A method and device for switching a box-type substation, equipment and medium

Abstract

The application provides a box-type substation switching method and device, equipment and medium, and belongs to the technical field of substation control. The method is applied to a double-capacity box-type substation configured with a main transformer and an auxiliary transformer, and the capacity of the main transformer is greater than that of the auxiliary transformer. In a current sampling period, three-phase voltage and current instantaneous values of each sampling moment of a power grid bus are obtained, and a new energy power generation side grid-connected power change rate is determined. In combination with a total power load of a station and a preset load threshold and the power change rate, an operation scene is determined. According to an output distribution standard corresponding to the scene, a switching instruction and / or an output adjustment instruction containing a target phase selection closing moment are generated, and the instructions are sent to control transformer switching and output adjustment. The box-type substation switching method and device, equipment and medium provided by the application can improve power grid operation reliability.

Description

Technical Field

[0001] This application belongs to the field of substation control technology, and more specifically, relates to a switching method, device, equipment, and medium for a prefabricated substation. Background Technology

[0002] In new energy power generation stations, dual-capacity prefabricated substations, with their main and auxiliary transformers of different capacities, are increasingly widely used to meet the needs of large fluctuations in new energy power generation and dynamic changes in station load. However, existing prefabricated substation switching methods have a core problem: the real-time parameters of the power grid are not accurately obtained during the switching process, making it impossible to judge the operating scenario by combining the station load and the trend of grid-connected power changes on the new energy generation side. This results in large transformer switching impacts, unreasonable output distribution, poor adaptability, and susceptibility to equipment failures, affecting the stability of power grid operation and failing to meet actual operating requirements. Therefore, it is urgent to solve these problems to improve the reliability of power grid operation. Summary of the Invention

[0003] This application provides a switching method, apparatus, equipment, and medium for a prefabricated substation to address the problems of poor adaptability and large closing impact in existing switching methods. The aim is to achieve precise transformer switching and coordinated control, thereby improving the reliability of power grid operation. To achieve the above objectives, the technical solution provided by this application is as follows: Firstly, a switching method for a prefabricated substation is provided, applicable to a dual-capacity prefabricated substation equipped with a main transformer and an auxiliary transformer, wherein the capacity of the main transformer is greater than the capacity of the auxiliary transformer. The switching method for the prefabricated substation includes: In the current sampling period, obtain the instantaneous values ​​of the three-phase voltage and the three-phase current of the power grid bus at each sampling time; Based on the instantaneous values ​​of each three-phase voltage and each three-phase current, the rate of change of grid-connected power on the new energy generation side is determined; Based on the comparison between the total load power value of the power supply side of the power station in the current sampling period and the preset load threshold, and combined with the rate of change, the current operating scenario of the power station is determined. The operating scenarios include peak power generation scenario, low power generation scenario, or extreme weather scenario. Based on the output allocation standards of the main transformer and auxiliary transformer corresponding to the operating scenario, the switching status command of the main transformer and / or the output adjustment command of the auxiliary transformer are generated. The switching status command includes the target phase selection closing time calculated based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux value of the main transformer core. Based on the target phase selection closing time, a switching status command is sent to the switching controller. The switching status command is used to control the main transformer to complete the switching. And / or an output adjustment command is sent to the auxiliary controller. The output adjustment command is used to control the auxiliary transformer to achieve output adjustment.

[0004] Secondly, a switching device for a prefabricated substation is provided, applicable to a dual-capacity prefabricated substation equipped with a main transformer and an auxiliary transformer, wherein the capacity of the main transformer is greater than the capacity of the auxiliary transformer. The switching device for the prefabricated substation includes: The data acquisition module is used to acquire the instantaneous values ​​of the three-phase voltage and the three-phase current of the power grid bus at each sampling time during the current sampling period. The rate of change calculation module is used to determine the rate of change of grid-connected power on the new energy generation side based on the instantaneous values ​​of each three-phase voltage and each three-phase current. The scenario determination module is used to compare the total load power value of the power supply side of the power station in the current sampling period with the preset load threshold, and combine the rate of change to determine the current operating scenario of the power station. The operating scenarios include peak power generation scenario, low power generation scenario, or extreme weather scenario. The instruction generation module is used to generate switching status instructions for the main transformer and / or output adjustment instructions for the auxiliary transformer based on the output allocation standards of the main transformer and auxiliary transformer corresponding to the operating scenario. The switching status instructions include the target phase selection closing time calculated based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux value of the main transformer core. The instruction sending module is used to send a switching status instruction to the switching controller based on the target phase selection closing time. The switching status instruction is used to control the main transformer to complete the switching, and / or send an output adjustment instruction to the auxiliary controller. The output adjustment instruction is used to control the auxiliary transformer to achieve output adjustment.

[0005] Thirdly, embodiments of this application also provide an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the switching method for a prefabricated substation provided in the first aspect.

[0006] Fourthly, embodiments of this application also provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the switching method for a prefabricated substation provided in the first aspect.

[0007] The beneficial effects of the technical solution provided in this application are as follows: This application provides a switching method, device, equipment, and medium for a prefabricated substation. Compared with related technologies, this application provides basic data for accurate calculation of the grid-connected power change rate of the new energy generation side by collecting the instantaneous values ​​of three-phase voltage and three-phase current at each sampling moment of the power grid bus during the current sampling period. By combining the comparison results of the total load power value of the current power supply side of the substation with the preset load threshold and the power change rate, three operating scenarios of peak power generation, valley power generation, and extreme weather can be accurately divided, avoiding the limitations of single parameter judgment. Based on the output allocation standard corresponding to the scenario, the application generates switching status commands for the main transformer and / or output adjustment commands for the auxiliary transformer. The switching status commands include the target phase selection closing time calculated based on the voltage zero-crossing phase and the residual magnetic flux value of the iron core, which can effectively reduce the impact when the main transformer is switched. By sending corresponding commands to the switching controller and / or auxiliary controller, the application achieves coordinated control of the main transformer and auxiliary transformer, adapts to the fluctuations of new energy generation and load changes, and ultimately ensures the stable operation of the prefabricated substation and improves the reliability of power grid operation. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application, 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 A schematic flowchart illustrating a switching method for a prefabricated substation provided in this application embodiment; Figure 2 A structural block diagram of a switching device for a prefabricated substation provided in this application embodiment; Figure 3 A schematic block diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0010] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0011] This application provides a switching method for a prefabricated substation, applicable to a dual-capacity prefabricated substation equipped with a main transformer and an auxiliary transformer, wherein the capacity of the main transformer is greater than the capacity of the auxiliary transformer.

[0012] In this embodiment, the dual-capacity prefabricated substation can be used in new energy power generation plants (such as photovoltaic power plants and wind farms), adapting to scenarios with large fluctuations in new energy power generation and dynamic changes in the power load of the plant. The main transformer is the larger capacity transformer in the dual-capacity prefabricated substation, mainly used to bear higher loads (such as peak power generation scenarios), responsible for efficiently integrating new energy power generation into the grid or supplying power to the plant load. The auxiliary transformer is the smaller capacity transformer in the dual-capacity prefabricated substation, mainly used in scenarios with lower loads or requiring precise output regulation (such as off-peak power generation scenarios). It can operate in conjunction with the main transformer or independently, achieving precise load matching and smoothing of grid fluctuations.

[0013] To make the objectives, technical solutions, and advantages of this application clearer, the following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0014] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a switching method for a prefabricated substation provided in an embodiment of this application. The method can be executed by electronic equipment and may include: S101: In the current sampling period, obtain the instantaneous values ​​of the three-phase voltage and the three-phase current of the power grid bus at each sampling time.

[0015] In this embodiment, the sampling period is a preset fixed time interval for continuously collecting power grid parameters. One sampling period contains multiple sampling moments. Each sampling moment is a specific point in time within the sampling period. At each sampling moment, the instantaneous values ​​of the three-phase voltage and three-phase current of the power grid bus are simultaneously collected. The data from multiple sampling moments together constitute the complete data for one sampling period. For example, if the sampling period is set to 0.1s, a complete sampling process is completed every 0.1s. The interval between each sampling moment is 10ms, meaning each sampling period contains 10 sampling moments. At each sampling moment, the instantaneous values ​​of the A, B, and C phase voltages and the three-phase current of the power grid bus are simultaneously collected.

[0016] The instantaneous values ​​of three-phase voltage are the instantaneous voltage magnitudes of phases A, B, and C of the power grid bus at a given sampling moment, serving as fundamental data reflecting the real-time voltage status of the power grid. The instantaneous values ​​of three-phase current are the instantaneous current magnitudes of phases A, B, and C of the power grid bus at a given sampling moment. Both the instantaneous values ​​of three-phase voltage and three-phase current can be acquired using voltage sensors and current sensors, respectively.

[0017] In this embodiment, within the set current sampling period, the instantaneous values ​​of the three-phase voltage and the three-phase current corresponding to each sampling moment on the power grid bus are synchronously collected by voltage and current sensors to ensure that the collected data covers the entire sampling period and to guarantee the continuity and integrity of the data.

[0018] S102: Determine the rate of change of grid-connected power on the new energy generation side based on the instantaneous values ​​of each three-phase voltage and each three-phase current.

[0019] In this embodiment, the rate of change of grid-connected power on the renewable energy generation side is the change in power connected to the grid on the renewable energy generation side per unit time, which is used to characterize the fluctuation trend of renewable energy generation power.

[0020] In one embodiment of this application, the rate of change of grid-connected power on the new energy generation side is determined based on the instantaneous values ​​of each three-phase voltage and each three-phase current, including: The instantaneous values ​​of each three-phase voltage and each three-phase current are discretely multiplied according to the sampling time to obtain the instantaneous active power sampling sequence; Digital filtering is performed on the instantaneous active power sampling sequence to extract the fundamental active power characteristic value; Calculate the difference between the mean of the fundamental active power characteristic value in the current sampling period and the mean of the historical fundamental active power characteristic value in the previous sampling period. Divide the difference by the time interval between adjacent sampling periods to obtain the rate of change of grid-connected power on the new energy generation side.

[0021] In this embodiment, discrete product operation refers to multiplying the instantaneous values ​​of phase A voltage and phase A current, phase B voltage and phase B current, and phase C voltage and phase C current for each sampling time, and then adding the three product results to obtain the instantaneous active power at that sampling time. The instantaneous active power at all sampling times is arranged in chronological order to form an instantaneous active power sampling sequence. For example, if the instantaneous values ​​of phase A voltage and phase A current are 220V, 10A, 220V, 10A, and 220V and 10A respectively at a certain sampling time, then the instantaneous active power at that time is 220×10 + 220×10 + 220×10 = 6600W.

[0022] Digital filtering is a data processing method that uses software algorithms to remove harmonic interference and noise from sampled signals, thereby refining the effective power frequency signal. Digital filtering can employ finite-length unit impulse response filters to remove higher-order harmonic interference from the instantaneous active power sampling sequence, retaining the fundamental active power signal.

[0023] The fundamental active power characteristic value refers to the active power component corresponding to the fundamental frequency (50Hz) of the power grid in the instantaneous active power sampling sequence after digital filtering. The extraction method is as follows: perform Fourier transform on the filtered instantaneous active power sampling sequence to decompose it into active power components of different frequencies, and select the active power component corresponding to the fundamental frequency as the fundamental active power characteristic value.

[0024] The method for calculating the average fundamental active power characteristic value within the current sampling period is as follows: add up the fundamental active power characteristic values ​​corresponding to all sampling times within the current sampling period, and then divide by the number of sampling times within the sampling period (10). The average historical fundamental active power characteristic value within the previous sampling period is pre-calculated and stored using the same calculation method. The time interval between adjacent sampling periods is the sampling period (0.1s). For example, if the average fundamental active power characteristic value within the current sampling period is 6000W, the average value of the previous sampling period is 5000W, and the time interval between adjacent sampling periods is 0.1s, then the rate of change of the grid-connected power on the new energy generation side is (6000-5000) / 0.1=10000W / s=10kW / s.

[0025] In this embodiment, firstly, the instantaneous values ​​of three-phase voltage and current at each sampling time are discretely multiplied to obtain the instantaneous active power at each time, thus forming an instantaneous active power sampling sequence to capture the instantaneous changes in the grid-connected power of the new energy generation side. Then, the instantaneous active power sampling sequence is digitally filtered to remove high-order harmonic interference and avoid the influence of harmonic signals on the calculation of the power change rate. Next, the filtered signal is subjected to Fourier transform to extract the fundamental active power feature value, obtaining the core signal that can truly reflect the power of new energy generation. Finally, by calculating the difference between the mean of the fundamental active power feature value of the current sampling period and the previous sampling period, and dividing it by the sampling period interval, the change rate of the grid-connected power of the new energy generation side is obtained, accurately characterizing the fluctuation trend of the new energy generation power and providing accurate data support for the judgment of subsequent operating scenarios.

[0026] As can be seen from the above, this embodiment accurately obtains the instantaneous active power sampling sequence through discrete product operation, providing a basis for calculating the power change rate; through digital filtering, harmonic interference in the sampling data is effectively filtered out, improving the extraction accuracy of the fundamental active power characteristic value; by calculating the power change rate by the ratio of the mean difference to the time interval, the impact of instantaneous fluctuations on the calculation results is reduced, making the obtained power change rate more reflective of the real fluctuation trend of new energy power generation, providing a reliable basis for subsequent operation scenario judgment, and thus improving the rationality of transformer switching and output regulation.

[0027] S103: Based on the comparison between the total load power value of the power supply side of the station in the current sampling period and the preset load threshold, and combined with the rate of change, determine the current operating scenario of the station. The operating scenarios include peak power generation scenario, low power generation scenario, or extreme weather scenario.

[0028] In this embodiment, the total load power value on the power supply side of the substation is the total power consumed by all electrical equipment in the substation (such as a new energy power station) served by the prefabricated substation during the current sampling period (including the power consumption of the new energy power generation equipment itself and the external power supply load). The preset load threshold is a load critical value pre-set based on the rated capacity of the prefabricated substation, historical load data of the substation, and grid operation requirements. It is used to classify high and low load levels and provide a basis for judging the operating scenario. The operating scenario is a three-stage operating condition divided according to the power load of the substation and the rate of change of new energy power generation. It is used to formulate differentiated transformer control strategies, including peak power generation, low power generation, and extreme weather scenarios.

[0029] In one embodiment of this application, the preset load threshold includes a first load threshold and a second load threshold, wherein the first load threshold is greater than the second load threshold; Based on a comparison of the total load power value on the power supply side of the substation during the current sampling period with a preset load threshold, and combined with the rate of change, the current operating scenario of the substation is determined, including: When the absolute value of the rate of change is less than the rate of change mutation threshold, if the total load power value of the power supply side of the power station is greater than or equal to the first load threshold, then the current operating scenario of the power station is determined to be the peak power generation scenario. When the absolute value of the rate of change is less than the rate of change mutation threshold, if the total load power value of the power supply side of the power station is greater than or equal to the second load threshold and less than the first load threshold, then the current operating scenario of the power station is determined to be the power generation off-peak scenario. When the absolute value of the rate of change is greater than or equal to the threshold for abrupt change in the rate of change, the current operating scenario of the station is determined to be an extreme weather scenario.

[0030] In this embodiment, the first load threshold is a high-power threshold for determining high-load operation of the power station, and the value is larger; the second load threshold is a low-power threshold for determining low-load operation of the power station, and the value is smaller.

[0031] The total load power value of the power supply side of the station refers to the total power consumed by all electrical equipment in the station during the current sampling period. The active power of each device is calculated by collecting the current and voltage signals of each device, and then the total power is obtained by summing them.

[0032] If the absolute value of the rate of change is less than the rate of change mutation threshold, it indicates that the renewable energy power generation is in a steady-state operation with stable fluctuations. In this case, there is no need to consider the upward or downward trend of power generation; the operating scenario is determined solely by the range of the total load power value on the power supply side of the power plant: if the total load power value on the power supply side of the power plant is greater than or equal to the first load threshold, it indicates that the power plant load is at a high level, and this is classified as a peak power generation scenario; if the total load power value on the power supply side of the power plant is greater than or equal to the second load threshold but less than the first load threshold, it indicates that the power plant load is at a medium or low level, and this is uniformly classified as a low-load power generation scenario. If the absolute value of the rate of change is greater than or equal to the rate of change mutation threshold, it indicates a sudden increase or decrease in renewable energy power generation. In this case, regardless of the load size, it is classified as an extreme weather scenario (such as power generation mutations caused by extreme weather such as heavy rain, strong winds, or blizzards). The rate of change mutation threshold is a critical value used to determine whether a sudden change has occurred in renewable energy power generation, and it can be dynamically determined by combining the meteorological warning level and power fluctuation characteristics.

[0033] As can be seen from the above, this embodiment distinguishes between peak power generation scenarios and off-peak power generation scenarios by setting a first load threshold and a second load threshold, based on the high and low ranges of load power values. Simultaneously, it distinguishes between steady-state operation scenarios and extreme weather scenarios by comparing the rate of change of grid-connected power on the renewable energy generation side with the threshold for sudden changes in the rate of change. The hierarchical judgment logic can prioritize the identification of extreme weather scenarios, ensuring timely countermeasures can be taken when power generation changes abruptly, avoiding equipment damage and grid fluctuations. This judgment rule covers all load ranges, eliminating logical gaps in scenario judgment, making scenario division more closely aligned with the actual operating conditions of the power station, and significantly improving accuracy and robustness.

[0034] In one embodiment of this application, the method for determining the threshold for a sudden change in rate of change includes: Based on the meteorological warning level of the area where the dual-capacity prefabricated substation is located, a pre-set mapping table is queried to obtain the basic meteorological threshold. The mapping table is pre-built and stored to characterize the relationship between the meteorological warning level and the basic meteorological threshold. Obtain the historical grid-connected power change rate corresponding to each sampling period within a preset time window, and calculate the real-time fluctuation standard deviation of the historical grid-connected power change rate; Based on the real-time fluctuation standard deviation, the compensation value is obtained, and the meteorological baseline threshold is summed with the compensation value to obtain the change rate mutation threshold. The process of constructing the mapping relationship table includes: Obtain the historical meteorological warning levels and the historical sequence of the grid-connected power change rate of new energy generation in the area where the dual-capacity box-type substation is located; The historical change rate series were grouped according to the historical weather warning level, and the preset percentile value of the historical change rate series in each group was extracted as the statistical benchmark value of the corresponding weather warning level. A mapping table is generated based on the meteorological warning level and its corresponding statistical benchmark value.

[0035] In this embodiment, the meteorological warning levels adopt the nationally unified meteorological warning standard, which is divided into four levels: blue warning, yellow warning, orange warning, and red warning. Different warning levels correspond to different meteorological disaster intensities, and the meteorological disaster intensities corresponding to blue warning, yellow warning, orange warning, and red warning increase sequentially. The mapping relationship table between meteorological warning levels and basic meteorological thresholds is pre-constructed and stored in memory, and its specific form is shown in Table 1 below: Table 1. Mapping Relationship Between Meteorological Warning Levels and Basic Meteorological Thresholds

[0036] In the mapping table, different meteorological basic thresholds are set for different meteorological warning levels to adapt to the power change characteristics caused by meteorological disasters of different intensities. In practical applications, the meteorological basic thresholds can also be adjusted according to the specific meteorological conditions of the area where the station is located. This embodiment does not limit this.

[0037] The preset time window is a pre-set continuous historical period used to retrieve all power change rate data within the preset time window for statistical calculations.

[0038] The real-time fluctuation standard deviation is a statistical parameter used to reflect the degree of oscillation and dispersion of the rate of change of grid-connected power within a preset time window. The real-time fluctuation standard deviation can be calculated using the standard deviation calculation formula, specifically: ; in The standard deviation of the real-time fluctuation is given, where n is the number of sampling periods within the preset time window. Let be the historical grid-connected power change rate during the i-th sampling period. It is the average of the historical grid-connected power change rate within the preset time window; the larger the real-time fluctuation standard deviation, the more drastic the recent power generation fluctuation, and vice versa.

[0039] The compensation value is a correction value calculated based on the recent real-time power fluctuation amplitude, used to dynamically adjust the threshold for sudden changes in the rate of change. The calculation method for the compensation value is as follows: ; The 0.5 is the compensation coefficient, which can be set based on experience. The setting of the compensation coefficient can reasonably reflect the impact of historical fluctuations on the mutation threshold, avoiding both excessive compensation leading to an excessively high threshold and insufficient compensation leading to an excessively low threshold.

[0040] Threshold for rate of change abrupt change = meteorological baseline threshold + compensation value; For example: If the current weather warning level is yellow, the basic meteorological threshold is 50 kW / s, the real-time fluctuation standard deviation is 10 kW / s, and the compensation value is 5 kW / s, then the change rate mutation threshold is 50 + 5 = 55 kW / s.

[0041] In this embodiment, the construction process of the mapping table is as follows: Historical meteorological warning levels for the area where the dual-capacity prefabricated substation is located are obtained from the local meteorological department, and historical sequences of the grid-connected power change rate for the corresponding time period are obtained from the historical sampling data of the prefabricated substation. The historical sequences of change rate are grouped according to the historical meteorological warning levels, and each group contains power change rate data for all time periods under that warning level. A preset percentile value is extracted from the historical sequences of change rate within each group as the statistical benchmark value for the corresponding meteorological warning level. This preset percentile value is used to eliminate interference from abnormal and extreme data. In this embodiment, it is set to the 95th percentile (i.e., 95% of the data in each group of historical sequences of change rate are less than or equal to this value; in practical applications, 90% or 99% can also be selected). The statistical benchmark value is the meteorological basic threshold for the corresponding meteorological warning level. A mapping table is generated based on each meteorological warning level and its corresponding statistical benchmark value, and then stored. In the real-time calculation phase of the mutation threshold, the mapping table is first queried based on the meteorological warning level of the current power station's location to obtain the corresponding basic meteorological threshold. Then, the historical grid-connected power change rate within a preset time window is obtained, and its real-time fluctuation standard deviation is calculated to obtain the compensation value. Finally, the basic meteorological threshold and the compensation value are summed to obtain the real-time rate of change mutation threshold. This mutation threshold can adapt to current meteorological conditions and recent power generation fluctuation characteristics, ensuring accurate identification of extreme weather scenarios when used for operational scenario judgment.

[0042] As can be seen from the above, this embodiment constructs a mapping relationship table and determines the basic meteorological threshold by combining the current meteorological warning level, so that the sudden change threshold can be adapted to different meteorological disaster intensities; by introducing real-time fluctuation standard deviation to calculate compensation value, the sudden change threshold can be adapted to the fluctuation characteristics of recent new energy power generation, realizing dynamic adjustment of the sudden change threshold; it avoids the misjudgment and omission problems caused by fixed thresholds, improves the accuracy of judgment of extreme weather scenarios, provides a precise basis for transformer switching and output adjustment under extreme scenarios, and further ensures the stable operation of box-type substations and power grids.

[0043] S104: Based on the output distribution standards of the main transformer and auxiliary transformer corresponding to the operating scenario, generate the switching status command of the main transformer and / or the output adjustment command of the auxiliary transformer. The switching status command includes the target phase selection closing time calculated based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux value of the main transformer core.

[0044] In this embodiment, the power distribution standard is a pre-set power allocation rule for the main transformer and auxiliary transformer corresponding to different operating scenarios. This clarifies the operating status of both in different scenarios and serves as the basis for generating control commands. For example, in peak power generation scenarios, the main transformer operates at full load while the auxiliary transformer supplements the output; in off-peak power generation scenarios, the main transformer is shut down while the auxiliary transformer outputs power as needed.

[0045] The switching status command is used to control the main transformer to start or stop operation, including the target phase selection closing time, to ensure the safety and stability of the main transformer switching process; the output adjustment command is used to control the auxiliary transformer to adjust the output power, so that the output of the auxiliary transformer is adapted to the load demand and grid status of the current operating scenario.

[0046] The zero-crossing phase is the phase corresponding to the instantaneous change of the three-phase voltage value from negative to positive or from positive to negative, used to determine the real-time phase state of the grid voltage. The specific method for obtaining the zero-crossing phase is as follows: the instantaneous three-phase voltage signals are filtered to remove interference signals. Then, a zero-crossing detection algorithm is used to capture the zero-crossing point of each phase voltage. Combining the sampling time and the grid frequency, the phase corresponding to the zero-crossing point of each phase voltage is calculated, which is the zero-crossing phase.

[0047] The residual magnetic flux value in the iron core is the magnetic flux remaining in the iron core after the main transformer is shut down. It can be collected in real time by installing a magnetic flux sensor on the iron core of the main transformer. Its magnitude will affect the inrush current when the main transformer is closed.

[0048] The target phase selection closing time is the optimal closing time of the main transformer calculated based on the zero-crossing phase of the three-phase voltage and the residual magnetic flux value of the main transformer core. The purpose is to minimize the inrush current during closing, protect the equipment, and stabilize the power grid.

[0049] In this embodiment, for different defined operating scenarios, a preset power distribution standard for the main transformer and auxiliary transformer is invoked to generate corresponding control commands. If it is necessary to control the switching of the main transformer, the command must include the target phase selection closing time; if it is necessary to adjust the output of the auxiliary transformer, a corresponding output adjustment command is generated to achieve precise matching of the transformer operating status under different scenarios.

[0050] Specifically, in one embodiment of this application, the target phase-selection closing time is calculated based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux of the main transformer core, and is obtained in the following manner: The fundamental phase angle of the grid voltage is determined based on the zero-crossing phase of the instantaneous three-phase voltage values. Based on the difference between the residual magnetic flux of the iron core and the rated steady-state flux linkage of the main transformer, the target closing phase angle of each phase is solved by using the integral relationship model between the transformer flux linkage and voltage to minimize the transient flux linkage offset of the iron core after closing. Obtain the fundamental period duration of the current grid voltage and calculate the phase difference between the target closing phase angle of each phase and the fundamental phase angle of the grid voltage; Based on the fundamental period duration and phase difference, the time delay calculated from the current moment is obtained; Based on the time delay, the target phase selection closing time is obtained.

[0051] In this embodiment, the fundamental phase angle of the grid voltage refers to the instantaneous phase of the fundamental component of the grid voltage, determined based on the zero-crossing phase of the three-phase voltage: taking the zero-crossing point of phase A voltage (from negative to positive) as a reference, at this time the fundamental phase angle of phase A voltage is 0°, the fundamental phase angle of phase B voltage lags phase A by 120°, and the fundamental phase angle of phase C voltage lags phase A by 240°. The fundamental phase angle of the grid voltage at the current moment is calculated based on the time difference between the current sampling time and the zero-crossing point; for example, if the time from the zero-crossing point of phase A is 1ms and the grid fundamental period is 20ms, then the fundamental phase angle of phase A voltage is... Phase B is C phase is .

[0052] Rated steady-state flux linkage is the standard rated flux linkage value inside the core of the main transformer when it is operating stably under rated conditions. The calculation formula is: ; in For rated steady-state flux linkage, The rated voltage of the main transformer, The rated frequency of the power grid is N, and the number of turns in the main transformer winding is N.

[0053] The integral relationship model between transformer flux linkage and voltage is established based on the principle of electromagnetic induction. It is a mathematical model describing the correspondence between the integral change of grid voltage and the change of transformer core flux linkage. The integral relationship model between transformer flux linkage and voltage is as follows: ; in The transient flux linkage of the iron core at time t after the switch is closed. This represents the residual magnetic flux value of the iron core. This is the instantaneous value of the grid voltage after the switch is closed; To find the target closing phase angle for each phase that minimizes the transient flux linkage offset of the iron core after closing, i.e., to find the closing phase angle when... With rated steady-state flux When the difference is minimized (the offset is minimized), the phase angle of each phase voltage when closing is specifically solved by a numerical iterative algorithm. The iteration accuracy is set to 0.1°. The advantage of this accuracy is that it can ensure the accuracy of the target closing phase angle. In practical applications, this iteration accuracy can also be adjusted, but this application embodiment does not limit it.

[0054] The fundamental period duration of the current power grid voltage is obtained by periodically detecting the instantaneous values ​​of the three-phase voltage. Specifically, the time difference between two consecutive zero-crossing points of phase A voltage (from negative to positive) is the fundamental period duration. The rated fundamental period duration of the power grid is 20ms, but there will be slight fluctuations in actual operation (such as 19.9ms-20.1ms). Real-time detection ensures the accuracy of the period duration.

[0055] The phase difference is the difference between the target closing phase angle of each phase and the fundamental phase angle of the grid voltage at the current moment. If the difference is positive, it means that it is necessary to wait for a period of time before closing; if the difference is negative, it means that it is necessary to close the corresponding phase in the next cycle; if the difference is zero, it means that the optimal closing phase condition has been met at the current moment, and closing should be performed immediately without delay.

[0056] The formula for calculating the time delay is: ; in For time delay amount, Let T be the phase difference, and T be the fundamental period duration. For example, if the target closing phase angle of a certain phase is 30°, the current grid voltage fundamental phase angle is 18°, and the fundamental period duration is 20ms, then the phase difference is 12°, and the time delay is (12 / 360)×20≈0.67ms. When =0°, =0 indicates that the current time is the target phase selection closing time.

[0057] The target phase selection closing time is the current time plus a time delay. For example, if the current time is t0 and the time delay is 0.67ms, then the target phase selection closing time is t0 + 0.67ms. The target phase selection closing time for the three-phase voltage is calculated separately according to their respective time delays to ensure that the phase angle when each phase is closed is the target closing phase angle.

[0058] In this embodiment, firstly, the zero-crossing phase of the instantaneous three-phase voltage is determined through zero-crossing detection and waveform analysis, thereby obtaining the fundamental phase angle of the grid voltage at the current moment, providing a grid voltage phase reference for closing phase control. Then, the residual magnetic flux value of the main transformer core is collected by a flux sensor, combined with the pre-calculated rated steady-state flux linkage, and using the integral relationship model between transformer flux linkage and voltage, a numerical iterative algorithm is used to solve for the target closing phase angle of each phase that minimizes the transient flux linkage offset of the core after closing, ensuring that the core flux linkage is in a stable state during closing. Next, the fundamental period duration of the grid voltage is detected in real time, and the phase difference between the target closing phase angle of each phase and the current grid fundamental phase angle is calculated, thereby obtaining the time delay. Finally, the current moment is added to the time delay to obtain the target phase selection closing time of each phase. The switching controller controls the closing of each phase of the main transformer according to this moment to achieve precise phase selection closing.

[0059] As can be seen from the above, this embodiment provides an accurate phase reference for phase selection and closing by precisely detecting the zero-crossing phase and fundamental phase angle of the grid voltage; by considering the residual magnetic flux value of the iron core and solving the target closing phase angle by combining the integral relationship model, the offset of the transient magnetic flux of the iron core after closing is effectively reduced, thereby significantly reducing the inrush current when the main transformer is closed, avoiding damage to the iron core by the inrush current, and extending the service life of the main transformer; by accurately calculating the time delay and the target phase selection and closing time, the closing phase of each phase is ensured to be accurate, further suppressing the inrush current, while reducing the impact of closing on the grid voltage fluctuation, and ensuring the stability of grid operation.

[0060] S105: Based on the target phase selection closing time, send a switching status command to the switching controller. The switching status command is used to control the main transformer to complete the switching, and / or send an output adjustment command to the auxiliary controller. The output adjustment command is used to control the auxiliary transformer to achieve output adjustment.

[0061] In this embodiment, the switching controller is a control device that receives switching status instructions and executes the switching operation of the main transformer. Its function is to accurately control the main transformer to be put into or taken out according to the target phase selection closing time.

[0062] The auxiliary controller is a control device that receives output adjustment commands and executes output adjustment operations of the auxiliary transformer. Its function is to adjust the output power of the auxiliary transformer according to the commands to adapt to the current operating scenario.

[0063] In this embodiment, the generated switching status command is sent to the switching controller according to the calculated target phase selection closing time. The switching controller executes the command to control the main transformer to complete the switching on or off operation. At the same time, the output adjustment command is sent to the auxiliary controller, which controls the auxiliary transformer to adjust the output power. Ultimately, the dual-capacity prefabricated substation is adapted to the stable operation of the current operating scenario, ensuring the safety of the power grid and equipment.

[0064] As can be seen from the above, this embodiment provides basic data for the accurate calculation of the grid-connected power change rate of the new energy generation side by collecting the instantaneous values ​​of the three-phase voltage and the three-phase current at each sampling moment of the power grid bus within the current sampling period. By combining the comparison results of the total load power value of the current power supply side of the substation with the preset load threshold and the power change rate, three operating scenarios of power generation peak, valley and extreme weather can be accurately divided, avoiding the limitations of single parameter judgment. According to the output allocation standard corresponding to the scenario, the switching status command of the main transformer and / or the output adjustment command of the auxiliary transformer are generated. The switching status command includes the target phase selection closing time calculated based on the voltage zero crossing phase and the residual magnetic flux value of the iron core, which can effectively reduce the impact when the main transformer is switched on. By sending corresponding commands to the switching controller and / or auxiliary controller, the coordinated control of the main transformer and auxiliary transformer is realized, adapting to the fluctuation of new energy power generation and load changes, and ultimately ensuring the stable operation of the box-type substation and improving the reliability of power grid operation.

[0065] In one embodiment of this application, the method further includes: obtaining the ambient temperature parameters inside the dual-capacity box-type substation, and performing temperature drift compensation on the residual magnetic flux value of the iron core based on the ambient temperature parameters to obtain the compensated residual magnetic flux value of the iron core. In this embodiment, the ambient temperature parameter can be collected by a temperature sensor installed near the core of the main transformer to collect the ambient temperature in real time. The collection frequency is consistent with the sampling frequency of the power grid parameters.

[0066] The formula for calculating temperature drift compensation is: ; in The residual magnetic flux value of the iron core after compensation. The measured residual magnetic flux value of the iron core is given by k, which is a temperature coefficient. In practical applications, the specific value of k can be determined based on the measured magnetotemperature characteristic curve of the iron core material. The k value of different grades of silicon steel sheets is usually between 0.0005 / °C and 0.003 / °C. For example, for commonly used oriented silicon steel sheets, in the working temperature range of 25°C to 100°C, its permeability temperature coefficient is about -0.001 / °C (that is, for every 1°C increase, the permeability decreases by about 0.1%). Therefore, k can be taken as 0.001 (in absolute value). For the collected ambient temperature parameters, The reference temperature is set at 25°C, which is the standard ambient temperature for normal operation of the prefabricated substation. In actual applications, this reference temperature can be adjusted, but this application does not limit it. For example, if the measured residual magnetic flux value of the iron core is 0.5Wb and the ambient temperature is 35°C, then the compensated residual magnetic flux value of the iron core is 0.5×(1+0.001×(35-25))=0.505Wb.

[0067] Among them, based on the difference between the residual magnetic flux value of the iron core and the rated steady-state flux linkage of the main transformer, the target closing phase angle of each phase is solved using the integral relationship model of transformer flux linkage and voltage, which minimizes the transient flux linkage offset of the iron core after closing. This includes: Based on the difference between the compensated residual magnetic flux value of the iron core and the rated steady-state magnetic flux of the main transformer, the target closing phase angle of each phase is solved by using the integral relationship model between the transformer magnetic flux and voltage to minimize the transient magnetic flux offset of the iron core after closing. The grid frequency offset is obtained, and the fundamental frequency period duration is dynamically corrected based on the grid frequency offset to obtain the corrected fundamental frequency period duration. Based on the above embodiments, the time delay calculated from the current moment is obtained based on the fundamental period duration and phase difference. Specifically, this may include obtaining the time delay calculated from the current moment based on the corrected fundamental period duration and phase difference.

[0068] The power grid frequency offset refers to the difference between the current actual frequency of the power grid and the rated frequency (50Hz). It is calculated by collecting the current actual frequency of the power grid using a frequency sensor. ; in This is the frequency offset. This is the current actual frequency of the power grid. The rated frequency of the power grid is 50Hz.

[0069] The dynamic correction formula for the fundamental period duration is: ; in This is the corrected fundamental frequency period duration. The fundamental period duration is the measured value. For example, if the measured fundamental period duration is 20.1ms, the current actual frequency of the power grid is 49.8Hz, and the frequency offset is -0.2Hz, then the corrected fundamental period duration is 20.1 / (1+(-0.2) / 50)≈20.18ms.

[0070] The process of solving the target closing phase angle is the same as before, except that the measured residual magnetic flux value of the iron core is replaced with the compensated residual magnetic flux value of the iron core to ensure that the solved target closing phase angle is more accurate. The calculation process of the time delay is the same as before, except that the measured fundamental period duration is replaced with the corrected fundamental period duration to ensure the calculation accuracy of the time delay, thereby improving the accuracy of the target phase selection closing time.

[0071] In this embodiment, firstly, the ambient temperature parameters inside the prefabricated substation are collected in real time by a temperature sensor. Based on a preset temperature drift compensation formula, the measured residual magnetic flux value of the iron core is compensated to eliminate the influence of ambient temperature on the measurement of residual magnetic flux, resulting in an accurate compensated residual magnetic flux value. Then, using the difference between the compensated residual magnetic flux value and the rated steady-state flux linkage, combined with the integral relationship model between transformer flux linkage and voltage, the target closing phase angle of each phase is solved, improving the accuracy of the target phase angle solution. Simultaneously, the actual frequency of the current power grid is collected by a frequency sensor, the frequency offset is calculated, and the measured fundamental period duration is corrected based on a dynamic correction formula to eliminate the influence of power grid frequency offset on period measurement, resulting in an accurate corrected fundamental period duration. Finally, based on the corrected fundamental period duration and phase difference, the time delay is calculated, thereby obtaining a more accurate target phase selection closing time, ensuring that the inrush current during main transformer closing is effectively suppressed.

[0072] As can be seen from the above, this embodiment compensates for the temperature drift of the residual magnetic flux value of the iron core by using the ambient temperature parameter, thereby eliminating the influence of temperature on the measurement of residual magnetic flux and improving the measurement accuracy of the residual magnetic flux value; it also dynamically corrects the fundamental frequency period duration by using the grid frequency offset, thereby eliminating the influence of frequency offset on period measurement and improving the measurement accuracy of period duration; based on the compensated residual magnetic flux value and the corrected fundamental frequency period duration, the calculation accuracy of the target phase selection closing time is further improved, ensuring that the inrush current is suppressed to the maximum extent during closing, better protecting the main transformer equipment, reducing grid voltage fluctuations, and further improving the operational stability of the prefabricated substation and the power grid.

[0073] In one embodiment of this application, the method further includes: obtaining the instantaneous value of the three-phase closing current and the instantaneous value of the grid bus voltage after the main transformer is closed; if the instantaneous value of the three-phase closing current exceeds the preset inrush current safety limit or the instantaneous value of the grid bus voltage is lower than the preset voltage sag threshold within the preset transient evaluation window, then the reactive power support identifier is added to the output adjustment command. Among them, the reactive power support indicator is used to control the auxiliary transformer to output the target reactive power within a preset dynamic response time, so as to smooth the transient fluctuations of the grid bus voltage.

[0074] In this embodiment, the instantaneous value of the three-phase closing current after the main transformer is closed is collected by a current sensor installed on the primary side of the main transformer, and the instantaneous value of the grid bus voltage is collected by a voltage sensor installed on the grid bus. The collection frequency is once every 1ms to ensure that the transient parameter changes after closing can be captured in real time.

[0075] The preset transient evaluation window is set to 500ms, meaning that after the main transformer is closed, the three-phase closing current and the grid bus voltage are monitored and evaluated in real time for 500ms.

[0076] The preset inrush current safety limit is set to 6 times the rated current of the main transformer. For example, if the rated current of the main transformer is 57.7A, then the inrush current safety limit is 346.2A. The preset voltage sag threshold can be set to 90% of the grid rated voltage. For example, if the grid rated voltage is 10kV, then the voltage sag threshold is 9kV. That is, when the instantaneous value of the grid bus voltage is lower than 9kV, it is judged as an abnormal voltage sag. Both the inrush current safety limit and the preset voltage sag threshold can be set based on experience.

[0077] The reactive power support flag is a binary flag (0 indicates no reactive power support is needed, and 1 indicates reactive power support is needed). When any of the above transient anomalies occur in the transient evaluation window, the flag is set to 1 and added to the output adjustment command; the dynamic response time of the auxiliary transformer is set to 50ms.

[0078] The target reactive power is determined based on the severity of the transient anomaly, and the specific calculation formula is as follows: ; in For target reactive power, This is the reactive power regulation coefficient. The value of [value] can be determined based on the voltage fluctuation characteristics of the power grid and the reactive power compensation requirements. Taking a 10kV distribution network as an example, when the main transformer is closed, the voltage of the power grid bus temporarily drops to 8.5kV. If it is necessary to restore the voltage to above 9.5kV, the voltage deviation is 1.5kV. Combining the rated capacity of the auxiliary transformer (500kVA) and the power grid voltage level, the required reactive power can be calculated to be approximately 75kvar. Based on this, [the following can be deduced]. It is approximately 0.8. Therefore, in this embodiment... The value is set to 0.8, which provides appropriate reactive power support during voltage dips, avoiding both insufficient adjustment that prevents voltage recovery and excessive adjustment that causes voltage overshoot.

[0079] This is the rated voltage of the power grid. This represents the instantaneous value of the current power grid bus voltage. This refers to the rated capacity of the auxiliary transformer. For example, if the rated voltage of the power grid is 10kV, the instantaneous voltage of the current power grid bus is 8.5kV, the rated capacity of the auxiliary transformer is 500kVA, and the reactive power regulation coefficient is 0.8, then the target reactive power is 0.8×(10-8.5)×500 / 10=60kvar.

[0080] After receiving the output adjustment command with the reactive power support indicator, the auxiliary transformer adjusts its own reactive power output through the auxiliary controller within the preset dynamic response time (50ms) to output the target reactive power. The specific adjustment method is as follows: the auxiliary controller adjusts the reactive power output by controlling the reactive power compensation device on the secondary side of the auxiliary transformer until the grid bus voltage is restored to more than 90% of the rated voltage and the instantaneous value of the three-phase closing current drops below the excitation inrush current safety limit.

[0081] In addition, after the transient assessment window ends, the main control unit continuously monitors the grid bus voltage and the main transformer current. If both voltage and current return to normal, the reactive power support flag in the output regulation command is set to 0, the auxiliary transformer stops reactive power support, and the normal output regulation mode is restored. If the transient abnormality persists (e.g., the voltage is still below 9kV after the transient assessment window ends), the main control unit issues an alarm signal, controls the auxiliary transformer to continuously output the target reactive power, and triggers the protection mechanism of the main transformer to avoid equipment damage.

[0082] In this embodiment, after the main transformer is closed, the instantaneous values ​​of the three-phase closing current and the instantaneous values ​​of the grid bus voltage are acquired in real time at a sampling frequency of 1ms using current and voltage sensors. These parameters are continuously monitored and evaluated within a preset transient evaluation window. If the instantaneous value of the three-phase closing current exceeds the inrush current safety limit, or the instantaneous value of the grid bus voltage is lower than the preset voltage sag threshold, a transient anomaly is indicated. The reactive power support flag is immediately added to the output adjustment command and sent to the auxiliary controller. After receiving the command, the auxiliary controller controls the auxiliary transformer to output the target reactive power through the reactive power compensation device within a 50ms dynamic response time. The target reactive power is calculated using a preset formula based on the severity of the transient anomaly. By supplementing the reactive power, the transient fluctuations of the grid bus voltage are smoothed out, while the continuous increase of the inrush current is suppressed. After the transient evaluation window ends, the parameters continue to be monitored. If the anomaly is eliminated, the reactive power support is stopped. If the anomaly persists, an alarm is issued and the protection mechanism is triggered to ensure the safety of the equipment and the grid.

[0083] As can be seen from the above, this embodiment achieves accurate monitoring and timely identification of transient anomalies during the closing process by real-time acquisition of transient parameters after the main transformer is closed, thus preventing the amplification of transient anomalies. By adding a reactive power support indicator, the auxiliary transformer is controlled to quickly output the target reactive power, effectively smoothing transient fluctuations in the grid bus voltage, suppressing excessive inrush current, and ensuring the stability of grid operation. The dynamic response time setting ensures the timeliness of reactive power support, avoiding damage to equipment caused by voltage fluctuations and inrush current. At the same time, the continuous monitoring and alarm mechanism after transient assessment further improves the operational safety and reliability of the prefabricated substation and reduces operation and maintenance risks.

[0084] Based on the same principle as the switching method for a prefabricated substation provided in this application embodiment, this application embodiment also provides a switching device for a prefabricated substation, applied to a dual-capacity prefabricated substation equipped with a main transformer and an auxiliary transformer, wherein the capacity of the main transformer is greater than the capacity of the auxiliary transformer, such as... Figure 2 As shown, the switching device 20 of this type of prefabricated substation may specifically include: a data acquisition module 21, a rate of change calculation module 22, a scenario determination module 23, an instruction generation module 24, and an instruction sending module 25, wherein, Data acquisition module 21 is used to acquire the instantaneous values ​​of three-phase voltage and three-phase current of the power grid bus at each sampling time during the current sampling period; The rate of change calculation module 22 is used to determine the rate of change of the grid-connected power of the new energy generation side based on the instantaneous values ​​of the three-phase voltage and the instantaneous values ​​of the three-phase current. The scenario determination module 23 is used to compare the total load power value of the power supply side of the station based on the current sampling period with the preset load threshold, and combine the rate of change to determine the current operating scenario of the station. The operating scenarios include peak power generation scenario, low power generation scenario, or extreme weather scenario. The instruction generation module 24 is used to generate the switching status instruction of the main transformer and / or the output adjustment instruction of the auxiliary transformer based on the output allocation standard of the main transformer and the auxiliary transformer corresponding to the operating scenario. The switching status instruction includes the target phase selection closing time calculated based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux value of the main transformer core. The instruction sending module 25 is used to send a switching status instruction to the switching controller based on the target phase selection closing time. The switching status instruction is used to control the main transformer to complete the switching, and / or send an output adjustment instruction to the auxiliary controller. The output adjustment instruction is used to control the auxiliary transformer to achieve output adjustment.

[0085] In one embodiment of this application, the rate of change calculation module 22 is specifically used for: The instantaneous values ​​of each three-phase voltage and each three-phase current are discretely multiplied according to the sampling time to obtain the instantaneous active power sampling sequence; Digital filtering is performed on the instantaneous active power sampling sequence to extract the fundamental active power characteristic value; Calculate the difference between the mean of the fundamental active power characteristic value in the current sampling period and the mean of the historical fundamental active power characteristic value in the previous sampling period. Divide the difference by the time interval between adjacent sampling periods to obtain the rate of change of grid-connected power on the new energy generation side.

[0086] In one embodiment of this application, the preset load threshold includes a first load threshold and a second load threshold, wherein the first load threshold is greater than the second load threshold; Scene determination module 23 is specifically used for: When the absolute value of the rate of change is less than the rate of change mutation threshold, if the total load power value of the power supply side of the power station is greater than or equal to the first load threshold, then the current operating scenario of the power station is determined to be the peak power generation scenario. When the absolute value of the rate of change is less than the rate of change mutation threshold, if the total load power value of the power supply side of the power station is greater than or equal to the second load threshold and less than the first load threshold, then the current operating scenario of the power station is determined to be the power generation off-peak scenario. When the absolute value of the rate of change is greater than or equal to the threshold for abrupt change in the rate of change, the current operating scenario of the station is determined to be an extreme weather scenario.

[0087] In one embodiment of this application, the switching device 20 of the prefabricated substation may further include: a threshold determination module, which, when determining the threshold for a sudden change in the rate of change, is specifically used for: Based on the meteorological warning level of the area where the dual-capacity prefabricated substation is located, a pre-set mapping table is queried to obtain the basic meteorological threshold. The mapping table is pre-built and stored to characterize the relationship between the meteorological warning level and the basic meteorological threshold. Obtain the historical grid-connected power change rate corresponding to each sampling period within a preset time window, and calculate the real-time fluctuation standard deviation of the historical grid-connected power change rate; Based on the real-time fluctuation standard deviation, the compensation value is obtained, and the meteorological baseline threshold is summed with the compensation value to obtain the change rate mutation threshold. The switching device 20 of this type of prefabricated substation may further include: a construction module, which, in the process of constructing the mapping relationship table, is specifically used for: Obtain the historical meteorological warning levels and the historical sequence of the grid-connected power change rate of new energy generation in the area where the dual-capacity box-type substation is located; The historical change rate series were grouped according to the historical weather warning level, and the preset percentile value of the historical change rate series in each group was extracted as the statistical benchmark value of the corresponding weather warning level. A mapping table is generated based on the meteorological warning level and its corresponding statistical benchmark value.

[0088] In one embodiment of this application, the target phase-selection closing time is based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux of the main transformer core, and is calculated in the following manner: The fundamental phase angle of the grid voltage is determined based on the zero-crossing phase of the instantaneous three-phase voltage values. Based on the difference between the residual magnetic flux of the iron core and the rated steady-state flux linkage of the main transformer, the target closing phase angle of each phase is solved by using the integral relationship model between the transformer flux linkage and voltage to minimize the transient flux linkage offset of the iron core after closing. Obtain the fundamental period duration of the current grid voltage and calculate the phase difference between the target closing phase angle of each phase and the fundamental phase angle of the grid voltage; Based on the fundamental period duration and phase difference, the time delay calculated from the current moment is obtained; Based on the time delay, the target phase selection closing time is obtained.

[0089] In one embodiment of this application, the switching device 20 of the prefabricated substation may further include: a compensation module, specifically used for: The ambient temperature parameters inside the dual-capacity prefabricated substation are obtained, and the residual magnetic flux value of the iron core is compensated for temperature drift based on the ambient temperature parameters to obtain the compensated residual magnetic flux value of the iron core.

[0090] In one embodiment of this application, the switching device 20 of the prefabricated substation may further include: a detection module, specifically used for: Obtain the instantaneous values ​​of the three-phase closing current and the instantaneous values ​​of the grid bus voltage after the main transformer is closed; If, within the preset transient evaluation window, the instantaneous value of the three-phase closing current exceeds the preset inrush current safety limit, or the instantaneous value of the grid bus voltage is lower than the preset voltage sag threshold, then the reactive power support flag will be added to the output regulation command. Among them, the reactive power support indicator is used to control the auxiliary transformer to output the target reactive power within a preset dynamic response time, so as to smooth the transient fluctuations of the grid bus voltage.

[0091] The apparatus in this application embodiment can execute the method provided in this application embodiment, and the implementation principle is similar. The actions performed by each module in the apparatus of each embodiment of this application correspond to the steps in the method of each embodiment of this application. For detailed functional descriptions of each module of the apparatus, please refer to the descriptions in the corresponding methods shown above, which will not be repeated here.

[0092] See Figure 3 , Figure 3This is a schematic block diagram of an electronic device provided according to an embodiment of this application. Figure 3 The electronic device 300 in this embodiment may include one or more processors 301, one or more input devices 302, one or more output devices 303, and one or more memories 304. The processors 301, input devices 302, output devices 303, and memories 304 communicate with each other via a communication bus 305. The memories 304 store computer programs, including program instructions. The processors 301 execute the program instructions stored in the memories 304. Specifically, the processors 301 are configured to invoke the program instructions to perform the functions of each module / unit in the above-described device embodiments, for example... Figure 2 The functions of the data acquisition module 21, the rate of change calculation module 22, the scene determination module 23, the instruction generation module 24, and the instruction sending module 25 are shown.

[0093] It should be understood that, in the embodiments of this application, the processor 301 may be a central processing unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0094] Input device 302 may include a touchpad, a fingerprint sensor (for collecting the user's fingerprint information and fingerprint orientation information), a microphone, etc., and output device 303 may include a display (LCD, etc.), a speaker, etc.

[0095] The memory 304 may include read-only memory and random access memory, and provides instructions and data to the processor 301. A portion of the memory 304 may also include non-volatile random access memory. For example, the memory 304 may also store device type information.

[0096] In specific implementations, the processor 301, input device 302, and output device 303 described in the embodiments of this application can execute the implementation method described in the switching method of a box-type substation provided in the embodiments of this application, or they can execute the implementation method of the electronic equipment described in the embodiments of this application, which will not be repeated here.

[0097] In another embodiment of this application, a computer-readable storage medium is provided. This computer-readable storage medium stores a computer program, which includes program instructions. When executed by a processor, the program instructions implement all or part of the processes in the methods described above. Alternatively, the computer program can instruct related hardware to complete the process. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include any entity or device capable of carrying computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0098] The computer-readable storage medium can be an internal storage unit of the electronic device in any of the foregoing embodiments, such as a hard disk or memory of the electronic device. The computer-readable storage medium can also be an external storage device of the electronic device, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc., equipped on the electronic device. Furthermore, the computer-readable storage medium can include both internal and external storage units of the electronic device. The computer-readable storage medium is used to store computer programs and other programs and data required by the electronic device. The computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

[0099] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0100] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the electronic devices and units described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0101] In the several embodiments provided in this application, it should be understood that the disclosed electronic devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces or units, or they may be electrical, mechanical, or other forms of connection.

[0102] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of this application, depending on actual needs.

[0103] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0104] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A switching method for a prefabricated substation, characterized in that, This method is applied to a dual-capacity prefabricated substation equipped with a main transformer and an auxiliary transformer, wherein the capacity of the main transformer is greater than the capacity of the auxiliary transformer. The switching method of the prefabricated substation includes: In the current sampling period, obtain the instantaneous values ​​of the three-phase voltage and the three-phase current of the power grid bus at each sampling time; Based on the instantaneous values ​​of the three-phase voltages and the instantaneous values ​​of the three-phase currents, the rate of change of the grid-connected power on the new energy generation side is determined; Based on the comparison between the total load power value of the power supply side of the power station in the current sampling period and the preset load threshold, and combined with the rate of change, the current operating scenario of the power station is determined. The operating scenario includes peak power generation scenario, low power generation scenario, or extreme weather scenario. Based on the output allocation standard of the main transformer and auxiliary transformer corresponding to the operating scenario, a switching state command for the main transformer and / or an output adjustment command for the auxiliary transformer are generated. The switching state command includes the target phase selection closing time calculated based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux value of the main transformer core. Based on the target phase selection closing time, the main transformer is sent to the switching controller to complete the switching, and / or the output adjustment command is sent to the auxiliary controller to control the auxiliary transformer to achieve output adjustment.

2. The switching method for a prefabricated substation as described in claim 1, characterized in that, The determination of the rate of change of grid-connected power on the new energy generation side based on the instantaneous values ​​of each of the three-phase voltages and the instantaneous values ​​of each of the three-phase currents includes: The instantaneous values ​​of the three-phase voltages and the instantaneous values ​​of the three-phase currents are discretely multiplied according to the sampling time to obtain the instantaneous active power sampling sequence; Digital filtering is performed on the instantaneous active power sampling sequence to extract the fundamental active power characteristic value; Calculate the difference between the mean of the fundamental active power characteristic value in the current sampling period and the mean of the historical fundamental active power characteristic value in the previous sampling period, and divide the difference by the time interval between adjacent sampling periods to obtain the rate of change of the grid-connected power on the new energy generation side.

3. The switching method for a prefabricated substation as described in claim 1, characterized in that, The preset load threshold includes a first load threshold and a second load threshold, wherein the first load threshold is greater than the second load threshold; The comparison of the total load power value of the power supply side of the substation based on the current sampling period with a preset load threshold, and in conjunction with the rate of change, determines the current operating scenario of the substation, including: When the absolute value of the rate of change is less than the rate of change mutation threshold, if the total load power value of the power supply side of the power station is greater than or equal to the first load threshold, then the current operating scenario of the power station is determined to be the peak power generation scenario. When the absolute value of the rate of change is less than the rate of change mutation threshold, if the total load power value of the power supply side of the power station is greater than or equal to the second load threshold and less than the first load threshold, then the current operating scenario of the power station is determined to be the power generation off-peak scenario. When the absolute value of the rate of change is greater than or equal to the rate of change mutation threshold, the current operating scenario of the station is determined to be the extreme weather scenario.

4. The switching method for a prefabricated substation as described in claim 3, characterized in that, The method for determining the threshold for sudden change in the rate of change includes: Based on the meteorological warning level of the area where the dual-capacity box-type substation is located, a pre-set mapping table is queried to obtain the basic meteorological threshold. The mapping table is pre-built and stored to characterize the relationship between the meteorological warning level and the basic meteorological threshold. Obtain the historical grid-connected power change rate corresponding to each sampling period within a preset time window, and calculate the real-time fluctuation standard deviation of the historical grid-connected power change rate; Based on the real-time fluctuation standard deviation, a compensation value is obtained, and the meteorological baseline threshold is summed with the compensation value to obtain the rate of change abrupt change threshold. The process of constructing the mapping table includes: Obtain the historical meteorological warning levels and the historical sequence of the grid-connected power change rate of the new energy power generation side for the corresponding time period in the area where the dual-capacity box-type substation is located; The historical sequence of change rate is grouped according to the historical meteorological warning level, and the preset percentile value of the historical sequence of change rate within each group is extracted as the statistical benchmark value of the corresponding meteorological warning level. The mapping table is generated based on the meteorological warning level and its corresponding statistical benchmark value.

5. The switching method for a prefabricated substation as described in claim 1, characterized in that, The target phase-selection closing time is based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux of the main transformer core, and is calculated in the following way: The fundamental phase angle of the grid voltage is determined based on the zero-crossing phase of the instantaneous three-phase voltage values. Based on the difference between the residual magnetic flux value of the iron core and the rated steady-state magnetic flux of the main transformer, the target closing phase angle of each phase is solved by using the integral relationship model between the transformer magnetic flux and voltage to minimize the transient magnetic flux offset of the iron core after closing. Obtain the fundamental period duration of the current grid voltage, and calculate the phase difference between the target closing phase angle of each phase and the fundamental phase angle of the grid voltage; Based on the fundamental period duration and the phase difference, the time delay calculated from the current moment is obtained; Based on the time delay, the target phase selection closing time is obtained.

6. The switching method for a prefabricated substation as described in claim 5, characterized in that, Also includes: The ambient temperature parameters inside the dual-capacity prefabricated substation are obtained, and the residual magnetic flux value of the iron core is compensated for temperature drift based on the ambient temperature parameters to obtain the compensated residual magnetic flux value of the iron core.

7. The switching method for a prefabricated substation as described in claim 1, characterized in that, Also includes: Obtain the instantaneous values ​​of the three-phase closing current and the instantaneous values ​​of the grid bus voltage after the main transformer is closed; If, within the preset transient evaluation window, the instantaneous value of the three-phase closing current exceeds the preset inrush current safety limit, or the instantaneous value of the grid bus voltage is lower than the preset voltage sag threshold, then the reactive power support flag will be added to the output adjustment command. The reactive power support indicator is used to control the auxiliary transformer to output the target reactive power within a preset dynamic response time, so as to smooth the transient fluctuations of the grid bus voltage.

8. A switching device for a prefabricated substation, characterized in that, A switching device for a dual-capacity prefabricated substation equipped with a main transformer and an auxiliary transformer, wherein the capacity of the main transformer is greater than the capacity of the auxiliary transformer, comprises: The data acquisition module is used to acquire the instantaneous values ​​of the three-phase voltage and the three-phase current of the power grid bus at each sampling time during the current sampling period. The rate of change calculation module is used to determine the rate of change of the grid-connected power on the new energy generation side based on the instantaneous values ​​of the three-phase voltages and the instantaneous values ​​of the three-phase currents. The scenario determination module is used to compare the total load power value of the power supply side of the power station in the current sampling period with the preset load threshold, and combine the change rate to determine the current operating scenario of the power station. The operating scenario includes peak power generation scenario, low power generation scenario or extreme weather scenario. The instruction generation module is used to generate switching state instructions for the main transformer and / or output adjustment instructions for the auxiliary transformer based on the output allocation standards of the main transformer and auxiliary transformer corresponding to the operating scenario. The switching state instructions include the target phase selection closing time calculated based on the zero-crossing phase of the instantaneous three-phase voltage and the residual magnetic flux value of the main transformer core. The instruction sending module is used to send the switching status instruction to the switching controller based on the target phase selection closing time. The switching status instruction is used to control the main transformer to complete the switching. And / or send the output adjustment instruction to the auxiliary controller. The output adjustment instruction is used to control the auxiliary transformer to achieve output adjustment.

9. An electronic device, characterized in that, The electronic device includes a memory and a processor. The memory stores a computer program, and the processor executes the switching method of a prefabricated substation according to any one of claims 1 to 7 when running the computer program.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the switching method for a prefabricated substation as described in any one of claims 1 to 7.

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