on real-time acquired fault characteristic data, the real-time fault scenario category is determined, including: If the fault duration is less than or equal to the first preset duration and / or the voltage drop depth meets the first drop range, the real-time fault scenario category will be determined as an instantaneous three-phase ground fault. If the duration of the fault is greater than the first preset duration and less than or equal to the second preset duration, and / or the voltage drop depth meets the second drop range, the real-time fault scenario category will be determined as a continuous three-phase short-circuit fault. If at least one of the following conditions is met: the fault duration is greater than the second preset duration, the number of fault types is greater than 1, and the voltage drop depth is greater than the upper limit of the second drop interval, the real-time fault scenario category is determined to be a composite disturbance fault.

[0007] Furthermore, in the multiple control stages that are sequentially experienced, the target reactive current reference value is determined based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage, including: During the fault persistence phase, the real-time fault scenario category is determined based on the fault characteristic data acquired in real time, and the lower limit of the reactive current constraint corresponding to the real-time fault scenario category is taken as the target reactive current reference value. During the rapid recovery and stable maintenance phases after fault clearance, the initial reactive current reference value is calculated based on the real-time voltage deviation and the equivalent reactance of the receiving-end grid. The initial reactive current reference value is then corrected based on the scenario matching coefficient to obtain the target reactive current reference value. The scenario matching coefficient is determined based on the real-time fault scenario category and the scenario matching coefficient adjustment strategy for the current phase.

[0008] Furthermore, during the rapid recovery phase, the calculation process for the target reactive current reference value includes: The grid strength correction coefficient is matched based on the grid short-circuit capacity, and the new energy fluctuation correction coefficient is matched based on the grid new energy access ratio when the grid new energy access ratio is greater than the preset access ratio threshold. The real-time voltage is compared with the time-series voltage recovery target corresponding to the real-time fault scenario category, and the scenario matching coefficient is maintained or increased based on the comparison result. The product of the adjusted scenario matching coefficient, the power grid strength correction coefficient and / or the new energy fluctuation correction coefficient and the initial reactive current reference value is used as the target reactive current reference value. During the stable maintenance phase, the calculation process for the target reactive current reference value includes: The grid strength correction coefficient is matched based on the grid short-circuit capacity, and the new energy fluctuation correction coefficient is matched based on the grid new energy access ratio when the grid new energy access ratio is greater than the preset access ratio threshold. The adjustment step size of the scenario matching coefficient is determined based on the deviation between the real-time voltage and the rated voltage. The recovery time and the target value of the scenario matching coefficient for matching the real-time fault scenario category are determined. Within the recovery time, the scenario matching coefficient is adjusted down to the target value of the scenario matching coefficient according to the adjustment step size. The product of the adjusted scenario matching coefficient, the power grid strength correction coefficient and / or the new energy fluctuation correction coefficient and the initial reactive current reference value is used as the target reactive current reference value. In this process, the adjustment of the scene matching coefficient at any stage must satisfy the constraint that the voltage change rate is less than the voltage change rate threshold of the matching stage.

[0009] Furthermore, the active power absorption of different generator sets is determined based on the active power absorption strategy, including: For any type of generator set, the allocation weight of the generator set of the type is calculated based on the number of generator sets of the type and the inertial time constant. The power absorption of the generator set of the type is determined by multiplying the allocation weight with the surplus active power of the sending grid. The surplus active power of the sending grid is calculated based on the total output power of the feed-in side and the real-time absorption power of the receiving grid. After determining the power absorption of the generator set of the aforementioned type, the method further includes: If the deviation between the real-time voltage and the rated voltage is less than or equal to the preset voltage deviation, the power absorption of the generator set of this type will be maintained. If the deviation between the real-time voltage and the rated voltage is greater than the preset voltage deviation, the product of the surplus active power of the sending-end grid and the preset upward adjustment coefficient is taken as the total power absorption. The power absorption of the generator set of this type is updated according to the product of the allocation weight and the total power absorption.

[0010] Furthermore, in the control process of reactive power output at the receiving-end converter station, the method further includes: Obtain control performance parameters during the fault duration phase, including reactive power support response delay, voltage recovery time during the rapid recovery phase, and voltage fluctuation amplitude during the stable maintenance phase; If any control performance parameter exceeds the corresponding preset threshold, the grid strength adaptation coefficient or scenario matching coefficient is optimized using an incremental PID algorithm. The optimization process specifically includes: If the reactive power support response delay is greater than the preset response delay threshold, the grid strength adaptation coefficient is increased to improve the response speed of reactive power support. If the voltage recovery time is greater than the preset recovery time threshold, the scenario matching coefficient is increased to enhance the reactive power support capability during the voltage recovery process. If the voltage fluctuation amplitude is greater than the preset fluctuation threshold, the adjustment step size of the scenario matching coefficient is reduced to suppress the over-adjustment of reactive power output.

[0011] Furthermore, the method also includes: In the event of a communication interruption, the feed-in side employs a DC voltage deviation adaptive adjustment mechanism to generate a DC voltage deviation adjustment power reference value based on the measured DC voltage deviation. On the converter station side, a reactive current reference value is calculated based on local voltage measurements. In the event of a converter station failure, if the failure is of a partial valve group, the faulty unit will be automatically disconnected and the backup converter valve group will be activated; if the converter station fails completely, it will switch to the feed-side islanded operation mode and simultaneously report the fault information and operating status to the dispatch master station. When a generator set fails, the remaining normal generator sets redistribute the surplus active power according to a preset weighting coefficient. If the absorption capacity is insufficient after redistributing the surplus active power, the small DC resistance load of the converter station is started to maintain the stability of the receiving end voltage.

[0012] According to another aspect of the present invention, a voltage recovery control device based on multiple fault scenario division is provided, comprising: The scenario determination module is used to determine the real-time fault scenario category based on the fault characteristic data acquired in real time; The reactive power control module is used to determine the target reactive current reference value based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage during multiple control stages in sequence, and to control the reactive power output of the receiving-end converter station based on the target reactive current reference value. The active power control module is used to determine the active power absorption amount of different generator sets according to the active power absorption strategy under the condition of satisfying the active power absorption coordination, and to control the corresponding generator set to absorb the surplus active power of the receiving end grid with the active power absorption amount, so as to prioritize the reactive power output under the current limit constraint.

[0013] According to another aspect of the present invention, a storage medium is provided, wherein at least one executable instruction is stored therein, the executable instruction causing a processor to perform operations corresponding to the voltage recovery control method based on the above-described multi-fault scenario division.

[0014] According to another aspect of the present invention, a terminal is provided, comprising: a processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other through the communication bus; The memory is used to store at least one executable instruction, which causes the processor to perform the operation corresponding to the voltage recovery control method based on multiple fault scenarios described above.

[0015] By employing the above-described technical solutions, the technical solutions provided by the embodiments of the present invention have at least the following advantages: This invention provides a voltage recovery control method and apparatus based on multiple fault scenario classification. In this embodiment, the real-time fault scenario category is determined based on real-time acquired fault characteristic data. During multiple sequential control stages, a target reactive current reference value is determined based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage. The reactive power output of the receiving-end converter station is then controlled based on the target reactive current reference value. Under the condition of active power absorption coordination, the active power absorption amount of different generator sets is determined based on the active power absorption strategy. The active power absorption amount is used to control the corresponding generator set to absorb the surplus active power from the receiving-end grid, thereby prioritizing reactive power output under current limit constraints. By classifying fault scenarios based on real-time fault characteristic data and dynamically adjusting the reactive current reference value in multi-stage control, precise adaptation of reactive power output is achieved, reducing the risk of voltage oscillation caused by reactive power over-compensation or under-compensation. At the same time, during the active power absorption process, current limit constraints are strictly followed and reactive power output is prioritized, which not only ensures the reactive power support strength at the moment of fault, but also effectively suppresses the frequency rise caused by surplus active power through coordinated control, thereby greatly improving the voltage recovery capability of the receiving-end power grid under complex fault scenarios.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the specification. Furthermore, in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 The following is a flowchart of a voltage recovery control method based on multi-fault scenario division provided by an embodiment of the present invention; Figure 2 A flowchart illustrating the process of determining a target reactive current reference value according to an embodiment of the present invention is shown. Figure 3 This diagram illustrates a block diagram of a voltage recovery control device based on multi-fault scenario partitioning provided by an embodiment of the present invention. Figure 4 A schematic diagram of the structure of a terminal provided in an embodiment of the present invention is shown. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0019] To address the problem of insufficient AC voltage support capability after a receiving-end fault, this invention provides a voltage recovery control method based on multi-fault scenario partitioning, such as... Figure 1 As shown, the method includes: 101. Determine the real-time fault scenario category based on the fault characteristic data acquired in real time.

[0020] In this embodiment of the invention, after a power grid fault occurs, to provide adaptive fault response and reactive power support, it is necessary to determine the scenario type corresponding to the current fault based on real-time collected fault characteristic data, i.e., the real-time fault scenario category. This real-time fault scenario category is used to characterize the severity of the fault, providing a basis for the reactive power support output of the receiving-end converter station and the active power absorption of the sending-end power grid. The fault characteristic data may include the duration of the AC power grid fault at the receiving end, voltage drop depth, and external disturbance characteristics. The real-time fault scenario category can be instantaneous three-phase ground fault, continuous three-phase short-circuit fault, or composite disturbance fault, etc. The current real-time fault scenario category can be determined by matching the scenario judgment conditions configured in advance for different real-time fault scenario categories with the real-time collected fault characteristic data. Through accurate perception of faults with different levels of impact, the potential misjudgment or over-adjustment that may occur with traditional unified control strategies when facing different faults is avoided, providing accurate input conditions for subsequent refined control.

[0021] 102. In the multiple control stages that are experienced in sequence, the target reactive current reference value is determined according to the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage, and the reactive power output of the receiving-end converter station is controlled according to the target reactive current reference value.

[0022] In this embodiment of the invention, for most power grid faults, the power grid typically performs automatic repairs after a fault occurs. However, the voltage fluctuations caused by the fault do not disappear with the fault repair but continue, requiring voltage regulation through the reactive power output of the converter station to restore the voltage to its rated value. Therefore, the voltage recovery control needs to cover not only the period of fault occurrence and duration but also multiple control stages that occur sequentially, such as the rapid voltage recovery period and the stable voltage recovery period after the fault is repaired. Different reactive power output strategies are pre-configured for different control stages to calculate the target reactive current reference value for guiding the reactive power output of the receiving-end converter station, based on the corresponding voltage recovery adjustment strategy at the current specific voltage control stage. By configuring targeted voltage recovery strategies for different control stages based on different real-time fault scenario categories, the adaptability of voltage recovery can be further improved.

[0023] 103. Under the condition of satisfying the active power absorption coordination, the active power absorption amount of different generator sets is determined according to the active power absorption strategy, and the corresponding generator sets are controlled to absorb the surplus active power of the receiving end grid with the active power absorption amount, so as to give priority to ensuring reactive power output under the current limit constraint.

[0024] In this embodiment of the invention, the principle of prioritizing the reactive power output current of the receiving-end converter station during a fault is followed. Since the sum of the reactive power output current of the receiving-end converter station and the active power current of the sending-end is constrained by the maximum current of the power grid, the reactive power output current of the receiving-end converter station and the active power current of the sending-end are inversely related. To ensure reactive power output, the proportion of active power current at the sending-end needs to be minimized. Therefore, under the condition of active power absorption coordination, active power absorption at the sending-end needs to be initiated synchronously. Through the coordinated action of the sending end, the reactive power output of the receiving-end converter station is maximized. The active power absorption coordination condition can be that the surplus active power of the sending-end power grid exceeds a preset surplus active power threshold, and the generator capacity is within the power capacity limit. Specifically, the surplus active power of the sending-end power grid is calculated. When the surplus active power of the sending-end power grid is greater than the preset surplus power threshold, the active power absorption of different generator sets is allocated according to the active power absorption strategy to absorb excess electrical energy through the sending-end generator sets. This strategy does not directly discard electrical energy. Instead, it sends absorption commands to the sending-end generator units, such as the converters of wind turbines, and the excitation and speed control systems of thermal power plants. By coordinating and controlling these units, the surplus power is absorbed for a short period. Thus, under current limit constraints, priority is given to freeing up capacity for the converter to perform the aforementioned reactive power support task. The preset surplus active power threshold can be greater than or equal to zero, and can be customized according to actual application requirements.

[0025] It should be noted that the active power absorption ratio can be adjusted based on the real-time monitored DC voltage deviation. For example, during a fault, when the DC voltage deviation exceeds 8%, the active power absorption ratio can be appropriately increased, but reactive power output cannot be reduced at this time. By coordinating the absorption of surplus active power by the feed-in side generation units, and with DC voltage safety as a constraint, the reactive power injected into the receiving-end grid is maximized, ensuring that the priority of reactive power support is not weakened, and achieving coordinated optimization of reactive power support and active power absorption.

[0026] In one embodiment of the present invention, for further explanation and limitation, the step of determining the real-time fault scenario category based on the real-time acquired fault characteristic data includes: If the fault duration is less than or equal to the first preset duration and / or the voltage drop depth meets the first drop range, the real-time fault scenario category will be determined as an instantaneous three-phase ground fault. If the duration of the fault is greater than the first preset duration and less than or equal to the second preset duration, and / or the voltage drop depth meets the second drop range, the real-time fault scenario category will be determined as a continuous three-phase short-circuit fault. If at least one of the following conditions is met: the fault duration is greater than the second preset duration, the number of fault types is greater than 1, and the voltage drop depth is greater than the upper limit of the second drop interval, the real-time fault scenario category is determined to be a composite disturbance fault.

[0027] In this embodiment of the invention, the fault characteristic data includes fault type, fault duration, and voltage dip depth. Voltage dip depth is 1 minus the ratio of real-time voltage to rated voltage. The key characteristics of an instantaneous three-phase ground fault are instantaneous line flashover, temporary equipment anomaly, small fault impact range, shallow voltage dip, and no external disturbance superposition. It can be determined based on one or both of the voltage dip depth and fault duration. For example, when judging the initial stage of the fault, if the fault duration is less than or equal to a first preset duration and the voltage dip depth meets the first dip interval, it can be determined as an instantaneous three-phase ground fault. If the voltage dip depth continues to increase, causing the voltage dip depth to meet the second dip interval, the real-time fault scenario category is updated from instantaneous three-phase ground fault to continuous three-phase short-circuit fault. The key characteristics of a continuous three-phase short-circuit fault are permanent line fault, equipment insulation damage, wide fault impact range, deep voltage dip, and stable fault state. It can also be determined based on one or both of the voltage dip depth and fault duration, but the judgment conditions are different. The key characteristics of compound disturbance faults are that they are caused by the superposition of external disturbances such as strong electromagnetic interference, extreme weather, and equipment failures. They are highly destructive, involve complex operating conditions, and cause severe voltage fluctuations. In this case, the superposition of multiple faults, such as single-phase grounding and line breakage, can also be used as a criterion for judgment. For example, if the duration of the fault is longer than the second preset duration or the voltage drop depth is greater than the upper limit of the second drop interval, and the number of fault types is greater than 1, it can be judged as a compound disturbance fault. Here, the first preset duration can be set to 0.5s, the first drop interval can be [10%, 30%], the second preset duration can be set to 2s, and the second drop interval can be (30%, 60%).

[0028] It should be noted that different voltage recovery targets can be configured for different fault scenarios. For example, in the case of a transient three-phase ground fault, the voltage should recover to above 95% of the rated voltage within 100ms after the fault is cleared, and stabilize at 98%-102% of the rated voltage within 5 seconds; in the case of a continuous three-phase short-circuit fault, the voltage should recover to above 90% of the rated voltage within 200ms after the fault is cleared, and stabilize at 98%-102% of the rated voltage within 5 seconds; in the case of a combined disturbance fault, the voltage should recover to above 85% of the rated voltage within 300ms after the fault is cleared, and stabilize at 98%-102% of the rated voltage within 5 seconds. These voltage recovery targets can be used as targets for continuous optimization in subsequent control processes.

[0029] In one embodiment of the present invention, for further illustration and limitation, such as Figure 2 As shown, the process for determining the target reactive current reference value includes: 201. During the fault persistence phase, the real-time fault scenario category is determined based on the fault characteristic data acquired in real time, and the lower limit of the reactive current constraint corresponding to the real-time fault scenario category is taken as the target reactive current reference value.

[0030] 202. During the rapid recovery phase and stable maintenance phase after fault clearance, the initial reactive current reference value is calculated based on the real-time voltage deviation and the equivalent reactance of the receiving-end power grid, and the initial reactive current reference value is corrected based on the scenario matching coefficient to obtain the target reactive current reference value.

[0031] In this embodiment of the invention, during the fault persistence phase, fine voltage regulation is not considered; the sole aim is to inject reactive current as quickly as possible, prioritizing the use of the converter or generator's current capacity to support the voltage and prevent voltage collapse. Therefore, the preset lower limit of reactive current constraint for this scenario is directly used as the target reactive current reference value. The lower limit of reactive current constraint corresponding to different real-time fault scenario categories can be: for instantaneous three-phase ground fault scenarios, the lower limit of reactive current constraint is 0.6 times the maximum current limit of the converter station; for continuous three-phase short-circuit fault and composite disturbance fault scenarios, the lower limit of reactive current constraint is 0.7 times the maximum current limit of the converter station.

[0032] After the fault was cleared, the voltage began to rise but had not yet stabilized. Therefore, the initial reactive current reference value was calculated based on the deviation between the real-time collected voltage and the rated voltage (i.e., the real-time voltage deviation) and the equivalent reactance of the receiving-end grid. Then, the initial reactive current reference value was corrected using a scenario matching coefficient to obtain the target reactive current reference value. The formula for calculating the initial reactive current reference value is expressed as follows: ;in, This is the unit value of the rated voltage. This represents the unit value of the real-time voltage after a fault. The unit value is obtained by standardizing the rated voltage as a reference value. The maximum current limit for the converter station can be set to 1.25.

[0033] It should be noted that the scenario matching coefficient is determined based on the real-time fault scenario category and the scenario matching coefficient adjustment strategy for the current stage. That is, the scenario matching coefficient is not fixed, but dynamically adjusted according to the current fault recovery stage and the real-time fault scenario category. This automatically adjusts the reactive current output intensity to address the differences in recovery characteristics under different fault types and grid strengths. At the moment of fault, by forcibly enforcing the lower limit of reactive current constraints, the system ensures maximum reactive voltage support capability during transient processes, effectively suppressing voltage sag depth and reducing the risk of transient instability in the receiving-end grid. During the recovery and steady-state phases, dynamic correction of the scenario matching coefficient avoids over-compensation or under-compensation of reactive power, achieving smooth voltage recovery and optimized reactive power flow, balancing speed and accuracy.

[0034] In one embodiment of the present invention, for further explanation and limitation, the calculation process of the target reactive current reference value during the rapid recovery phase includes: The grid strength correction coefficient is matched based on the grid short-circuit capacity, and the new energy fluctuation correction coefficient is matched based on the grid new energy access ratio when the grid new energy access ratio is greater than the preset access ratio threshold. The real-time voltage is compared with the time-series voltage recovery target corresponding to the real-time fault scenario category, and the scenario matching coefficient is maintained or increased based on the comparison result. The product of the adjusted scenario matching coefficient, the power grid strength correction coefficient and / or the new energy fluctuation correction coefficient and the initial reactive current reference value is used as the target reactive current reference value. During the stable maintenance phase, the calculation process for the target reactive current reference value includes: The grid strength correction coefficient is matched based on the grid short-circuit capacity, and the new energy fluctuation correction coefficient is matched based on the grid new energy access ratio when the grid new energy access ratio is greater than the preset access ratio threshold. The adjustment step size of the scenario matching coefficient is determined based on the deviation between the real-time voltage and the rated voltage. The recovery time and the target value of the scenario matching coefficient for matching the real-time fault scenario category are determined. Within the recovery time, the scenario matching coefficient is adjusted down to the target value of the scenario matching coefficient according to the adjustment step size. The product of the adjusted scenario matching coefficient, the power grid strength correction coefficient, and / or the new energy fluctuation correction coefficient with the initial reactive current reference value is used as the target reactive current reference value.

[0035] In this embodiment of the invention, during the rapid recovery phase, the calculation of the target reactive current reference value is achieved through multi-dimensional correction. The multiple maintenance positive parameters include a scenario adaptation coefficient, a grid strength correction coefficient, and a renewable energy fluctuation correction coefficient. The scenario adaptation coefficient is positively correlated with the voltage drop depth; for instantaneous three-phase grounding fault scenarios, it can be set to 1.0-1.2; for continuous three-phase short-circuit fault scenarios, it can be set to 1.2-1.5; and for composite disturbance fault scenarios, it can be set to 1.5-1.8, to achieve differentiation in reactive power support strength for different scenarios. The grid strength correction coefficient is adjusted based on the short-circuit capacity. When the short-circuit capacity ≥ 5000 MVA, it indicates high grid strength; to avoid overcompensation, this coefficient is set to 0.9-1.0. When the short-circuit capacity < 5000 MVA, it indicates low grid strength; to strengthen support, this coefficient is set to 1.0-1.1. The renewable energy fluctuation correction coefficient is activated when the renewable energy access ratio is greater than a preset access ratio threshold, and its value is 0.8-1.2. The larger the fluctuation, the closer the value is to 1.2, to offset the impact of renewable energy fluctuations on reactive power support. The preset access ratio threshold can be 30%. When the renewable energy access ratio is less than or equal to the preset access ratio threshold, the product of the adjusted scenario matching coefficient and grid strength correction coefficient with the initial reactive current reference value is used as the target reactive current reference value. The specific process includes: first, matching the grid strength correction coefficient based on the grid short-circuit capacity; then, adding a renewable energy fluctuation correction coefficient when the renewable energy access ratio is high; simultaneously, comparing the real-time voltage with the time-series voltage recovery target corresponding to the fault scenario; dynamically maintaining or increasing the scenario matching coefficient based on the voltage recovery effect; and finally, using the product of these correction coefficients with the initial reactive current reference value as the target reactive current reference value. The time-series voltage recovery target corresponding to the fault scenario refers to the percentage of the voltage that needs to be restored to the rated voltage at different time points for different fault scenarios. For example, in a transient three-phase ground fault scenario, the scenario matching coefficient is maintained at 1.2. If the voltage does not reach 85% of the rated voltage 50ms after the fault is cleared, the scenario matching coefficient is increased to 1.3 to restore the voltage to more than 95% of the rated voltage within 100ms after the fault is cleared. In a continuous three-phase short-circuit fault scenario, maintain a scenario matching factor of 1.5. If the voltage is less than 80% of the rated voltage 100ms after the fault is cleared, increase the scenario matching factor to 1.6 to restore the voltage to over 90% of the rated voltage within 200ms after the fault is cleared. In a combined disturbance fault scenario, maintain a scenario matching factor of 1.8. If the voltage is less than 75% of the rated voltage 150ms after the fault is cleared, increase the scenario matching factor to 1.9 to restore the voltage to over 85% of the rated voltage within 300ms after the fault is cleared.

[0036] After entering the stable maintenance phase, the calculation logic is adjusted to be guided by smooth voltage recovery. While still incorporating grid strength correction coefficients and renewable energy fluctuation correction coefficients, the adjustment step size is determined based on the deviation between the real-time voltage and the rated voltage. A preset recovery time and a target value for the scenario matching coefficient are then determined by combining the fault scenario. Within this preset recovery time, the scenario matching coefficient is smoothly reduced to the target value according to the determined adjustment step size. This ensures that reactive power support gradually weakens as voltage recovers, smoothly transitioning to the rated voltage and avoiding oscillations and over-adjustment. For example, in the case of a transient three-phase ground fault, the scenario matching coefficient is gradually reduced from 1.2 to 1.0 within a recovery time of 100ms-500ms; in the case of a sustained three-phase short-circuit fault, the scenario matching coefficient is gradually reduced from 1.5 to 1.0 within a recovery time of 200ms-1s; and in the case of a combined disturbance fault, the scenario matching coefficient is reduced from 1.8 to 1.0 within a recovery time of 300ms-2s. During the above adjustment process, the adjustment step size can be controlled. The closer the voltage is to the rated value, the smaller the adjustment step size should be within the range of 0.02-0.05. To avoid excessively rapid voltage recovery, the voltage change rate must be less than the voltage change rate threshold for the current matching stage during any stage of the scene matching coefficient adjustment. In the rapid recovery stage, the voltage change rate threshold can be 0.5% / ms, and in the stable maintenance stage, it can be 0.3% / ms. That is, if the voltage change rate exceeds the voltage change rate threshold, the scene matching coefficient adjustment is paused until the voltage stabilizes before resuming adjustment. This adjustment can be achieved through differential feedback control.

[0037] In one embodiment of the present invention, for further explanation and limitation, the step of determining the active power absorption amount of different generator sets based on the active power absorption strategy includes: For any type of generator set, the allocation weight of the generator set of that type is calculated based on the number of generator sets of that type and the inertial time constant. The power absorption of the generator set of that type is determined by multiplying the allocation weight by the surplus active power of the sending-end power grid. After determining the power absorption of the generator set of the aforementioned type, the method further includes: If the deviation between the real-time voltage and the rated voltage is less than or equal to the preset voltage deviation, the power absorption of the generator set of this type will be maintained. If the deviation between the real-time voltage and the rated voltage is greater than the preset voltage deviation, the product of the surplus active power of the sending-end grid and the preset upward adjustment coefficient is taken as the total power absorption. The power absorption of the generator set of this type is updated according to the product of the allocation weight and the total power absorption.

[0038] In this embodiment of the invention, the surplus active power of the sending-end grid is the difference between the total output power on the feeding side and the real-time absorbed power of the receiving-end grid. The generator sets include at least two of the following types: direct-drive units, doubly-fed units, and energy storage modules. For any type of generator set, the formula for calculating its allocation weight is expressed as follows: ; in, Assign weights to the i-th type of unit. Let be the inertial time constant (s) of the unit. m represents the number of generators of this type, where m is the total number of generator set types. This represents the sum of the products of the inertial time constant of all types of generator units at the sending end and the number of generator units. After obtaining the allocation weights for different types of generator units, the product of this allocation weight and the surplus active power of the sending-end grid is taken as the active power absorption of this type of generator unit. For example, in one allocation scheme, direct-drive units are allocated 60%-70% of the absorption capacity to store more surplus power by utilizing their large inertia advantage; doubly-fed induction generator units are allocated 30%-40% of the absorption capacity; and if the system is also equipped with energy storage modules, an additional 20%-30% of the absorption capacity is allocated to the energy storage modules on top of the grid's surplus active power to further reduce the risk of DC overvoltage.

[0039] The above method determines the initial active power absorption of each type of generator set. To achieve dynamic adjustment and adaptive active power absorption, closed-loop correction is further performed through voltage deviation monitoring. Specifically, if the deviation between the real-time voltage and the rated voltage is controlled within a preset range, i.e., the voltage is stable, the original power absorption remains unchanged. Once the real-time voltage deviation exceeds a preset threshold, indicating a voltage anomaly, the total power absorption is immediately recalculated based on the current surplus power multiplied by the upward adjustment coefficient. The newly added power absorption task is then dynamically allocated to the corresponding generator set according to the allocation weight of each unit. This enhances active power absorption to quickly suppress voltage transient deviations, achieving coordinated control of voltage and active power regulation. For example, when the DC voltage deviation is less than or equal to 5%, priority is given to ensuring sufficient reactive power output, without actively increasing the active power absorption ratio. When the DC voltage deviation is greater than 5%, the active power absorption ratio is increased by 10%-20%, while ensuring that the reactive power output current is greater than or equal to 0.7 times the maximum current limit of the converter station, avoiding sacrificing reactive power support.

[0040] In one embodiment of the present invention, for further explanation and limitation, in the control process of reactive power output of the receiving-end converter station, the method further includes: Obtain control performance parameters during the fault duration phase, including reactive power support response delay, voltage recovery time during the rapid recovery phase, and voltage fluctuation amplitude during the stable maintenance phase; If any control performance parameter exceeds the corresponding preset threshold, the grid strength adaptation coefficient or scenario matching coefficient is optimized using an incremental PID algorithm. The optimization process specifically includes: If the reactive power support response delay is greater than the preset response delay threshold, the grid strength adaptation coefficient is increased to improve the response speed of reactive power support. If the voltage recovery time is greater than the preset recovery time threshold, the scenario matching coefficient is increased to enhance the reactive power support capability during the voltage recovery process. If the voltage fluctuation amplitude is greater than the preset fluctuation threshold, the adjustment step size of the scenario matching coefficient is reduced to suppress the over-adjustment of reactive power output.

[0041] In this embodiment of the invention, the reactive power support response delay is the time consumed from the occurrence of a fault to the target reactive power output current reaching the lower limit of the current constraint, with a target value of less than or equal to 20ms. The voltage recovery time during the rapid recovery phase is the time from fault clearance to the initial recovery voltage, i.e., the actual voltage recovers to 85%-90% of the rated voltage. The initial voltage recovery ratio varies depending on the fault scenario, and the voltage recovery time target also differs for different scenarios. For example, in a transient three-phase ground fault scenario, the target is less than 100ms; in a continuous three-phase short-circuit fault scenario, the target is less than 200ms; and in a combined disturbance fault scenario, the target is less than 300ms. The voltage fluctuation amplitude during the stable maintenance phase is the difference between the maximum and minimum voltage deviation within the stable maintenance phase duration, with a target value of less than or equal to ±2%.

[0042] Based on the monitoring results of the aforementioned control performance parameters, the control process is optimized. Specifically, if a control performance parameter exceeds the corresponding preset threshold (corresponding to the target value), the grid strength adaptation coefficient or scenario matching coefficient is optimized using an incremental PID (Proportional-Integral-Derivative) algorithm. The optimization principle is: if the voltage recovery time exceeds the corresponding target value, the scenario matching coefficient is increased. To strengthen reactive power support. If the voltage fluctuation exceeds the target value, the scenario matching coefficient adjustment step size is reduced by 0.02 to mitigate reactive power changes. The adjustment of the scenario matching coefficient can be based on the following formula: ; in, , This represents the adjustment amount of the scene matching coefficient, where k represents the k-th adjustment and k+1 represents the k+1-th adjustment. The target recovery voltage for the kth adjustment. , , These are inherent parameters of the PID controller. .

[0043] If the reactive power support response delay exceeds the target value, the grid strength correction coefficient is increased by 0.03 to improve the response speed. By monitoring the control performance parameters throughout the fault process in real time and introducing incremental PID optimization, when the reactive power support response delay exceeds the standard, the grid strength adaptation coefficient is increased, effectively shortening the reactive current injection time in the initial stage of the fault and improving the support speed of transient voltage. When the voltage recovery time is too long, the scenario matching coefficient is increased, enhancing the reactive power compensation during the recovery phase and accelerating the process of voltage returning to steady state. When the voltage fluctuation amplitude is too large, the adjustment step size of the scenario matching coefficient is decreased, suppressing frequent fluctuations in reactive power output and avoiding voltage oscillations during the adjustment process, thereby achieving closed-loop adaptive correction of reactive power voltage control.

[0044] In one embodiment of the present invention, for further explanation and limitation, the method further includes: In the event of a communication interruption, the feed-in side employs a DC voltage deviation adaptive adjustment mechanism to generate a DC voltage deviation adjustment power reference value based on the measured DC voltage deviation. On the converter station side, a reactive current reference value is calculated based on local voltage measurements. In the event of a converter station failure, if the failure is of a partial valve group, the faulty unit will be automatically disconnected and the backup converter valve group will be activated; if the converter station fails completely, it will switch to the feed-side islanded operation mode and simultaneously report the fault information and operating status to the dispatch master station. When a generator set fails, the remaining normal generator sets redistribute the surplus active power according to a preset weighting coefficient. If the absorption capacity is insufficient after redistributing the surplus active power, the small DC resistance load of the converter station is started to maintain the stability of the receiving end voltage.

[0045] In this embodiment of the invention, the control commands are issued by the central control center. However, in the event of a communication interruption, the local control center cannot receive the control commands. To address this situation, control continues on both the feed-in side and the converter station side based on local data. On the feed-in side, the power reference value is adjusted using the local DC voltage deviation. The formula for calculating the power reference value for DC voltage deviation adjustment is: ; in, , This represents the measured DC voltage deviation. This indicates the rated active power of the converter. This indicates the maximum value of the DC voltage deviation; This represents the power reference value of the i-th converter station during the fault period, which is the power command value that needs to be actually sent to the control system after voltage deviation correction. This represents the original planned power reference value of the i-th converter station during normal operation.

[0046] At the converter station side, the local reactive power output current reference value is automatically calculated based on the local point of common coupling voltage. The calculation formula is expressed as: ;in, Represents the scene matching coefficient. Represents the power grid strength correction factor. This represents the unit value of the rated voltage. This represents the unit value of the measured voltage at the local common coupling point (based on the rated voltage). This indicates the maximum current limit of the converter station.

[0047] To verify the effectiveness of this invention, a simulation model was constructed with the following parameters: 1) MMC-HVDC (Modular Multilevel Converter-High Voltage Direct Current) Modular multilevel converter type high voltage direct current transmission system: rated capacity 1070MVA, DC voltage 135kV, AC voltage of receiving end converter station 230kV, maximum current limit 1.25pu; 2) Feed-in side: 3 new energy power stations, including 40 direct-drive units and 15 doubly-fed units, with a total installed capacity of 1070MW; 3) Receiving end power grid: voltage-sensitive loads account for 42%, equivalent reactance is 0.08Ω, and short-circuit capacity is 4800MVA.

[0048] Simulation scenario: At t=7s, a continuous three-phase short-circuit fault occurs in the receiving end of the power grid, and the voltage at the point of common coupling drops to 0.45pu (voltage drop depth = 55%). The fault is cleared after 1s.

[0049] Simulation results: 1) Multi-scenario recognition: Accurately identifies a continuous three-phase short-circuit fault within 0.1 seconds of the fault occurring, with no delay and no false judgment; 2) Reactive power priority coordination: Reference value of reactive power output current during faults. The reactive power support strength is increased by 28% compared with the traditional method, and the maximum DC voltage deviation is 6.8% (less than 8%). 3) Phased recovery: After the fault was cleared, the voltage recovered to 0.92 pu (meeting the standard) within 180ms, and stabilized at 1.01 pu after 5s, with a fluctuation range of ±1.2%; 4) Closed-loop optimization: After optimization, the voltage recovery time was shortened from 210ms to 180ms, and the voltage fluctuation amplitude was reduced from ±1.8% to ±1.2%.

[0050] This invention provides a voltage recovery control method based on multiple fault scenario classification. In this embodiment, the real-time fault scenario category is determined based on real-time acquired fault characteristic data. During multiple sequential control stages, a target reactive current reference value is determined based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage. The reactive power output of the receiving-end converter station is then controlled based on the target reactive current reference value. Under the condition of active power absorption coordination, the active power absorption amount of different generator sets is determined based on the active power absorption strategy. The active power absorption amount is used to control the corresponding generator set to absorb the surplus active power from the receiving-end grid, thereby prioritizing reactive power output under current limit constraints. By classifying fault scenarios based on real-time fault characteristic data and dynamically adjusting the reactive current reference value in multi-stage control, precise adaptation of reactive power output is achieved, reducing the risk of voltage oscillation caused by reactive power over-compensation or under-compensation. At the same time, during the active power absorption process, current limit constraints are strictly followed and reactive power output is prioritized, which not only ensures the reactive power support strength at the moment of fault, but also effectively suppresses the frequency rise caused by surplus active power through coordinated control, thereby greatly improving the voltage recovery capability of the receiving-end power grid under complex fault scenarios.

[0051] Furthermore, as a response to the above Figure 1 The implementation of the method shown in this invention provides a voltage recovery control device based on multi-fault scenario partitioning, such as... Figure 3 As shown, the device includes: The scenario determination module 31 is used to determine the real-time fault scenario category based on the fault characteristic data acquired in real time; The reactive power control module 32 is used to determine the target reactive current reference value based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage in the multiple control stages that are experienced in sequence, and to control the reactive power output of the receiving-end converter station based on the target reactive current reference value. The active power control module 33 is used to determine the active power absorption amount of different generator sets according to the active power absorption strategy under the condition of satisfying the active power absorption coordination, and to control the corresponding generator set to absorb the surplus active power of the receiving end grid with the active power absorption amount, so as to prioritize the reactive power output under the current limit constraint.

[0052] Furthermore, the scene determination module 31 includes: The first scenario determination unit is used to determine the real-time fault scenario category as an instantaneous three-phase grounding fault when the fault duration is less than or equal to the first preset duration and / or the voltage drop depth meets the first drop range. The second scenario determination unit is used to determine the real-time fault scenario category as a continuous three-phase short circuit fault when the fault duration is greater than the first preset duration and less than or equal to the second preset duration, and / or the voltage drop depth meets the second drop range. The third scenario determination unit is used to determine the real-time fault scenario category as a composite disturbance fault when at least one of the following conditions is met: the fault duration is greater than the second preset duration, the number of fault types is greater than 1, and the voltage drop depth is greater than the upper limit of the second drop interval.

[0053] Furthermore, the reactive power control module 32 includes: The first reactive power control unit is used to determine the real-time fault scenario category based on the fault characteristic data acquired in real time during the fault persistence phase, and to take the lower limit of the reactive current constraint corresponding to the real-time fault scenario category as the target reactive current reference value. The second reactive power control unit is used to calculate the initial reactive current reference value based on the real-time voltage deviation and the equivalent reactance of the receiving-end grid during the rapid recovery phase and the stable maintenance phase after fault clearance, and to correct the initial reactive current reference value based on the scenario matching coefficient to obtain the target reactive current reference value. The scenario matching coefficient is determined based on the real-time fault scenario category and the scenario matching coefficient adjustment strategy for the current stage.

[0054] Furthermore, in specific application scenarios, the second reactive power control unit is specifically used for calculating the target reactive current reference value during the rapid recovery phase, including: The grid strength correction coefficient is matched based on the grid short-circuit capacity, and the new energy fluctuation correction coefficient is matched based on the grid new energy access ratio when the grid new energy access ratio is greater than the preset access ratio threshold. The real-time voltage is compared with the time-series voltage recovery target corresponding to the real-time fault scenario category, and the scenario matching coefficient is maintained or increased based on the comparison result. The product of the adjusted scenario matching coefficient, the power grid strength correction coefficient and / or the new energy fluctuation correction coefficient and the initial reactive current reference value is used as the target reactive current reference value. During the stable maintenance phase, the calculation process for the target reactive current reference value includes: The grid strength correction coefficient is matched based on the grid short-circuit capacity, and the new energy fluctuation correction coefficient is matched based on the grid new energy access ratio when the grid new energy access ratio is greater than the preset access ratio threshold. The adjustment step size of the scenario matching coefficient is determined based on the deviation between the real-time voltage and the rated voltage. The recovery time and the target value of the scenario matching coefficient for matching the real-time fault scenario category are determined. Within the recovery time, the scenario matching coefficient is adjusted down to the target value of the scenario matching coefficient according to the adjustment step size. The product of the adjusted scenario matching coefficient, the power grid strength correction coefficient and / or the new energy fluctuation correction coefficient and the initial reactive current reference value is used as the target reactive current reference value. In this process, the adjustment of the scene matching coefficient at any stage must satisfy the constraint that the voltage change rate is less than the voltage change rate threshold of the matching stage.

[0055] Furthermore, the active power control module 33 includes: The first calculation unit is used to calculate the allocation weight of any type of generator set based on the number of generator sets of that type and the inertial time constant, and to determine the power absorption of the generator set of that type based on the product of the allocation weight and the surplus active power of the sending-end grid. The surplus active power of the sending-end grid is calculated based on the total output power of the feed-in side and the real-time absorption power of the receiving-end grid. The second calculation unit is used to maintain the power absorption of the generator set of the aforementioned type if the deviation between the real-time voltage and the rated voltage is less than or equal to a preset voltage deviation. The third calculation unit is used to take the product of the surplus active power of the sending-end grid and the preset upward adjustment coefficient as the total power absorption if the deviation between the real-time voltage and the rated voltage is greater than the preset voltage deviation, and update the power absorption of the generator set of the type according to the product of the allocation weight and the total power absorption.

[0056] Furthermore, the device also includes: The acquisition module is used to acquire control performance parameters during the fault duration phase, including reactive power support response delay, voltage recovery time during the rapid recovery phase, and voltage fluctuation amplitude during the stable maintenance phase. The optimization module is used to optimize the grid strength adaptation coefficient or scenario matching coefficient using an incremental PID algorithm if any control performance parameter exceeds the corresponding preset threshold. The optimization process specifically includes: if the reactive power support response delay is greater than the preset response delay threshold, the grid strength adaptation coefficient is increased to improve the response speed of reactive power support; if the voltage recovery time is greater than the preset recovery time threshold, the scenario matching coefficient is increased to enhance the reactive power support capability during the voltage recovery process; if the voltage fluctuation amplitude is greater than the preset fluctuation threshold, the adjustment step size of the scenario matching coefficient is decreased to suppress excessive adjustment of reactive power output.

[0057] Furthermore, the device also includes: The first fault handling module is used to generate a DC voltage deviation adjustment power reference value based on the measured DC voltage deviation when a communication interruption fault occurs. On the feed-in side, it adopts a DC voltage deviation adaptive adjustment mechanism to generate a DC voltage deviation adjustment power reference value based on the measured DC voltage deviation. On the converter station side, it calculates a reactive current reference value based on the local voltage measurement value. The second fault handling module is used to automatically disconnect the faulty unit and activate the backup converter valve group when a converter station fault occurs. If the fault is in a partial valve group, the module will switch to the feed-side islanded operation mode and simultaneously report the fault information and operating status to the dispatch master station. The third fault handling module is used to redistribute the surplus active power of the remaining normal generator sets according to a preset weighting coefficient when a generator set fails. If the absorption capacity is insufficient after redistributing the surplus active power, the small DC resistance load of the converter station will be started to maintain the stability of the receiving end voltage.

[0058] This invention provides a voltage recovery control device based on multiple fault scenario classification. In this embodiment, the real-time fault scenario category is determined based on real-time acquired fault characteristic data. During multiple sequential control stages, a target reactive current reference value is determined based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage. The reactive power output of the receiving-end converter station is then controlled based on the target reactive current reference value. Under the condition of active power absorption coordination, the active power absorption amount of different generator sets is determined based on the active power absorption strategy. The active power absorption amount is used to control the corresponding generator set to absorb the surplus active power from the receiving-end grid, thereby prioritizing reactive power output under current limit constraints. By classifying fault scenarios based on real-time fault characteristic data and dynamically adjusting the reactive current reference value in multi-stage control, precise adaptation of reactive power output is achieved, reducing the risk of voltage oscillation caused by reactive power over-compensation or under-compensation. At the same time, during the active power absorption process, current limit constraints are strictly followed and reactive power output is prioritized, which not only ensures the reactive power support strength at the moment of fault, but also effectively suppresses the frequency rise caused by surplus active power through coordinated control, thereby greatly improving the voltage recovery capability of the receiving-end power grid under complex fault scenarios.

[0059] According to one embodiment of the present invention, a storage medium is provided, the storage medium storing at least one executable instruction, the computer-executable instruction being able to execute the voltage recovery control method based on multiple fault scenario division in any of the above method embodiments.

[0060] Figure 4 The diagram shows a structural schematic of a terminal according to an embodiment of the present invention. The specific implementation of the terminal is not limited by the specific embodiments of the present invention.

[0061] like Figure 4As shown, the terminal may include: a processor 402, a communication interface 404, a memory 406, and a communication bus 408.

[0062] The processor 402, communication interface 404, and memory 406 communicate with each other via communication bus 408.

[0063] Communication interface 404 is used for network communication with other devices such as clients or other servers.

[0064] The processor 402 is used to execute program 410, which can specifically execute the relevant steps in the above embodiment of the voltage recovery control method based on multiple fault scenarios.

[0065] Specifically, program 410 may include program code that includes computer operation instructions.

[0066] Processor 402 may be a central processing unit (CPU), a specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention. The terminal may include one or more processors of the same type, such as one or more CPUs; or it may include processors of different types, such as one or more CPUs and one or more ASICs.

[0067] Memory 406 is used to store program 410. Memory 406 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0068] Specifically, program 410 can be used to cause processor 402 to perform the following operations: The real-time fault scenario category is determined based on the fault characteristic data acquired in real time; In the multiple control stages that are experienced in sequence, the target reactive current reference value is determined based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage, and the reactive power output of the receiving-end converter station is controlled based on the target reactive current reference value. Under the condition of active power absorption coordination, the active power absorption amount of different generator sets is determined according to the active power absorption strategy, and the corresponding generator sets are controlled to absorb the surplus active power of the receiving end grid with the active power absorption amount, so as to give priority to ensuring reactive power output under the current limit constraint.

[0069] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A voltage recovery control method based on multi-fault scenario partitioning, characterized in that, include: The real-time fault scenario category is determined based on the fault characteristic data acquired in real time; In the multiple control stages that are experienced in sequence, the target reactive current reference value is determined based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage, and the reactive power output of the receiving-end converter station is controlled based on the target reactive current reference value. Under the condition of active power absorption coordination, the active power absorption amount of different generator sets is determined according to the active power absorption strategy, and the corresponding generator sets are controlled to absorb the surplus active power of the receiving end grid with the active power absorption amount, so as to prioritize the reactive power output under the current limit constraint. In the sequentially experienced multiple control stages, the target reactive current reference value is determined based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage, including: During the fault persistence phase, the real-time fault scenario category is determined based on the real-time acquired fault characteristic data, and the lower limit of the reactive current constraint corresponding to the real-time fault scenario category is used as the target reactive current reference value. During the rapid recovery phase and stable maintenance phase after the fault is cleared, the initial reactive current reference value is calculated based on the real-time voltage deviation and the equivalent reactance of the receiving-end grid, and the initial reactive current reference value is corrected based on the scenario matching coefficient to obtain the target reactive current reference value. The scenario matching coefficient is determined based on the real-time fault scenario category and the scenario matching coefficient adjustment strategy for the current phase. The calculation process for the target reactive current reference value during the rapid recovery phase includes: A grid strength correction coefficient is matched based on the grid short-circuit capacity, and a new energy fluctuation correction coefficient is matched based on the grid new energy access ratio when the grid new energy access ratio is greater than a preset access ratio threshold. The real-time voltage is compared with the time-series voltage recovery target corresponding to the real-time fault scenario category, and the scenario matching coefficient is maintained or increased based on the comparison result. The product of at least one of the adjusted scenario matching coefficient, the grid strength correction coefficient, and the new energy fluctuation correction coefficient with the initial reactive current reference value is used as the target reactive current reference value. During the stable maintenance phase, the calculation process for the target reactive current reference value includes: A grid strength correction coefficient is matched based on the grid short-circuit capacity, and a renewable energy fluctuation correction coefficient is matched based on the renewable energy access ratio when the grid renewable energy access ratio is greater than a preset access ratio threshold. The adjustment step size of the scenario matching coefficient is determined based on the deviation between the real-time voltage and the rated voltage. The recovery time and target value of the scenario matching coefficient for matching the real-time fault scenario category are determined, and within the recovery time, the scenario matching coefficient is adjusted down to the target value according to the adjustment step size. The product of at least one of the adjusted scenario matching coefficient, the grid strength correction coefficient, and the renewable energy fluctuation correction coefficient, and the initial reactive current reference value is used as the target reactive current reference value. The scenario matching coefficient adjustment at any stage satisfies the constraint that the voltage change rate is less than the voltage change rate threshold for the matching stage. The active power absorption of different generator sets is determined based on the active power absorption strategy, including: For any type of generator set, the allocation weight of the generator set of that type is calculated based on the number of generator sets of that type and the inertial time constant. The power absorption of the generator set of that type is determined by multiplying the allocation weight by the surplus active power of the sending-end grid. The surplus active power of the sending-end grid is calculated based on the total output power of the feed-in side and the real-time absorbed power of the receiving-end grid.

2. The method according to claim 1, characterized in that, The fault characteristic data includes fault type, fault duration, and voltage drop depth. Based on real-time acquired fault characteristic data, the real-time fault scenario category is determined, including: If the fault duration is less than or equal to the first preset duration and / or the voltage drop depth meets the first drop range, the real-time fault scenario category will be determined as an instantaneous three-phase ground fault. If the duration of the fault is greater than the first preset duration and less than or equal to the second preset duration, and / or the voltage drop depth meets the second drop range, the real-time fault scenario category will be determined as a continuous three-phase short-circuit fault. If at least one of the following conditions is met: the fault duration is greater than the second preset duration, the number of fault types is greater than 1, and the voltage drop depth is greater than the upper limit of the second drop interval, the real-time fault scenario category is determined to be a composite disturbance fault.

3. The method according to claim 1, characterized in that, After determining the power absorption of the generator set of the aforementioned type, the method further includes: If the deviation between the real-time voltage and the rated voltage is less than or equal to the preset voltage deviation, the power absorption of the generator set of this type will be maintained. If the deviation between the real-time voltage and the rated voltage is greater than the preset voltage deviation, the product of the surplus active power of the sending-end grid and the preset upward adjustment coefficient is taken as the total power absorption. The power absorption of the generator set of this type is updated according to the product of the allocation weight and the total power absorption.

4. The method according to claim 1, characterized in that, In the process of controlling the reactive power output of the receiving-end converter station, the method further includes: Obtain control performance parameters during the fault duration phase, including reactive power support response delay, voltage recovery time during the rapid recovery phase, and voltage fluctuation amplitude during the stable maintenance phase; If any control performance parameter exceeds the corresponding preset threshold, the grid strength adaptation coefficient or scenario matching coefficient is optimized using an incremental PID algorithm. The optimization process specifically includes: If the reactive power support response delay is greater than the preset response delay threshold, the grid strength adaptation coefficient is increased to improve the response speed of reactive power support. If the voltage recovery time is greater than the preset recovery time threshold, the scenario matching coefficient is increased to enhance the reactive power support capability during the voltage recovery process. If the voltage fluctuation amplitude is greater than the preset fluctuation threshold, the adjustment step size of the scenario matching coefficient is reduced to suppress the over-adjustment of reactive power output.

5. The method according to claim 1, characterized in that, The method further includes: In the event of a communication interruption, the feed-in side employs a DC voltage deviation adaptive adjustment mechanism to generate a DC voltage deviation adjustment power reference value based on the measured DC voltage deviation. On the converter station side, a reactive current reference value is calculated based on local voltage measurements. In the event of a converter station failure, if the failure is of a partial valve group, the faulty unit will be automatically disconnected and the backup converter valve group will be activated; if the converter station fails completely, it will switch to the feed-side islanded operation mode and simultaneously report the fault information and operating status to the dispatch master station. When a generator set fails, the remaining normal generator sets redistribute the surplus active power according to a preset weighting coefficient. If the absorption capacity is insufficient after redistributing the surplus active power, the small DC resistance load of the converter station is started to maintain the stability of the receiving end voltage.

6. A voltage recovery control device based on multi-fault scenario division, the device being used to implement the voltage recovery control method based on multi-fault scenario division as described in claim 1, characterized in that, include: The scenario determination module is used to determine the real-time fault scenario category based on the fault characteristic data acquired in real time; The reactive power control module is used to determine the target reactive current reference value based on the real-time fault scenario category and the reactive power output strategy corresponding to the current control stage during multiple control stages in sequence, and to control the reactive power output of the receiving-end converter station based on the target reactive current reference value. The active power control module is used to determine the active power absorption amount of different generator sets according to the active power absorption strategy under the condition of satisfying the active power absorption coordination, and to control the corresponding generator set to absorb the surplus active power of the receiving end grid with the active power absorption amount, so as to prioritize the reactive power output under the current limit constraint.

7. A storage medium, characterized in that, The storage medium stores at least one executable instruction that causes the processor to perform the operation corresponding to the voltage recovery control method based on multiple fault scenario division as described in any one of claims 1-5.

8. A terminal, characterized in that, include: The processor, memory, communication interface, and communication bus are provided, wherein the processor, memory, and communication interface communicate with each other via the communication bus. The memory is used to store at least one executable instruction, which causes the processor to perform the operation corresponding to the voltage recovery control method based on multiple fault scenario division as described in any one of claims 1-5.

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